Heat Death of the Universe - Reconciling with the initial state

[JonathanCollins]

Predicted Heat Death of the Universe

 

In his thought provoking documentary “Wonder of the universe” (https://www.youtube.com/watch?v=Uu-tJmRxcVw

 

) Professor Brian Cox explains the thinking behind current predictions for the “Heat death of the universe”. He explains the predictions through the effect of the second law of thermodynamics whereby the universe gradually moves from an ordered state (low entropy) to a state of disorder (high entropy). He states:

 

“The last remaining matter in the universe will reside within black dwarves. We can predict how they will end their days. The last matter of the universe will evaporate away and be carried off into the void as radiation leaving absolutely nothing behind.

 

There won’t be a single atom left; all that’s left will be particles of light and black holes. After an unimaginable period even the black holes will have evaporated; the universe will be nothing but a sea of photons gradually tending to the same temperature as the expansion of the universe cools them towards absolute zero.

 

The story of the universe will come to an end. For the first time in its life the universe will be permanent and unchanging. Entropy will finally stop increasing because the cosmos cannot get any more disordered. Nothing happens and it keeps not happening for ever. There is no difference between past present and future, nothing changes, arrow of time has simply ceased to exist.

 

It is an inescapable fact written into the laws of physics that entire cosmos will die; all the stars will go out extinguishing possibility of life in the universe.”

 

Reconciling the predicted Heat Death of the Universe with the initial state

 

The assumption seems to be that the singularity from which the universe is thought to have arisen was an ordered state (low entropy) and that since the big bang the entropy is increasing with the inevitable end result that all matter will be converted to energy which will then cool to absolute zero after which entropy will be at its maximum value and nothing will occur in the universe.

 

The predictions appear to be correct according to the second law of thermodynamics. One can imagine an ever expanding universe whereby all its heat energy is dissipated until it reaches absolute zero temperature whereupon all events will cease.

 

There are fundamental difficulties in accepting this end state of the universe.

 

Firstly it is extremely depressing and counter intuitive for humans to envisage a universe in which there is no possibility of life and where no events will ever occur. However this difficulty does not preclude such an end state of the universe.

 

The second and more important difficulty in accepting this end state is in reconciling the predicted end state of the universe with the currently accepted initial conditions of the universe prior to the big bang.

 

The initial conditions of the universe prior to the big bang are assumed to be a singularity of infinite density and zero volume which according to the second law of thermodynamics would be considered to be a highly ordered state with low entropy. The question arises as to how the singularity came to be in this state and what caused it to suddenly expand so rapidly into the observable universe.

 

The singularity can only have been in existence for a finite period of time as otherwise it could not have suddenly expanded.

 

As in the predicted end state of the universe at a temperature of absolute zero no events can occur without events to precipitate such events.

 

Assuming the singularity to be an enclosed system with nothing outside (no space, no matter, no energy, no events) the expansion can only have occurred as a result of events within the singularity. Alternatively assuming no events inside the singularity the expansion can only have occurred as a result of events outside the singularity.

 

There is a finite number for all the possible permutations of events that could have precipitated the expansion. It follows that there must have been events prior to the existence of the singularity as a singularity. In other words the singularity must have come into existence from a previous state of its contents.

 

Assuming a finite amount of material within the singularity (and the previous states of the singularity) all possible permutations of events including the sequence of events in our current universe constituting the predicted “Heat Death of the universe” would have already occurred prior to the big bang.

 

From this it follows that either the predicted “Heat Death of the universe” is not possible or that it is predicated on an incorrect set of data or that the second law of thermodynamics is incomplete.

 

Edited July 24, 2015 by JonathanCollins

[Strange]

The second and more important difficulty in accepting this end state is in reconciling the predicted end state of the universe with the currently accepted initial conditions of the universe prior to the big bang.

 

If you are considering a model with a singularity, then there is no "before" the big bang.

 

The initial conditions of the universe prior to the big bang are assumed to be a singularity of infinite density and zero volume

I don't know of anyone who considers that a realistic possibility.

The singularity can only have been in existence for a finite period of time as otherwise it could not have suddenly expanded.

 

There are several model which give the universe and infinite age.

 

If there were a singularity, then there is no meaning to "period of existence"

Assuming the singularity to be an enclosed system with nothing outside (no space, no matter, no energy, no events) the expansion can only have occurred as a result of events within the singularity.

There can be no events inside a singularity, by definition.

Assuming a finite amount of material within the singularity

 

Not a reasonable assumption. The universe may be infinite in size (and therefore mass).

 

From this it follows that either the predicted “Heat Death of the universe” is not possible or that it is predicated on an incorrect set of data or that the second law of thermodynamics is incomplete.

 

As the heat death is based on current conditions, I can't really see how the initial state is relevant. But currently, all we know is that it was extremely hot, extremely dense and extremely homogeneous.

[studiot]

I note you adopted my suggestion and corrected your version of Entropy since you last posted this.

 

Thank you for the acknowledgement.

 

http://physicshelpforum.com/showthread.php?p=29829&posted=1#post29829

[Phi for All]

There is a finite number for all the possible permutations of events that could have precipitated the expansion. It follows that there must have been events prior to the existence of the singularity as a singularity. In other words the singularity must have come into existence from a previous state of its contents.

 

Correct me if I'm wrong, but you seem to be using "singularity" wrt BBT in a different way than I'm used to. Don't we call T=0 a singularity only because our models can't define it any other way? Isn't it more like the math stops giving us useful results, rather than the singularity being some kind of black hole? You talk about "events within the singularity" and it makes it sound like a physical place rather than a way to denote a lack of data that makes calculations break down.

[Sorcerer]

 

The singularity can only have been in existence for a finite period of time as otherwise it could not have suddenly expanded.

Why? You back this up with nothing. Also time is meaningless at the point of a singularity. You're using a gods eye view where you observe the singularity as a line before the expansion. Instead the only view which makes any sense to us is that from a point after expansion where we can look back in time towards it.

 

 

As in the predicted end state of the universe at a temperature of absolute zero no events can occur without events to precipitate such events.

You are drawing a comparison between the causal nature in a low entropy state, (I'm not sure if entropy even makes sense in the physical context of a singularity), and a maximum entropy state. You seem to find some paralelle where they bare very little resemblance, it is tempting to find similarities in near opposite contrasting events and then ascribe some meaning to the paralellism.

 

The reason why no events are occuring in a maximum entropy state are not the same as the reasons why something has "not yet" (if that even makes sense) occured in the low entropy state.

 

I know it's tempting because of the seeming symmetrical beauty to draw paralleles between opposites and try to tie them together. However often this "beauty" is misleading and it's actually just false pattern recognition and bad inductive logic.

 

From this it follows that either the predicted “Heat Death of the universe” is not possible or that it is predicated on an incorrect set of data or that the second law of thermodynamics is incomplete.

 

Invalid, sorry, your premises aren't correct.

 

Try assuming a singularity doesn't exist, start an argument from there.

 

 

There can be no events inside a singularity, by definition.

Is that because a singularity has 0 dimensions it doesn't have any "inside"? Any event would occur AT (even that makes no sense) the singularity.

 

Firstly it is extremely depressing and counter intuitive for humans to envisage a universe in which there is no possibility of life and where no events will ever occur.

Don't make the mistake of trying to dis/prove something because you do/n't like the idea of it, be impartial. Confirmation bias will hinder your ability to look at other avenues, you get tunnel vision on a problem which isn't actually a problem.

 

If there's heat death, there's heat death, bad luck. The science doesn't care. I wish the universe hadn't created mosquitoes, but I don't go around trying to disprove their existence.

Edited August 4, 2015 by Sorcerer

[MigL]

A singularity is defined as an 'edge' to space-time, or where space-time ceases to exist, sorcerer.

An event is defined as a co-ordinate in space-time.

 

Strange was merely asserting that there can be no co-ordinates where the co-ordinate system ceases to exist.