
Richard P. Feynman on the Distinction Between Past and Future - vkramnik
https://medium.com/cantors-paradise/richard-feynman-on-the-differences-between-the-future-and-past-9bb1a550519c
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nullspace
Related, here's an excellent lecture by Sean Carroll on the Arrow of Time:
[https://www.youtube.com/watch?v=hagHHV6RYZ8](https://www.youtube.com/watch?v=hagHHV6RYZ8)

As far as I understand, his central (layman-level) proposition, is that time
is just an emergent property when you consider that entropy always increases.

Fascinating stuff.

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echelon
How does this model accommodate systems that lower entropy locally (at expense
of the environment), such as biological systems?

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Enginerrrd
You'd draw the system boundary to include the entropy increases in the
environment.

But if you insist on drawing the boundary such that the entropy of the system
decreases, you could probably argue it behaves similarly to a system with time
reversed.

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amai
Then why is it that time doesn't run backwards in some volume, where the
entropy decreases, e.g. a fridge?

See [https://physics.stackexchange.com/questions/289628/why-
does-...](https://physics.stackexchange.com/questions/289628/why-does-time-
not-run-backwards-inside-a-refrigerator)

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forgotmypw
[http://archive.is/y74WU](http://archive.is/y74WU)

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csomar
I'm a little bit confused. My understanding (from General Relativity) is that
time does not exist and the universe (or reality) is a 4D construct; and that
our perception of the arrow of time is coming from our consciousness?

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gowld
Do you have a source for that? And did you mean special relativity? In
spacetime, time is different from space -- the metric tensor has opposite sign
for time dimension.

[https://www.quantamagazine.org/a-defense-of-the-reality-
of-t...](https://www.quantamagazine.org/a-defense-of-the-reality-of-
time-20170516/)

has a brief argument that you can rotate around in space because it has 3
dimensions, but time is only 1 dimension so you can't turn around. There are
two directions but you can't pass between them.

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GistNoesis
Just use an unmixing machine to make the entropy decrease ->
[https://www.youtube.com/watch?v=LrmK9kDc5SM](https://www.youtube.com/watch?v=LrmK9kDc5SM)

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0134340
Which was created by work and the by-product of that work is more entropy if
not locally but elsewhere in the system. The laws of thermodynamics yield for
no one. At least not yet.

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GistNoesis
>yet

Time is this funny thing the system subject to itself.

From the outside perspective of the simulator you can sample interesting
histories. If you want something to happen, you can set it up and back-
propagate the phase space through time so that then when run in order it
reaches the desired state.

From inside the system you could be on your way toward a cosmological
convergence without knowing it until suddenly all colors sort themselves out.
And once they do, the rules for your system "aren't" changed at all, but you
are left perplexed on how your universe was fine-tuned for color alignment.

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dagav
Things may reverse in an unlikely fashion in the case of the water separation,
but your shattered glass will never jump back into your hand and become whole
again no matter how long you wait.

Some things are truly irreversible because death is a one way door.

It's no wonder we have different psychological feelings about past and future.
Some aspects of the future are potential which have yet to crystallize, and so
they can be changed before they set. Some things in the future are inevitable.
Some aspects of the past are set in stone and you must accept that they cannot
be changed. Some aspects of the past can change with new found understanding
of past events. Hence the distinction in emotions. It doesn't take a scientist
to figure that out, although I appreciate the line of thinking.

~~~
lacker
I think you are missing the point. There's no difference between the water
separation and a shattered glass. Both are based on physical laws that, on a
molecular scale, will run backwards just as well as they run forwards. But in
practice entropic processes only run one way.

~~~
dagav
Time is the non-spatial fourth dimension along which things travel in only one
direction. Even if in the three physical dimensions the process could go in
reverse, has it really reversed in time? The history of it breaking and being
fixed has persisted, and so now it's not the same glass that it was before.
It's now a glass which had been broken but is now fixed. It's a non-material
distinction, but time is non-material. And in that way, it hasn't reversed at
all.

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riversflow
Am I the only one who just doesn’t understand what there is to be reverent
about? As I see it, time is simply an imperative, without it there wouldn’t
even be a reality for nothing to exist in as existence itself is dependent
upon the arrow of time. I dunno what I’m missing, but I feel similarly about
this as I do when people try to explain things like spirit/spirituality. I
just don’t get it. Am I missing something?

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kirykl
Seems like thoughts or ideas themselves are inherently not time reversible.

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chillacy
Hasn’t Time Parity been shown to be violated? There are a number of quantum
effects which behave differently when going forwards vs backwards in time.

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gowld
Yes but only in special cases. That's not enough to explain increasing-entropy
in general.

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guramarx11
though lower in probability to recall/remember future event but I "believe"
when the reversal happen, people call them "dejavu"

