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Jan
9
revised Does conformal gravity explain the Bullet cluster lensing effects?
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Jan
9
revised Does conformal gravity explain the Bullet cluster lensing effects?
Fixed grammar and text flow.
Jan
9
asked Does conformal gravity explain the Bullet cluster lensing effects?
Nov
27
awarded  Caucus
Oct
26
comment Is there a quantum state for a large system
No, if I understand John correctly he is saying that a burger will in principle follow quantum behaviour regardless of the number of degrees of freedom but that in practice this cannot be observed because of the fast interaction with the environment (and this behaviour is still quantum actually, it just happens also to coincide with the classical physics).
Oct
26
comment Faster than light due to reference position
This thinking is exactly where special theory of relativity comes from. Concluding that light would travel at twice the speed of light is Newton, concluding that light would travel at the speed of light in all reference frames is Einstein.
Oct
25
comment Why we use $L_2$ Space In QM?
This question reduces to "Why Born rule?". As of this moment we don't have a fully satisfactory answer.
Oct
25
revised Entanglement Entropy
added 303 characters in body
Oct
25
answered Entanglement Entropy
Oct
24
comment Many-worlds: Where does the energy come from?
@Killercam This is actually one of the main arguments made in favour many worlds. The question for those not supporting it is usually "Why should observers not themselves be quantum?". The formulae I wrote are just the usual quantum decoherence, about which you can read more on wikipedia: en.wikipedia.org/wiki/Quantum_decoherence
Oct
24
comment Many-worlds: Where does the energy come from?
No, what I am saying is that you start with an initial state $|\psi>\otimes|0>$, where $|0>$ is the observer remembering not having measured anything. Now you measure the state and what happens is the joint state is transformed to $\sum_k M_k |\psi> \otimes |k>$, where $M_k$ are measurement operators and $|k>$ is observer remembering outcome $k$. In general this is an entangled state. The Schmidt number of this state is your number of branches. Notice that for a different observer who does not know anything of this measurement there is still just one universe.
Oct
24
comment Many-worlds: Where does the energy come from?
The problem is that you consider branches as worlds, where in fact they are not worlds. This is a misunderstanding. What actually happens is that you must consider your own brain to be a quantum object. When measurement occurs it becomes entangled with the measured wavefunctions. So what you call different words are merely different states of your brain with distinct memories of the measurement outcome. If you have a problem with energy conservation here then you must also have a problem with conservation in quantum mechanics in general.
Oct
23
comment Is the statistical interpretation of Quantum Mechanics dead?
Yeah, Bell inequalities basically reduce to the marginal problem, where given a number of marginal probability distributions you cannot construct a joint distribution. If you could Bell inequalities would be satisfied. We had a discussion about this on mathoverflow (mathoverflow.net/questions/107007/…) and I am also currently writing a doctoral thesis which will contain a discussion of this. If you are interested I can send it to you by email. I have not found any other reference where this is proven directly.
Oct
22
comment Energy can't be created or destoryed?
Good question. There is still a lot we don't understand about the early universe and your question essentially reduces to how did the universe with its energy content pop into existence. Whether it popped into existence in the first place is still a matter of debate (since one can say Einsteinian time started with the universe and therefore one cannot talk about before the universe). Until we figure it out, not knowing is the exciting part about physics as lots of people try to figure this out.
Oct
22
comment Is the statistical interpretation of Quantum Mechanics dead?
Arnold is right. The problems with locality begin only when you try to take the statistical interpretation further and insist that all outcomes of all observables must have a joint probability distribution. Say if for a pair of particles you require that $p(x_1, x_2, p_1, p_2)$ exists, where $x_i$, $p_i$ are position and momentum, then you can show that Bell inequality is always satisfied when observables correspond to momentum and position. If you extend this requirement to all observables, you find Bell inequality is always satisfied. This is how far precisely you can go with statistics.
Oct
19
comment Does the nonlocality of the preferred basis mean QM is nonlocal?
If you start with input into only one port of the first beamsplitter then the second beamsplitter should reconstruct that state and the photons come out at one of the output ports of the second beamsplitter. This is probably what he means by the preferred basis. But the "basis" is really only generated through the virtue of inputting photons into only a single port of the first beamsplitter. If that did not happen you would need a measurement somewhere to generate the basis.
Oct
19
revised Why does bad smell follow people (assuming they are not the source)?
added 1 characters in body
Oct
19
comment Why does bad smell follow people (assuming they are not the source)?
Interesting. In combination with what anna said above in a comment to my question, it explains what I have observed circumstantially.
Oct
19
awarded  Scholar
Oct
19
accepted Why does bad smell follow people (assuming they are not the source)?