The Universe is Deterministic

[sol invictus]

If I take 1/3x 12 I get a definite number. BUT if I divide 1 by 3 FIRST and then multiply by 12, I get an indefinite number. Definite/ indefinte - merely a matter of math choice?

You're drawing a distinction that doesn't exist.

.99999.... = 1. There is no difference between them at all. They are just two different notations for the same number.

 

[Tumbleweed]

If the entangled particles involve no communication or sending out of electromagnetic information, how will they comprehend the mechanism using electromagnetism? Doesn't the saying go, it makes no sense to talk about things you cannot measure? So how then do we "measure" or define this effect. It would seem thought experiments would be one way, no electromagnetism needed ( outside of the brain of course). So it makes sense to THINK about the things you cannot measure as opposed to proving them? Do we have to say this is out of the realm of the physicists and in the domain of the math guys who are free to ignore the no communication conundrum, and just make up new math to fit instantaneous events that defy relativity?

 

[ben m]

Question: Once the spin of entangled particles are known, can they be changed?

Once the spins of the entangled particles are known, they are no longer entangled; obviously you can do whatever you like to either of them.

 

[ben m]

If the entangled particles involve no communication or sending out of electromagnetic information, how will they comprehend the mechanism using electromagnetism? Doesn't the saying go, it makes no sense to talk about things you cannot measure? So how then do we "measure" or define this effect. It would seem thought experiments would be one way, no electromagnetism needed ( outside of the brain of course). So it makes sense to THINK about the things you cannot measure as opposed to proving them? Do we have to say this is out of the realm of the physicists and in the domain of the math guys who are free to ignore the no communication conundrum, and just make up new math to fit instantaneous events that defy relativity?

a) Who said anything about electromagnetism? That's completely irrelevant.

b) Who said this is something you can't measure? You can do all kinds of experiments on entanglement---the "entangled" oddities appear when you *compare* data from two end stations, and they really do appear. The only thing you can't do is perform the comparison faster than light.

c) Most physicists, including me, escape the "conundrum" (if indeed there is one) by subscribing to the Many-Worlds interpretation, in which it's not the slightest problem, rather than the Copenhagen interpretation in which it's weird-but-experimentally-consistent.

 

[martu]

If I take 1/3x 12 I get a definite number. BUT if I divide 1 by 3 FIRST and then multiply by 12, I get an indefinite number. Definite/ indefinte - merely a matter of math choice?

Convert all your numbers to base 3 and what do you see?

 

[Xulld]

http://philsci-archive.pitt.edu/archive/00000948/00/HiddenDeterminismus.pdf

1 Determinism Does not Deal with Predictions
A large part of the difficulty with the “determinism versus indeterminism” debate lies in the failure to define the terms of discussion clearly. Many physicists and philosophers do not make the important distinction between determinism and the concept of predictability, and thereby commit a category mistake by claiming that determinism implies the possibility of prediction the future course of the universe. For example, Max Born considers the distinction between determinism and predictability as hairsplitting and completely superfluous.1 He maintains that classical point mechanics is not deterministic since there are unstable mechanical systems which are epistemically not predictable. I think the following remarks by John Earman are appropriate:2
“The history of philosophy is littered with examples where ontology and epistemology have been stirred together into a confused and confusing brew. . . . Producing an ‘epistemological sense’ of determinism is an abuse of language since we already have a perfectly adequate and more accurate term – prediction – and it also invites potentially misleading argumentation – e.g., in such-an-such a case prediction is not possible and, therefore, determinism fails.” That is, determinism does not deal with predictions. Nevertheless, ontic descriptions are often confused with epistemic ones.3 In the philosophical literature there are many examples for such category mistakes. For example Rudolf Carnap says: “Causal relation means predictability.”4 Likewise, Karl Popper maintains: “Scientific determinism is the doctrine that the state of any
closed physical system at any future instant can be predicted.” 5 Physicists
drop similar careless assertions. For example Leon Brillouin: “The Poincar´e
discontinuities correspond to conditions where prediction is actually impossible
and determinism cannot exist.”6

This is a good start we must realize that prediction have NOTHING to do with determinism, indeterminacy, or even causation at all. Causation is ontic, predictions are epistemic. Categorically wrong to compare the two.

2 Terminology and Basic Concepts

In order to set the stage for my discussion, I introduce some definitions and notions I will use in the following. Determinism: First of all, determinism will be taken to refer exclusively to ontic descriptions, and should not be confused with statements concerning our knowledge or beliefs. In particular, according to the definition adopted here, determinism does not to imply predictability. Both, predictability and retrodictability have their proper place only in the framework of epistemic descriptions. Causal relations: A process within which one event is a necessary condition for another event is described by a causal relation. The producing event is known as the cause and the event produced as its effect. A causal relationship is an irreflexive, antisymmetric and transitive binary relation between two events.
That is:
• no event can be the cause of itself;
• if a is the cause of b, then b cannot be the cause of a;
• if a is the cause of b, and b the cause of c, then a is the cause of c.
Causal ordering: A causal nexus requires some universal order. A fundamental
issue is the relation of causality to time. According to David Hume
causal relations have three components: contiguity of time and place, temporal priority of the cause, and constant conjunction.7 For Hume “all inferences from experience . . . are effects of custom, not of reasoning”,8 so that according to Hume’s view the idea of cause and effect is not a matter of fact but a mental habit of association, that is, essentially subjectively fabricated. Hume’s characterization implies that causal and temporal arrows are related by definition. Yet, this merging of the two very different ideas of causal order and temporal order is conceptually not sound. Moreover, it precludes many logical possibilities, like a backward causation, or a time-independent ordering of the causal
nexus.
Arrowless time in physics: If one wants to characterize causal ordering by
temporal ordering, then one has first to introduce temporal direction. Yet, the
generally adopted first principles of physics do not distinguish the future from
the past. First principles are characterized by high symmetries. A corresponding physical law is said to be fundamental if it is as independent as possible of any particular context. For example, we assume that the laws of nature are the same all the time and everywhere.
The assumption that there is neither a favored point of the origin nor a
preferred direction in time and space is a basic symmetry postulate required in
in all fundamental physical theories. Since a fundamental theorem by Emmy
Noether theorem implies a deep connection between symmetries and conservation laws, the idea that fundamental laws should be characterized by high symmetries is not just an aesthetic concept.9 For example, Noether’s theorem requires that the time-translation symmetry implies and is implied by the conservation of energy. In fundamental physical theories the basic dynamical laws are not only taken as a time-translation-invariant but also as time-reversalinvariant. In the mathematical jargon we say that a fundamental dynamics is given by a time-translation-invariant and time-reversal-invariant one-parameter group of automorphisms of the underlying mathematical structure.
If we consider the time-reversal symmetry as primary, then there is no ordering so that we cannot use the concepts of cause and effect. In such a formulation of physics all reality is already pre-existent, and nothing new can come into existence. In order for time and causality to be genuinely active, some degree of freedom is necessary to provide a mechanism by which the events “come into being”. Without breaking the time-reversal symmetry nothing new can ever arise. Within special contexts a spontaneous breaking of this symmetry is possible, so that the direction of time has to be considered as contextual.

 

[martu]

If the entangled particles involve no communication or sending out of electromagnetic information, how will they comprehend the mechanism using electromagnetism? Doesn't the saying go, it makes no sense to talk about things you cannot measure? So how then do we "measure" or define this effect. It would seem thought experiments would be one way, no electromagnetism needed ( outside of the brain of course). So it makes sense to THINK about the things you cannot measure as opposed to proving them? Do we have to say this is out of the realm of the physicists and in the domain of the math guys who are free to ignore the no communication conundrum, and just make up new math to fit instantaneous events that defy relativity?

All you need to know is this - for an entangled pair of particles one will always have the opposite spin to the other one. No information is transferred between them but if you measure the spin of one you know the spin of the other. That's it.

Consider a machine that pumps out two balls and all we know is that one ball will always be red and the other will always be blue. If we catch the blue ball we know that if someone catches the other ball it has to be a red ball. We don't have to see the other ball to know this or 'tell' the other ball it is red.

 

[Ziggurat]

Back to pi and its indeterminate nature. If I cut a string and define its length as either the diameter or circumference of a circle there is no way that I can cut a string to get an exact complimenting circumference or diameter.

To the extent that you can cut anything exactly, yes, you can indeed do this. Limitations are purely physical (how stretchy is your string? How sharp are your scissors? etc), and have nothing to do with the nature of pi.

 

[INRM]

According to what I read in the wikipedia article it investigated the principle of complimentarity, and the results of the experiment claimed to violate or disprove it.

Part of complimentarity is the Heisenberg Uncertainty principle

 

[Reality Check]

According to what I read in the wikipedia article it investigated the principle of complimentarity, and the results of the experiment claimed to violate or disprove it.

Part of complimentarity is the Heisenberg Uncertainty principle

This is your original post

What about the Afshar Experiment?

That experiment involved them able to measure the energy state and velocity/location of the particles at the same time, which AFAIK kind of defeats the whole Heisenberg uncertainty principle.

The points that sol invictus made (in expanded form) were the Afshar experiment

• can be interpreted in various ways and so does not "kind of defeats the whole Heisenberg uncertainty principle".
• did not "measure the energy state and velocity/location of the particles at the same time".

 

[Tumbleweed]

Let's see if I have quantum tunneling down concept wise. Imagine hydrogen atoms bouncing against each other. They can never merge because like charges repel, and the closer they get the stronger the repulsion, and so helium cannot exist according to classical physics. So if you picture a hydrogen atom trapped in box with other hydrogen atoms surrounding the box, the sides of the box represent an infinite force of repulsion- an asymptote of sorts- as the atom nears them. Hence the atom can never escape the box and unite with other atoms. . But when the atom in the box is represented as a wave function and then collapsed by bouncing a photon off of it, it can and does appear as a particle on the outside of the box -outside the asymptotes - and hence helium. So quantum tunneling in a sense is a way of overcoming seeming unsurpassable asymptotes on a graph
And since this is taking place at a very high temp in the sun, photons are bouncing off of wave function atoms all the time, collapsing the function and creating particles.

 

[Ziggurat]

Let's see if I have quantum tunneling down concept wise. Imagine hydrogen atoms bouncing against each other. They can never merge because like charges repel, and the closer they get the stronger the repulsion, and so helium cannot exist according to classical physics.

No. Nuclear forces overcome electric forces at short range, even classically. The relevant fact about tunneling in terms of fusion is not that fusion is prohibited classically, but that the required energies to overcome the potential barrier are much higher, and thus fusion rates would be much lower, without any quantum tunneling through the barrier.

 

[ben m]

Let's see if I have quantum tunneling down concept wise. Imagine hydrogen atoms bouncing against each other. They can never merge because like charges repel, and the closer they get the stronger the repulsion, and so helium cannot exist according to classical physics. So if you picture a hydrogen atom trapped in box with other hydrogen atoms surrounding the box, the sides of the box represent an infinite force of repulsion- an asymptote of sorts- as the atom nears them. Hence the atom can never escape the box and unite with other atoms. . But when the atom in the box is represented as a wave function and then collapsed by bouncing a photon off of it, it can and does appear as a particle on the outside of the box -outside the asymptotes - and hence helium. So quantum tunneling in a sense is a way of overcoming seeming unsurpassable asymptotes on a graph
And since this is taking place at a very high temp in the sun, photons are bouncing off of wave function atoms all the time, collapsing the function and creating particles.

Sorry, Tumbleweed, I concur with Zig in that that's almost entirely wrong. Even in the classical picture, fusion obviously doesn't involve getting two protons infinitely close together---which would, classically, require an infinitely strong force---since the fused nucleus has a finite, nonzero size. Your statements about wavefunction collapse and photons and whatnot are entirely wrong and irrelevant to fusion.

Fusion is not a good place to learn about quantum tunnelling. Why not start with the Wikipedia article on Quantum tunneling?

 

[Tumbleweed]

No. Nuclear forces overcome electric forces at short range, even classically. The relevant fact about tunneling in terms of fusion is not that fusion is prohibited classically, but that the required energies to overcome the potential barrier are much higher, and thus fusion rates would be much lower, without any quantum tunneling through the barrier.

Okay, I stand corrected about fusion. But fusion is being caused by quantum tunneling as well as classical physics, correct?. Any ratio?

 

[ben m]

Okay, I stand corrected about fusion. But fusion is being caused by quantum tunneling as well as classical physics, correct?. Any ratio?

It sounds like you're saying "sometimes the particles get over the fusion barrier classically and sometimes by tunneling". Sorry, this is still not quite right. It's a quantum-mechanical process by nature. As an approximation you can describe fusion by pretending that there's a classical potential barrier that the incoming particle has to exceed. As a second approximation, you can probably pretend that there's a classical potential barrier that the incoming particle either has to exceed or to tunnel through. But in reality there's no classical potential barrier, there's a separation-dependent wavefunction overlap which is completely quantum-mechanical all the time.

You could probably go through the quantum calculation and hand-pick some criterion for whether a given bit of phase space was or was not "classical" fusion, but I doubt that there's a unique such criterion, and I strongly doubt that there's anything interesting about the numbers you get out.

ETA: OK, some Googling suggests that the latter approximation---a classical barrier that a projectile can tunnel through---is more interesting than I expected, at least for heavy ion fusion (and fission). Search for "sub-barrier fusion"

 

[Paul C. Anagnostopoulos]

No, the grad student on Mars cannot tell what, if anything, has happened on Earth. The only way the Mars observer can interact with this electron's spin is by collapsing its wavefunction. Collapsing the wavefunction does not tell you whether you are collapsing from a pure state or from a superposition. Unfortunately for sci-fi authors, the Earth-measurement's only effect is on exactly the one thing you can't measure---taking a measurement on Earth snaps the Mars particle out of its superposed state and puts it in a pure state. But this is utterly undetectable to you.

What about quantum teleportation? It gets around this problem because Alice performs an operation on her qubits, transmits classical information to Bob, and then Bob performs an operation on his qubit based on that classical information. At no point does Bob have to detect a wavefunction collapse.

Is that right?

~~ Paul

 

[ben m]

What about quantum teleportation? It gets around this problem because Alice performs an operation on her qubits, transmits classical information to Bob, and then Bob performs an operation on his qubit based on that classical information.

Yes, that's something you can do. What problem do you think it gets around, and how does it get around it?

 

[Elf Grinder 3000]

The definition of deterministic here means - (more or less) if you observe a system in a particular state you cannot predict a future state with 100% certainty, based on QM.

This is a dumb question but this doesn't seem like that is what the novice means when they ask "is the universe deterministic". I think this is what confuses people when they say the universe is non-deterministic they think it means events can just happen without any explanation. But QM doesnt mean things just happen correct without cause?

The other question is really is if we have a system at state A is it only possible to be in State B at a future time. We might not be able to predict state B with 100% certainty, but... is there only one state possible given state A. That is what people probably mean when they think of determinism.

If an event is triggered by another event does it mean that there is only one possible event given a state, even though we cannot predict it?

Sorry if you already answered this question and I missed it.

 

[Perpetual Student]

Let's place 10 unstable particles (e.g.: neutrons) with a half-life of a few minutes in a row before us so that we can number them 1, 2, ... 10. Call this situation "state A." Now there is no science that can tell us which of these particles will decay first, second, or third, etc. It is my understanding of QM that it is not true that our sceince is not yet adequate for the task; it is actually the case that there is absolutely no underlying basis for the order of decay. After a few minutes when (about) half of the 10 particles have decayed, we can call this "state B."
We know that State A can give rise to several states other than B in the same time frame. How then can there be any case for the universe being deterministic?

 

[Elf Grinder 3000]

Let's place 10 unstable particles (e.g.: neutrons) with a half-life of a few minutes in a row before us so that we can number them 1, 2, ... 10. Call this situation "state A." Now there is no science that can tell us which of these particles will decay first, second, or third, etc. It is my understanding of QM that it is not true that our sceince is not yet adequate for the task; it is actually the case that there is absolutely no underlying basis for the order of decay. After a few minutes when (about) half of the 10 particles have decayed, we can call this "state B."
We know that State A can give rise to several states other than B in the same time frame. How then can there be any case for the universe being deterministic?

State A is the 10 nuetrinos and State B is 8 nuetrinos left. You might not know which one will be left. But this doesnt matter because it does not have to do with determinism - the way we are defining it and the way that the OP probably meant.

A "force" causes #4 and #7 of the 10 nuetrino's to "decay". But since everything happens for a reason - something must have caused the 2 nuetrinos to decay. And something caused the force so it was determined by the previous force.

So although QM says you cannot predict with 100% accuracy which 2 or 3 etc.. nuetrinos will decay. This does not show that the universe is not deterministic.

Because the 2 that actually end up decaying did so because of some force, they did not "just happen" for no reason. So there was one outcome that was "determined" by some force and the universe is deterministic not non-deterministic. That is if you assume that everything is caused by some force/reason etc..