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3
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1answer
110 views

On a measurement level, is quantum mechanics a deterministic theory or a probability theory?

Quantum mechanics is a non-commutative probability theory. As such, it fundamentally behaves differently from classical probability theories. This manifests itself most pronouncedly in the uncertainty ...
-3
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0answers
39 views

Would it be possible to foresee the quantum theory via this thought experiment?

If the Newtonian understanding of universe (I only mean the philosophical understanding, not the scientific theory) would be correct, then we could build a machine that can observe the solar system ...
1
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1answer
73 views

Ball spontaneously rolling down hill [duplicate]

I'm trying to remember a problem in classical mechanics involving a special surface that allows a ball to roll to the top and lose all it's momentum in finite time. This leads to some interesting ...
1
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1answer
88 views

How is no-conspiracy theory compatible with determinism? [closed]

Bell's theorem states that any physical theory that incorporates local realism and the no-conspiracy assumption cannot reproduce all the predictions of quantum mechanical theory. Hence, we cannot ...
5
votes
5answers
182 views

What is the explanation for the interference patterns in MWI?

In Young's double-slit experiment, MWI states that in some "worlds" the particle goes through one slit, and in others it goes through the other. If this is so, why do we get an interference pattern? ...
0
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1answer
44 views

What causes the universe to manifest a given value upon measurement in super-deterministic theory? [closed]

Bell's inequalities show that we have to give up freedom or local realism. If we give up freedom, we have super-determinism, if we give up local realism, we have free-will. In super-deterministic ...
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0answers
51 views

Quantum mechanics - “God does not play dice” - does he? Or might he not? [duplicate]

I'm a mechanical engineer by training, so please forgive ignorance in my question. Heisenberg's uncertainty principle states (to my understanding) that one cannot measure both position and momentum ...
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2answers
81 views

If I repeated a quantum measurement, would it be the same? [closed]

I was thinking about the probabilistic nature of quantum mechanics and that if I measured the position of an electron twice in succession, the outcomes would depend on a probability. However, what if ...
-1
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1answer
60 views

Equation for everything?

Suppose, I throw a ball and it bounce. If we observe it from the time of it hitting the ground, we can see it moves due to the initial velocity it had and the interaction it had with the ground. We ...
5
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2answers
174 views

“Randomness” versus “uncertainty”

Highly rated PhysicsSE contributor @CuriousOne regularly makes the following claim about quantum mechanics (e.g. here): There is no randomness in quantum mechanics, there is only uncertainty. I ...
0
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1answer
55 views

Shouldn't local realism imply the superdeterminism?

I see that Bell has ruled out Einstein's local realism but not supredeterminism. I see that Bell has confessed that superdeterminism kills his inequality. You cannot apply Bell's inequality if ...
1
vote
1answer
35 views

How to quantify the level of non determinism / randomness in the universe

I recently read a little about the Bell test (I'm not a physicist, but reasonably well educated) and I started wondering if there is a way to express the level of non-determinism as a single number ...
1
vote
1answer
67 views

Would two identical universes evolve identically? [duplicate]

What if there were 2 universes (completely disconnected - not part of the same multiverse) which were identical and a given point in time (say when they first began). Would these 2 universes evolve in ...
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2answers
2k views

Could the randomness of quantum mechanics be the result of unseen factors? [duplicate]

The possibility of randomness in physics doesnt particularly bother me, but contemplating the possibility that quarks might be made up of something even smaller, just in general, leads me to think ...
0
votes
1answer
116 views

What does it mean that an electron's position is described by probability?

I just read an answer to a Phys.SE question about why electrons don't collide with protons where an answering user said: In quantum mechanics, an electron doesn't have a definite position or ...
2
votes
1answer
52 views

Bell's Theorem - Why does $\lambda$ have a probability?

I'm reviewing Bell's theorem. In his proof by contradiction, he assumes the world is deterministic and defines a vector $\lambda$ as the set of all hidden variables which play a role in determining ...
6
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0answers
129 views

Uniqueness of solution in newtonian mechanics

Recently I came across the problem of Norton's dome. I thought of two questions, for which I found no answer. Does there exist a newtonian initial value problem, where the total force on each body ...
1
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1answer
61 views

Quantum physics and determinism [duplicate]

According to classical physics if we know space-time coordinates of every atom in the universe, we can predict the future. But quantum physics introduced probability throwing determinism out of ...
1
vote
3answers
308 views

How can the past, the present and the future coexist at the same time? [closed]

We all heard it many times, the theory of Time suggest it is parallel rather than being linear. This leaves the door opened for alternate realities and well, immortality. However, even after reading ...
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0answers
173 views

Quantum Mechanics in your face

In this lecture Quantum Mechanics in your face by Sidney Coleman http://www.youtube.com/watch?v=EtyNMlXN-sw Does he state that there's only evolution according to Schrodinger's equation in QM and it ...
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votes
1answer
70 views

Probabilistic realism

On consideration of Bell's inequalities and this Why is quantum entanglement considered to be an active link between particles?. Either localism or realism has to be given up. Can't we have a non-...
1
vote
3answers
300 views

Can we predict throwing a dice?

What happens if we throw a dice from same position, with same force, by creating a vacuum environment on earth? Will it be predictable now i.e. will the dice have same results all the time? If answer ...
2
votes
2answers
80 views

Have David Wolpert's findings really “slammed the door” on scientific determinism?

I recently read an article describing how mathematician/physicist David Wolpert's research closed the door on scientific determinism. I have huge doubts about the implied conclusion, considering the ...
3
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4answers
646 views

Is quantum physics truly random or does it just appear that way because of Heisenberg uncertainty principle

The behavior of an electron (and other tiny things) is said to be probabilistic because we can't say where an election will be when we measure it, but only where it will probably be. As I understand ...
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votes
1answer
89 views

Does the uncertainity principle actually attack determinism? [closed]

It's not really clear to me how does QM attacks determinism. It sure attacks computability, which is a component of newtonian, naive determinism, but it's often claimed to destroy determinism itself (...
0
votes
2answers
146 views

Does Bell's theorem exclude local hidden variables as explanation for radioactive decay?

Often it is said that Bell's theorem (and the observed violations thereof) rules out local hidden variable theories as the explanation for the seeming non-determinism found in quantum mechanics. I'm ...
0
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2answers
54 views

Generalised velocities enough to be deterministic in Lagrangian mechanics?

In classical determinism we need to know $2n$ quantities of our system and the equation of motion to predict it's future. In Lagrangian mechanics this is equivalent to knowing $q$ and $\dot q$, the ...
1
vote
1answer
86 views

Does the Heisenberg uncertainty principle preclude moving in a straight path with certainty?

The uncertainty principle is σₓσₚ ≥ 0.5 ℏ where x is position and p is momentum. Consider a 2d plane. If one moves along a straight line along the plane (possibly backtracking or moving forwards but ...
2
votes
3answers
613 views

How do particles “know” when to decay?

So, as I understand it, in a substance that is made of radioactive elements, the half-life tells us how long until the half of those atoms decay into their next atom [is there a name for that: the ...
-1
votes
1answer
92 views

Is there anything random? [duplicate]

Is there (in universe, wherever) anything random? Do we know any event (or whatever else) which has no reason? Of course there are some things that we cannot see, measure but it doesn't mean that they ...
2
votes
1answer
145 views

Deterministic universe for dummies [duplicate]

Is there a general consensus about whether the universe is deterministic? Is it still up in the air? I have attempted to read other physics.stackexchange answers and do some independent research, but ...
0
votes
3answers
190 views

Can universe or anything be simulated with absolute accuracy? [duplicate]

In a simulation everything is known which makes any apparent random event a pre-calculated event. Taking that into account is it possible to simulate the universe with absolute accuracy in a way that ...
3
votes
3answers
222 views

Collisions and time-reversal

Shorter version: I am wondering if non-elastic collisions preserve time-symmetery; i.e., given a set of objects with positions and velocities known at a given time, we can calculate forward in time ...
0
votes
1answer
75 views

Determinism of Quantum Mechanics [duplicate]

I am sorry for the title, which seems to be into the philosophical discussions about reality going random in quantum scale. My aim is to approach the question in a definite and most reasonable, though ...
0
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2answers
68 views

Is there enough information in a given quantum state to determine the state beforehand?

If I knew all the information about a state, and I knew the laws of physics in their complete totality, could I "reverse engineer" it to find, with 100% certainty, the state before it?
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2answers
1k views

Why does the Stern–Gerlach quantum spin experiment conflict with classical mechanics?

My understanding of the Stern–Gerlach experiment is that neutral (0 total charge) particles are sent through a non-homogeneous magnetic field, with the expectation that the field will push that ...
2
votes
0answers
492 views

Are radioactive decays truly random? [duplicate]

By truly random I mean that IF we knew the position and velocity of every particle in radioactive isotope, could we predict when the decay would happen?
4
votes
1answer
80 views

Is the world Markovian according to modern theories (QM, GR, etc.)?

Is the world Markovian according to modern theories (QM, GR, etc.)? According to modern theories, is it true that there is no additional knowledge to be gained from the past for predicting the future ...
1
vote
1answer
89 views

When everything follows strict laws in the universe, where does probability come from? [duplicate]

I am told that we can't predict whether we shall get a head or tail. We can only say that for an unbiased coin there is 50% probability for either. But coin is not case of Quantum Physics! I have ...
1
vote
5answers
500 views

Why are position and velocity enough for prediction and acceleration is unnecessary?

In classical mechanics, if you take a snapshot and get the momentary positions and velocities of all particles in a system, you can derive all past and future paths of the particles. It doesn't seem ...
2
votes
2answers
164 views

Can string theory get rid of randomness in quantum processes?

I am not a physicist, but I am very much into popular science, especially string theory. I would like to know if it is conceivable that string theory might be able to get rid of the randomness ...
3
votes
1answer
85 views

Are there any viable toy models of superdeterministic quantum mechanics?

As far as I know, superdeterminism in quantum mechanics is only considered as a theoretical possibility. Are there any fleshed out superdeterministic toy models so far which isn't nonlocal?
6
votes
2answers
407 views

If entropy is increasing does it mean universe is non-deterministic?

I watched some video where they said entropy can be considered as information. They also stated that universe's entropy is always increasing... Now here comes the problem my IT mind can't understand: ...
1
vote
1answer
143 views

Argument for proving that the universe must be indeterministic [duplicate]

Can there exist an argument that could be used for proving that the universe is indeterministic? If this one seems to be too strict (rigorous), I would also be interested to know a 1-sentence ...
0
votes
0answers
91 views

I don't get the concept of “God plays with dice” - In what scenario is it proven that he does? [duplicate]

Does God Play With Dice? by Stephen Hawking I am no physicists, but I don't get the concept of God playing with dice. Logic shows me that the entire universe is calculated very precisely according ...
0
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0answers
62 views

How can randomness exist? [duplicate]

Apparently radioactive decay cannot is entirely random (I'm just picking something that's currently accepted as random). However, since it's caused by something, if you had the means to do so, surely ...
0
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2answers
261 views

Does quantum mechanics contradict macroscopic determinism?

I am wondering whether it is true to ask whether determinism is still completely viable at macroscopic scales given that the constituent particles behave according to QM when the dimensions get small ...
0
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0answers
74 views

Interesting (new to me) things in the exposition of Landau's book on QM

In section I.1 (The uncertainty principle), a principle I already know, the author suggests a "relaxing" picture (Unusual): "We have defined "apparatus" as a physical object which is governed, ...
3
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1answer
128 views

In QFT, do the fields evolve with determinism, in principle?

In quantum mechanics, the outcomes of a certain measurement might not be deterministic. However, the wavefunction evolves with determinism according to Schrodinger's equation. Is QFT analogous in ...
5
votes
4answers
458 views

Radioactive decay - What mechanism decides when an unstable nucleus decays?

My first question on Stackexchange (if it is formatted wrong or something please tell me so I know in future) - here it is: Given an unstable nucleus (exactly which nucleus is not particularly ...