/sci/ - Science & Math » Thread #12701351

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Anonymous Sat 13 Feb 14:08:58 2021 No.12701351 View Reply Original Report

Quoted By: >>12701480 >>12701484 >>12701553 >>12701618

>energy is just our name for quantities that are conserved if a process is time invariant
>time isn't invariant in general relativity
>conservation of energy ISN'T ACTUALLY A THING in GR and the real world
Inb4 clever killing vector, you know what I mean. Wtf, why do physicists keep people in the dark about this. This is worse than teaching people Bohr's atom model.

Anonymous

Anonymous Sat 13 Feb 2021 14:29:36 No.12701376 Report

Quoted By: >>12701475 >>12701507

It's funny isn't it? The law of conservation of energy, touted as the pillar of physics one that fundamentally cannot be broken, yet it doesn't work neither in QM nor in GR which are the modern theories that describe the world.

In QM, the Heisenberg uncertainty principle $\Delta E\Delta t \ge \frac{\hbar}{2\pi}$ allows you to create or destroy energy out of nothing as long you return the energy in $\Delta t$ time hence virtual force carrying particles are allowed exist. Hence, shit attracts and repels one other specifically because conservation of energy is fundamentally broken.

In GR, the photon becomes red shifted and loses energy due to expansion of space. That energy goes well.. nowhere.. hence energy isn't conserved. However notice it's never "energy is destroyed" it's always "oh, it isn't conserved!". Hmmm. Really makes you think why, doesn't it?

Anonymous

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Anonymous Sat 13 Feb 2021 15:32:33 No.12701475 Report

Quoted By: >>12701507 >>12701535

>>12701376
In addition to this, they say when black holes merge the final mass of the black hole is smaller than the sum of masses of constituent black holes while the missing mass radiated as gravitational waves. How can space itself carry energy in form of gravitational waves when energy = mass which would imply space itself has mass? Why is energy conserved in this case and why isn't it just "lost"? It's so dumb.

Anonymous

Anonymous Sat 13 Feb 2021 15:35:14 No.12701480 Report

Quoted By:

>>12701351
>energy is just our name for quantities that are conserved if a process is time invariant
You can do that, but in classical moments that which is conserved (let's call it Hamiltonian) isn't always kinetic plus potential energy, and I'd rather denote the latter (T+V) as energy, not the Hamiltonian (with which is usually coinincides).

Anonymous

Anonymous Sat 13 Feb 2021 15:36:17 No.12701484 Report

Quoted By:

>>12701351 (OP)
>energy is just our name for quantities that are conserved if a process is time invariant

You can roll with this.
But in classical moments that which is conserved (let's call it Hamiltonian) isn't always kinetic plus potential energy, and I'd rather denote the latter (T+V) as energy, not the Hamiltonian (with which is usually coincides).

Anonymous

Anonymous Sat 13 Feb 2021 15:50:00 No.12701507 Report

Quoted By: >>12701547

>>12701376
>>12701475
If that’s the case, it could be that energy is conserved if spacetime could store energy

Anonymous

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Anonymous Sat 13 Feb 2021 15:54:36 No.12701514 Report

Quoted By:

You're just fucking with us physicslets, aren't you.

Anonymous

Anonymous Sat 13 Feb 2021 16:05:29 No.12701535 Report

Quoted By:

>>12701475
For starters, I am a retard, so if it sounds like I'm spewing bullshit, I might be.

But isnt there a permeability of space? That space has some form of resistance? I remember learning about it when doing calculations for particles moving in a vacuum. I think people get into theories like quantum foam or dark matter from this.

Anonymous

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Anonymous Sat 13 Feb 2021 16:12:44 No.12701547 Report

Quoted By: >>12701551 >>12701575

>>12701507
If spacetime could store energy (and mass is energy) that would mean spacetime itself has mass, which means that mass would warp spacetime and cause gravity. While this sounds like the way gravity waves could propagate (it's how EM waves work i.e. E influences B, B influences E, hence a wave is propagated, which is called a photon) the problem is gravitational waves travel at the speed of light. If the "mass" of spacetime itself is what causes gravitational waves, remember that "having mass" itself means the particle can only propagate at less than a speed of light (in this case a graviton), which means gravitational waves should travel less than a speed of light.

Anonymous

Anonymous Sat 13 Feb 2021 16:15:53 No.12701551 Report

Quoted By:

>>12701547
Not really. See photons, they carry energy and travel at the speed of light

Anonymous

Anonymous Sat 13 Feb 2021 16:16:38 No.12701553 Report

Quoted By: >>12701558

>>12701351
It's a meme. No one even KNOWS what energy is. It's a value that is conserved for the most part.

Anonymous

Anonymous Sat 13 Feb 2021 16:19:15 No.12701558 Report

Quoted By: >>12701562 >>12701666

>>12701553
If no one knows, why do we talk about it?

Anonymous

Anonymous Sat 13 Feb 2021 16:23:45 No.12701562 Report

Quoted By:

>>12701558
Because it's a value that is conserved for the most part. So it's useful.

Anonymous

Anonymous Sat 13 Feb 2021 16:32:27 No.12701575 Report

Quoted By:

>>12701547
Oh right, isn't mass densely compacted energy?

Anonymous

Anonymous Sat 13 Feb 2021 16:48:47 No.12701618 Report

Quoted By: >>12702023

>>12701351
There appears to be some confusion in this thread. Energy is conserved in GR. Where it's not conserved is in the Big Bang model, which should be a huge indicator that we need to drop that. As far as GR is concerned, there are no problems with conservation of energy.

Anonymous

Anonymous Sat 13 Feb 2021 17:10:25 No.12701666 Report

Quoted By:

>>12701558
Just because we don't know what it is doesn't mean we can't observe it and produce repeatable results to form theories and laws. It adheres to these laws and talking about it is the only way we can step closer to answering that very question.

Anonymous

Anonymous Sat 13 Feb 2021 19:07:43 No.12702023 Report

Quoted By:

>>12701618
Only in a pure de Sitter universe. Not the case for a Friedmann–Lemaître–Robertson–Walker metric.
>is in the Big Bang model, which should be a huge indicator that we need to drop that
ur a lil bitch

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