Thermodynamics & the Big Bang?

[raid517]

Hi, hopefully this isn't too dumb a question. However if the first law of thermodynamics states that energy cannot be created or destroyed, would this not imply that whatever existed immediately prior (given that there is no time period we can refer to as 'prior') to the big bang (and therefore before the planck epoch) must also have been another form, or state of energy?

 

If this is the case, then couldn't it be used to imply that something did indeed exist during this period and that consequently the universe can't be said to have emerged from nothing?

 

Or alternatively, is it believed that the laws of physics only came into being after the big bang? Is there no case in which the laws of physics (and specifically in this case the laws of thermodynamics) could be said to have been continuously present, even from the very earliest beginnings (and prior to this) of the Universe itself?

[timo]

Hi, hopefully this isn't too dumb a question. However if the first law of thermodynamics states that energy cannot be created or destroyed, would this not imply that whatever existed immediately prior (given that there is no time period we can refer to as 'prior') to the big bang (and therefore before the planck epoch) must also have been another form, or state of energy?

1) Not exactly a dumb question.

2) I'd not call it "another form of energy" but "some state with the same energy". Might sound like the same but the difference is that the former statement sounds like energy was something like a substance while the latter statement considers energy to be the property of something which in my opinion is a more defensive and more reliable statement.

3) General Relativity has the nasty habit that total energy must not be conserved, as far as I know. But the mechanism by which this violation of conservation of energy occurs is not accounted to causing something to pop out of nothing, though (still: as far as I think or remember from my relativity classes).

4) Conservation of energy is not unique to thermodynamics and should not be thought of as a consequence of thermodynamic laws. Instead, consider it as a very basic property of nature which is so important that it explicitly gets re-mentioned in thermo.

 

 

If this is the case, then couldn't it be used to imply that something did indeed exist during this period and that consequently the universe can't be said to have emerged from nothing?

I think it is fair to say so. But note that to my knowledge no one (in the scientific community outside the scope of having to attract public interest or funding) really claims the big bang to be the universe being emerged out of nothing. Technically, you trace the current state of the universe back in time. Then, according to current knowledge, all points in space must have had a distance of zero at some time in the past -> this is called the big bang. However, when going arbitrarily close to that point in the past you encounter physical environments in which the current mathematical framework do describe nature is not expected to work. So it is not really clear what happened close to the big bang and, in effect, what the big bang really is.

 

Or alternatively, is it believed that the laws of physics only came into being after the big bang?

I am not sure if at the moment this is more than a brain teaser/cramp: Assuming there really is a point where the universe begins, do the laws of the universe really have to hold before the existence of the universe? Edited April 7, 2010 by timo