Ashbo
All talk about the singularity at the start of the big-bang tends to be on the basis that all matter was at that time condensed into a tiny space. Some people say that all this matter was located within something as small as the volume of an atom. I understand that the vast majority of an atom is made up of empty space between the nucleus and the first electron shell. However, given the sheer size of the universe (billions of stars, galaxies etc.) it seems to me that no matter (no pun intended) how tightly you pack all the protons and neutrons in the universe together the actual physical size of the singularity would still be significantly bigger than that which can be fitted into the volume of a single atom.

Surely there are some reasonable estimates of the number of atoms in the universe? If so surely it would then be a simple matter to calculate the smallest volume into which all these could fit assuming that all 4 forces did not exist - I guess 'packing theory' might have something to say about this. Anyway - if we merely summed the volumes of all the protons and neutrons in the universe we would get a measure of the diameter of the singularity - has this been done and what is the answer?

Before you all tell me that at a singularity matter is of zero size and infinitly dense which we all struggle with conceptually, I know that.

Put another way....

What I am trying to get at I guess, is if you started packing together into a 'bag' every neutron, proton and electron tightly together as it is possible to do - what would be the diameter of that 'bag'? My supplementary question is how can that volume get any smaller - again if you tell me that at that point (or earlier!) the laws of physics have broken down then ok - but it is not a very satisfactory answer.
prometheus
Any physicist worth their salt will tell you that there is only a singularity at the beginning of the universe or in a black hole if only general relativity is right. What the singularity is really telling you is that GR is not sufficient to explain the start of the universe or the center of a black hole.

Theres not really that much mystery about dense materials. In a neutron star the neutrons are basically close packed, but there is still a fair bit of empty space inside a nucleon, which contains 3 quarks and a bunch of gluons.

Remember, the fundamental particles (the important ones are the quarks, gluons, electrons and photons) are modeled as being points - they have no volume, so if you lined a million of them up next to each other they would still take up no space.

Also remember that very soon after the big bang there were no atoms, but a mess of quarks and gluons, which are elementary as far as we know. We can create a quark gluon plasma reasonable easily, RHIC can do it, and the LHC will too when it's turned on and is smashing heavy nuclei.
mudderrunner
QUOTE (prometheus+Mar 13 2008, 05:52 PM)
Remember, the fundamental particles (the important ones are the quarks, gluons, electrons and photons) are modeled as being points - they have no volume, so if you lined a million of them up next to each other they would still take up no space.

this reminds me of a seinfeld episode

George: Hey Jerry I got a theory for what fundamental particles could be.
Jerry: Oh really, lets hear it...
Geoge: Nothing!
Jerry: Nothing?
George: Yes! Nothing!
Jerry: Well there's got to be something. A particle's got to be something.
George: These particles are nothing.
Jerry: They have no volume?
George: Nope.
Jerry: I still don't know what your particle theory is.
George: It's nothing.
Jerry: Right.
George: Everybody's theorizing something, we'll say nothing.
Jerry: So, we go to the editors of a prominent quantum physics journal, we tell them we've got a theory about fundamental particles.
George: Exactly.
Jerry: They say, "What's your fundamental particle theory?" I say, "Nothing."
George: There you go.
(A moment passes)
Jerry: (Nodding) I think you may have something there.
Ashbo
Firstly mudderrunner's response is excellent - I love Seinfeld (and Curb) and I remember this episode very well - so thanks for the dialogue.

From theoretical dialogue to theoretical physics...

Prometheus - you say that gluons etc are 'modeled' as having zero volume - i.e. a point mass, but that surely is a convenience for physicists and for us mortals to conceptualise what is going on?

I still need help in understanding what happens as matter condenses lets say from a neutron star shrinking towards a black hole - once all the space between the particles has gone that entity will be massive and dense but surely will still occupy a measurable volume ? All I am saying is that at the start of time when all the matter in the universe was condensed into a single entity I am struggling to understand how all that matter - whether gluons,quarks neutinos, bosons etc - can be condensed beyond a certain minimum volume when all the empty space that can be squeezed out has been - what would that minimum volume have been? I cannot see it being zero - it is either matter or energy and must therefore have a mass and therefore a measurable or estimatable volume.
dwaynefries
Ashbo,
to more accurately answer your question, which seems to be what kind of space exists when everything appears to be smashed down to a very small space, this gets a little complicated. Space is relative. Einstein made one very important assumption that the speed of light is the same from every point of view.
Einstein had problems with the idea of a black hole even though he did much work on the physics behind it. He did the math to show that it could not exist.
Several years after his death, they were discovered.
Also consider that space is relative. If we use the same assumption that Einstein did, that the speed of light is the same everywhere, from every perspective, we find that when something is condensed down to the size of a black hole singularity, or really really small, many things change. For example, if we take a space ship to the center of a black hole, the ship length shrinks. From the perspective of the astronought, it would seem like space is pretty normal aboard the ship. Time also slows down on the ship. Space is streched out elsewhere, outside the ship.
I have been working with the Lorentz equation a bit. I believe a far better answer lies just in this equation that tells a very accurate picture of what the big bang was all about. So far, the preliminary results show that as the acceleration of the universe was initially accelerating at 1m/sec^2, the universe had a size about 10 X that of what we currently guess it at.
I am doing some more work with the equations, but I have a gut feeling that as I modify the variables to fit the big bang theory, it will likely show that the size is quite small in size. This is if we were assuming the Earth was setting next to the big bang mass and we were messuring it in terms of our space.
It seems a bit complicated, but valid.
Hey, if someone would like to help me cruch some of these numbers with the theory I am working on, let me know and I would be happy to include you as a key component in the published work.
The math gets complicated in the model I am working on.
prometheus
QUOTE (Ashbo+Mar 14 2008, 09:23 AM)
Prometheus - you say that gluons etc are 'modeled' as having zero volume - i.e. a point mass, but that surely is a convenience for physicists and for us mortals to conceptualise what is going on?

I still need help in understanding what happens as matter condenses lets say from a neutron star shrinking towards a black hole - once all the space between the particles has gone that entity will be massive and dense but surely will still occupy a measurable volume ? All I am saying is that at the start of time when all the matter in the universe was condensed into a single entity I am struggling to understand how all that matter - whether gluons,quarks neutinos, bosons etc - can be condensed beyond a certain minimum volume when all the empty space that can be squeezed out has been - what would that minimum volume have been? I cannot see it being zero - it is either matter or energy and must therefore have a mass and therefore a measurable or estimatable volume.

Firstly, the important thing to remember is that black holes and in particular, their singularities, are slippery creatures because they are both very small and very massive.

Just consider GR for a second. Imagine you are the proverbial astronaut on the surface of a collapsing star. Suppose you are looking at your feet all the way down. Think about this: inside the black hole light cannot move away from the center because if that was possible then light could escape, so looking at your feet inside the black hole you would see nothing (!).

The point is that GR has nothing at all to say about the interior of a black hole that we can measure. Even if you were inside a black hole you would know nothing about the singularity until you hit it, and presumably became messily part of it! In terms of GR, the question you're asking about the nature of the matter in a black hole is not a good question.

It's the same for the big bang. The singularity always exists in the absolute past or the absolute future so theres no way to really describe what it looks like or even what it's made of.

prometheus
PS. Maybe I've been in theoretical physics too long, but to me when people say "modeled as a point particle" they actually mean the particle is a point and has no volume.

If a particle has mass and it's a point then you could think of an effective physical size of the particle by working out the Schwarzschild radius for such a mass. The size of the event horizon for all fundamental particles is a lot less than the Planck length though, so it's unclear how physical such a description really is.
Ron
Hi All,
I'm not going to try to explain a singularity, because as far as I know, no one has been able to do this yet. I would like to point out , though, Prometheus, that the event horizon is where the BH's gravity reduces to below the threshold of light not being able to escape. The singularity does not extend to the event horizon, if that is what you were trying to imply. If not, nevermind!
Peace,
Ron
prometheus
QUOTE (Ron+Mar 18 2008, 02:08 PM)
Hi All,
I'm not going to try to explain a singularity, because as far as I know, no one has been able to do this yet. I would like to point out , though, Prometheus, that the event horizon is where the BH's gravity reduces to below the threshold of light not being able to escape. The singularity does not extend to the event horizon, if that is what you were trying to imply. If not, nevermind!
Peace,
Ron

Hi Ron,

I was trying to say that you can never see a singularity because they're always shielded from view by a horizon (in reasonable circumstances) You wouldn't be able to see your feet inside a black hole because no light would be going from your feet to your eyes. Nuts eh?!
Shard
The OP is assuming that the size of subatomic particles is constant.

We don't know how big the universe is, so we can't calculate the number of subatomic particles that exist.
yor_on
First of all.
If you accept the idea of the Big Bang you accept the singularity.
Singularity meaning 'here there might be thygers' meaning 'nuthing, I know nuthing' :)
Whatever that singularity consisted of it was enough to fill up our universe.
As it seems that 'space' itself could produce 'matter' that leaves the field wide open for how much, of what, that singularity owned:)
So in another way, as long as we can't explain what the f* is going on with 'empty space' producing matter, we do seem to have an extremly lot of singularities in 'every point', which as someone pointed out has no physical meaning whatsoever in space time, ahh, that is, more than existing that is. And if you to that add Feynman's 'many paths'?