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Awful article title glosses over nuance in advanced physics theories about gravity
- Thread starter Trojita
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Mgoblue201, sorry about that.
Hmm... symmetry is based around the concept of invariance. But, it can often be used in very obscure ways that aren't obvious.
So, like, you hit on the reason a gas cloud is spatially symmetric: you can reduce down to the statistical mechanics of simple diffusion and so the probability of finding each molecule diffusing on away after t time yields the symmetrical shape you see.*
Some Laws like Newton's 2nd are time symmetrical, so you can sign inverse and it still works.
Other times you'll hear about "supersymmetry" (usually around string theory) and maps one type of particle called a boson with a specific spin (integer) to fermions with half-integer spin. So, again, they are thought you be related by an underlining invariance, but not necessarily what you'd think instinctively.
I don't know if that's an answer, but maybe others can help?
*So, think of it as just in one dimension and that each particle moves v velocity to the right or left at each moment t time. The distance is +/-(vt). When you compute it out, we can do it if you want, you find that the particle go nowhere on average (since for every right movement, there is one to the left on average). Yet, although the average is zero, in an ensemble there are enough outliers that they do spread: some will take two right moves and a left, maybe all three right.... The RMS displacement scales with the sqrt(t).
EDIT: Spelling is bad, really bad
The_Technomancer said:
Hmm... symmetry is based around the concept of invariance. But, it can often be used in very obscure ways that aren't obvious.
So, like, you hit on the reason a gas cloud is spatially symmetric: you can reduce down to the statistical mechanics of simple diffusion and so the probability of finding each molecule diffusing on away after t time yields the symmetrical shape you see.*
Some Laws like Newton's 2nd are time symmetrical, so you can sign inverse and it still works.
Other times you'll hear about "supersymmetry" (usually around string theory) and maps one type of particle called a boson with a specific spin (integer) to fermions with half-integer spin. So, again, they are thought you be related by an underlining invariance, but not necessarily what you'd think instinctively.
I don't know if that's an answer, but maybe others can help?
*So, think of it as just in one dimension and that each particle moves v velocity to the right or left at each moment t time. The distance is +/-(vt). When you compute it out, we can do it if you want, you find that the particle go nowhere on average (since for every right movement, there is one to the left on average). Yet, although the average is zero, in an ensemble there are enough outliers that they do spread: some will take two right moves and a left, maybe all three right.... The RMS displacement scales with the sqrt(t).
EDIT: Spelling is bad, really bad
The Technomancer
card-carrying scientician
Hm, oh yeah I know about supersymmetry, and how it really isn't "symmetry" like most of us think, but rather a way of describing relationships between families and types of particles. And then there are uses of the word symmetry like saying that at high energies the electromagnetic and weak forces become symmetric, able to kind of slide among each other. Physics likes to get a lot of use out of that word, it seems.BigSicily said:
Trent Strong
Banned
OuterWorldVoice said:
:lol
speculawyer
Member
I always assumed that referred to the equations.The_Technomancer said:
For example, the symmetry of Maxwell's equations.
Edit: I approve of the thread title change.
Mgoblue201
Won't stop picking the right nation
Technically what I said was incorrect. It is not a measurement of energy. I was being careless with my words. I do have one question: how does entropy relate to absolute zero?BigSicily said:
Oh sure, like Gravity just popped into existence.
Clearly it's Intelligent Falling.
I dunno, I'd rather take bad science from the NYT over the shitty celebrity/sport features that most of my local Sydney papers have.
I enjoy reading my NYT Editors Choice iPad app every morning.
Clearly it's Intelligent Falling.
BigSicily said:
I dunno, I'd rather take bad science from the NYT over the shitty celebrity/sport features that most of my local Sydney papers have.
I enjoy reading my NYT Editors Choice iPad app every morning.
The Technomancer
card-carrying scientician
Assuming you're being serious, that still is one of the theories, that gravity is a fundamental force, and we haven't found the gravity particle because as the weakest of the forces its particle is the hardest to observe. (I think?)max_cool said:
CHEEZMO
Obsidian fan
Nexus Zero
Member
I just do not see how gravity emerges from entropy. The solar system works like clockwork, that is perhaps the most anti-entropic thing I can think of.
Isn't that the Higgs Boson?
Isn't that the Higgs Boson?
Hari Seldon
Member
Physicists should quick fucking around with gravity and get to work on my holodeck. Shit falls, quit worrying about it.
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