Heisenberg's Uncertainty Principle and determinism

[riballoon]

TL;DR Summary

Hello everyone,

I was wondering if anyone had any insight to what Heisenberg's Uncertainty Principle says about (super)determinism?

Will determinism forever remain speculative?

As I understand it the principle states that the more accurately you measure one factor of an object, for example speed, the less you can tell of any other factors, for example position. To me this seems we will every only be able to measure an approximation of reality and thus determinism becomes unfalsifiable.

With all this said, I am but a lay enthusiast that barely passed math, so please, any and all insight would be greatly appreciated!

Thanks for your time,
-Riley

 

[phinds]

As I understand it the principle states that the more accurately you measure one factor of an object, for example speed, the less you can tell of any other factors, for example position

First, that is NOT true for just any "other factors", it is only true of complementary characteristics such as position and momentum.

Second, it is not so much about single simultaneous measurements as it is about consistent measurements. What I mean is, in classical physics if you know EXACTLY the initial conditions / setup of an experiment, then you can be confident that the subsequent results of measuring complementary characteristics will always be the same. In Quantum Mechanics, what the HUP tells us is that if you know EXACTLY the initial conditions / setup of the experiment, then when you measure the complementary characteristics you not only do NOT know the what the results will be, you know in fact that they won't be the same over a series of measurements.

 

[phinds]

To give a specific example, classical physics predicts that if you were to fire an electron with a precisely known velocity in a precisely known direction, then you could predict what the position and momentum of that electron would be a microsecond later. But in reality, what the HUP tells us that if you were to fire an electron with a precisely known velocity in a precisely known direction and then measure the position a microsecond later, then the more precisely you were to measure the position, the LESS precisely you would know the momentum. You could perform the same experiment over and over and depending on the precision with which you measured the position, you would get various values of the momentum as specified by the HUP limitations. **

** To be even more precise, you would get a range of the PAIR of values (position and momentum) as specified by the HUP limitations.

 

[phinds]

As a further note, there are approximately 6.3 zillion threads here on PF about the HUP so you could do a forum search (but be warned, some of them will make your head hurt ).

 

[riballoon]

Thanks for you reply! I didn't realize that distinction of complimentary characteristics vs "any" other factors.

So I guess my question becomes, how can one ever know the exact conditions of the setup if one can only measure, to the maximal degree, one of the complimentary characteristics? Will this still not lead to the approximation issue? It seems to me an infinite regress of how to set up exact conditions, especially since particles are not static and the only type of real measurement would be continuous observation?

If I've made some improper assumptions I'd love to know, this does confuse me if determinism turns out to be testable in any practical way.

 

[PeroK]

Summary: Hello everyone,

I was wondering if anyone had any insight to what Heisenberg's Uncertainty Principle says about (super)determinism?

It's clear what the Heisenberg UP says, but it's not clear what superdeterminism says. When superdeterminism has been discussed on here it seems everyone has their own idea about what the superdeterminists claim.

I would turn your question round, therefore, and ask what superdeterminism says about the HUP?

 

[riballoon]

I would turn your question round, therefore, and ask what superdeterminism says about the HUP?

Thanks for the question!

I don't necessarily think superdeterminism says anything for HUP except adding back local hidden variables, and taking away QM's probabilistic results.

I would think that only continuous monitoring of preset unaltering variables would be able to test for superdeterminism, otherwise how can you rule out that your hidden variables have changed from measurement 1 and 2? And how can that be set up in a practical way?

 

[PeroK]

Thanks for the question!

I don't necessarily think superdeterminism says anything for HUP except adding back local hidden variables, and taking away QM's probabilistic results.

That's more what Bohmian mechanics does. That's a legitimate theory in the sense that it includes a full mathematical model.

In order to understand what SD (superdeterminism) says you must understand the concept of correlation, especially in respect of quantum entanglement. SD tries to explain the experimental results that support QM by proposing that all things are correlated in a way that falsely makes QM appear to be true. In that sense, a lot of physicists believe it's not even a valid theory and is possibly just sheer nonsense.

To give an example of a SD theory of gravity. That would suggest that there is no law of gravity. Instead, objects can fall upward or downward. But, we are correlated with them in such a way that whenever we release an object it falls downward. And experimenters are prevented from seeing objects falling upwards, not because they can't, but because their decision to release an object is correlated with the object's decision to go downwards. By this means the law of gravity simply appears to be true. And no one can prove otherwise.

And many people believe that approach to physics is nonsensical.

 

[PeroK]

PS I would refer you to Scott Aaronson for a sane view of superdeterminism from a quantum physicist. I agree with everything he says.

https://scottaaronson.blog/?p=6215

 

[riballoon]

To give an example of a SD theory of gravity. That would suggest that there is no law of gravity. Instead, objects can fall upward or downward. But, we are correlated with them in such a way that whenever we release an object it falls downward. And experimenters are prevented from seeing objects falling upwards, not because they can't, but because their decision to release an object is correlated with the object's decision to go downwards. By this means the law of gravity simply appears to be true. And no one can prove otherwise.

I really don't see why you assume objects "decide" anything as opposed to react to the environment. If there is a sufficient gravitational pull, then the object will gravitate towards it. That does not mean the object chose to obey gravity.

 

[riballoon]

SD tries to explain the experimental results that support QM by proposing that all things are correlated in a way that falsely makes QM appear to be true

This is essentially proposing hidden variables, no?

 

[riballoon]

And experimenters are prevented from seeing objects falling upwards, not because they can't, but because their decision to release an object is correlated with the object's decision to go downwards.

Do you propose that observers observe what the object "decides" to reveal, and not what actually is?

 

[PeroK]

I really don't see why you assume objects "decide" anything as opposed to react to the environment. If there is a sufficient gravitational pull, then the object will gravitate towards it. That does not mean the object chose to obey gravity.

I was illustrating the absurdity of a SD theory of gravity. Not proposing one!

 

[PeroK]

This is essentially proposing hidden variables, no?

No. Bohmian mechanics is a valid hidden variables. Superdeterminism is an unjustified and unsupported theory that asserts that QM only appears to be correct. In other words, as Scott Aaronson says, we have to ignore what experiment is telling us directly and trust the instincts of a few contrarians!

In one respect, superdeterminism is not that different from a capricious god!