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14

What you describe in your question is the "Copenhagen interpretation" of quantum mechanics. There are more nuanced views of this nowadays that don't treat "measurements" quite so asymmetrically, see e.g. sources that talk about decoherence. I recommend watching the classic lecture "Quantum Mechanics in your face" by Sidney Coleman for a nice take on this ...


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 ...


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 ...


9

Assuming that the incoming "first" particle is prepared in a pure state, interaction with another particle does seem necessary. Such an interaction might simply be the spontaneous emission of a photon or other particle by the original incoming particle, however. Most importantly, such an interaction is not itself sufficient. For a measurement event to ...


8

Interactions merely involve a correlation developing. For example, if an electron is put through a Stern-Gerlach apparatus, a correlation develops between the distance travelled in the x direction and the distance deviated in the y direction. It is reversible. The measurement which occurs when the particle hits the photographic plate is irreversible. It ...


8

I basically agree with Argus, though I take a slightly different perspective. Physicists try to explain the world by constructing mathematical models to approximate it. The phrase mathematical model can sound mysterious, but it just means an equation or equations that predict what's going to happen given some initial conditions. For example Newton's laws of ...


6

First of all, the big desert hypothesis isn't in contradiction with – isn't a competitor of – the seesaw mechanism for neutrino masses. Quite on the contrary, assuming a big desert between the electroweak scale and the GUT scale is the most natural way to be sure that the small seesaw terms in the neutrino masses are the dominant ones that matter. The seesaw ...


5

QM is often called counterintuitive, but by itself, that doesn't mean much; many things get called counterintuitive, for diverse reasons. It seems the real question here is, how often does QM get called "counterintuitive", with an implication that there's something about it which you just shouldn't try to understand. I say something, because obviously ...


5

There's a prescription by Deutsch for the quantum mechanics of closed timelike curves. It works on the level of density states, instead of Hilbert space states. Given his prescription, he showed that a fixed point solution always exists no matter what the initial conditions are. However, this solution isn't unique in general. Also, pure states can be ...


4

Much has been covered in these answers, but one aspect has been left out. The actual physics going on in any measurement process includes amplification. Feynman thought this was significant. Here is a perhaps little-known quotation of his: We and our measuring instruments are part of nature and so are, in principle, described by an amplitude function ...


4

The wave function is a solution of an equation. It is as subjective and as objective as all mathematical solutions to equations describing physical fields, whether classical or quantum mechanical. Certainly as a solution it is objective, a formula written on paper. Subjectivity enters in the choice of the equation to be solved and thus the choice of the ...


4

Simple Answer: Nothing is guaranteed 100%. (In life or physics) Now to the physics part of the question. Soft-Answer: Physics uses positivism and observational proof through the scientific process. No observation is 100% accurate there is uncertainty in all measurement but repetition gives less chance for arbitrary results. Every theory and for ...


3

"Collapse the waveform" is a loaded term, that would not be agreed to by all physicists. There are a great many "no-collapse" interpretations out there in which there is no special role for measurement that directly alters the wavefunction. There are also collapse-type interpretations in which the collapse happens more or less spontaneously, as in Roger ...


3

I think that Wolfram is arguing that the study of cellular automata and perhaps similar computational systems could serve as an organizational principle, providing a coherent framework to look at different problem (just like the more familiar frameworks provided by physics and chemistry). This explains the title of his new book, A new kind of Science (i.e. ...


3

The first report of non-baryonic matter that I know was Evidence for Detection of a Moving Magnetic Monopole, Phys. Rev. Lett. 35, 487–490 (1975). However I'd guess you were thinking of more conventional dark matter candidates, and the first remotely credible publication I know of was the DAMA experiment. I should add that neither experiment is viewed as a ...


3

Much of how you answer this question comes down to your view of the wavefunction or state. If you think that the quantum state is a state of reality (that is, an ontic state), then you must either reproduce the predictions of orthodox (Copenhagen) QM without the measurement postulate or you must explain why nature provides two forms of evolution. The former ...


3

My two lepta on this mainly conceptual and semantic problem: It seems that people have an initial position/desire: those who want/expect/believe that measurements should be predictable to the last decimal point and those who are pragmatic and accept that maybe they are not. The first want an explanation of why there exists unpredictability. An ...


3

The wave function is not an observable, so you can characterize it however you want. However, any alternative explanation you want to put forth must agree with experimental reality, which in the end will mean it must be mathematically equivalent to the usual approach and will accordingly have some object that is isomorphic to the wave function. That makes ...


2

The indeterminism does not originate from Quantum Mechanics. It has a wider philosophical origin. For example, consider the multi-world interpretation of quantum mechanics. It is a completely deterministic theory which describes unitary, reversible and predictable evolution of a quantum system or the Universe (Multiverse in terms of MWI) as a whole. But ...


2

It is the case that all measurements proceed via the exploitation of the natural interactions that we understand theoretically. But once the measurement is completed and the result in hand, the QM analysis of the subsequent evolution of just those systems that yielded that particular result can no longer employ the original state function (which allows for ...


2

Because we can't actually go back in time to test the idea behind this question, what you're asking in some sense boils down to a question of what theory you really believe governs the universe. According to the mathematics of QM, if you run experiments backwards in time (mathematically, of course), you only recover your starting state if you do not ...


2

No (understandable/explainable) physical quantity could be infinite. "Infinity" is is physically very vague. When we say something is "infinite", it almost means we're throwing our hands up in despair that we can't explain something, or that quantity doesn't make sense in some particular framework. The whole point of physical quantities (observables) is to ...


2

This is a philosophical question so here is a philosophical answer. The scientific method in based on repeated observations and experiment. The whole science is just a collectivist instrument of acquiring knowledge. Being an instrument, it has its own limitations. Among them are: The tools employed by science are built by humans. As such, all tools use ...


1

The reason you can not prove things in real life, as apposed to in mathematics, is that you can not check your theory for all variables x and t. For example, you can not test that the theory of gravitation holds everywhere in the universe (it will take an almost infinite amount of experiments). And you especially can not prove that it holds at every moment ...


1

The mechanism of choice in one particular instant of a quantum-mechanical experiment is unknown in all physics today - it's just that this fact for many physicists is too uncomfortable to accept or to admit. Einstein couldn't accept it, Bohr and Feynmann admitted it though. The question leads us to the never ending Bohr–Einstein debates. A fundamental ...


1

That goes with the epistemic, ontic or complete interpretations of the quantum state. By the way the options are: .-only one pure quantum state corrrespondent/consistent with various ontic states. .-various pure quantum states corrrespondent/consistent with only one ontic state. .-only one pure quantum state corrrespondent/consistent with only one ontic ...


1

You might want to read about Bohmian mechanics. Bohmian mechanics is perfectly deterministic. The reason randomness appears is explained in the same way as the appearance of randomness in thermodynamic equilibrium. Here's some further reading with links to several papers at the bottom of the page: http://plato.stanford.edu/entries/qm-bohm/#qr


1

You can never be certain of anything, except possibly mathematical theorems. This is the conclusion after long debates on epistemology. The ancient Greek skeptics were of the opinion that knowing the uncertainty of everything will give you peace of mind.


1

The philosopher David Hume pointed out induction can never be proven. Even if we have some proposed "law" describing everything we know so far, there is no guarantee the next observation will completely violate it. The world might not be what we think it is. There could be some malicious demon messing with our minds.



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