Origins of the Universe by dreamtrove

Quote:
Originally posted by dreamtrove:
To Mal's question

V(escape)= squareroot[(2GM)/r]
M is 3.14×10⁵⁴ kg, the mass of the observable universe more or less
G is the gravitational constant = 6.67300 × 10-¹¹ m³ kg-¹ s-²
R=(I see the universe has expanded since I was in college, now I have a reference to 46.5B LY instead of 16 billion light years)
V=√2gm/r

Where did you get 46.5 billion (I take it you meant billion) light years?

You realize that if the universe is bigger, the gravitational force on any object within it is weaker, because we're all further apart? That escape velocity equation has distance in the DENOMINATOR. Big distance = lower escape speed.

Anyway, the simple form of the equation can't be applied to a system of multiple objects. It was derived for escape speed from one mass, based on conservation of energy. When you are dealing with the potential energy of all the mass in the universe, it's not so simple.

Or do you think you know where the center of mass of the universe is?

Quote:
Since you're expanding out from the center in three dimensions, the volume 4/3πr³ will increase exponentially greater than r, until V>C

You really aren't understanding the equation.

There is also a misunderstanding of universal expansion that I'm still coming to terms with myself. The universe isn't like a firecracker that went off in one spot and all the little pieces are spreading out from that center point. If it were, we'd see the center of the "explosion" in that background radiation that bytemite talked about. But we don't. The radiation is fairly uniform from all directions, with smaller scale heterogeneities. (I disagree with the way bytemite stated it in the other thread, btw.)

Space itself is expanding. I think of that scene from poltergeist (for those children of the 80s who remember this) where the woman starts running down the hallway, but it gets longer while she runs. Andromeda isn't moving away from us as a baseball would move away from us after we throw it. The space between us and Andromeda is getting bigger. It is expanding, as if your upstairs hallway could suddenly be two feet longer when you walk down it tomorrow morning. Space time is not stationary.

Quote:
I'm not an astrophysicist, but I can see the conclusion as an inescapable result. This prevents the otherwise stable idea of an infinite static state universe.

The stable universe idea is related to whether there is enough mass in the universe to make it stop expanding and collapse again. This is MUCH less mass than is required for a black hole.

From what I've read in the literature, the visible mass of the universe is not enough to make it collapse into a Big Crunch. But there is dark matter that brings us almost up to that limit... suspiciously close. It seems that it would fit the symmetry of nature if we were right at that limit.

Then again, if we were in a universe that was going to expand forever until entropy wins and nothing ever happens again, how likely would it be that we just happen to be aware and sentient in the brief spell between a really hot universe and a spread out, cold one? Not much, I think. I think it more likely that we're in an oscillating universe. Bang to crunch to bang again.

Quote:
But if you accept that outside of the visible universe is more universe, which I have no reason to doubt, then yes, it will exceed the threshold for a black hole.

Are you at all aware of how much empty space there is in the universe, compared to the density of matter in a black hole? Mass of sun all in a 3 km diameter sphere. Really. Think about it. Picture it.

The question of what is outside the universe is an interesting one. It is possible that dimensions bend back on themselves. For a ship sailing the earth in the 1700's, the question of what is beyond the edge of the earth was meaningless. When you go out to explore the earth, you just go in a circle and come back to where you started. We now have very good evidence that space-time is curved, much like the surface of the earth is curved. But space-time is curved in more dimensions.

So the question of what is outside the universe is really meaningless. There is no space-time outside the universe, no mass, no energy. The Void has no effect on us, our past, or our future.

Damn, I love astrophysics! The one reason I want to live longer is to see what comes of all this...

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Wednesday, December 21, 2011 9:52 PM

Quote:
If it were, we'd see the center of the "explosion" in that background radiation that bytemite talked about. But we don't. The radiation is fairly uniform from all directions, with smaller scale heterogeneities. (I disagree with the way bytemite stated it in the other thread, btw.)

I might have given a poor explanation, or equally poor impression. We can model the irregularities of the universe, mass clusters and changes in the background radiation, but ultimately it's very difficult really for us to tell just how uniform or not the universe might be. The best effort I've heard at pinning that down is tied to the anthropic principle - the universe can't be TOO un-uniform or it would be too unstable to establish consistent physical laws across it, and mass wouldn't coalesce, and of course we couldn't be here.

But I'm not overly fond of the anthropic principle myself. It feels too much like a logical fallacy of begging the question. "The universe is the way it is because we couldn't exist if it were any different." Ultimately it's a meaningless argument, that provides very little insight.

I don't claim to have a favourite explanation for redshift, or light at long distance, or whether the universe is contracting or expanding. But I do think that the universe as we know it may be inside a black hole, based on observations and predictions we've been able to make about black holes.

The thing is, once you break down time and space at the "singularity" of a black hole, (for lack of a better term and quantum mechanical fuzziness aside), I'm not sure we can really say it's governed by the restrictions of being in a black hole. When time and space break down like that, what's to say that other things don't break down, like the physical laws? What's to say gravity is still working right to keep all that matter compacted into a point of infinite density for indefinitely? Because you don't need much matter for that, all you need is zero volume. And to the outside of the blackhole, the gravity of everything pulled in would still seem to be experienced (everything is still technically in the black hole), even if on the other side of that black hole matter had exploded outward again into a fecund universe. A white hole (which a fecund universe would require) seems physically impossible anywhere else, as it would violate the second law of thermodynamics, but there's no knowing if that holds true in a black hole.

Which is itself an intriguing possibility, since we know that either the four major forces were the same force in the newborn universe, or the forces didn't exist at all and established themselves later under less extreme conditions.

The matter is trapped past the event horizon of the blackhole, when it hits the singularity there is some great violence done to it. A human traveler would not be able to survive the experience, let alone find out if a black hole has only a singularity, or a singularity AND a white hole, or if they are one and the same. The information of the particles and energy making up matter falling into the black hole is very likely lost, except for the very red-shifted echo that might be observed by an observer outside the pull of the blackhole. But I don't know that we can say that the energy or matter pulled into a blackhole is destroyed completely due to Hawkings radiation. So I think that leaves some question open about what might happen to it.

Sorry, that was probably rambling, and this is all speculative, but there IS some support for the idea of fecund universes like I mentioned in the other thread. Very difficult to get experimental evidence for, but it's not without predictions.

I like these pages, they depict blackhole phenomenon in a very accessible way.

http://casa.colorado.edu/~ajsh/collapse.html
http://casa.colorado.edu/~ajsh/schww.html

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:12 AM

Byte,

About black hole, from the outside we can tell that the center of gravity is not a singularity because if it were, it would exhibit uniform gravitational behavior, when it's really just very nearly uniform, indicating everything is in a small space, but not infinitely small. Logically I think we can conclude that things would orbit an infinitely small center. As to whether a new network of spacetime is created inside or it is simply a new tangle of old spacetime I'm not sure, I'd suspect a mixture. It's clearly still pulling from the outside, as it gravitates from the outside.

As we are in one, I think we can use what we see as a model for what we would see.

Gravity would be towards the center of gravity, but we can't be sure that new matter is being entered at the edges of the interior and not towards the center. If the spacetime network inside the hole is a new network, then I would expect the spacetime to actually be poured in to the middle of the universe, but if it is the old one continued, then it would be towards the edge.

Of course even this black hole universe could be infinitely larger than what we can see, regardless of what's outside.

I suspect the only way to travel inside would be in the form of information. If a strand of space time continues to the inside, it would be possible to send a signal along it, through some sort of dual-wave phenomenon. If you could send enough information to send a sentience, that sentience could then reconstruct a being on the other side. This strikes me as way passed star trek level of technology, but theoretically possible.

Mal,

Escape velocity would go down if the fringes of the universe were not also filled with matter, but they are. As you increase the volume of matter, the escape velocity would go up.

Logically you can infer that the universe must be a black hole because its mass is larger than that necessary, but what's curious is that degree of internal space which exists within it.

This is parallel to looking at a two dimensional plain with a needle stuck in it, the volume of the needle being much larger than would be apparent by the two dimensional space it occupies.

This all makes sense because mass is secondary, being the creation of the interaction of spacetime, and so it is really spacetime which has been drawn into the whole, so naturally it is larger on the inside than on the out, just as the needle-hole is.

ETA: The number came from a cosmology site but wikipedia also has it.

ETA2: I'm familiar with the "space is expanding" theory, which goes with the "the spacetime network is a new spacetime network" which could create this effect. Alternatively, it could be the old one from outside. I can't find anything that would conclusively indicate one vs. the other as correct, or exclusive. If the redshift were truly a guarantee of expansion then it would indicate new, but it's not. There are other perfectly valid explanations for the redshift.

Either way, you get an expanding universe, but it's the rate of expansion, including at different stages of the development that would be altered. I find the current dominant model distasteful because it contains numerous epicycles to justify its initial assumption, which is vaguely reminiscent of the way in which the geocentric model of the solar system developed before it was discarded.

ETA3: I wasn't really going in to the fate of the universe yet. I think that as long as you're adding spacetime, the universe will not collapse. Areas of the universe may collapse, and create new universes, but in so doing, they drawn spacetime from the old universe. If the quantity of spacetime is infinite, then the universe will grow forever, even as it loses on the other side. If it is finite, then the holes will catch up with the edge, and there will be a final collapse and everything will cross the event horizon of some massive black hole in the center which will then become the universe, and, as it possesses all of the spacetime, will be just as large as it ever was.

Another curious question is how soon do black holes form within a black hole. Do we already have "hole within a hole" somewhere in our universe?

ETA4: Re: where's the middle? If it's a new network, there is no middle. It's it's an existing one draw from outside, then the center is a void somewhere, with a high orbit, and though we don't see it, that's no guarantee that it doesn't exist, because what we see might be a small portion of the greater hole.

Auraptor,

Yes, it has. The universe got bigger when I wasn't looking. Alas my professor who was a really sharp guy is no longer among the quick or I would ask him about some of the theories I got from there, but some are my own.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 6:17 AM

Quote:
About black hole, from the outside we can tell that the center of gravity is not a singularity because if it were, it would exhibit uniform gravitational behavior, when it's really just very nearly uniform, indicating everything is in a small space, but not infinitely small.

Good point.

It's interesting how both of us can logically reach the same conclusion from different angles. I don't think a singularity CAN be a singularity because of quantum mechanics and Hawkings Radiation. But yours is perhaps a better angle because it can be theoretically observed and measured.

Oooh. I just had a thought. I think if we're adding matter to the universe (which I'm not sure about, but it is an interesting idea), then I think it WOULD be around the edge of the universe. I'm envisioning the predicted models of just how matter orbits as it falls through the event horizon. The thought of course is that any matter or energy stops orbiting and freefalls due to the escape velocity exceeding the speed of light. But what if, even though it's freefalling, it's angular momentum of the initial orbit doesn't chance? If the universe is a black hole, material that did not pass through the white hole/big bang event WOULD be orbiting at the edges as the fecund universe expanded. And maybe kept there by the forces of the inside of the black hole...

The pages I linked to suggest that another way to stabilize the throat of a black hole is to project something with negative mass but positive surface area. They suggest some kind of exotic matter, but I think you could trick the physics with a machine that could generate its own gravitational field.

Quote:
I think that as long as you're adding spacetime, the universe will not collapse. Areas of the universe may collapse, and create new universes, but in so doing, they drawn spacetime from the old universe. If the quantity of spacetime is infinite, then the universe will grow forever, even as it loses on the other side. If it is finite, then the holes will catch up with the edge, and there will be a final collapse and everything will cross the event horizon of some massive black hole in the center which will then become the universe, and, as it possesses all of the spacetime, will be just as large as it ever was.

Another curious question is how soon do black holes form within a black hole. Do we already have "hole within a hole" somewhere in our universe?

I also think the universe might be perpetual, even if we do reach a thermodynamic death, I think there'd be a collapse some time afterward which would redistribute mass (hydrogen) and energy.

As for whether some blackholes have blackholes inside them, I think that's well within predictions for fecund universes.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 7:52 AM

Hawkings Radiation can be theoretically observed, but I recall the counter argument of "radiation caught in orbit *at* the speed of light.

I think that the idea that the escape velocity inside must also always escape the speed of light assumes many things, 1) that all the matter is in the center, because if it's not, then there will be places of multiple gravities, and 2) that space itself is of a constant density, and the hole is not larger on the inside than it is on the out.

Quote:
I think if we're adding matter to the universe (which I'm not sure about, but it is an interesting idea), then I think it WOULD be around the edge of the universe.

If the space is old space, that is, the space that is outside. But the space inside could be that space, or entirely new space created by energy which could in theory be pouring in to the center, creating the initial vibrations of the early universe.

Quote:
But what if, even though it's freefalling, it's angular momentum of the initial orbit doesn't chance?

I assume that it wouldn't, and thus it would miss the empty center, and as it approached the center, large numbers of variable, such as the density of space, the gravitation of the hole and the speed of light might all be subject to change, thus suspending it in perpetuity in orbit around the center of the hole which may not exist.

If you look at a whirlpool in a two dimensional field consider what is not at the center. There is no water, no ocean, the center is a void. Same for a storm cloud. If this principle applies to the fabric of space time, then the center of a black hole might be more empty than just empty space, it may have no space in it at all.

I recall a while back reading that the curve of space was actually resembling a torus curve (or saddle shape, outward on one axis, inward on the other) and they postulated two proposals that would apply in place of the spherical universe, one being a donut shaped universe, and the other being an infinite saddle shaped universe.

If I may propose a third, consider this:

http://3.bp.blogspot.com/-cGy0g1H99L4/TaWHRzYtz3I/AAAAAAAAAEU/mMF8rrep
zJY/s1600/whirlpool.PNG

If we were on the inside curve of the nexus, we would see this shape. Curving inward around the vortex, and curving outward up and down towards and away from the center.

Now picture that our observable universe is just a small circle on the edge of that vortex, and past it are a vast array of superclusters drawing down.

This in turn, was together, a giant black hole far larger than our known universe, and it was resting inside a much larger megaverse, that it was drawing on. That in turn was a seemingly infinite field from which other vortexes of other universes was also drawing down.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 8:59 AM

Quote:
I assume that it wouldn't, and thus it would miss the empty center, and as it approached the center, large numbers of variable, such as the density of space, the gravitation of the hole and the speed of light might all be subject to change, thus suspending it in perpetuity in orbit around the center of the hole which may not exist.

Yeah! Exactly!

Dang this is cool.

And another thought occurs, those modeling the possible shape of the universe as a saddle shape, that could actually be reconsidered as a section of an elliptic hyperboloid... A perfect representation of the throat of a black hole, possibly centered around the void ("singularity"?) in the middle.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 11:13 AM

There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened. Douglas Adams

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 11:34 AM

Quote:
Originally posted by AURaptor:

Wow, it's been a long time since you were in college, huh?

30 billion years, apparently.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 11:40 AM

Well, correction, that would be a perfect representation of the throat of a black hole, if that black hole happened to also be a Einstein-Rosen bridge.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 11:48 AM

PIZMOBEACH

... fully loaded, safety off...

Bumped into this this morning:

http://harpers.org/archive/2011/12/0083720

Multi-verse - when one universe isn't enough...

"The concept of the multiverse is compelling not only because it explains the problem of fine-tuning. As I mentioned earlier, the possibility of the multiverse is actually predicted by modern theories of physics. One such theory, called eternal inflation, is a revision of Guth’s inflation theory developed by Andrei Linde, Paul Steinhardt, and Alex Vilenkin in the early and mid-1980s. In regular inflation theory, the very rapid expansion of the infant universe is caused by an energy field, like dark energy, that is temporarily trapped in a condition that does not represent the lowest possible energy for the universe as a whole—like a marble sitting in a small dent on a table. The marble can stay there, but if it is jostled it will roll out of the dent, roll across the table, and then fall to the floor (which represents the lowest possible energy level). In the theory of eternal inflation, the dark energy field has many different values at different points of space, analogous to lots of marbles sitting in lots of dents on the cosmic table. Moreover, as space expands rapidly, the number of marbles increases. Each of these marbles is jostled by the random processes inherent in quantum mechanics, and some of the marbles will begin rolling across the table and onto the floor. Each marble starts a new Big Bang, essentially a new universe. Thus, the original, rapidly expanding universe spawns a multitude of new universes, in a never-ending process."

Scifi movie music + Firefly dialogue clips, 24 hours a day - http://www.scifiradio.com

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 11:52 AM

Quote:
Space itself is expanding. I think of that scene from poltergeist (for those children of the 80s who remember this) where the woman starts running down the hallway, but it gets longer while she runs. Andromeda isn't moving away from us as a baseball would move away from us after we throw it. The space between us and Andromeda is getting bigger. It is expanding, as if your upstairs hallway could suddenly be two feet longer when you walk down it tomorrow morning. Space time is not stationary.

I read somewhere that they should call it 'The Big Stretch' rather than the 'Big Bang'. Space time is being stretched outward like a 3D rubber band.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 12:13 PM

Pizmo,

Yes, that sounds like a similar idea, if you envision the possibility that also, within each marble, there are little marbles, and the whole table maybe resting within a giant marble.

Magon,

Watch out for the big snap.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 12:15 PM

Quote:
Originally posted by dreamtrove:
Yes, it has. The universe got bigger when I wasn't looking. Alas my professor who was a really sharp guy is no longer among the quick or I would ask him about some of the theories I got from there, but some are my own.

I have the same question as Mal. Where did you get the 46 billion LY figure? And are you saying the universe expanded from 13-14 billion to 46 billion LY within your lifetime? I want to make sure I understand what you are saying.

My immediate reaction is it looks like you may have used angular diameter distance back at college and now are using comoving distance. But I venture that tentatively while ducking my head.

What a fascinating discussion. Just to let you guys know, I am reading every word attentively. Makes me want to study astrophysics and cosmology!

-----
"Christmas is a time when kids tell Santa what they want and adults pay for it. Deficits are when adults tell the government what they want - and their kids pay for it." - Richard Lamm

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 1:22 PM

Quote:
Originally posted by dreamtrove:
Escape velocity would go down if the fringes of the universe were not also filled with matter, but they are. As you increase the volume of matter, the escape velocity would go up.

This is not true. So very not true! A black hole happens because of a strong gravitational field. Gravitational field is strongest at points that are very close to a lot of mass. Increasing the volume of matter means that no point is sufficiently close to enough matter for the gravitational field to be strong.

Quote:
Logically you can infer that the universe must be a black hole because its mass is larger than that necessary, but what's curious is that degree of internal space which exists within it.

This is not logical in any way. Again, the total mass of the universe is not enough to make a black hole. The spatial distribution of the mass is what's key.

I'm really not sure where you're going with the needle analogy. I can see that you and Bytemite are going for the idea that our universe came out of a black hole, which is a fun idea, but it does not mean we are inside a black hole.

Being inside a black hole means that the gravitational field is so strong that light cannot escape. That's it. That's all there is to it. This is clearly not true. You can measure the gravitational field where you are, and it is not at all strong enough to be the inside a black hole.

You seem to be creating a false premise to build all your fancier philosophy on. I can't address that fancier stuff, because the basics you start are so off.

Bigger volume means higher escape speed? Sheesh. Don't go to a physics conference and say that aloud. Rotten tomatoes will fly.

Quote:
ETA2: I'm familiar with the "space is expanding" theory, which goes with the "the spacetime network is a new spacetime network" which could create this effect. Alternatively, it could be the old one from outside. I can't find anything that would conclusively indicate one vs. the other as correct, or exclusive. If the redshift were truly a guarantee of expansion then it would indicate new, but it's not. There are other perfectly valid explanations for the redshift.

If red shift was purely caused by velocity we have a problem. Far away galaxies are red shifted so much that they are apparently moving faster than the speed of light. This is not possible.

Quote:
ETA4: Re: where's the middle? If it's a new network, there is no middle. It's it's an existing one draw from outside, then the center is a void somewhere, with a high orbit, and though we don't see it, that's no guarantee that it doesn't exist, because what we see might be a small portion of the greater hole.

The reason this question is important is that you are trying to use the equation for escape velocity to argue that the universe is a black hole. As you already posted, he equation involves a constant and two variables. I urge you to deepen your understanding of those two variables. The "M" is mass of the object or collection of objects to be escaped from. You use the mass of the universe. OK.

But here's where you're all wrong: the "r" is distance from a point in space to the CENTER OF MASS of the object to be escaped from. If you are trying to find escape velocity from the entire universe, which you are, you have to know how far a point is from the COM.

So, basically, you are grossly misapplying this equation. Going back to that volume issue: "r" is in the denominator of the equation. Go look. Bigger r (ie bigger volume) means LOWER escape speed. It's right there in the math. Wishful thinking won't change it.

Bytemite - sorry, I haven't had time to read your post in detail. Out all day. Will get to it.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 1:29 PM

Sorry, I can't leave this one alone. One more point to make:

Yes, there is lots and lots of mass in the universe. How much of it is affecting you right here and right now? Very damned little.

The piddly little 5.98E24 kg of the earth is the only that's really significantly affecting your personal path through space. OK, the moon gives us tides. But the gravitational force of the sun, all 2E30 kg of her, has very little effect on you.

As for all that other mass in the universe - the gravitational force on you by all that is essentially nil because it is so so so so far away.

Get it? r is in the denominator!

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 1:33 PM

Quote:
I can see that you and Bytemite are going for the idea that our universe came out of a black hole, which is a fun idea, but it does not mean we are inside a black hole.

That is a technically more accurate way to put it. I think we've both proposed that not only does a black hole pull in mass and energy, it also pulls in space time, and if there's a fecund universe on the other side the space time pulled in might feed the expansion of that universe.

However, from an observer of the initial black hole, it would probably look like everything that went into that black hole is still in it, and not gone to the other side. Which would be represented by the gravitational field of that black hole. The event horizon is like a snap shot of everything that falls through at the moment it falls through, including, perhaps, the gravitational properties of some mass, added to the gravitational property of other mass that fell through.

This is all speculative, of course, but it's a really fascinating idea, and I think it has a lot of potential, and I also think at least part of may be able to be observed, or might make predictions that could be tested.

For me, it's better at least then saying the big bang had no cause or origin but itself - which I know no one is arguing, I'm just saying.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 1:40 PM

Quote:
Originally posted by canttakesky:

I have the same question as Mal. Where did you get the 46 billion LY figure? And are you saying the universe expanded from 13-14 billion to 46 billion LY within your lifetime? I want to make sure I understand what you are saying.

Wikipedia. When I was in college, we were given a smaller figure in our text book, a radius of 16 billion light years. I figure the intervening years provided better estimates of the size of the universe.

I was not saying that in the intervening decades the universe had expanded 30 billion light years in radius, or that I was in college 30 billion years ago.

Quote:
you may have used angular diameter distance back at college and now are using comoving distance.

maybe, but I would need to ahve some vague idea what this meant.

It's a great topic, esp. when you get into the existential concepts of matter as information. (In the chapter I call "why I love string theory")

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 1:55 PM

I'm looking at the paper referenced in wikipedia as the source for the 46b ly number. It's a long, dense paper, which I'm frankly not motivated or experienced enough to sort out in any detail. But I'll peck away at it and see what happens.

One thing I've caught reminded me of what I wanted to follow up with Bytemite about: the background radiation. I can't recall exactly what you said, but I got the impression that you called it not smooth.

My understanding is different - the background radiation is shockingly uniform. In the paper I'm looking at ( http://www.astro.princeton.edu/universe/ms.pdf) They say on page 10: "the cosmic microwave background is uniform to one part in 100,000 all over the sky."

This presented something of a problem for astrophysics: how can it be so damned uniform when the big bang came from one single point? And how do we have smaller scale heterogeneities--galaxies and such--when the large scale is so smooth? Which the basis of the inflation theory, the accelerated expansion of the universe during the first 10^-34 seconds of its existence.

Bytemite, re your latest post (unless I've missed more while writing this!) I do enjoy the idea that black holes are some kind of door, and who knows if the broken down laws of physics inside them lead to things as cool as creation of new universes. I like that.

But a few caveats: the mass that falls into a black hole doesn't disappear. The mass can still be measured by the gravitational effects of the BH on everything around it. Ditto with angular momentum and charge. These three things are conserved. If the mass "passed through" the black hole to become building blocks of another universe, we'd see the mass disappear. To my knowledge, we don't.

One last thing, and I may be beating a dead horse here: I highly recommend that you don't use the phrase "Inside a black hole". That has a specific meaning that is not what you mean, and it leads to misapplication of principles like what DT has done with the escape speed equation. It makes it seem that there is quantitative support for this idea, which there most definitely is not.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 2:01 PM

Quote:
Originally posted by dreamtrove:

Magon,

Watch out for the big snap.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

LOL> Maybe that is what I am experiencing now and why my neck hurts.

I recommend people download and watch Brian Cox's Wonders of the Universe. He's clever, clear and cute. What a man.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 2:08 PM

Mal,

Without spending all day at this, first:

Gravity is greatest when the entirety of a gravitating object is on one side of you, not when you are "close to a lot of mass." If you are, as we are, inside of a gravitating object (the universe) then it is not exerting gravity on you because it is on all sides of you. That means it cancels out, but it does not mean that as a body it does not gravitate.

Quote:
The spatial distribution of the mass is what's key.

Do we have to argue about everything? Okay, no, it's not. The spacial distribution of mass in the universe is exactly what I would expect to see in a black hole. Why not? It's not too dissimilar from what we see in galaxies and stellar systems from which a black hole is not very far removed, and it is predicted by chaos theory and fractal geometry.

But furthermore, the black hole is decided by the total mass within the total area, being at one side and not competing with outside gravitation. One such body is the universe.

Quote:

Being inside a black hole means that the gravitational field is so strong that light cannot escape.

Almost. The event horizon is where gravity is so strong that light cannot escape. That does not mean that gravity inside the hole is this strong.

Quote:

Bigger volume means higher escape speed? Sheesh.

Did you even read what I wrote? It's inescapable, a larger volume of mass will lead to an increase of gravity. That is, unless you radically reduce the density. That's because the volume is cubed and the distance is linear.

We're not talking about a larger volume of empty space, but a larger volume of mass. In this case, the massive body being the universe.

If you think just because we are inside the universe and there is space to move around that means that the universe is empty space and not a gravitating object, then doesn't it also stand to reason that a marble, being 2000 times more empty space than silcate, is also an empty space, and not really a solid object?

Perhaps marbles are a figment of my imagination.

Quote:
far away galaxies are red shifted so much that they are apparently moving faster than the speed of light. This is not possible.

I agree* it's a problem. It not impossible, but I only have two explanations. One is the one I gave, that redshift is caused by atrophy of light, which is what I think is the principle contributing factor; but there is another valid explanation: space feeding into the black hole universe is new space and not old space and so is being added to the interior, thus increasing the amount of space which separates us.

* in agreeing with me and you, we are disagreeing with classic big bang theory which accepts the acceleration as a pure redshift.

As for the equation, I don't think so. I think the conclusion is inescapable because I cannot see how the universe could exist without fitting the definition, because in order to exist, it must be getting space from somewhere, in order for there to be space.

Quote:
Mal
Get it? r is in the denominator!

Seriously, kill this attitude or folks might be inclined to give up.

Backing up

Quote:
OK, the moon gives us tides.

Yes, but we are 238.9 million miles from the moon. If the moon had a radius of 238.9 million miles, the impact of the moon would be greater.

If the moon had a radius of 20 million light years, the effect would be less predictable, but we would all live inside the moon.

Quote:
I can see that you and Bytemite are going for the idea that our universe came out of a black hole

Not necessarily, but it's likely. However, it's also possible that the universe was not initially a black hole, but is one now. It's hard to say how it happened. All I can see is that it is.

My guess would be yes, it started as a black hole, and it is still a black hole, and it always will be, because you can't unbecome a black hole. Unless there's some dark nova phenomenon that someone knows about.

Another way of looking at it is that we are on the other side of a black hole.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 2:27 PM

Quote:
Originally posted by mal4prez:

But a few caveats: the mass that falls into a black hole doesn't disappear. The mass can still be measured by the gravitational effects of the BH on everything around it. Ditto with angular momentum and charge. These three things are conserved.

Actually, it's worse than that. The observational data is that it increases. This does actually bend slight towards the "new space" idea IMHO, but not conclusively. Any number of phenomenon not yet discovered or perhaps even suggested may account for this.

Quote:
If the mass "passed through" the black hole to become building blocks of another universe, we'd see the mass disappear. To my knowledge, we don't.

No, we wouldn't. Once it passes through the event horizon, we "see" nothing, but the gravitational pull on the other strings is going to be there forever. It's impossible to tell conclusively from the data we have what actually happens to it.

Quote:

One last thing, and I may be beating a dead horse here: I highly recommend that you don't use the phrase "Inside a black hole".

Why not? Have you been inside one? Do you know what the inside of a black hole looks like or how it operates?

I propose that we do have a living example of inside a black hole: the universe. I have little reason to thing that any black hole of large enough size wouldn't be constructed similarly on the inside.

That said, it would also be expanding, as black holes expand. They drawn fabric from the outside, and that adds to space on the inside. It's a pretty perfect parallel for what we see all around us. IMHO.

CTS,

This is a good example of when the inverse square law does not apply. I know this is pretty basic stuff for you, but it illustrates the point quite well:

Mal is using the inverse square law for the universe in the same way as one would for the moon, wherein the logical fallacy is that when you retreat from the moon, you are not passing through more moon thus increasing the overall mass of the moon; however, when you retreat from the center of the universe, you are indeed passing through more universe, adding to the total mass of the universe. This is the case I gave you earlier where something would be adding to the overall signal, in this case gravity, as you travel outwards, doing so at a rate of x³, increase the overall strength on the exterior sphere. (before I get bashed for calling gravity a "signal" I mean it behaves like a signal, even though it is actually driven by microscopic kittens tangling yard of infinite length.)

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 2:30 PM

Quote:
Originally posted by Magonsdaughter:

LOL> Maybe that is what I am experiencing now and why my neck hurts.

I recommend people download and watch Brian Cox's Wonders of the Universe. He's clever, clear and cute. What a man.

Thanks, I'll take a look, sometime when I have more time.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 2:31 PM

Quote:

One thing I've caught reminded me of what I wanted to follow up with Bytemite about: the background radiation. I can't recall exactly what you said, but I got the impression that you called it not smooth.

My understanding is different - the background radiation is shockingly uniform. In the paper I'm looking at ( http://www.astro.princeton.edu/universe/ms.pdf) They say on page 10: "the cosmic microwave background is uniform to one part in 100,000 all over the sky."

This presented something of a problem for astrophysics: how can it be so damned uniform when the big bang came from one single point? And how do we have smaller scale heterogeneities--galaxies and such--when the large scale is so smooth? Which the basis of the inflation theory, the accelerated expansion of the universe during the first 10^-34 seconds of its existence.

I was mostly speaking of what I remember from reading Stephen Hawking. There's a part in A Brief History of Time where he shows computer models of the roughness of the universe. As I was remembering it, those models were based on discrepancies in the cosmic background, but I might be misremembering.

I think no matter which way you start looking when it comes to the universe, there are going to be stumbling blocks. Whether it's "why isn't matter uniformly distributed if the universe is uniformly expanding" or whether it's "why is the background radiation uniformly distributed if well all came from a big bang?"

Quote:
Bytemite, re your latest post (unless I've missed more while writing this!) I do enjoy the idea that black holes are some kind of door, and who knows if the broken down laws of physics inside them lead to things as cool as creation of new universes. I like that.

But a few caveats: the mass that falls into a black hole doesn't disappear. The mass can still be measured by the gravitational effects of the BH on everything around it. Ditto with angular momentum and charge. These three things are conserved. If the mass "passed through" the black hole to become building blocks of another universe, we'd see the mass disappear. To my knowledge, we don't.

That's the beauty of this. Technically that mass doesn't disappear because from the perspective of the other universe it's all still in the black hole (or maybe represented by the snapshot of the event horizon). The only thing lost is the information and arrangement of the energy and matter, neither one seems to be completely destroyed or we wouldn't see Hawkings Radiation. And, if the space time of the new universe is space time from the old universe, it could be argued they're different "layers" of the same universe.

That might actually get around the arguments against white holes based on the second law of thermodynamics. But we might not need a white hole or a singularity either for this to work, if some of the matter in the fecund universe is orbiting around the edges like DT and I were talking about.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:17 PM

Quote:
Originally posted by dreamtrove:

Actually, it's worse than that. The observational data is that it increases.

Source?

Quote:
No, we wouldn't. Once it passes through the event horizon, we "see" nothing, but the gravitational pull on the other strings is going to be there forever. It's impossible to tell conclusively from the data we have what actually happens to it.

We see how the motion of objects near the black hole are effected by its gravity, so yes indeed, we can measure the mass of the black hole.

This is basic. Wikipedia:

The no-hair theorem states that, once it achieves a stable condition after formation, a black hole has only three independent physical properties: mass, charge, and angular momentum.[25] Any two black holes that share the same values for these properties, or parameters, are indistinguishable according to classical (i.e. non-quantum) mechanics.

These properties are special because they are visible from outside a black hole.

Quote:
Quote:

One last thing, and I may be beating a dead horse here: I highly recommend that you don't use the phrase "Inside a black hole".

Why not? Have you been inside one? Do you know what the inside of a black hole looks like or how it operates?

Have you? You're the one throwing away equations because they don't fit what you'd "expect inside a black hole."

Many principles of physics support that collapse of matter inside a black hole into a single point, a singularity. No principles of physics support your proposition that the mass is somehow able to resist collapse.

Quote:
Mal is using the inverse square law for the universe in the same way as one would for the moon, wherein the logical fallacy is that when you retreat from the moon,

Whoa - so you're throwing out the UNIVERSAL LAW OF GRAVITY - universal meaning it applies EVERYWHERE, because... why?

The big deal with Newton's UG is that gravity acts the same on everything. The inverse square law applies when you are inside the moon. How long has it been since you took physics? Cause... wow.

Please, let me know if I'm misunderstanding. Are you saying that the inverse square law of gravity, Newton's universal gravity F = GMm/r^2, does not apply everywhere?

Quote:
gravity, as you travel outwards, doing so at a rate of x³, increase the overall strength on the exterior sphere.

WTF are you talking about? Source, please.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:22 PM

Oops, I thought I posted this earlier but it didn't go. Luckily, I copied it!

Quote:
Originally posted by dreamtrove:
Gravity is greatest when the entirety of a gravitating object is on one side of you, not when you are "close to a lot of mass."

A point on the surface of the sun has an escape speed of 437 km/s. This is because a point at the surface of the sun is 6.96E8 m away from the center of mass of the sun, with a mass of 2E30 kg.

Vesc = sqrt(G*Ms/Rs) = sqrt(6.67E-11*2E30/6.96E8) = 437 km/s

If you increase the volume of the sun, with the same mass, the escape speed goes DOWN. For example, let's double the radius of the sun:

Vesc = sqrt(G*Ms/Rs) = sqrt(6.67E-11*2E30/14E8) = 310 km/s

310 is SMALLER than 437. See - more volume, lower escape speed.

Quote:
If you are, as we are, inside of a gravitating object (the universe) then it is not exerting gravity on you because it is on all sides of you. That means it cancels out, but it does not mean that as a body it does not gravitate.

Yes, it gravitates, but the mass that is "outside" your position does not contribute to escape velocity. ie, the total gravitational force exerted by the sun on an object located in the exact center of the sun is zero.

Quote:
Do we have to argue about everything?

Your application of this principle of physics is wrong, and that must be pointed out. If you see this as arguing and get emotional about it, all you're doing is ensuring that [edited to be nicer] the discussion will die.

Quote:
The spacial distribution of mass in the universe is exactly what I would expect to see in a black hole.

Inside a black, the force of gravity is so strong that everything collapses to a single point. This is very basic, and your idea that mass is somehow spread out in there, that gravity miraculously goes away, is your own invention that has no support in any actual science that I've seen.

Going into a black hole is not like going into the earth.

Quote:
It's not too dissimilar from what we see in galaxies and stellar systems from which a black hole is not very far removed, and it is predicted by chaos theory and fractal geometry.

You're making that up. OK, I know you're not, but please give a source, because I don't believe it.

Quote:
But furthermore, the black hole is decided by the total mass within the total area, being at one side and not competing with outside gravitation. One such body is the universe.

And the distance to the total mass is important. The black hole in the center of the Milky Way is all on one side of you. If you got close enough to it, escape speed would exceed the speed of light and then you'd be inside it. But you are not that close to it, so you are not inside it.

And please note that it is demonstrably true that the mass of the universe is NOT all one side of you, so all that mass cannot be contributing to the escape speed.

Quote:
Quote:

Being inside a black hole means that the gravitational field is so strong that light cannot escape.

Almost. The event horizon is where gravity is so strong that light cannot escape. That does not mean that gravity inside the hole is this strong.

It means that gravity inside the event horizon is STRONGER, because you get closer to the mass. Which is all concentrated at one point, because that is what happens to mass in that strong of a gravity field.

Question: since you seem to think that mass inside an event horizon is scattered about and not all centrally located, what force do you propose is stopping the mass from collapsing? In the sun, the thermal energy of fusion prevents the collapse. In neutron stars, the Pauli exclusion principle prevents further collapse. In black holes, the gravity is so strong that these forces aren't enough. So what do you think is doing it?

Quote:
Quote:

Bigger volume means higher escape speed? Sheesh.

Did you even read what I wrote? It's inescapable, a larger volume of mass will lead to an increase of gravity. That is, unless you radically reduce the density. That's because the volume is cubed and the distance is linear.

This has nothing to do with escape speed.

v = sqrt(GM/r)

Make r bigger, holding the rest constant. v gets smaller.

QED

Quote:
We're not talking about a larger volume of empty space, but a larger volume of mass. In this case, the massive body being the universe.

If you're increasing volume AND mass at the same time, you're not looking at the dependence on just volume.

Quote:
If you think just because we are inside the universe and there is space to move around that means that the universe is empty space and not a gravitating object, then doesn't it also stand to reason that a marble, being 2000 times more empty space than silcate, is also an empty space, and not really a solid object?

Fill the volume of the sun with styrofoam - lots of empty space. Gravity on the surface of the sun would be weak. Make the sun out of degenerate matter - no empty space, even between nuclei. Gravity on the surface is really fucking high.

Yes, empty space must be considered.

Quote:
space feeding into the black hole universe is new space and not old space and so is being added to the interior, thus increasing the amount of space which separates us.

I don't agree as to the source of it, but I see it similarly: empty space is growing. Well, I think all space is growing, but you don't see it unless you stare across a very very large void.

Quote:
* in agreeing with me and you, we are disagreeing with classic big bang theory which accepts the acceleration as a pure redshift.

Well, the classical big bang theory is pretty much out the window.

Quote:
As for the equation, I don't think so. I think the conclusion is inescapable because I cannot see how the universe could exist without fitting the definition, because in order to exist, it must be getting space from somewhere, in order for there to be space.

You can't throw out equations just because they don't fit your pet theory. That's not science.

Quote:
Quote:
Mal
Get it? r is in the denominator!

Seriously, kill this attitude or folks might be inclined to give up.

Wow. That's some pretty serious attitude from you. You know how it sometimes comes up that you cannot handle being disagreed with? This is your chance to prove that wrong.

Quote:
Yes, but we are 238.9 million miles from the moon. If the moon had a radius of 238.9 million miles, the impact of the moon would be greater.

No. As long as we are located outside the surface of the moon, it doesn't matter if all it's mass is squished into a tiny ball centered on that point 238.9 million miles from us, or if it's widely spread. We are that distance from the center of THAT mass, so the gravitational effects are the same.

True, it's different if the moon is so spread that we are located inside it. Then the gravitational force of the moon decreases.

Hey - kind of like how being located INSIDE the universe makes it's gravitational field weaker, because there's mass on all sides of us!

OK, I went back through to proofread, which means my dinner is cold...

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:31 PM

By the way, this is fun. And it's good to have to go out and look this stuff up. It's been a while. I might have to read Brief History of Time again. Good book. I read it as a senior in high school and it's the reason I majored in physics.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:32 PM

I heartily encourage you to have dinner, because I'm going to take a nap, because I think the headache that I've had since noon might be sleep deprivation and not enough caffeine catching up with me.

This is a fun conversation though. I think we're all trying to keep it fun, so, hopefully...

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 3:55 PM

Quote:
Originally posted by Bytemite:
I heartily encourage you to have dinner, because I'm going to take a nap, because I think the headache that I've had since noon might be sleep deprivation and not enough caffeine catching up with me.

This is a fun conversation though. I think we're all trying to keep it fun, so, hopefully...

Oh - meant to say that I like your idea that all the mass in the black hole is still in the black hole, even if it's a whole big universe in there. I feel like that almost reminds me of some very cool sci-fi, but I can't quite remember...

Hope the headache goes away.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 4:08 PM

http://www.guardian.co.uk/science/2011/oct/23/brian-cox-jeff-forshaw-a
nswers

Is there a centre of the universe?
Marjorie Ainsworth, via email

JF: It's a common misunderstanding of the big bang that the universe exploded into something, like a firework went off or something like that, and there was a centre that spewed out into something.

BC: That seems to imply that everything is flying away from us and we're therefore somehow in a privileged position; that isn't true. The way it's often described is if you imagine some bread with raisins in it that you're baking in the oven and as you heat it, it expands. On any particular raisin, if you look, you can see all the other raisins receding from it. So it's space that stretching, it's not that everything's flying away.

JF: It's the big stretch, not the big bang.

If everything came from a singularity, what created it?
bbmatt, via web

JF: What created the singularity? No idea. But that doesn't mean that some people haven't tried to come up with ideas. Anyway, everything coming from a singularity is a confusing line of questioning because the universe was probably infinite at the time of the big bang so it didn't really come from a singularity. It came from a singularity in the density, but I expect that the person who's asked that question imagined that the universe came from a point.

… but that's very unlikely. We don't know what happens deep inside a black hole, so when the density of the universe gets very, very large then our calculations cease to work, so the honest answer is that before we reach the singularity, our ability to calculate fails. But that's not to undermine how accurately we can calculate, because we claim to understand the behaviour of the entire visible universe winding back through the big bang to a time when it was the size of a beach ball. So that's all the billions of galaxies and all the billions of stars in the galaxies compressed to about the size of a beach ball, which is pretty impressive.

BC: General relativity, quantum mechanics, those things break down in there, so the idea that there is such a thing as a singularity in nature is unlikely. A lot of people think that if you have a proper theory of gravity that works smaller than the beach ball metaphor then you don't have these issues, but it's not known.

JF: Another misunderstanding, which stems from that question, is the idea that the universe was small at the big bang. What was small at the time of the big bang was the entire visible universe, so everything we can see now, which is about 14bn light years away, all of that was compressed to the size of a pinhead. But it was one pinhead in an infinite space, so there's an infinite amount of stuff, as far as we can tell, outside our universe. So it's right to say that it's 14bn years old, but it's wrong to say that it's 14bn light years in size because it's probably infinitely big.

However, the question that's probably been asked is what happened before the beginning and the answer to that is that nobody has a clue – so that's the honest answer.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 5:23 PM

At the end you got the point, I think we were just miscommunicating. There were some different assumptions being made about what was constant (mass vs. density) For instance, you were talking about a constant mass sphere of galaxies expanding, I was talking about increasing the scope of a sphere with a constant density of galaxies. So, read through, and then answer. I won't have the kind of free time that I have had today for a long time.

Quote:
Source?

Some scientific article I read, somewhere. This stuff is all over if you search for it. Maybe it's since been dismissed as observational error, or some new elaborate theory is built on it, I don't know. I also think it's what logic would dictate re strings and tangles.

We were speculating about internal properties of black holes, not external, I think we all agree on the latter.

Quote:
Have you?

Yes, I live in one.

Quote:
Many principles of physics support that collapse of matter inside a black hole into a single point, a singularity.

That makes a lot of assumptions about the interior of a black hole that I'm not willing to make. The interior properties of matter as some super compressed soup just ignores the existence of space time, and the concept of a singularity I find absurd, and I'm logically force to reject it, but my rejection of them does not mean it isn't so, but that they cannot be determined, and thus I cannot support them.

I think that these ideas exist in a newtonian world, and perhaps creep into an einsteinian one, but don't fully endorse einstein, and force a rejection of string theory which I'm also not willing to do. At some point this ceases to be about billiard balls and becomes about fabric and energies.

Quote:
Whoa - so you're throwing out the UNIVERSAL LAW OF GRAVITY - universal meaning it applies EVERYWHERE, because... why?

I wasn't, but I would if need be. Gravity is the effect of fabric being pulled upon.

But what I was saying is that gravity is acted upon the outside of a gravitating body, not wholly on the inside. It is not only possible that the escape velocity in the interior of a black whole is less than the speed of light, it appears to be a foregone conclusion.

ETA: I see by the end you get this point, so I won't harp on it.

Quote:
The inverse square law applies when you are inside the moon.

Not to the entire moon. I may apply to a theoretical sphere of moon which has a radius of your distance from the center. Sometimes the inverse square law does not apply. In order for the inverse square law to apply you have to be outside of the object.

There is more light in my living room than the inverse square law would suggest because, as luck would have it, my living room possesses its own light source. More fortunately, it is not inside the sun, so in terms of solar radiation, the inverse square law applies.

There is not a predictable 1/9 as much light 300,000 miles from solar center as there is at 100,000 miles, because both are inside the sun. There is not 1/9 the gravity either.

Quote:
How long has it been since you took physics?

30 billion years, apparently.

Quote:
If you increase the volume of the sun, with the same mass,

Why would you keep the same mass? I mean, you could expand the sun into a red giant, but that's not what we're talking about. The question was if we ventured further out into the universe. If we did so, we wouldn't be taking the galaxy with us, there would be more galaxies there, adding to the collective mass. We're not talking about venturing out into a void, we're talking about more space-time with more mass.

ETA2: i see now this was the principle miscommunication.

Quote:
Inside a black, the force of gravity is so strong that everything collapses to a single point.

I've noticed black people collapse into a singularity. It's disturbing to watch.

Quote:
Quote:
It's not too dissimilar from what we see in galaxies and stellar systems from which a black hole is not very far removed, and it is predicted by chaos theory and fractal geometry.

You're making that up. OK, I know you're not, but please give a source, because I don't believe it.

Source what? That the distribution of matter in the universe is not entirely dissimilar to that of other large scale orbital systems? I assume you know. If you want an explanation of how chaos theory predicts the formation of spiral galaxies around wormholes, I really don't have the time, and I'm not the best person to explain it. Any of this stuff that isn't our person theories is background that anyone can look up, it's really a waste of our time to write it out here anyway. I assume we all have a pretty strong background in the subject and are capable of looking things up.

Quote:
And please note that it is demonstrably true that the mass of the universe is NOT all one side of you, so all that mass cannot be contributing to the escape speed.

Of course it does, but I happen to not be at the edge of the universe. My location is irrelevant. The point at which gravity is being exhibited is relevant, but it has nothing to do with where I am. It means that where I am right now has a lower escape velocity than c, yes, which predicts what we already know, which is that we can travel through the universe.

Except we can't, because we don't have a spaceship. We'd like to get there, which we can't do if we don't know and apply physics.

Assume I'm familiar with physics, and try to see what I'm getting at. If it doesn't seem that way, it's most likely a communication problem.

The universe is like a marble, externally, rolling down a drain. Internally, it is a ball of yarn, and at the center is a colony of microscopic kittens that are more numerous than all of the grains of sand in all the beaches of the universe.

In terms of physics, the gravity of that marble applies to those outside it. Or would, in theory, if there were an outside. Which was part of what we were trying to figure out.

Quote:

Quote:
Quote:
Being inside a black hole means that the gravitational field is so strong that light cannot escape.
Almost. The event horizon is where gravity is so strong that light cannot escape. That does not mean that gravity inside the hole is this strong.

It means that gravity inside the event horizon is STRONGER, because you get closer to the mass. Which is all concentrated at one point, because that is what happens to mass in that strong of a gravity field.

Ah, here in lies the assumption: That all the mass is at the center. I have no reason to assume that this is the case. There is a center of gravity, which comes from orbiting energies in a tightly woven fabric. How much so? We don't know. I proposed a model.

I suspect the active black hole may be smaller than the event horizon in some cases, but larger in others, as you see black holes with outer disks, like the milky way.

But the assumption that everything exists at a single point violates everything we know about physics. It seems more like magic than science. Logically, we need to stick to what we know.

Here's what we actually know: The material is inside the hole. It orbits the center. This makes that center a center of gravity. The entire sphere is defined by its escape velocity = c radius. Somewhere in there is the matter. It has a center of gravity at the center. This is what we know.

Anything else is a guess. That includes the idea that all matter lies at the center in an infinitely small space. I see no reason to think that would be true, and I have reason to reject it, like that we don't have any laws of physics that would predict that, we have no similar models in the universe that resemble that, and it's hard to see how that would generate predictable properties like a magnetic field, and if it were true, I feel fairly sure that the universe would not exist. Thus I can extrapolate that it is not the case because I believe the universe does exist, which I admit is fairly abstract.

Quote:
Question: since you seem to think that mass inside an event horizon is scattered about and not all centrally located, what force do you propose is stopping the mass from collapsing?

Gravity. What prevents the earth from falling into the sun? Or the sun from falling into the center of the milky way? Sure, it's angular momentum, but where did that angular momentum come from? Gravity.

Also, we know that the black hole is sucking up an incredible amount of material, which means fabric. Therefore the amount of internal space inside the hole is harder to predict, but I suspect is almost certainly larger than the outside.

So, Gravity and Space-time, those are the forces. Eventually the introduction of the latter into a black hole might be termed the expansive force, if the universe as black hole theory is correct. But I don't think internal expansion will cause a black hole to externally decay. I'm not even sure it would externally grow.

Quote:
Fill the volume of the sun with styrofoam - lots of empty space. Gravity on the surface of the sun would be weak. Make the sun out of degenerate matter - no empty space, even between nuclei. Gravity on the surface is really fucking high. Yes, empty space must be considered.

Matter will differentiate into chaotic patterns, but the volume of the object is going to be a far greater determinant than density. In the end, the mass is the largest factor in gravity.

Think about where the gravity is coming from: Tangles. The more threads, the more tangles. Sure, the more density, the more tangles, but that's far less of a factor, until you get to the black hole level.

Quote:
you cannot handle being disagreed with?

I am not up for wasting my time. I have not that much time to give, and nitpicking well understood physics is wasting it. If you're looking for errors by making assumptions as if I were ignorant, it's just insulting.

Try to figure out what I'm trying to say. If it's not clear, try asking me to clarify those points which weren't clear.

Quote:
True, it's different if the moon is so spread that we are located inside it. Then the gravitational force of the moon decreases. Hey - kind of like how being located INSIDE the universe makes it's gravitational field weaker, because there's mass on all sides of us!

This is what I've been trying to say all along. But it doesn't change the gravity at the edge of the universe which would be high.

A long painful argument could have been avoided here to reach this communication. I'm not up for doing it again. So, next time, if I'm not clear, try to tell me that instead. My communications skills, I will freely admit, suck. My scientific ones I think are pretty good. My strong point, I think, is logic. There are some people here who are much more scientific than I am, which is why I work better as part of a team than by myself, but I'm good at spotting logical fallacies and coming up with possibilities that no one has thought of, and one that I think I do well that can get me in a lot of trouble is using logic to rule out possibilities which I don't think logically follow.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 5:49 PM

Aw. Thread is about to blow.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 6:27 PM

Quote:
Originally posted by Bytemite:
Aw. Thread is about to blow.

Okay, I edited it down a little, but I agree it was too much. I just couldn't lose the line about blacks collapsing into singularities, even if it was kind of uncalled for, it made for a humorous snark. Besides, you remember Herman Cain, right? It does happen.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 6:30 PM

:)

I'm going to be pretty worthless for conversation, I think this might be a migraine rather than just a tension or caffeine headache, it gets worse when I move around. At least it's a mild one, I've had the ones with nausea and vision disturbance and nervous symptoms before.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Thursday, December 22, 2011 9:52 PM

To start at the end of your post:

Quote:
Originally posted by dreamtrove:
Try to figure out what I'm trying to say. If it's not clear, try asking me to clarify those points which weren't clear.

Is exactly what I'm doing. But if you claim escape velocity from the universe is greater than c, and you plug in numbers that make no conceptual sense... well, that's your mis-communication and your poor application of the laws of physics. That's your job to fix, not mine.

Because let's not skip past this - trying to calculate the escape velocity of the universe using the mass of the entire universe and size of the entire universe is not a failure of communication. It's just wrong.

Quote:
At the end you got the point, I think we were just miscommunicating. There were some different assumptions being made about what was constant (mass vs. density) For instance, you were talking about a constant mass sphere of galaxies expanding, I was talking about increasing the scope of a sphere with a constant density of galaxies. So, read through, and then answer. I won't have the kind of free time that I have had today for a long time.

That makes no sense. There's no reason to suppose that the universe grows with the density of galaxies. what you are doing is assuming that what you want to be true is true, then calculating outcomes based on your assumptions. Then the outcomes fit your assumptions and you claim victory.

Yeah. Go figure.

The universe is mostly empty space. This is undeniably true. If you start adding on density of galaxies you change the universe and force it to fit your assumptions. This is ridiculous.

Quote:
Quote:
Source?

Some scientific article I read, somewhere. This stuff is all over if you search for it.

No. That's not how it works. If you want to back up your claims, you need to provide your own references.

Quote:
We were speculating about internal properties of black holes, not external, I think we all agree on the latter.

Assuming that only makes an ass of you. (Not me!)

Quote:
Quote:
Have you?

Yes, I live in one.

As do I. Your point?

Quote:
Quote:
Many principles of physics support that collapse of matter inside a black hole into a single point, a singularity.

That makes a lot of assumptions about the interior of a black hole that I'm not willing to make.

Such as: there is an attraction force between masses. You are apparently willing to throw this basic truth away to fit your preconceived ideas. You haven't answered the question: if mass gets dense enough that escape velocity exceeds the speed of light, what prevents this incredibly dense mass from collapsing to a point?

Angular momentum is no good answer, since gravitational force from the central body cannot provide angular momentum. Right angles are a bitch.

Quote:
The interior properties of matter as some super compressed soup just ignores the existence of space time, and the concept of a singularity I find absurd, and I'm logically force to reject it, but my rejection of them does not mean it isn't so, but that they cannot be determined, and thus I cannot support them.

There is nothing logical or sensible in this statement.

Quote:
I think that these ideas exist in a newtonian world, and perhaps creep into an einsteinian one, but don't fully endorse einstein, and force a rejection of string theory which I'm also not willing to do. At some point this ceases to be about billiard balls and becomes about fabric and energies.

Besides throwing some big names out there, these are completely meaningless statements.

Quote:
Quote:
Whoa - so you're throwing out the UNIVERSAL LAW OF GRAVITY - universal meaning it applies EVERYWHERE, because... why?

I wasn't, but I would if need be. Gravity is the effect of fabric being pulled upon.

But what I was saying is that gravity is acted upon the outside of a gravitating body, not wholly on the inside. It is not only possible that the escape velocity in the interior of a black whole is less than the speed of light, it appears to be a foregone conclusion.

BS. The inverse square law works perfectly fine when inside a body of mass.

Have you studied calculus? Have you integrated over a spherical shell? Gravity obeys the inverse square law, inside a body or not. In fact, if it didn't, we'd be living in a very different universe.

Quote:
Quote:
The inverse square law applies when you are inside the moon.

Not to the entire moon. I may apply to a theoretical sphere of moon which has a radius of your distance from the center. Sometimes the inverse square law does not apply. In order for the inverse square law to apply you have to be outside of the object.

Pure and compete bullshit. Learn some calculus, young man. Inverse square perfectly explains gravity inside a body.

Quote:
Quote:
How long has it been since you took physics?

30 billion years, apparently.

Clearly.

Quote:
Quote:
If you increase the volume of the sun, with the same mass,

Why would you keep the same mass? I mean, you could expand the sun into a red giant, but that's not what we're talking about. The question was if we ventured further out into the universe. If we did so, we wouldn't be taking the galaxy with us, there would be more galaxies there, adding to the collective mass. We're not talking about venturing out into a void, we're talking about more space-time with more mass.

and there'd be more empty space between the galaxies. Did you actually look at that paper you referenced (indirectly, through wiki) for the size of the universe? The density of the universe is NOT the density of a galaxy. There is empty space. You may overlook this because it's convenient, but that only makes your conclusions wrong.

Quote:

Source what? That the distribution of matter in the universe is not entirely dissimilar to that of other large scale orbital systems? I assume you know.

It is not at all similar to the distribution of mass inside a black hole. I do not assume that you know this, because clearly you don't.

Quote:
Quote:
And please note that it is demonstrably true that the mass of the universe is NOT all one side of you, so all that mass cannot be contributing to the escape speed.

Of course it does, but I happen to not be at the edge of the universe. My location is irrelevant. The point at which gravity is being exhibited is relevant, but it has nothing to do with where I am. It means that where I am right now has a lower escape velocity than c, yes, which predicts what we already know, which is that we can travel through the universe.

Which means that you are not living inside a black hole.

**BIG CONCLUSION HERE** did you catch it? You are not living inside a black hole, because escape speed is not c.

Quote:
Assume I'm familiar with physics, and try to see what I'm getting at.

I would, if your application of physics wasn't so blatantly wrong.

Quote:
The universe is like a marble, externally, rolling down a drain. Internally, it is a ball of yarn, and at the center is a colony of microscopic kittens that are more numerous than all of the grains of sand in all the beaches of the universe.

Uh... are you smoking something?

Quote:
Ah, here in lies the assumption: That all the mass is at the center. I have no reason to assume that this is the case. There is a center of gravity, which comes from orbiting energies in a tightly woven fabric. How much so? We don't know. I proposed a model.

OK. HUGE gravitational forces are collapsing mass into the center of a black hole. Please - as I asked before - propose a force that can balance that and prevent the mass from collapsing.

I'm waiting.

But it can't be the force of wishful thinking.

ETA: because I demanded above that you provide sources for your ideas, it's only fair that I have to do the same. I'm going to take the easy path and use wikipedia: http://en.wikipedia.org/wiki/Black_hole

At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the spacetime curvature becomes infinite.[52] For a non-rotating black hole this region takes the shape of a single point and for a rotating black hole it is smeared out to form a ring singularity lying in the plane of rotation.[53] In both cases the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution.[54] The singular region can thus be thought of as having infinite density.

Quote:
But the assumption that everything exists at a single point violates everything we know about physics.

See the above reference.

Anyhow - this is what I was talking about yesterday. The laws of physics break down inside a black hole. I can't even post a reference for this, because it's everywhere. Look it up - the wiki page will do it for you.

The laws of physics do not apply inside a black hole. The force of gravity is so strong that the usual laws of matter and energy do not apply. Accept it, live with it. This is how it is.

Quote:
Here's what we actually know: The material is inside the hole. It orbits the center.

Look into ANY reference on black holes and you will see how wrong you are.

Go ahead and look. I'm waiting.

Quote:
Quote:
Question: since you seem to think that mass inside an event horizon is scattered about and not all centrally located, what force do you propose is stopping the mass from collapsing?

Gravity. What prevents the earth from falling into the sun? Or the sun from falling into the center of the milky way? Sure, it's angular momentum, but where did that angular momentum come from? Gravity.

Bullshit. Angular momentum comes from a force acting along the tangential path, Gravity does NOT act along the tangential path. Angular momentum has to come from some outside force.

You're not stupid DT, but you REALLY need to take a physics class.

Quote:
Quote:
Fill the volume of the sun with styrofoam - lots of empty space. Gravity on the surface of the sun would be weak. Make the sun out of degenerate matter - no empty space, even between nuclei. Gravity on the surface is really fucking high. Yes, empty space must be considered.

Matter will differentiate into chaotic patterns, but the volume of the object is going to be a far greater determinant than density. In the end, the mass is the largest factor in gravity.

And mass is a factor of density. Higher density=more mass to increase the gravitational force.

It's becoming clearer and clearer to me. Please. Take a physics class.

Quote:
Think about where the gravity is coming from: Tangles. The more threads, the more tangles. Sure, the more density, the more tangles, but that's far less of a factor, until you get to the black hole level.

Sort out the basics before you try tackling string theory. A denser sun will exert a stronger gravitational force on any mass at its surface. Period.

Quote:
Quote:
you cannot handle being disagreed with?

I am not up for wasting my time. I have not that much time to give, and nitpicking well understood physics is wasting it. If you're looking for errors by making assumptions as if I were ignorant, it's just insulting.

You claimed that spreading mass over a greater volume would increase escape velocity. If you don't want to sound ignorant, don't make such silly claims.

Quote:
Quote:
True, it's different if the moon is so spread that we are located inside it. Then the gravitational force of the moon decreases. Hey - kind of like how being located INSIDE the universe makes it's gravitational field weaker, because there's mass on all sides of us!

This is what I've been trying to say all along. But it doesn't change the gravity at the edge of the universe which would be high.

BS. If the volume of the universe is increasing, while mass stays the same (as it would for a hugely inflating moon) the gravitational force goes DOWN.

Quote:
My scientific ones I think are pretty good. My strong point, I think, is logic.

I disagree. You are applying physics in a blatantly incorrect way, whatever it takes for you to support your preconceived ideas.

It's not just me. Try taking your ideas to any educated physicist. Every single one will shoot you down. You'll probably start thinking that people are out to get you, but you ought to consider the fact that your application of these laws is just plain wrong.

Please, try. And get back to me.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 2:34 AM

Interesting arguments! I just want to jump in real quick re inverse square law.

The question is, as I understand it, "Does ISL apply to the inside of the moon?"

ISL is a mathematical model which operates out of the following assumptions:

1. Source is a point.
2. Influence spreads isotropically and uniformly from point source.
3. No interference in influence (e.g. for light, no absorption, diffraction, refraction etc.) in the distance traveled.

Shell theorem states that a spherical body of mass exerts gravitational influence as though all of its mass were concentrated at a point in the center. In other words, we can treat the entire moon shell like a point source, satisfying the assumption#1.

However, shell theorem has its own assumptions:
1. Constant density of the sphere.
2. Spherical symmetry.

Assuming that all the assumptions are true, Mal is right in that it is simply a question of mathematics.

DT is right in questioning whether the assumptions are met. After all, the moon probably does not have constant density and spherical symmetry. Maybe the deviation is so minor we can still use shell theorem and ISL from the shell. But do the deviations affect finer calculations from inside the moon? I believe these are excellent questions.

I am not sure why the finer gravitational influences inside a body of mass is important in the overall discussion. It seems to me that if the assumptions of shell theorem are satisfied well enough to apply to the shell, then they are good enough to apply inside the shell--for the purposes of the current discussion.

Maybe I'm missing something?

-----
"Christmas is a time when kids tell Santa what they want and adults pay for it. Deficits are when adults tell the government what they want - and their kids pay for it." - Richard Lamm

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 3:37 AM

Mal,

Your post contained no new information. All of your above questions are already answered by my previous posts. I've tried to be patient, but I have no time for this nonsense. If you look back you will see answers to all of your questions, including that we are talking about a overall constant density sphere (internal distribution notwithstanding) and not a sphere of constant mass. If you read over the thread again looking for answers to your questions, you'll find them.

CTS,

Alas, the dispute was more basic than that: The gravity inside the moon is less than on the surface because the moon is not a point. If you're standing, say, 400 miles from the center, then you have an 800 mile sphere of moon more pulling you in one direction vs. every other direction. Ergo, density aside, there's a 400 mile radius or 800 mile diameter sphere of moon on one side of you causing net gravity, and that is smaller than the moon. You proximity to is not enough to make that gravity higher.

A secondary question might be whether the surrounding moon gravitational force pulling you in separate directions would be enough to pull you apart, but we can calculate that it isn't. We can also speculate about that force inside a black hole, but that depends on the internal space within the hole, which is not known. I suspect that number of being very large, so again, the force as being comparatively weak, relatively to the force on the event horizon. Finally, this was all a way of getting back to the universe as a whole, and in the universe as a whole we already know that those conflicting forces do not have that power of pulling us apart, as we living in the universe, and are not being pulled apart by them.

This is all a rather tiresome diversion on questioning one of the underlying subtopics which is a way of avoiding the discussion or bringing it to a halt.

All of Mal's questions are already answered in the above posts, mostly in the post she's responding to.

I'm up for continuing the discussion of the universe, if there's any chance we can get back to it.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 4:06 AM

Quote:
Originally posted by dreamtrove:
If you're standing, say, 400 miles from the center, then you have an 800 mile sphere of moon more pulling you in one direction vs. every other direction.

I don't think this is how ISL works. ISL assumes a point source. That is a requisite: a point source with isotropic, radial, and unidirectional influence. You are arguing if the "point" were a large sphere, then the "point" doesn't start until you reach the outer shell. I may be wrong, but it seems to me you are arguing that shell theorem, which says you can assume the "point" starts at the center of mass, is invalid.

On one hand, I agree that the validity of shell theorem is tangential to the main topic.

On the other hand, I think we must clarify assumptions and premises before continuing the discussion. That is simply the kind of tedious work that must be done in a conversation of this sort. If people want argue about shell theorem, that should have its own thread. On this thread, list assumptions at the beginning so that we all start at the same place. So if you're assuming that shell theorem is not valid, you should state it, and we should concede that for the purposes of argument at the beginning and move on.

This is a problem for the other issues Mal brought up as well.

-----
"Christmas is a time when kids tell Santa what they want and adults pay for it. Deficits are when adults tell the government what they want - and their kids pay for it." - Richard Lamm

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:10 AM

>_> I want to say that gravity still seems to work inside a body of mass. That plus the extracellular matrix and weak hydrogen bonds keeps our cells in arrangement with each other. Pressure increases as you go down inside the earth because of the overlaying rock weighing down on the underlaying rock (weight is a property of gravity). All of the rock wants to freefall to the center of gravity but can't because stuff is in the way. On Jupiter you could be crushed by the weight of the atmosphere.

Gravity clearly still works in the vicinity of a black hole, and it would (eventually) work in any universe coming out the outside. But I'm not as sure it may work the same way IN a black hole.

Black hole --> thing collapsing under it's mass so much that it distorts space time as it continues collapse past a point of no return. Most stars just collapse to neutron stars, very dense but not black holes.

Gravity drove the creation of the black hole, but once all the matter forming the black hole falls past it's own event horizon, all that mass is in VERY close proximity to each other, but ultimately the charges involved in the electromagnetic force and the strong force are MUCH stronger than gravity. You'd think that since both involve both attraction and repulsion between the gluons and quarks making up the matter and light energy carries it's own charges that eventually all that mass would stabilize before succumbing completely to gravity and having all matter occupy the same place. That's why I bring up Quantum Indeterminancy and Hawkings Radiation against the idea. We can estimate that the universe itself could only collapse to the size of a pinhead (others say a beach ball), and that's without factoring in likely stray particles momentarily inside and outside that mass. Most black holes would have less mass then that, so we could expect they wouldn't collapse as far.

And that's only if those forces still work inside a black hole. Rather like how we know that the initial universe did not have the forces functioning as we know them, the conditions inside a black hole are speculated to be similar.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:22 AM

Quote:
Originally posted by canttakesky:
I don't think this is how ISL works. ISL assumes a point source. That is a requisite: a point source with isotropic, radial, and unidirectional influence.

...

This is a problem for the other issues Mal brought up as well.

CTS - see the articles I linked to. When you are outside a mass, gravity acts as if all that mass was concentrated at a point, at its center of mass. This is true whether it is uniform or of varying density. The inverse square law does not need to be an integral.

However, as I already went into (and that pdf shows) one does not need to assume a point mass.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:32 AM

Quote:
Originally posted by Bytemite:
Gravity drove the creation of the black hole, but once all the matter forming the black hole falls past it's own event horizon, all that mass is in VERY close proximity to each other, but ultimately the charges involved in the electromagnetic force and the strong force are MUCH stronger than gravity.

Where do you get this? It does not gel with anything I've read.

See the wikipedia quote above. Also:

We can imagine a place where gravitational field are so strong that creates the collapse of the atomic structure of the matter; where matter and energy were put together in a proto nuclear arrangement, that’s open the possibility of reunion of the four forces – nuclear week, nuclear strong, electromagnetic and gravitational. That makes possible very very high levels of density, impossible within the atomic and molecular structure of matter that we know through the rest of the universe, in stars or planets, for example.
http://www.science20.com/amateur_scientist_new_look_over_science/blog/
what_probably_happens_inside_black_hole

Once inside a black hole, beyond the Event Horizon, we can only speculatewhat the fate of captured matter is. General relativity tells us that there are two kinds of black holes; the kind that do not rotate, and the kind that do. Each of these kinds has a different anatomy inside the Event Horizon.For the non-rotating 'Schwarzschild black hole', there is no way for matter to avoid colliding with the Singularity. In terms of the time registered by a clock moving with this matter, it reaches the Singularity within a few micro seconds for a solar-massed black hole, and a few hours for a supermassive black hole. We can't predict what happens at the Singularity because the theory says we reach a condition of infinite gravitational force.For the rotating ' Kerr Black holes', the internal structure is more complex, and for some ingoing trajectories for matter, you could in principle avoid colliding with the Singularity and possibly reemerge from the black hole somewhere else, or at some very different future time thousands or billions of years after you entered.

Some exotic theories say that you reemerge in another universe entirely, but physicists now don't believe that interpretation is accurate. The problem is that for black holes created by real physical events, the interior of a black hole is awash with gravitational radiation which makes the geometry of space-time very unstable, preventing just these kinds of trips.
http://www.astronomycafe.net/qadir/q475.html

Quote:
You'd think that since both involve both attraction and repulsion between the gluons and quarks making up the matter and light energy carries it's own charges that eventually all that mass would stabilize before succumbing completely to gravity and having all matter occupy the same place. That's why I bring up Quantum Indeterminancy and Hawkings Radiation against the idea.

Gluons, quarks, etc, no longer exist at the singularity. All mashed together.

I need to look Quantum Indeterminancy... like exclusion principle?

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:36 AM

Damn! Again, the first post I wrote today didn't get posted. (It's what I was referring to in my short post to CTS.) I found it:

First things first. This:

How long has it been since you took physics?
--30 billion years, apparently.
Clearly.

Was exceptionally bitchy. I'm sorry I said that DT.

But you do continue to miss the point... (More on this below)

Inverse square law: it ALWAYS applies. If you are trying to find the gravitational force due to a body which is irregular in either shape or density, you have to integrate. The force of gravity becomes:

F(x)=∫ΔF(y,x)dy

Where your "force density" function ΔF is something like ΔF(y,x)=Gm(x)ρ(y)|y−x|2

(This is copied from http://www.physicsforums.com/showthread.php?t=212711)

It is true that when talking about gravity inside a body, like DTs example of being inside the moon, we generally assume constant density. It's convenient, as is written up quite nicely here: www.gi.alaska.edu/~jvo/P211/SphericalShell.pdf

But we don't need to have constant density. One of my research topics was using gravity to measure density variations in the earth. ie there are gravities lows over low density spots, such as caves, and gravity highs over areas of more dense stone. These can be modeled using the inverse square law as an integral with a spatially varying density inside the earth.

DT: I have clearly pointed out several ways in which you are incorrect. There are not questions for you, because it's become quite clear to me that you do not have the correct answers, nor are you interested in finding them.

I do find it amazing that, as often happens, you've appoint yourself an expert while simultaneously admitting that you haven't studied it in years. It is an unfortunate approach for you, because you are guaranteeing that you will never correct your mistakes.

In any case, I am also ready to get back to discussing the universe, but only the correct one. If you continue to presents fictions, I will continue to point out that they are fictional.

So, getting back to it, how about returning to wikipedia's statement:

At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the spacetime curvature becomes infinite.[52] For a non-rotating black hole this region takes the shape of a single point and for a rotating black hole it is smeared out to form a ring singularity lying in the plane of rotation.[53] In both cases the singular region has zero volume/ It can also be shown that the singular region contains all the mass of the black hole solution.[54] The singular region can thus be thought of as having infinite density.

I was thinking about this this morning, about how incredibly powerful the forces are inside a black hole, that they compress matter so that it isn't even matter anymore. That's just cool.

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:40 AM

Quote:
Originally posted by mal4prez:
When you are outside a mass, gravity acts as if all that mass was concentrated at a point, at its center of mass.

Yes, that is what shell theorem states. Which DT appears to be disputing.

Quote:
Inverse square law: it ALWAYS applies.

As long as assumptions are met of course. I don't have a problem accepting it. But I also don't have a problem questioning whether assumptions are met.

-----
"Christmas is a time when kids tell Santa what they want and adults pay for it. Deficits are when adults tell the government what they want - and their kids pay for it." - Richard Lamm

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:41 AM

It's an elaboration of Heisenberg's Uncertainty Principle.

As for strong force and electromagnetic force, both are stronger than gravity.

Quote:
In particle physics, the strong interaction (also called the strong force, strong nuclear force, or color force) is one of the four fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation. At atomic scale, it is about 100 times stronger than electromagnetism, which in turn is orders of magnitude stronger than the weak force interaction and gravitation.

Quote:
The word strong is used since the strong interaction is the "strongest" of the four fundamental forces; its strength is 100 times that of the electromagnetic force, some 10^6 times as great as that of the weak force, and about 10^39 times that of gravitation.

http://en.wikipedia.org/wiki/Strong_force

Interestingly, most of the mathematical models of falling into a blackhole, some of what are then visually modeled on a computer, suggest that you would get a brief glimpse of another universe before complete obliteration. That could be another echo (of the universe you left?) or a trick of the bizarre physics of the blackhole, maybe a brane or a hologram, or maybe an actual universe on the other side.

What we do know is that you couldn't make it to the other side INTACT. Whether you could get to the other side at all or whether that other universe is real is a much more interesting and complicated question.

I'm wondering if perhaps there's been a change in perception in the past few years where Fecund universes have become more accepted. Most of the literature I've read recently allows for their existence. Let me check wikipedia on that - the possibility is also that I've been reading some sensational science more than the concrete and not realizing it.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:52 AM

Quote:
Originally posted by dreamtrove:
Quote:
CTS: you may have used angular diameter distance back at college and now are using comoving distance.

maybe, but I would need to ahve some vague idea what this meant.

Angular diameter distance is the distance of the farthest visible object from Earth, which is about 14 billion LY or so. The light we see now from that object was emitted 14 billion years ago.

Comoving distance is the distance of the same farthest object today, 14 billion years later. Assuming expansion of the universe, it is estimated as around 47 billion LY away now.

So I suspect you simply were looking at two different types of measurements, both of which are valid today for different aspects of distance.

Here is a nice summary.
http://www.atlasoftheuniverse.com/redshift.html

-----
"Christmas is a time when kids tell Santa what they want and adults pay for it. Deficits are when adults tell the government what they want - and their kids pay for it." - Richard Lamm

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:52 AM

Quote:
Originally posted by Bytemite:
...eventually all that mass would stabilize before succumbing completely to gravity and having all matter occupy the same place. That's why I bring up Quantum Indeterminancy and Hawkings Radiation against the idea.

OK, QI is from the uncertainty principle, and relates to the quantum fluctuations in "empty" space that make for Hawking radiation. (I know you know this, just summing up for myself and everyone else.) I don't see how it could prevent gravitational collapse of the singularity inside the BH.

But, supporting your idea, here's a cool bit of news that I had no idea about:

http://www.technologyreview.com/blog/arxiv/26626/

Today, [4/11/11] Vyacheslav Dokuchaev at the Institute for Nuclear Research of the Russian Academy of Sciences in Moscow points out that certain black holes can have a complex internal structure. And that this structure ought to allow photons, particles and perhaps even planets to orbit the central singularity without ever getting sucked all the way in.

A black hole is a region of space where gravity is so strong that nothing can escape, not even light. However, cosmologists have known for some time that there are regions inside charged, rotating black holes where objects such as photons can survive in stable periodic orbits.

...

It's well known that a traveller passing through a black hole's event horizon arrives in a region in which the radial dimension becomes time-like, rather than space-like. Conventional orbits are clearly impossible here.

But travel further in and there is another horizon where the dimensions switch back again (at least, inside charged and rotating black holes). This is the inner Cauchy horizon and it's beyond here that Dokuchaev says the interesting orbits for massive planets exist.

He calculates that the stable orbits are nonequatorial and have a rich structure (see picture above). They would also be brightly illuminated by the central singularity and by photons trapped in the same orbit.

That raises an interesting question: whether a planet in such an orbit could support a complex chemistry that is rich enough to allow life to evolve.

Dokuchaev clearly thinks so. "Advanced civilizations may live safely inside the supermassive BHs in the galactic nuclei without being visible from the outside," he says, somewhat speculatively.

Of course, such a civilisation would have to cope with extraordinary conditions such as huge tidal forces and the huge energy density that builds up in these stable orbits as photons become trapped. There's also the small problem of causality violations, which some cosmologists predict would plague this kind of tortured space-time.

Dokuchaev has taken an interesting idea and pushed it as far as he can. It's one I suspect readers can have a lot of fun with too.

So here's a place we can meet - I had no idea that orbits could exist in there, and that matter could avoid falling into the singularity.

However, it doesn't change the act that most of the mass of the BH is in the singularity itself. Unfortunately, I still don't see a whole universe in there.

But I do see a very bizarre environment on this orbiting planet. A 21st century version of journey to the center of the earth, but the center of the galaxy instead? What would life be like in there? (See the article for a picture of the orbit's shape.)

Cool!

ETA: Thanks CTS for the distance clarification. I hadn't heard of this "comoving" thing before. That 50 page paper I got from wikipedia has some cool images in it - maps of all the known structures in the universe. It illustrates those different distances nicely. http://www.astro.princeton.edu/universe/ms.pdf

-----------------------------------------------
hmm-burble-blah, blah-blah-blah, take a left

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 6:56 AM

It's a distortion of ISL but it works. If you consider that you are somewhere 400 miles from the center of the moon, you can mentally break the moon into two bodies: 1) a 400-mile radius sphere, and 2) a shell with a hollow center.

In this case, the second is a body you are inside of and the effects of gravities from all angles more or less cancel out, so the shell we can pretty much ignore. This leaves us with the first, an if you were standing on the surface of a 400-mile radius sphere of moon.

Hopefully we're still communicating clearly this far. Now, if you are outside of the object, the distance from the object would be zero if this were radiation, but it is the inverse square law of gravity, which Newton said acts just like radiation of light, and at the same time, indistinguishable from a universal acceleration, which lead einstein to say that was really more or less what was going on, which lead us to where we are now: Kittens tugging on strings. But what is actually going on isn't as important mathematically as what it is resembling.

If you're using ISLG then you should be calculating from center of gravity, in this case, the center of the theoretical 400 mile radius sphere of moon rock. This mass has a certain gravity at the surface, being radius 400 miles from the center. This would give you a rough approximation of the gravity you would experience if you were there, which is much smaller than the gravity on the surface of the moon, which you could observe or calculate.

Now, that said, it's not perfect, because midway through I discarded the anti-gravitational pull of the hollow moon-shell you would be inside of. This is actually non-zero, because you are not in the actual center of the moon-shell, so there would be a slight anti-grav force, making the resulting real gravity at 400 miles from lunar center less than would be calculated by the formula.

This was the basic point I was trying to make. Add to that, the point you brought up: the non-uniformity of the moon. If you were to use the median density of the moon that figure would be too low and the figure for gravity 400 miles form lunar center would be too low, so you would need to recalculate based on lunar core density. This would bring the gravity up again.

But these are minor tweaks, which we would make after we had agreed that we could get to the first part, which was the separate size and gravity of lunar core, and then go about refiguring for local density and adding the anti-grav effect of lunar shell.

The specific application of this that we were on was the universe as a whole. We are currently inside the universe, where the gravity is less than it would be if we were at the edge of the universe, should such a place happen to exist.

I tend to agree with Byte here that the universe is situated on a warped portion of space, or perhaps super-space we should term it, and is not a self contained unit.

Quote:
shell theorem

I'm a pretty ignorant hillbilly so I'm not familiar with this, but I just looked it up. Yes, it appears to be saying the same thing I'm saying.

Quote:
From Wikipedia:

A solid, spherically symmetric body can be modelled as an infinite number of concentric, infinitesimally thin spherical shells.

Yes, that, and the outer one providing an anti-grav effect and the inner one not necessarily being the same density, though in the case of the universe I suspect it is, unless we go to the vortex extreme and say that the center doesn't exist as me and Byte were talking about earlier in the thread.

It's much more fun and I'd like to get back to that.

So,

If I'm making and applying an assumption here it's that the internal construction of a black hole is not a known quantity, and in particular, I'm rejecting the idea that all mass within exists at a non-existent point of singularity, while at the same time saying that because of the nature of the warping of space time, it may very well appear that way to an outside observer, or some approximation thereof, in the same way that from outside the circular pattern of any maelstrom phenomenon that the energy is derived from a small vortex in the center.

Byte,

Quote:
But I'm not as sure it may work the same way IN a black hole.

Very much so. But we never even got that far. The simplest point is that it would automatically be less even if nothing funky were going on structurally with space time because some of the mass would be behind you. But yes, absolutely, since more space time is inside the hole then the whole is larger than it appears.

Back to Jupiter, the "stuff in the way" is actually the motion of atoms bouncing around like billiard balls, and the atmosphere does not collapse in because there is this constant ping pong madness bumping into it. It's not that there isn't space between molecules, it's that you can't sail through that space without being hit by someone else, so as a molecule, you get bounced back up.

Ergo, inside, there is something in the way, but it is in the way with respect to the pressure it is putting on the non-collapse. The first of these is orbit, that things would fall into orbit, but that assumes a large black hole with space time and objects, before we get there, there has to be a transitional stage.

Quote:

Black hole --> thing collapsing under it's mass so much that it distorts space time as it continues collapse past a point of no return. Most stars just collapse to neutron stars, very dense but not black holes.

After the star collapses, energy increases, and the whole thing enters into a soup, protomatter plasm. We don't know what happens in the middle, but I suspect it could be extrapolated by what happens as the hole collapses and what we see in the dawn of the universe.

Quote:

Gravity drove the creation of the black hole, but once all the matter forming the black hole falls past it's own event horizon, all that mass is in VERY close proximity to each other, but ultimately the charges involved in the electromagnetic force and the strong force are MUCH stronger than gravity. You'd think that since both involve both attraction and repulsion between the gluons and quarks making up the matter and light energy carries it's own charges that eventually all that mass would stabilize before succumbing completely to gravity and having all matter occupy the same place. That's why I bring up Quantum Indeterminancy and Hawkings Radiation against the idea.

Yes, and also, the quantity of space time being sucked in, and possibly created inside. Of course, the later stages of the black hole there would be space inside, but the force of being sucked in might be too much for anything to survive, depending on all the various forces in place. It's possible all at enters the hole is liquified into a new protomatter or some sort of proto-space-time plasma.

Quote:

And that's only if those forces still work inside a black hole. Rather like how we know that the initial universe did not have the forces functioning as we know them, the conditions inside a black hole are speculated to be similar.

Just to speculate here, I think we might be able to guess based on what goes in to the black hole collapse, and what comes out of the big bang. A unified equation of transition could make a major physics project.

Also, entering and existing a mature black hole, being one with a universe inside, is something that might be possible in a craft that had its own space warping technology, which is perhaps more attractive to sci-fi than my transmission as information through the fabric of space time idea, though I think that has possibilities.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 7:15 AM

Quote:
Mal

DT: I have clearly pointed out several ways in which you are incorrect. There are not questions for you, because it's become quite clear to me that you do not have the correct answers, nor are you interested in finding them.

Whatever. It is clear to me that if anyone disagrees with you it must be because they are stupid, and that once they have disagreed with you one one thing, like politics, then you must always assume that they are a moron, and this must be true of all things. I have no interest in communicating with someone with this perspective.

CTS,

Why was I disputing it? I just posted to you basically the same thing as what shell theorem said in wikipedia. No, I think I was saying the exact same thing, not disputing it at all.

Byte,

Good points. The nuclear forces are already taking over, but when it compresses to some plasmic goo, we're not sure what the dominant rules of force are.

One thing we can at least suspect, if not be sure of, is that the co-location of strings does not result in the end of strings, so, while some constructs of space time cannot exist at such pressures, that does not mean space time ceases to exist, and given enough space time, the result ultimately is enough space and time for common structures of the universe to exist.

However, I'm not sure that the pressures of a late stage black hole are the same as those of an early stage black hole, and it may be possible, theoretically, to sail across the boundary with relatively little difficulty. Relative, say, to sailing into it at the point of creation.

Take a black hole of 180 million stars in mass. Inside it might have some very complex structure, even a nascent universe.

That's what a ship is, you know - it's not just a keel and a hull and a deck and sails, that's what a ship needs.

NOTIFY: Y | REPLY | REPLY WITH QUOTE | TOP | HOME

Friday, December 23, 2011 7:19 AM