[reply to post by Illustronic
I rather suspected an answer like that but in at least my head, that answer is a bit evasive in describing the massive scale of distances
theoretically observed in the time frame also theoretically postulated without, say for instance, light speed being exceeded in expansion (by mass)
from a point in space to the distances observed today. That's where I have a problem with a point in location, and not just brushing away the idea of
everything in one location by advancing the idea of space and time creation, and everything before is inconsequential.
Alrighty...let's get down to some real physics.
Special Relativity, as you know, concludes that nothing with real mass at rest can have a velocity greater than the speed of light. However, this
conclusion has a limit. Consider why no massive object can travel faster than the speed of light: as velocity increases, so does mass, which, in turn,
increases the amount of force needed to accelerate that mass... and, at the speed of light, mass becomes infinite, requiring an infinite force to
accelerate that mass to the speed of light, which, of course, is impossible. But, now, consider the expansion of the universe. Is the matter in the
universe (galaxies, stars, whatever) really travelling with a true velocity (proper motion
)? Short answer: nope. As far as expansion is
concerned, no force is causing objects in the universe to move. It is space, itself, which is stretching. This stretching, then, can give distant
objects an apparent velocity greater than the speed of light (actually, there's something interesting about this, which I'll get to in a sec), but
the objects, themselves, are not being moved.
A decent (and well-known) illustration of this is two dots on a balloon. When you blow up the balloon, the dots move further away from each other, but
neither dot is actually moving... if they were, their positions on the balloon would change. They do not. There is no proper motion - only apparent
motion. Apparent motion can exceed the speed of light, but proper motion cannot.
Now, what's "interesting about this" is, sometimes, people will say, "The speed at which objects are moving away from us increases with distances,
so that, beyond a certain distance, objects appear to be moving away faster than the speed of light." This is wrong. First of all, like I just said,
the objects aren't really moving away from us - the space between us and the objects is stretching. Second, and the thing I really want to point out,
the edge of the observable universe is the point where the apparent speed of those objects is almost equal to the speed of light. Nothing that we can
see even appears to be moving away from us at faster than the speed of light. This should actually be obvious. If an object appears to be moving away
at a velocity of or greater than the speed of light, then the light it emits will never reach us. At the edge of the observable universe, the apparent
motion of the objects we see approaches, but never reaches, the speed of light.
I find the descriptions you summarized on what space is very interesting as a teaser, and I understand a little about the space between mass in
particle physics but I just cannot wrap my head around everything compressed to a point of location observed today in that amount of finite space
without creation from nothing along the expansion way. So to keep my head from exploding I view singularity as a point in time and not location in
space. I think its rather presumptuous for us to say 13.8 (or whatever it is) light years away is the furthest we can see (in any direction) would by
logic place our observation point in the Universe at the center. That's a rather Godly idea to propose, don't you think?
As I explained above, there is a reason that what we see is called the "observable universe." Objects beyond the edge of what we see have an
apparent motion greater than the speed of light, so the light from them never reaches us and we never see them. What we see is not the whole
universe... we only see our little sphere of it. You could be on one of those supernovae 10 billion light-years away and, if you were to look out in
all direction, you would see the exact same expansion we see from Earth. This is another point that the balloon analogy helps to illustrate...
Let's say you had a balloon covered with equally-spaced dots, and you pick one of those dots to represent Earth. As you inflate the balloon, the dots
closest to "Earth" are going to move away from Earth slowly, while dots further from Earth are going to move away faster. This is exactly what we
see - objects close to us barely seem to move at all, while, at the edge of the observable universe, objects seem to be flying away from us at near
the speed of light.
Now, what would happen if you picked another dot to represent Earth? The observation would be the same, wouldn't it? In the same way, no matter where
you are in the universe, the expansion looks the same - it appears to increase with distance. And this is what the Hubble "constant" measures, the
rate at which the expansion of the universe appears to increase with distance (currently measured at around 72 km/s for every million parsecs).
Also, no matter where you are in the universe, the furthest out you can (currently) see is about 13.75 billion light-years (the distance light can
cover in the time since the universe formed - about 13.75 billion years). So, for an object 20 billion light-years away, the Earth is outside of its
"observable universe" - they can't see us, and we can't see them.
Now, I want to cover the inflation (the early rapid expansion) of the universe a little more. You also mentioned the creation of matter out of
nothing. This should answer that, as well.
I've already said that, according to the current theory, LCDM Cosmology, that sudden inflation was a result of the energy released by the collapse of
the original zero-point vacuum. But, I never went into any detail. This is me going into detail...
Within the tiniest fraction of a second after the "singularity" formed, the simplest way to picture it might very well be as an empty ball - no
matter, no energy. It was pure space-time with nothing occupying it. However, there's a funny thing about a quantum vacuum. Classically, a vacuum is
void of all matter and energy. And, this is basically true in Quantum Mechanics, as well. But, in QM, a vacuum also hides a form of energy called
(or, colloquially, "free energy"). To illustrate this, imagine standing on the ground. It's solid, and is effectively the
lowest you can go. This is the quantum definition of a vacuum - it is the lowest energy level a region of space can obtain. But, now, back to you on
the ground... suppose you're walking along, and, suddenly, you fall through into an old mineshaft. The ground had been the lowest you could go, but,
now, you find yourself even lower. This can also happen with a vacuum. The zero-point energy can spontaneously collapse, falling to an even lower
energy level and releasing energy (zero-point energy) in the process.
This is what cosmologists believe happened to trigger the early rapid inflation of the universe. The "singularity" was a vacuum having a high
zero-point energy which spontaneously collapsed to a much lower level, releasing an immense amount of energy. This energy was what powered that period
This also explain where matter came from. That energy "condensed" to form real particles, which, as the universe matured, became the matter we see
today. And, over the past 13.75 billion years, that matter has gravitationally collected to form galaxies, stars, planets, and so on.
Now, the only question left to answer is where the "singularity" came from. What created it