# Does entropy drive our conscious experience of time?

1. Apr 17, 2013

### bcrelling

From what I can gather, the laws of physics are time sysmmetrical- the exception being the second law of thermodynamics.

So could it be that our whole experience of time is driven souly by increasing entropy?

Assuming that we live in a deterministic universe(controversial I know) all past and future are determined- the difference is we can infer more information about the past than the future(other than that there is no qualitive difference). And so we have the illusion of choice about future events because they appear undecided.

An explanation I heard, was that objectively analyzing frames in a sequence which depict a sequence changing in steps from a low entropy state to a high entropy state is harder to predict than vice versa. Hence we percieve the past as fixed and the future as undecided, simply because more information can be infered in the direction of events which lead to lower entropy

The extprapolation of this is:
Free will is an illusion
Time is an illusion
Expectations of the future are no different to memories of the past

This isn't so much a specific question I'm asking- I'm just interested in anyone's thoughts on the nature of time and conscious experience.

2. Apr 17, 2013

### mikeph

I'd disagree with the explanation in your 4th paragraph. Take a simple example of entropy, a block of iron at 300 degrees lying on a table. Now if I asked you to predict what was going on with this block of iron 3 days ago you'd have trouble deciding. Flip the situation around, and now you're standing there and one half of the block of iron is heated to 400 degrees, and the other half is cooled to 200 degrees (using thermal contacts or something; not important). Now if you saw this half-hot and half-cold block of iron, and I asked you what would it look like in 3 days, you'd quite easily be able to predict that the temperature will have equalised.

That's the problem- the lattice vibrations inside the block are totally time-reversal invariant, but the macroscopic behaviour is clearly time-reversal variant.

I don't really follow the second sentence of the same paragraph. We perceive the past as fixed because our memories of it do not change, and we perceive the future is undecided because we don't have any memories of it, not because of entropy considerations.

3. Apr 17, 2013

### consciousness

My two cents-What your reasoning implies is that you can put a person in a test room and correctly predict his every action. If that were true I would say that every person would be able to predict his own actions. The situation becomes very complicated and philosophical now. I believe physics cant answer this question (Atleast right now). There are some interesting movies like the Minority Report made on these assumptions. In the end its all subjective.

4. Apr 17, 2013

### bcrelling

I agree we can predict that the iron block will reach theomodynamic equalibrium with time but we can't predict the microstate as there are so many microstates which fullfill the criterea of thermodynamic equilibrium(high entropy) compared to the number of microstates which fullfill the criteria for half hot/cold iron block(low entropy).

If I may I'd like to modify your example slightly:
Imagine the iron block as a 2dimensional latice of molecules which are attached to each other by springs in a grid formation. Then imagine at t=0 a single molecule is put into a very high energy state and bounces around vigorously (without breaking the springs which attatch it to its neighbours) and with time the motion spreads throughout the latice radially until all molecules are jiggling at roughly the same energy state. You film this process and then gave the footage to someone except you only gave them the middle portion of the sequence and no information on which way to play the frames. Now they might be able to infer the exact original state(a single molecule at high energy) by tracing back the radial spread, more easily than predicting the exact end (micro)state. It's always going to be easier predicting low order to high order as there are less ways a highly ordered state can be.

Sure we have memories of the past and not the future and it's totally integral to our conscious experience. But why this should be in terms of physical laws which are time symmetrical(except the second law of thermodynamics)?
It's like saying the past is the past because it happened- it makes sense only as part of our conscious experience, not in terms of physics.

Last edited: Apr 17, 2013
5. Apr 17, 2013

### micky_gta

@ bcrelling I'm afraid you posted this subject in the wrong forum.

It was made clear to me from the moderators when they said "We strive to teach mainstream physics, not develop new ideas."

6. Apr 17, 2013

Agreed.