meta user
network profile
| bio | website | |
|---|---|---|
| location | New York City | |
| age | 39 | |
| visits | member for | 1 year, 9 months |
| seen | yesterday | |
| stats | profile views | 23,618 |
I do not participate on this site any longer, except to respond to comments regarding my own text, if that text is unavailable in another form. I do not accept the political moderation atmosphere here, it is not compatible with open science.
|
May 16 |
comment |
From where (in space-time) does Hawking radiation originate? @Nathaniel: Yes, locally, the outgoing photons are of such small wavelength that they pass through anything, it's unphysical. |
|
May 15 |
comment |
From where (in space-time) does Hawking radiation originate? @Nathaniel: Yes, of course a planck size region, single point is meaningless. The star is diffuse wispy gas because you are talking about a super-trans-planckian mode, the scale of variation is wildly off--- this mode has (if it were occupied) 10^(10^10) GeV. This is the reason some people were skeptical of Hawking's calculation, because the modes end up so unphysical. |
|
May 15 |
comment |
From where (in space-time) does Hawking radiation originate? @Nathaniel: the radiation is from a transplanckian point, you are missing that all the far-future radiation is essentially hugging the 45-degree line in your diagram, because in the Penrose diagram it just can't get away from it. The star is irrelevant, the photon is transplanckian and hugging the horizon, and the star-matter is like the most diffuse of wispy gas. The way to understand this is to understand the analytic derivation of Hawking radiation, the equivalence principle interpretation, and then to follow Hawking's calculation and see where the mode originates--- it's at that spot. |
|
May 15 |
comment |
From where (in space-time) does Hawking radiation originate? @Nathaniel: this is why the Penrose diagram is misleading--- when you are looking at late times, the photon that escapes the black hole is SMOOSHED so close to the 45-degree line of the horizon (as is everything else, including you) that you are completely misled. Write down a normal r-t coordinate description, and see how mushed up it gets at late times--- the photons that peel off the horizon and go to infinity in the normal picture stay close to the horizon forever in the Penrose picture. It's good for conformal structure, nothing else, it's not physical. |
|
May 14 |
revised |
From where (in space-time) does Hawking radiation originate? explain |
|
May 13 |
awarded | Nice Answer |
|
May 13 |
comment |
What causes an electric shock - Current or Voltage? @endolith: You are completely right of course, I wasn't thinking about nuances, I just wanted to explain the energetics is the product of the charge times voltage difference, and I used P=IV. I don't want to bump this, but if you feel strongly, edit the answer as you like. |
|
May 12 |
comment |
Are W & Z bosons virtual or not? @drake: Maybe Polyakov's book "Gauge Fields and Strings". I don't know a good reference, because the availability of a field formalism which is correct and consistent puts a damper on the development of a particle formalism which is complete and consistent, so right now we only have a perturbative formalism. I don't think this is intrinsic, but nobody works on it, and I don't know if the reward is worth the effort. The problem is that in the particle formalism, the interactions are not forward in proper time, particles interact when they come to the same point in space-time at any proper time. |
|
May 12 |
comment |
What causes an electric shock - Current or Voltage? @endolith: You know what I meant, I meant "charge delivered", so you get the energy out when you multiply. |
|
May 12 |
comment |
Bell's theorem and why nonlocality is problematic ... this principle requires a locality on the boundary theory, and further requires a reconstruction of an approximate space-time in the interior, so it is much more restrictive than local physics. The locality idea is wrong, it is shown to be wrong by string theory, holography, even just Hawking's information loss paradox. It's the major lesson of physics since 1960. |
|
May 12 |
comment |
Bell's theorem and why nonlocality is problematic ... Einstein is basically summarizing the 100 years of 19th century physics that led to the consensus that physics is supposed to be local fields. The proper formalism for nonlocal physics was worked out by the S-matrix folks, especially Mandelstam, in the late 1950s, throughout the 1960s (you can see hundreds of articles on S-matrix formulation of the locality principle, or "causality"). The modern formulation boils down to light-cone locality and holographic locality, the principle that you can't send a signal faster than light to the boundary by fiddling with boundary stuff. |
|
May 12 |
comment |
Bell's theorem and why nonlocality is problematic @becko: Einstein is overstating things--- he means that nonlocality would make local experiments impossible. that's not true, and it's not what I meant. I meant, without locality, you can basically make up an infinite number of whatever you want, for example, consider $S = \int (|\nabla \phi|^2)^p$ for $0<p<1$, this is nonlocal and relativistically invariant for p<1, creating a Levy field theory. Even more extreme, consider Bohm theory. This requires picking a frame, and then the nonlocal laws are different in details from frame to frame, and there are infinitely many frame choices. |
|
May 11 |
awarded | Nice Answer |
|
May 9 |
awarded | Nice Answer |
|
May 9 |
awarded | Good Answer |
|
May 7 |
comment |
How does the holographic principle imply nonlocality? @Gugg: Great job, thanks, I always misspell the dude's name, it's embarassing. |
|
May 4 |
awarded | Popular Question |
|
Apr 30 |
awarded | Good Answer |
|
Apr 29 |
awarded | Nice Answer |
|
Apr 25 |
awarded | Necromancer |
