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paper-machine comments on Identity Isn't In Specific Atoms - Less Wrong
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Why did you not write this as a reply to me?
[Citation needed]
Quantum mechanics is the theory that reality is described by the Schrodinger equation; loop quantum gravity includes the Schrodinger equation. Its proponents claim that it includes the general relativity field equations as a long distance limit; that is what we mean when we say that one theory is a quantization of another, just like quantum and classical electrodynamics.
95% probability less than 10% of the physics you read is from journals/arXiv.
So I was somewhat surprised that Wikipedia claims that the above is a "popular claim", and goes on to cite some yoga involving the quantum mechanics of gravitons, whatever that means. I'm a mathematician, dammit Jim, not a theoretical physicist.
I think a more accurate version of what the grandparent meant is that one cannot merely take QM and GR, stick them together, and hope to get a coherent theory. One needs something more (for example, the above requires the existence of gravitons), and that's why people go hunting for unified theories.
Relying upon Wikipedia is not advised here. QM and GR, if you stick them together, entail everything. (On the assumption that from a contradiction one can derive anything. Paraconsistent logical systems deny this assumption.) For some proposition, sentence, statement or utterance that P, QM entails P. GR entails not-P. Absent abandoning classical logic (and moving to something like paraconsistent logic), GR and QM are inconsistent.
Let's assume that a theory is false if the theory entails P and not-P (that is, let's ignore paraconsistent logical sytstems). Then sticking GR and QM together entails P and not-P. Any theory that entails both P and not-P is false. So sticking them together fails.
Almost all physicists are happy with the above claims, and so there is an ongoing search for theories that preserve what's supposedly right about QM with what's supposedly right about GR. Enter theories of quantum gravity. These theories might be in some respects "quantum mechanical". That is, they preserve some aspects of QM. These theories aren't QM or GR, however. They're attempts to preserve what's right (let's suppose) about QM and make that compatible with what's right (let's suppose) about GR.
We're utterly in the dark about which such theories might be true. Sadly, that's the state of the game. If you appeal to QM in defense of some interesting claim, you are failing to appeal to a theory you ought, as an intelligent and well-educated person, place a high degree of credence in. Here our favorite blogger is is screwing up.
I'm confused how you got this out of the above -- I didn't mean to imply that QM+GR was consistent. They need fixing, and the article supports this viewpoint. Grandparent asked for citations; the relevant article has several. I didn't see the earlier comments between you and endoself, because they're not in this thread, but in another, for some reason. For what it's worth, I think you're misinterpreting statements intended for poetic effect.
So while endoself is wrong when he claims QM isn't inconsistent with GR, you're equally wrong for believing EY supports QM over GR, when in fact it's incredibly likely (based on everything we know about EY's stance on updating) that for now EY supports QM when it talks about small things and GR when it talks about big things, and that if some better theory would come along that explained the evidence better, EY would update to follow that.
Of course, I can't speak for him, but I claim the above is a more reasonable interpretation of the state of affairs.
EDIT: So there's a simpler litmus test to apply here -- has EY directly said anything about GR? If so, what evidence is leading you to believe he denies it?
The source of your confusion is the meaning of the phrase 'Citation Needed'. It seldom has anything to do with wanting citations. Actually giving them to him is like answering a (bad) rhetorical question with a literal answer that effectively refutes the rhetorical point of asking it.
What else does it mean?
Basically, if someone told me 'Citation Needed!' in the same conversation that they out of the blue told me I was insane then I would expect them to do whatever they could to find a way to sneer at or dismiss the citations I proceed to give them. I would expect them to feel like their grasp for dominance backfired and try to dig themselves out of what feels like a hole.
This isn't to say that 'citation needed' is never used literally or never appropriate. But I usually find that anyone who is actually interested in whether there are citations available tends to use different language in their reply.
Ah, I see.
Those two things weren't done by the same person. endoself used [Citation Needed]; PhilosophyFTW called him insane in the followup, for a different reason.
Ahh. That changes the likely meaning somewhat (greater weight to the first bullet point, less to the last one).
I interpreted "QM is inconsistent with GR" as stating that GR cannot be quantized. This is usually what is mentioned in such discussions, as GR is much harder, maybe even impossible, to quantize as compared to other theories. There are very large advantages to only using the word 'consistent' in its precise mathematical definition, so I will do that from now on.