2,895 reputation
1325
bio website staff.science.uu.nl/~hooft101
location Utrecht, Netherlands
age
visits member for 2 years, 10 months
seen Jan 20 at 23:07

Theoretical physicist, Utrecht University.

University Professor. Elementary particle physics, quantum gravity, black holes, quantum mechanics.

Won some prizes (such as the nobel prize 1999), but please don't hold that against me.


Sep
7
comment Why do people categorically dismiss some simple quantum models?
@user7348: No, quantum field theory as it stands has causality built in; for that, it is sufficient to demand that all commutators vanish outside the light cone. This guarantees that no signal ever will go faster than light. So qft obeys relativity and has ordinary qm particles in its non-relativistic limit. Everything is fine, no problem with relativity, until you try to understand what the ontology is. You have to remember that spacelike correlations are fine if you can explain them in terms of intial states in the past.
Sep
6
comment Why do people categorically dismiss some simple quantum models?
If you repeat an experiment, or do it many times, you therefore can't modify one observable without affecting an other one, somewhere, somehow. It is difficult to understand how this happens, you have to remember that the vacuum surrounding us is a very complicated entangled state. All this is the real reason why Bell may be violated in the CA. So I ignore Bell, and in that case qm (rather: qft) is local.
Sep
6
comment Why do people categorically dismiss some simple quantum models?
@ user7348: I do not accept Bell's theorem that easily. It is difficult to see exactly what happens, but it is crucial that all CA observables at all times commute. After my unitary mapping, therefore, only observables that are orthogonal to each other are uniquely defined in terms of CA variables. Now, since the mapping is complicated, these observables are different every time you do an experiment. Therefore we can have counterfactual observables that do not commute.
Sep
6
comment Why do people categorically dismiss some simple quantum models?
@ drake: I don't know what theories you talk about. In my theory, obtained from a local mapping from a local CA, the only non-locality is over a small number of lattice sites. Further away, all commutators outside the light cone do vanish.
Sep
6
comment Does any particle ever reach any singularity inside the black hole?
Your theory about leaving the black hole alive is not going to hold up at all, it's wild guesses that would create totally unnecessary conflicts with everything we do know about black holes. Simple thermodynamical arguments tell us that, in the real world, the only thing that can get out of a black hole is Hawking radiation. Astronauts would be suppressed by gigantic Boltzmann exponentials. The classical story would have you come out in some other universe; that's against any thermodynamical law so with hbar, it won't happen, even there.
Sep
6
comment Does any particle ever reach any singularity inside the black hole?
Mass is defined asymptotically, yes, but the mass term always comes in the combination $Mr$, so when $r\rightarrow-\infty$, where the angular part of the metric goes as $r^2$, you have to replace $r$ by $|r|$ to see what happens. So $M$ goes to $-M$. Look up the Penrose diagrams in Hawking and Ellis for example. And look up the Kerr metric (too long for these "comments"). If you do AdS/CFT you are doing quantum, and you won't avoid thermalization. Only the classical theory would seem to allow you to get out, God knows in which universe.
Sep
6
comment Does any particle ever reach any singularity inside the black hole?
You were talking of rotating black holes. If they don't rotate the negative $r$ region is closed off by a singularity. But if the holes rotates, you can get at $r<0$ because the singularity is only at the equator - you need to take a northern or southern route, also to avoid the region with closed timelike curves (at small negative $r$ and large $\sin^2\theta$. I'm talking of the Kerr and Kerr-Newmann metric (necessary for rotation).
Sep
5
comment Does any particle ever reach any singularity inside the black hole?
And then, sorry, but the location of a horizon is a function of the $r$ variable, not $t$, so after passing that second horizon you will enter into the negative $r$ regime. The coordinates $r$ and $t$ do interchange, in the sense that, between the two horizons, $t$ becomes spacelike and $r$ timelike. But does the BH get opposite spin? Please think: how did you define the spin direction, in which coordinates? The statement is empty.
Sep
5
comment Does any particle ever reach any singularity inside the black hole?
@Ron I'm afraid you were saying some more incorrect things: you "believe" that the observer comes out in the same universe. But what will he (it) look like? Quite likely is that the observer will not be noticed by the other inhabitants in his (former) universe since he turned into Hawking radiation. All modern theories say that the best he could do is give some subtle twists in the Hawking particles of the same BH that he entered. He (it) turned into a ghost.
Sep
5
comment Why do people categorically dismiss some simple quantum models?
For many physicists, this is all that matters, also in the 1960s. I presume Einstein did think of something like hidden variables. 2: WITH Hidden variables, Bell claims that the hidden variables are non-local, but what he really means is that the Ansatz equation that he starts with cannot be satisfied. My claim is that in a superdeterministic scenario that equation cannot hold, even if the evolution laws of a CA are local.
Sep
5
comment Why do people categorically dismiss some simple quantum models?
@user 7348: 1: if you don't care about hidden variables, quantum mechanics as it is, or more precisely quantum field theory, is entirely local. Locality means that if we have, in the Heisenberg notation, two field operators depending on space-time: $Op_1(x_1,t_1)$ and $Op_2(x_2,t_2)$, then they must commute if $(x_1,t_1)$ and $(x_2,t_2)$ are completely space-like separated. This holds for QFT and even (in spite of claims to the contrary) for string theory (if two points are spacelike separated in target space, they also are so in the world sheet - assuming we may ignore certain projections).
Aug
30
comment Why do people categorically dismiss some simple quantum models?
OK let me correct that last statement. Some pseudo-non-locality can enter in two ways: 1: the description of the vacuum state as a superposition of CA states. The vacuum makes discussion of Bell's inequalities very difficult in CA. 2: There are good reasons for imagining information loss to occur in the CA. You can still map that onto a quantum system (with full CPT invariance), but that mapping leads to holography and apparent non-locality.
Aug
30
comment Why do people categorically dismiss some simple quantum models?
They even don't violate locality, since the QFT has commutators that always vanish outside the light cone. It could be that there is some rudimentary non-locality in the mapping, but I have not really encountered that yet.
Aug
30
comment Why do people categorically dismiss some simple quantum models?
Superdeterminism is obviously there, if you care to give it some thought. Now, when people talk of "conspiracy" they really mean that they don't understand the result. But you can understand it this way: the CA can be treated as a fully grown quantum system, as a QFT. This QFT leads to correlations that look like conspiracy. Hence this apparent conspiracy is there. Don't be afraid of spooks. Mathematically, there's nothing wrong with them, just a bit difficult.
Aug
29
comment Why do people categorically dismiss some simple quantum models?
@user7348, Do you mean those pilot waves? I think these are ugly concoctions, but I do agree that they show that there is a possibility in principle. I think that elegance and plausibility will be important assets of a healthy theory. I can't make working field theories using Bohm. I am talking about much more fundamental principles. And most importantly: my theory IS quantum mechanics, not an "alternative".
Aug
28
comment Can superdeterminism resolve contextuality, entanglement and Shor's algorithm in quantum mechanics?
It's essential to add interactions, making the CA non-trivial. Only then my arguments make sense. Without that, they also work but it's just formalities and semantics. Interactions turn your CA into a universal computer. You can still "solve" the CA equations but you can't speed them up using, say, renormalization group (RG) techniques, to go to larger time and distance cales. Therefore you would need a computer with Planckian dimensions. That does not exist today.
Aug
28
comment Can superdeterminism resolve contextuality, entanglement and Shor's algorithm in quantum mechanics?
I'd be happy to continue in "chat" but I am not going to waste my time trying to figure out how to do this.
Aug
27
revised In 't Hooft beable models, do measurements keep states classical?
added 698 characters in body
Aug
27
revised In 't Hooft beable models, do measurements keep states classical?
added 698 characters in body
Aug
27
comment Can superdeterminism resolve contextuality, entanglement and Shor's algorithm in quantum mechanics?
That these correlations are "absurd" or "ridiculous" is not a good enough argument to me. The mouse gut, the brain, a flipper machine, they all obey conservation laws such as energy and angular momentum, and the laws of thermodynamics. So they also obey unitarity. There's nothing absurd or ridiculous about that. Just do the CA - quantum mapping.