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JEROME - Black holes do not exist

bonavada said:
Again my question (or rather the pre-amble to it) is obviously worded wrong, sorry.
Of course, the void must exactly be just that,I mean it is a concept of no-thing (nothing) existing.
Anyway space, as something, expanded. My question still stands, what is it about space that is expanding? It seems to me that space, as an entity in itself, to expand thus, must have some sort of structure or fabric. What is the fabric and the mechanism that allows or enables space to expand? Please could anyone point out a good source that I might learn more about this. I haven't had much luck googling or my local library. Thanks
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I'm not sure if, with this post, you really came to understand the "void" portion of your original question or not. If you do, then never mind.

The concept of spacetime is often compared to an analogy of blowing up a balloon, but there are two generally misunderstood elements to this analogy. The first is that spacetime/the universe is represented by the 3D space inside the balloon rather than 2D surface of the balloon itself. The second is that there is a pre-existing 4D spacetime into which the balloon (i.e. spacetime) is expanding into. It's this second one that your original question reflects.

As far as we know, there is no meta-space in which our spacetime sits, expands, or perhaps floats around in. Further, we have no reason to think that such a meta-space exists. What's worse is if we were to posit such a meta-space, we'd have to at least consider the possibility that the meta-space exists in a meta-meta-space and soon we have the world sitting on the backs of a string of turtles that goes all the way down. Now, if there were a reason for us to consider a meta-space, aside from pure speculation, that is definitely a possibility we would have to content with.

The short answer is that spacetime appears, in every respect, to be self-contained and growing.
 
bonavada said:
Anyway space, as something, expanded. My question still stands, what is it about space that is expanding? It seems to me that space, as an entity in itself, to expand thus, must have some sort of structure or fabric. What is the fabric and the mechanism that allows or enables space to expand?
Click to expand...

In our best theories of physics, spacetime itself is dynamical - it vibrates when you perturb it, for example. Those vibrations are called gravitational waves, and we have very strong indirect evidence that they exist (and they will probably be detected directly within a few years by an experiment called LIGO).

More speculatively we believe that those waves are composed of particles called gravitons (in much the same way that light is composed of photons). Going further, spacetime itself is composed of an enormous collection of gravitons. An analogy is the ocean - it's made of water molecules, but for most purposes we can ignore that and treat it as a continuous fluid on which waves can propagate. A slightly more exact analogy is an electric or magnetic field - it is a coherent state of photons, a special superposition of many electromagnetic waves, each of which is composed of photons.

So to answer your question - our best guess is that spacetime is composed of gravitons (which interact with each other, giving it a tension and allowing for ripples). The expansion is a collective motion of those gravitons.
 
Thanks for the pointers everybody. Seems I've got a lot to learn about a lot.
I find this subject fascinating and will be delving into it with gusto in the next few months.
Cheers

BV
 
Upchurch said:
As far as we know, there is no meta-space in which our spacetime sits, expands, or perhaps floats around in. Further, we have no reason to think that such a meta-space exists. What's worse is if we were to posit such a meta-space, we'd have to at least consider the possibility that the meta-space exists in a meta-meta-space and soon...
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Exactly; and soon we'd have someone with a voice remarkably similar to Morpheus' in The Matrix telling us: "Welcome... to the Real world." :p:D
 
bonavada said:
Please forgive my relative noobiness to the physics here. I have a question about the structure of the Universe. To put it simply, addressing the Big Bang theory, once, the singularity existed along with nothing else. The singularity, by whatever mechanism, "exploded". Along with the "explosion", matter, energy, space, time, everything we know to exist in the Universe was created. So then the everything expanded into the void (the nothing). My question is about space, what is it about space that is it expanding? Is there a "fabric" to space? If anyone could point me to a source ie a book that might explain this element of theory to me, thanks.

BV
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I recommend John Gribbin: In Search Of The Big Bang.
 
bonavada said:
Thanks. Hopefully my local libray will have a copy or order one. If not I'll even buy a copy looks like just the ticket....

BV
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You're welcome. I haven't actually read it, but I've read several of his others, and they're quite comprehensive while still being accessible. He writes for a lay audience very well.
 
I see jermome the troll is back.
Any answer to my question yet:
What is your evidence for the statement:
Gravity is not strong enough and as such we need make-believe things to account for certain observations.
Click to expand...
 
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