# Tag Info

32

I only see these writings now, since usually I ignore blogs. For good reason, because here also, the commentaries are written in haste, long before their authors really took the time to think. My claim is simple, as explained umpteen times in my papers: I construct REAL quantum mechanics out of CA like models. I DO have problems of a mathematical nature, ...

30

I can tell you why I don't believe in it. I think my reasons are different from most physicists' reasons, however. Regular quantum mechanics implies the existence of quantum computation. If you believe in the difficulty of factoring (and a number of other classical problems), then a deterministic underpinning for quantum mechanics would seem to imply one of ...

28

You're right; the Schrödinger's equation induces a unitary time evolution, and it is deterministic. Indeterminism in Quantum Mechanics is given by another "evolution" that the wavefunction may experience: wavefunction collapse. This is the source of indeterminism in Quantum Mechanics, and is a mechanism that is still not well understood at a fundamental ...

26

First of all, "loopholes" is no disrespect. It's standard nomenclature. Given a law, a "loophole" is a way to circumvent it. Bell's inequalities, in their mathematical formulation, are laws that prevent superdeterminism, so if we believe it should exist, we have to find loopholes in the assumptions. It might be that the loophole is so big that the whole law ...

20

The idea of my latest paper is simple. I experienced in other blogs that most people refuse to go with me all the way. I'll give my argument step by step and you may choose where you want to step out. Consider superstring theory, in its original, completely quantized version. Many people believe it might have something to do with the world we live in. It ...

19

I'll briefly respond to these critics in the order I read them. To Mitchell: Since I reconstruct ordinary QM, I can make any state I like, including EPR states, GHZ states or whatever. At the level of the CA, most of these states will be blurred to some extent, and they contain complex phases that may seem to be physically meaningless. But, well, that's ...

16

While NKS came out with much hype, and with a lot of skepticism from scientists, the scientific ideas there are not completely trivial. I just think they are not foundational for the science of physics (at least not as we know it so far), rather they are foundational for the science of biology. The main discovery made by Wolfram (although with an important ...

16

The alien doesn't really see our future. He's still seeing our past, but a more recent past than he did before. Assuming that the alien is 100 light years away when he starts cycling then he is seeing what happened to us 100 years ago. If he "cycled" fast enough (i.e. at an appreciable percentage of the speed of light) so that he was now only 50 light ...

16

There are a few ways to answer your question, and I will try to list some of them. According to Quantum Mechanics, and due to the Heisenberg Uncertainty Principle, we cannot predict the future state (position and momentum) of any system. Given the state of a system in classical phase space $(\textbf{r}(t_0), \textbf{p}(t_0))$, we cannot determine the state ...

15

A deterministic universe need not be predictable. And even a deterministic universe not hampered by any limits to observability need not be predictable. As an example take a toy universe consisting of an infinite chain of $0$'s and $1$'s. This 1D cellular universe evolves according to cellular automata rule-110: the state of a cell becomes $1$, unless the ...

15

This question was studied fairly recently by a team at Edinburgh University. Their paper is available here, though I'm not sure if you can get it without having to hand over some cash. The bottom line is that in principle the trajectory of a die can be calculated, but it is a chaotic system and that means tiny inaccuracies in the measured initial conditions ...

15

You are misunderstanding the Uncertainty Principle. The Uncertainty Principle says that a particle cannot simultaneously have a definite momentum and a definite position. This is not due to our incomplete knowledge of parameters. This is a fundamental law of the universe and arises from the fact that the momentum and position operators do not commute in ...

15

Wolfram's early work on cellular automata (CAs) has been useful in some didactical ways. The 1D CAs defined by Wolfram can be seen as minimalistic models For systems with many degrees of freedom and a thermodynamic limit. Insofar these CAs are based on a mixing discrete local dynamics, deterministic chaos results. Apart from these didactical achievements, ...

14

This could have been a comment, but as it actually anwers the question asked in the title, I'll post it as such: As far as I can tell there's no rational reason to dismiss these models out of hand - it's just that quantum mechanics (QM) has set the bar awfully high: So far, there's no experimental evidence that QM is wrong, and no one has come up with a ...

14

The idea of superdeterminism is not really about free will. Free will is a concept that is very hard to define in a logical-positivistic way. If you don't believe me, try to define it! If you can't say exactly what you mean by a notion, in terms of "If I do this and that, what happens?" then it is not clear that the notion is well-defined. There are many ...

14

First of all, let me start out by pointing out to you that there have been experimental violations of Bell's inequalities. This provides damning evidence against hidden variable models of quantum mechanics, and thus essentially proves that the random outcomes are an essential feature of quantum mechanics. If the outcomes of measurements in every basis were ...

13

Well, yes. In a purely mathematical world where you can specify initial conditions exactly, chaotic systems are fully deterministic. It's not like a quantum system with wavefunction collapse, whose evolution can never be specified exactly by the initial conditions. But in practice, we can never specify (or know) the initial conditions exactly. So there will ...

13

(I apologize if this comment pops up twice, I don't quite understand how it works here) To Ron: Don't worry about the authority issue, It's fine with me if you don't take my authority for granted. But it helps if you look at my papers more carefully. Back to the issue: remember that the true, "ontological" state of the universe is assumed to be one ...

13

You say "ridiculous sounding ideas often end up becoming standards science" - but take into account that "ridiculous sounding ideas" much more often, by a large factor, end up becoming no science at all. I agree that "that form of idealogical bullying should never exist" - except that it's not ideological, but just a practical matter of deciding which ...

12

This is a very general question, and can be answered from several perspectives. I shall try to give an overview so you can perhaps research the areas that interest you a bit more. Firstly, the most fundamental interpretation of probability (as considered by most mathematicians) is Bayesian probability. This effectively states that probability measures state ...

12

Bell's theorems indeed rule out simple theories where hidden variables obey local equations. However, no matter how you reason, it's always at some point where you need another assumption. In its simplest form, it is the assumption that two observers, Bob an Alice, have the "free will" to choose along which axis they will measure the spin of a particle ...

12

We can satisfy your requirement "the photon was emitted at a correct angle" by "the photon was prepared in a momentum eigenstate". If the photon has definite momentum $\bf{k}$, then its direction of travel is well defined, as you have specified. A photon is a discrete excitation of a "mode", i.e. a solution of Maxwell's equations. For a photon in a ...

11

The short answer is that we do not know why the world is this way. There might eventually be theories which explain this, rather than the current ones which simply take it as axiomatic. Maybe these future theories will relate to what we currently call the holographic principle, for example. There is also the apparently partially related fact of the ...

11

Generally, when you make a quantum calculation, you have to make some sort of measurement of the qubits at the end of the algorithm where the result you're looking for is a very probable (but not necessarily certain) result. In any interpretation that actually agrees with the basic results of quantum mechanics, these probabilities will still hold and the ...

11

To Ron: The difference between the automaton states representing a filter in one direction, and a filter that is slightly rotated, is huge, because these systems are macroscopic. Now you might wonder however, whether, in principle, we could be dealing with a device that rotates the filter in response to the outcome of the measurement of some quantum ...

10

To Ron: Maybe we are getting somewhere. You say: "Taking a formal Hilbert space, asserting that one has an unknown ontic state, and then formally defining operators is not justified..." Wait, isn't that what we always do in science in general and in QM in particular? We concoct a model, conjecture an evolution operator, and ask how any initial state ...

10

I think the correct answer is that such models are both quantum mechanical and classical, although this could be considered as a question of semantics. It is a fact that, as soon as you found a basis in your quantum system where the evolution is just a permutation, the "quantum probabilities" for the states in this basis, (as defined by Born's rule) become ...

10

Laplace's determinism is not physically correct over long periods of time. That is, it neglects chaos/"sensitive dependence on initial conditions"/exponential growth of microscopic perturbations already in Newtonian dynamics, which was seriously thought about only in the 20th century. Being true, this also will not be overcome. Stochasticity enters ...

10

I think the following from the wikipedia entry clears up well the terminology: Chaos theory is a field of study in applied mathematics, with applications in several disciplines including physics, economics, biology, and philosophy. Chaos theory studies the behavior of dynamical systems that are highly sensitive to initial conditions; an effect which is ...

10

Classical mechanics is perfectly integrable for two bodies as a closed or isolated system. However, early on it was found that problems existed, where Newton found he could not find a solution for the motion of the planets in a complete form. He made his famous statement that God had to readjust the solar system now and them. Poincare solved the Sweden ...

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