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Author Topic: What happens to time  (Read 3912 times)

Offline MikeS

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What happens to time
« on: 29/04/2011 07:00:51 »
What happens to time in a hypothetical universe that contains only matter, no energy.


 

Offline Geezer

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What happens to time
« Reply #1 on: 29/04/2011 07:21:52 »
Just about anything you like  ;D

Science is only meaningful as it relates to this Universe.
 

Offline imatfaal

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What happens to time
« Reply #2 on: 29/04/2011 10:53:48 »
I think we can consider universes with different compositions.  It is fairly standard cosmology to calculate the scale factors under FLRW-metric - ie matter dominated, radiation dominated, dark energy dominated etc.  The universe will never be entirely matter - although it will eventually be all radiation (and prob started as such).

Time is time in these cosmologies to the very low level that I understand them

ps - I realised that I had typed the LVMC-metric.  Luckily I  noticed before I posted - LVMC is Louis-Vuiton-Moet-Chandon, not a collection of great physicists but two wine-sellers and a glorified bag-maker
 

Offline JP

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What happens to time
« Reply #3 on: 29/04/2011 15:27:14 »
Time would be meaningless in such a universe.  But that's not the biggest problem.  All the laws of physics would be meaningless, since there could be no forces so that nothing would ever interact, nor could anything be measured.
 

Offline amogh

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What happens to time
« Reply #4 on: 29/04/2011 18:01:13 »
there will be no time, i mean like the quantum of time will be eternity
 

Offline Soul Surfer

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What happens to time
« Reply #5 on: 29/04/2011 23:42:31 »
it is not possible for a universe to contain only matter and no energy because matter is purely a form of localised energy.
also if it consisted of neutral atoms the electrons bound to the atoms have energy and the quarks that are bound in the nucleus have so much energy that their mass is more than doubled by their energy  furthermore all matter exhibits gravitation and even if the energy in the atoms was discounted any arrangement other than the single lowest possible energy one will have gravitational energy.
 

Offline yor_on

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What happens to time
« Reply #6 on: 30/04/2011 17:37:30 »
SoulSurfers point is mine too. Matter is a form of 'energy'. Energy is interactions, and all 'particles' interact as long as there is an 'arrow of time', at least as far as we can observe, meaning that it you define a electrons location in a 'orbital' at two, after each other following, instants it will be found to have 'moved'.

If the question is if anything can exist outside that arrow of time? Not to us it can, as far as I know?
 

Offline MikeS

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What happens to time
« Reply #7 on: 03/05/2011 06:49:52 »
From the above posts we seem to be generally agreeing that energy has something to do with the passage of time.

Question
What happens to time in a hypothetical universe that contains only energy and no matter.


Yes, I know it could not actually exist but the question is about time, not whether the hypothetical universe could exist.
 

Offline Soul Surfer

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What happens to time
« Reply #8 on: 03/05/2011 09:13:07 »
You have reversed the concept, a universe with matter and no energy is not possible, but a universe with no matter and only energy is possible.  Also, time would not exist in this universe

This is the argument used by Roger Penrose in his recent book "Cycles of Time" to define that our universe must have a cyclic element. 

His argument is that in a universe containing only energy, that is particles travelling at the velocity of light, the universe would have no "knowledge" of time, in that all the particles would experience was all the interactions that they did.  This is agreed by most theorists as the most likely ultimate fate of our universe after all the black holes have absorbed all the matter and evaporated into very long wavelength electromagnetic radiation.  This could allow a  "big bang" to happen when something created massive particles and expansion in a great cascade.

I tend to agree with this but would be prepared to take it further and argue that the same thing is likely to happen when the contents of a black hole collapse towards the hypothetical "singularity". This gives a much more probable big bang scenario.  However to go any further than this would take this into the New theories area and I am most definitely not proposing this.
 

Offline MikeS

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What happens to time
« Reply #9 on: 03/05/2011 11:54:48 »
I haven't read cycles of time but do know from what I have heard that Roger Penrose in the cycles of time is advocating some of the ideas I proposed to him 18 years ago.  At the time he was a big advocate of the big bang.  It's interesting to see that ideas from Sir Roger a top leading theoretical mathematician are being taken seriously, because, I assume he has done the maths to back them up.  As I have been told on these forums previously, if you want to be taken seriously in science you have to do the math.  Nevertheless you have to have good, provable and original ideas before you can make a new mathematical model.

His argument is that in a universe containing only energy, that is particles travelling at the velocity of light, the universe would have no "knowledge" of time, in that all the particles would experience was all the interactions that they did.  This is agreed by most theorists as the most likely ultimate fate of our universe after all the black holes have absorbed all the matter and evaporated into very long wavelength electromagnetic radiation.  This could allow a  "big bang" to happen when something created massive particles and expansion in a great cascade.
This could allow a  "big bang" to happen when something created massive particles and expansion in a great cascade.

Sir Roger does sometimes say things without, to the best of my knowledge, backing them up.  He takes part of an idea and changes the reasoning behind it so that he stays within mainline peer reviewed science.  It' rather like throwing the baby out with the bathwater and hoping no one will notice.  The proposal and mechanism for that proposal have to actually be feasable and sometimes that takes you outside mainline science.  Taking an idea outside of mainline science does not in itself make it wrong. 
Let's face it, in physics the 'truth' often boils down to what is accepted by your peers.  This is not necessary the same thing as being true.

Theoretical physicists by definition think up theoretical physics.  String theory, brain theory, multiple dimensions, non baryonic dark matter (to explain invisible mass, dark energy, massive particle as mentioned above are all sophisticated examples of gobbledygook until proved correct.  I believe that, on the macroscopic scale the universe is very simple and non of the above unproven ideas are necessary.  So why have them.  Not meaning to knock science, that is not my intention but if, as I maintain, the universe on a large scale is very simple then theoretical scientists and mathematicians are not the most qualified people to investigate the universe.  Einstein had his first brilliant ideas when he was sixteen.  It took him another 10 years and having to learn the mathematics required to refine and model it

If matter and antimatter are exactly the same but with the arrow of time reversed (as I believe) then the universe (on the large scale) becomes very simple to explain using existing physics. Non of the exotic and highly theoretical physics mentioned above are required, they can be modelled mathematically but that does not make them real.  Antimatter and matter, either do or do not have the same arrow of time.  That gives this idea a 50% chance of being right and before the start of any debate, not bad odds.  It could be argued that this is getting into new physics or simply a better understanding of existing physics which I believe is a more likely explanation.

I know I digress in this post from the subject of my original post.  You could argue this is just 'sour grapes' and you would be right.
 

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What happens to time
« Reply #9 on: 03/05/2011 11:54:48 »

 

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