Time

>>8307212
Is time a lebesgue measure?

>>8307212
It's an illusion

>>8307212
Time is just one dimension in 4d curved space.

the more you move through space, the less you move through time

>>8307225
I used to think it was that until I stumbled upon some reading that was way above my level. All in all it seemed to show that 4D space and a spacetime universe are note equialent.

>inb4 this doesn't prove anything, you said yourself you didn't understand it

Well yes but I still trust the evidence for climate change when I'm no expert on such matter.

>>8307287
Both spacetime and 4D Euclidean space are 4D spaces, they're just different spaces. The difference is the formula for distance, in 4D Euclid it's
[math]\sqrt{\Delta w^2 + \Delta x^2 + \Delta y^2 + \Delta z^2}[/math]
and in spacetime it's
[math]\sqrt{- c^2 \Delta t^2 + \Delta x^2 + \Delta y^2 + \Delta z^2}[/math].

https://www.youtube.com/watch?v=msVuCEs8Ydo

>>8307212
Time exists because entropy exists.
If nothing changed, time wouldn't be measurable.

Time dilation is a direct result of relativity.
Special relativity looks at objects under constant velocity.
General relativity looks at objects under acceleration.

Consider that the speed of light is constant for everyone.
Speed = d/t
If I'm standing still relative to you, and you are moving, light that you see will move less distance than the distance I would measure the same light moving.

Since the speed is the same for both of us, and the distances are different, the time we measure also has to change, otherwise we would measure different speeds for the light.

>>8307563
Wow thanks

>>8307563
>Time exists because entropy exists.
this meme needs to die
> If nothing changed, time wouldn't be measurable
you're implying there's no such thing as reversible processes

>>8308066
>this meme needs to die
it's not a meme

it's general relativity

>>8308091
>relativity
>>>/x/

>>8308091
> GR and entropy
alright I'll bite.
Can you explain further?

Pretty sure even in GR you can create a reversible process.

>>8308104
Quantum mechanics don't allow for reversible processes

Time is the fourth dimension xD

>>8308109
> it's GR
> not it's QM
make up your mind.

to be honest time doesnt exist... in fact i wish i could know what year we are actually living on... i dont believe in religion at all for which i dont follow the B.C. / A.C. Bullcrap. anyone else have come across this thought???

>>8308115
GR is the reason time comes from entropy

Your question about reversible processes is unrelated, but QM tells us that no such thing is possible

File: 1368622426938.png (298KB, 600x600px) Image search: [Google]

298KB, 600x600px

>>8308139
>but QM tells us that no such thing is possible
the fuck are you talking about negro

>>8308139
> GR is the reason time comes from entropy
alright. proof of this then.
I was under the impression that entropy was basically the measure of the irreversibility of a process, but I know physicists define it as their own thing

>>8308143
The only definition of entropy in science is the number of microstates available to a macrostate.

Thermodynamics shows us that statistically, it's extemely likely that a system will tend to the maximum possible number of states. If you actually study thermo, this is a time independent process.

We perceive time because we perceive this increase in entropy.
If we for example, measured the energy of particles in a box repeatedly, and saw no change in the energy distribution, it would seem as though time didn't exist for that system. (Ignoring the fact that our observation of the system is part of the system)

>>8308174
I see no GR in this post.
> If you actually study thermo, this is a time independent process.
exactly. You can have a system sit there for a set period of time, see no entropic change, yet still time will have passed.

> We perceive time because we perceive this increase in entropy.
> If we for example, measured the energy of particles in a box repeatedly, and saw no change in the energy distribution, it would seem as though time didn't exist for that system.
restating your claim is not proof of the claim
If we took two gravitationally attracted particles with some initial state and watched them orbit each other, they'd still experience time and a state change without any entropic change

>>8308174
> The only definition of entropy in science is the number of microstates available to a macrostate.
This is just wrong. Stop talking out of your undergraduate ass.
https://en.wikipedia.org/wiki/Entropy_(classical_thermodynamics)

>>8308192
I wouldn't say the only definition, but measured entropy is pretty unanimously associated with the micro and macro states.

>>8308192
>Stop talking out of your undergraduate ass.
Fuck me the irony

>>8308232
Why do you say that?
The statement given was clearly incorrect as anyone who has ever used classical thermodynamics could tell you.

>>8308189
I wasn't the one arguing about qm or gr. I have no idea what he was talking about.

>>8308236
The wiki says exactly what I said as boltzmann defined it.

Nobody cares about clasious. And no one uses that definition.

>>8308279
>And no one uses that definition.
The fuck? That's literally the first one you'll encounter in any thermodynamics textbook.
The statistical definition is only relevant once you get into statistical mechanics.

>>8307563
>light that you see will move less distance than the distance I would measure the same light moving
Why? Please explain

>>8308122

are you retarded... this information is readily available.

i don't remember exactly but the year is 12 billion-something

>>8308314
Because you use thermo without using stat mech in an applied field. Jesus christ, let it go. >>8308336
If you're on an airplane and drop a bomb, to you it looks like it drops straight to the ground.
If I'm standing on the ground and see you drop the bomb, the apparent path is parabolic.
If it was light instead of a bomb, the motion of the light is still skewed.
Obviously the measured distances will be different. In non relativistic physics, the discrepancy in distance means I measure it going faster than you. But since light speed is fixed, that is no longer the case.