Always allow for inflation

[mistermack]

The science world is buzzing about the recent announcement about the inflation stage of the big bang.

The physics of the big bang never worked, unless a theoretical stage was inserted, when the universe grew at an incredible pace. It was named inflation, and has remained hypothetical till now.

Now these people have detected the effect of the predicted gravitational waves, that would be caused during inflation. This means that inflation should jump from the hypothetical to the accepted physics.

http://www.smithsonianmag.com/science-n ... 09/?no-ist

[Tyrannical]

Yeah, but i still think the idea of space expanding faster than the light speed bound gravity seems a bit fishy.
But since it allows the chance for warp drive and Zero point energy I suppose I like it.

[Calilasseia]

The restriction on velocities, as far as I'm aware, only applies to particles moving within a spacetime metric. It doesn't apply to the spacetime metric itself. Hence the Alcubierre paper in 1994.

[Mysturji]

I like to think of inflation as the observable 3-D effect of a 4-D (or more-D) event.
But it's easier to visualise if you scale things down a bit:

e.g. Suppose the speed of light is 1 metre/second, and you're standing on the surface of a huge 3-D sphere (say, something approximately Earth-sized).
You look up and see a 2-dimensional plane moving down towards you at almost 1 m/s, but it's not solid - it passes through normal matter with no effect, although you can see it.
You're nearly 2 metres tall, so the plane takes about 2 seconds to pass through your body from head to toes, but then something seemingly impossible happens: 1 second later, the plane is 1 metre below ground level, but the size of the Earth's surface area it has covered (passed through) is a fuck of a lot more than 1 metre across: More like hundreds of kilometres.
Think of colliding branes (one possible explanation for the big Bang)
Just an idea.

[mistermack]

The question that pop into my head, is what does c actually mean, when all of space and time is contained in a volume smaller than an orange.
c is about 300,000 metres per second, but what actually is a metre, in those circumstances?
If what defines a metre is expanding at a phenomenal rate, what does that mean?
Are we imposing our modern concept of c on a time when it didn't mean anything?

Fucked if I know.

[Tyrannical]

The question that pop into my head, is what does c actually mean, when all of space and time is contained in a volume smaller than an orange.
c is about 300,000 metres per second, but what actually is a metre, in those circumstances?
If what defines a metre is expanding at a phenomenal rate, what does that mean?
Are we imposing our modern concept of c on a time when it didn't mean anything?

Fucked if I know.

e = m c^2

Given energy and mass, c could also be computed without the need for time or distance. I think

[mistermack]

Oh yeh, of course you can always produce a figure for c.

But was the speed of light through empty space relevant, before there was light, and before there was any empty space?

[JimC]

Fiat lux!

[Blind groper]

The speed of light is absolute, meaning nothing can move through space/time at a greater velocity. However, there is nothing within the laws of physics which prevent space/time itself expanding at a greater velocity, and that is what happened.

The universe is 13.8 billion years old, but is estimated to have an effective diameter of 84 billion light years. Obviously light cannot cross that distance in the lifetime of the universe so far. But space/time itself can expand at a great velocity, which is what happened.

During inflation, space/time expanded at a speed multiple times that of light. Even when the universe was no bigger than a proton, a photon could not have crossed it from one side to the other, because the expansion of that tiny universe was too fast for the photon to catch up.

This brings me to the question of whether the universe is finite or infinite. It is, in fact, both, depending on which definition you use.

It is infinite because nothing can cross it, not even a beam of light. That is because it is expanding faster than light speed. However, it is finite, because it is possible to calculate how big it is. (A bit less than 500 trillion cubic light years). If it has a definable size, then it is finite. But you cannot cross it, so it is infinite.

[mistermack]

One thing always puzzled me.

If space is expanding, is the metre expanding with it? Are the atoms in my body expanding.
There's only one part of my body that expands noticeably, and that never lasts long.

And if EVERYTHING is expanding, how could you know, and is there a difference? In that case, nothing would be expanding relative to anything else so how could you tell?

[cronus]

The space between galaxies is expanding not so much the space within galaxies. The force pushing the expansion is very weak yet near constant since the big bang, it is a hugely accelerative thing on account of the duration it has been switched on - with no causal mechanism I suggest magic in play. Cannot overcome gravity except where gravity is weakest, which is between galaxies.

[mistermack]

Does that mean that you would expand, if you could leave the Galaxy?
And shrink, when you came back?

And do the Astronauts expand when they are halfway to the moon?

[cronus]

Does that mean that you would expand, if you could leave the Galaxy?
And shrink, when you came back?

And do the Astronauts expand when they are halfway to the moon?

I figure dark matter might be places where the acceleration force equates the graviton force and weird fuck happens like all hell of creative randomness breaking loose on a small scale. Stuff appearing out of nowhere merely by thinking it and stuff appearing out nowhere cos it wants to and disappearing to elsewhere. I call this the 'absolutely anything can happen some places' theorem of the universe.

[mistermack]

Does that mean that you would expand, if you could leave the Galaxy?
And shrink, when you came back?

And do the Astronauts expand when they are halfway to the moon?

I figure dark matter might be places where the acceleration force equates the graviton force and weird fuck happens like all hell of creative randomness breaking loose on a small scale. Stuff appearing out of nowhere merely by thinking it and stuff appearing out nowhere cos it wants to and disappearing to elsewhere. I call this the 'absolutely anything can happen some places' theorem of the universe.

It's never been disproved.