Determinism - a scientific or a philosophical position?

[Beth Paulkey]

Which one is it? If it is a scientific theory, what is the evidence that the universe is completely deterministic? If it's a philosophical theory (which would make it a metaphysical one I suppose), what are the arguments for it?

Does any physicist today hold a strict deterministic theory?

Thank you.

 

[Stimpson J. Cat]

Beth,

Which one is it? If it is a scientific theory, what is the evidence that the universe is completely deterministic? If it's a philosophical theory (which would make it a metaphysical one I suppose), what are the arguments for it?

Does any physicist today hold a strict deterministic theory?

That depends on what you mean by "deterministic". If you are using the mathematical definition of the term, then it is metaphysical, because no observation can distinguish between acausal determinism and non-determinism*.

Most people simply mean causality when they talk about determinism, though. Under that definition, it is a falsifiable theory, and thus scientific. Unfortunately, it has been falsified.

The Universe is not temporally causal, which is to say that there are events which are not, and cannot, be caused by the conditions prior to the event.

As for mathematical determinism as a metaphysical position, there are no logical arguments for it, or against it. So long as there is no evidence, it is blind speculation, and there is no logical reason to think it is one way or the other.

*Such a distinction is not possible according to our current understanding of the laws of physics. It is possible, at least in principle, that this could change. Future scientific theories might provide for some way to test whether the Universe is mathematically deterministic or not.

Dr. Stupid

 

[Soubrette]

Stimpy

Could you give me an example of an event that cannot be caused by the conditions prior to the event?

Thanks

Sou

 

[Stimpson J. Cat]

Sou,

Could you give me an example of an event that cannot be caused by the conditions prior to the event?

Sure, the decay of a neutron into a proton.

It has been empirically verified that quantum event (like nuclear decay) cannot be described in terms of deterministic local variables. This means that either they are random, or they can be described in terms of non-local deterministic variables.

If the latter is the case, then they cannot be caused by prior conditions. If they are caused by anything at all, there will be inertial frames in which the effect precedes the cause (due to special relativity).

Dr. Stupid

 

[Soubrette]

Thanks Stimpy

And apologies for lowering the tone of this thread but what's the difference between a local determinic variable and a non-local one?

Sou

 

[Stimpson J. Cat]

Sou,

And apologies for lowering the tone of this thread but what's the difference between a local determinic variable and a non-local one?

Local is defined in terms of special relativity. A local variables scenario is one in which all observable phenomena are functions of some set of underlying deterministic quantities which obey special relativity. That means that an event at point A can only affect something at point B after a period of time has elapsed, equal to the time required for light to travel that distance.

In different inertial frames, distances and elapsed time periods change. But even so, if the system is "local" in one inertial frame, it will be local in all inertial frames. Under such a scenario, special relativity is obeyed, and causality makes sense.

In a non-local scenario, an event at point A can affect something at point B before that minimal time has elapsed. This means that in some inertial frames, an event at A could actually affect something at point B before it even happened. In other words, causality goes out the window.

Incidentally, this is also why faster than light travel would make travel backwards in time possible.

Dr. Stupid

 

[hammegk]

Sou:

Could you give me an example of an event that cannot be caused by the conditions prior to the event?


Sure, the decay of a neutron into a proton.

It has been empirically verified that quantum event (like nuclear decay) cannot be described in terms of deterministic local variables.

Although we might also add "according to current understanding & theory". Of course science may eventually better describe the TOE (what-is) that is Truth and if so, who knows. Tachyons, gravitons, what the heck!

Re non-locality

If they are caused by anything at all, there will be inertial frames in which the effect precedes the cause (due to special relativity).

At least the science will still be ok since the correlation will still be there....

 

[Stimpson J. Cat]

hammegk,

It has been empirically verified that quantum event (like nuclear decay) cannot be described in terms of deterministic local variables.
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Although we might also add "according to current understanding & theory". Of course science may eventually better describe the TOE (what-is) that is Truth and if so, who knows. Tachyons, gravitons, what the heck!

No. I have no doubt that our scientific theories will continue to change over time, but any new theories must still be consistent with what we have already observed. Special Relativity isn't just a theory, it is an observed phenomena. Non-locality implies[/b] acausality. It is that simple.

If they are caused by anything at all, there will be inertial frames in which the effect precedes the cause (due to special relativity).
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At least the science will still be ok since the correlation will still be there....

What correlation? The lack of correlations is exactly why we do not assume that there is a deterministic process at work, non-local or otherwise.

Dr. Stupid

 

[Jeff Corey]

At the micro level, as I understand that quantum effects are possibly indeterminant, at least so far. But at the macro level, causality, and hence, determinism, has had robust confirmation. The only quibbling about that has dealt with human behavior. Free willy, and all that.
So, without further adieu, how about it agin?
Is our behaviour determined or could I have spelt behavior correctly?

 

[hammegk]

What correlation? The lack of correlations is exactly why we do not assume that there is a deterministic process at work, non-local or otherwise.

Well, I thought it was funny. Past-future, cause-effect, which comes first, reference frames, and yet, viola! Correlation!.

 

[neutrino_cannon]

At the micro level, as I understand that quantum effects are possibly indeterminant, at least so far. But at the macro level, causality, and hence, determinism, has had robust confirmation. The only quibbling about that has dealt with human behavior. Free willy, and all that.
So, without further adieu, how about it agin?
Is our behaviour determined or could I have spelt behavior correctly?

This would be my understanding as well, and it would seem to me that the only reason anybody would care would be because of philisophical positions.

Why would causality seem to rule at marco levels which would seem to be ruled by the level lower down? Because of probability, and the enourmous amount of interactions at the basal level of reality, whatever that might be.

And how could you tell an extremly complex system from a totaly random (or somewhat random one) if you didn't know exactly how it worked? I see no way to ascertain whether the universe is at heart random or ordered, and since there is not enough evidence either way (at the universe's basal level), it would seem a position either way is philisophical rather than scientific.

 

[Tez]

At the micro level, as I understand that quantum effects are possibly indeterminant, at least so far. But at the macro level, causality, and hence, determinism, has had robust confirmation. The only quibbling about that has dealt with human behavior. Free willy, and all that.
So, without further adieu, how about it agin?
Is our behaviour determined or could I have spelt behavior correctly?

Well Jeff, to quibble with your quibble, I disagree that at the macro level (local) causality has had robust confirmation. For a start, one can only claim that it has had confirmation only over time periods short enough and measurements coarse grained enough that the nonlinear (chaos theory) amplification of our (quantum theory) indeterminedness becomes irrelevant. Secondly, how big is macro? Does a superconducting current in a SQUID which is several millimetres (fractions of an inch ) count as micro??

Basically we can only say that determinism works as an approximation under certain physical conditions we understand reasonably well. This is hardly going to allow us to probe very deeply into the problem...

 

[hammegk]

..... I disagree that at the macro level (local) causality has had robust confirmation. For a start, one can only claim that it has had confirmation only over time periods short enough and measurements coarse grained enough that the nonlinear (chaos theory) amplification of our (quantum theory) indeterminedness becomes relevant.

Shouldn't that be "irrelevant"?

Secondly, how big is macro? Does a superconducting current in a SQUID which is several millimetres (fractions of an inch ) count as micro??

Isn't superconductivity "deterministic", in that set the conditions correctly and, yup, it superconducts? (BTW, a small fraction of a millimeter sounds plenty macro to me.)

 

[Tez]

Shouldn't that be "irrelevant"?

yep - thanks.

[B}
Isn't superconductivity "deterministic", in that set the conditions correctly and, yup, it superconducts? (BTW, a small fraction of a millimeter sounds plenty macro to me.) [/B]

Well squids are the superconducting equivalent of the two-slit interferometer which is usually used as a paradigm example of quantum indeterminism. But of course thats only true if you do the single particle versions, so in fact youre right. I guess one has to do an experiment where the squid current is measured in such a way that it causes a non-deterministic collapse, which at the moment I cant really see how to do as something thats convincingly "macroscopic". So I'll concede that point...

 

[sorgoth]

Wait wait............................

Effect before Cause? ...Explain, please.

 

[Dymanic]

I'm going to challenge the central premise of the OP, and offer this quote by Daniel Dennett (the philosopher):

Scientists sometimes decieve themselves into thinking
that philosophical ideas are only, at best, decorations
or parasitic commentaries on the hard, objective
triumphs of science, and that they themselves are
immune to the confusions that philosophers devote their
lives to dissolving. But there is no such thing as
philosophy-free science; there is only science whose
philosophical baggage is taken on board without
examination.

 

[Guest]

Determinism (and its opposite) is pure philosophy.


----
The Universe is not temporally causal, which is to say that there are events which are not, and cannot, be caused by the conditions prior to the event.
----


List 17 such events.

 

[Stimpson J. Cat]

Whodini,

The Universe is not temporally causal, which is to say that there are events which are not, and cannot, be caused by the conditions prior to the event.
----

List 17 such events.

Is that supposed to be a joke?

Dr. Stupid

 

[Interesting Ian]

Which one is it? If it is a scientific theory, what is the evidence that the universe is completely deterministic? If it's a philosophical theory (which would make it a metaphysical one I suppose), what are the arguments for it?

Does any physicist today hold a strict deterministic theory?

Thank you.

No physicists are determinists. But that's not important or interesting. The real question you should be asking is whether the idea that all change in the world can be described by physical laws is a scientific or philosophical one. If all change in the world can be described by physical laws, then that contradicts libertarian free will as all our behaviour follows physical laws and we do not have the freedom to break out of such physical laws.

Obviously the question of whether all change in the world can be described by physical laws is a philosophical one.

 

[Stimpson J. Cat]

Ian,

Obviously the question of whether all change in the world can be described by physical laws is a philosophical one.

How so? If there is anything in the world that cannot be described by physical laws, then all you would have to do to falsify the hypothesis that all change in the world can be described by physical laws, would be to observe such a thing.

That means that the hypothesis that all change in the world can be described by physical laws, is a falsifiable hypothesis. That makes it a scientific question.

Of course, you could always argue that there are some non-observable things that exist, but which cannot be described by physical laws, but this is irrelevant. I could say the same about any scientific theory. You can always postulate that a hypothesis is false, but in such a way that it could never be demonstrated to be false. So what?

Dr. Stupid