Universe 'likely to grow forever'

[scooterscot]

I'm really not sure what you mean by "the substance of the universe can be anything".

My poor choice of words. Referencing how the appropriate control of energy could be used to recreate matter.

If we are to require that our theories about the universe tally with experience, and hence we reject those theories which are flat out contradicted by things we can observe, then clearly that places some constraints on the substance & nature of the universe.

Now the problem with your opinion is that there is something "timelike" involved in the structure of the universe i.e. there is something that has the particular relationship with space that time has. We can be sure of this, because we can create mathematical descriptions of universes that don't have it, and work out how they might behave, and that disagrees with what we observe.

Some "timeline" yes. Time suggests that it is inherent like a particle or pattern, yes time is natures way of preventing everything happening at once, however my point that I want to make is that for me time is a consequence of events and is not absolute and is unlikely to be uniform throughout the universe.

Light is electromagnetic radiation. It *is* different than other particles, actually, because it doesn't have mass and travels at the speed of light.

Agree. My poor choice of words once more. The effect which I refer is the energy that propagates through space is subject to change. I'm not talking about doppler shift, but rather how the colour of some deep sky objects throughout the visible spectrum takes a longer path to reach the telescope.

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I think you are confusing your numbers here. The universe is thought to be about 13.7 billion years old, but the observable universe is more than 27.4 billion light years across because of the expansion. It's reckoned to be around the 90 billion light years you state, but that space isn't "beyond the CMB", that's what we can see. There is quite possibly space beyond that that we will never be able to see because it's moving away so fast that the light will never reach us.

I'm not suggesting that we have the "laws of physics" exactly right, what I am pointing out is that we can make up alternative laws that don't have something "timelike" and work out roughly how such a universe would look, and it wouldn't look like this one. It really is a fundamental fact about the structure of the universe.

Indeed I did get my number mixed up.

Something "timeline" needs clarification, how can we define time better than the reactions between atomic structures?

[TimberWolf]

I'd like to believe that, and I've tried, but it doesn't cut the mustard. Many years ago someone else came up with a theory that space is curved, so as you keep going out deeper into it you end up coming back from the other direction. That doesn't cut it either.

There's an infinite amount of nothing (non-existence if you like) beyond whatever spacial limits we put on the universe. Wellington in the Daily Mirror regularly boggled his mind over things like that.

You're right, it [a balloon inflating analogy] doesn't cut the mustard, because it is wrong, not least because space is 3+1 dimensional. It helps illustrate the expanding nature of things and how there is no centre, in human terms though, while not addressing other areas, such as what the balloon is expanding into.

I think once you're outside our universe (whatever its bounds are defined to be), familiar things no longer exist. Time for instance. A place where everything could happen at once, not least the birth and death of an infinite number of other universes (not that I'm a 'many worlds' believer), including our own. It's hard to make sense out of a place like that though, and indeed there probably is no sense to make out of most of it. What's behind it all is the question, at the most fundamental level. What's to stop our universe from suddenly ceasing to exist? And where will it end.

[TimberWolf]

My poor choice of words. Referencing how the appropriate control of energy could be used to recreate matter.



Some "timeline" yes. Time suggests that it is inherent like a particle or pattern, yes time is natures way of preventing everything happening at once, however my point that I want to make is that for me time is a consequence of events and is not absolute and is unlikely to be uniform throughout the universe.



Agree. My poor choice of words once more. The effect which I refer is the energy that propagates through space is subject to change. I'm not talking about doppler shift, but rather how the colour of some deep sky objects throughout the visible spectrum takes a longer path to reach the telescope.



Indeed I did get my number mixed up.

Something "timeline" needs clarification, how can we define time better than the reactions between atomic structures?

Time isn't absolute, it runs at a different rate for everyone (always in the forward direction though). Which is why one could travel 1 light year distance in less than 1 year of [your wrist watch] time - and no observer will see you exceed the speed of light. All watches will tell a different time though.

You appear to be referring to "tired light" theories, none of which stand up to observation IIRC.

[scooterscot]

You appear to be referring to "tired light" theories, none of which stand up to observation IIRC.

I'm referring to the distant observation of gamma bursts and how they could reveal the fabric of space/time

Late Light Reveals What Space Is Made Of

What makes it exciting for me is the independent verifications, tickles my brain.

[TimberWolf]

I'm referring to the distant observation of gamma bursts and how they could reveal the fabric of space/time

Late Light Reveals What Space Is Made Of

What makes it exciting for me is the independent verifications, tickles my brain.

I wouldn't be surprised if General Relativity is going to buckle and probably break under the strain eventually, but questioning the postulates of Special Relativity is getting exciting.

The alternative approach favoured by Amelino-Camelia, loop quantum gravity, posits that space-time comes in indivisible chunks of about 10-33 metres, a size known as the Planck length.

Check out :Doubly-special relativity (DSR)— also called deformed special relativity or, by some, extra-special relativity — is a modified theory of special relativity in which there is not only an observer-independent maximum velocity (the speed of light), but an observer-independent maximum energy scale (the Planck energy).

Hmm, another postulate. Groovy.