Comment by stcredzero | Hacker News Reader

Comment by stcredzero | Hacker News Reader

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The entropic heat death of the universe comes more from the notion that R=1 is implied by the conservation of energy

{facepalm}

Physicists already know that on the scales of the universe, there is no conservation of energy.

I hate to break it to you folks, but most of you are dead wrong about conservation laws. Conservation laws are a fundamental part of your education, but they are not a fundamental part of the universe. They are dependent on symmetry, as German mathematician Emmy Noether figured out. What this means is that energy is not conserved on universal scales, though it is still a very powerful analysis tool on smaller scales. We already have good reasons to believe that there is no time symmetry in deep time. The part relevant to the above specifically is at 10:15, but the whole video is worth watching.

https://www.youtube.com/watch?v=PUn2izowBkw

We know that the universe is expanding, and that this expansion is accelerating. So, do you know what happens when the expansion of space itself starts pulling quarks apart? Can you describe the physics? Do we even know that is going to happen?

Also: Physics Girl -- On universal scales, energy is not conserved! https://www.youtube.com/watch?v=GHCc9b2phn0

>>Do we even know that is going to happen?

no one you can conceive of caring about will be alive and nothing you do now will have any noticeable effect on them.

But also yes we have worked out the math for a hyperbolic universe and it is still not effected by 21st century morality.

You’re not wrong, but you’re not a good teacher either. Rudeness and mockery don’t add anything, and in fact take away from your ability to inform people. You’re also only half right, insofar as nobody knows is a very accurate statement. You’re wrong however, that conservation laws definitely don’t apply. We just don’t know if they do, and there are reasons to believe (you reference Noether’s theorem) why they might not. The truth is, “Nobody knows” with a period and a full stop.

It’s also worth pointing out that universal expansion has an effect only on distance scales larger than galaxies. There is no reason to believe it will pull apart smaller structures, never mind subatomic ones. It’s a popular misconception that the expanding force is great on small distance scales. On the scale of a galaxy, that force is overcome by gravity, so needless to say the Strong force won’t even notice it.

Tl;DR Metric expansion is a powerful cumulative force on giant distance scales, weak on small (below galaxies) scales. Galaxies, stellar systems, stars, and Hadrons will be just fine, thanks.

If you’re going to scold people, you could at least be right. It is also a good idea not to rely on just YouTube videos for your arguments.

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