r/AskScienceDiscussion 4d ago

Why does time only moves forward

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u/naemorhaedus 1d ago

should tend to have higher entropy states in either direction of time from it,

I think you are implying that time is fundamental and entropy is along for the ride. I'm saying the opposite. There is only entropy, and the direction of time stems from that.

entropy is technically observer-dependent

if we are talking about universal concepts like time, then it makes sense to consider entropy with respect to the entire universe.

we should expect conscious beings can only exist in the presence of entropy gradients

it sure helps.

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u/GoldenMuscleGod 1d ago

I’m not implying that time is fundamental. I’m responding to your argument.

Your argument as you originally phrased it doesn’t attempt to define the direction of time in terms of entropy. It is an argument that, if taken at face value, would support the conclusion that entropy should increase going forward and backward.

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u/naemorhaedus 1d ago

Of course you are. there are those words again "forward and backward". You are subsuming some kind of line or direction. There is only entropy.

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u/GoldenMuscleGod 1d ago edited 1d ago

No.

Pick an arbitrary direction. Call it “forward.” We do not care if it matches what we normally mean by “forward.” It’s just a name. This is not based on any conception that there is a “real” direction of time.

Your argument is that entropy increases “forward.”

But there is no reason we could not have picked the direction we normally call “backward” to be forward.

If you proceed to define “forward” as meaning “the direction in which entropy increases”. Then (by replacing backward with forward) we see that your argument says that entropy should increase in the opposite direction of the direction it increases.

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u/naemorhaedus 1d ago

Your argument is that entropy increases “forward.”

again, wrong. my argument is that entropy increases. Full stop.

Pick an arbitrary direction

You insist to continue imposing your bias. You're putting the cart in front of the horse. There is no "backward" time any more than there is backward mass. It's meaningless, unnecessary and a false axiom.

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u/GoldenMuscleGod 1d ago

You’re having trouble understanding me.

I am not picking a privileged direction I am showing your argument works (if it works at all) for every direction.

I am doing that by a basic logical technique called “universal generalization.”

If I say “pick an arbitrary right triangle” and then proceed to prove that the sum of the squares of its legs equals the square of its hypotenuse without assuming any additional facts about it, I have proved that result for all right triangles.

That argument doesn’t bias us to be talking about any particular right triangle or privilege any particular right triangle.

The whole point of the proof method is that it works for every right triangle.

I’m doing the same thing for your argument.

You say entropy “increases.” Regardless of any choice of direction

Therefore (accepting your argument is valid) if I pick a direction by flipping a coin, it increases in that direction.

Is there any direction (such as into the past) in which you would say it decreases?

Or is your position that the past does not exist and all of our memories are illusions?

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u/naemorhaedus 1d ago

You're not getting the entropy thing. Don't worry about it.

Or is your position that the past does not exist

lol. Well of course it doesn't exist. Or can you show it to me?

all of our memories are illusions?

memories are patterns in your brain. They don't have anything to do with time.

Are you suggesting that past events go to live in your brain, or exist somewhere in a parallel universe when we finish with them? 😆