
Do electrons think? (1949) - benryon
https://quantumlifescience.wordpress.com/2014/04/10/do-electrons-think-erwin-schrodinger-bbc-1949/
======
crazygringo
Note that, contrary to popular understanding, it isn't even established that
quantum mechanics is indeterminate or not subject to strict cause-and-effect.

It's indeterminate according to the mainstream Copenhagen interpretation, but
de Broglie–Bohm theory [1] ("pilot wave theory") is an interpretation that is
entirely deterministic, and its assumptions result in exactly the same final
equations as the Copenhagen one. But every particle always has a definite
position+momentum and there's no notion of wave collapse or philosophical
trickiness of what constitutes an "observer". For more on the historical
reasons why Copenhagen became mainstream and de Broglie-Bohm didn't, see [2].

[1]
[https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory](https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory)

[2] [http://qr.ae/TUNXvC](http://qr.ae/TUNXvC)

~~~
jmcmichael
In this instance, the popular understanding corresponds to the latest research
better than realist theories like pilot-wave theory. Proponents of realist
interpretations of QM have relied for decades on identifying possible
classical channels of relativistic communication, or theorizing the existence
of hidden variables.

The double slit experiment has been used in various forms to, over time,
eliminate these channels. I'm not a physicist, but the language that they are
using quite a few papers leads me to believe that these channels have been
closed, and the realists are out of remaining options for maintaining realism.

For instance:

 _An experimental test of non-local realism_ , 2007

[https://arxiv.org/abs/0704.2529](https://arxiv.org/abs/0704.2529)

Wherein the authors show, using previously untested correlations between two
entangled photons, that maintaining realist interpretations of quantum
mechanics (such as pilot-wave theory) as a fundamental concept require the
introduction of locality-defying 'action at a distance' actions.

 _Quantum erasure with causally disconnected choice_ , 2012

[https://arxiv.org/abs/1206.6578](https://arxiv.org/abs/1206.6578)

Wherein the authors, using an interferometric quantum eraser experiment,
eliminate past and future communication channels by enforcing Einstein
locality via a mechanism that I don't understand yet. They conclude that, "No
naive realistic picture is compatible with our results because whether a
quantum could be seen as showing particle- or wave-like behavior would depend
on a causally disconnected choice. It is therefore suggestive to abandon such
pictures altogether."

 _Experimental non-classicality of an indivisible quantum system_ , 2011

[https://arxiv.org/abs/1106.4481](https://arxiv.org/abs/1106.4481)

I understand even less of this one, looks like it has to do with performing
the kinds of simultaneous measurements of various properties that one would
expect to be able to, if realist interpretations were true. They conclude,
"Not only is a single qutrit the simplest system in which such a contradiction
is possible, but, even more importantly, the contradiction cannot result from
entanglement, because such a system is indivisible, and it does not even allow
the concept of entanglement between subsystems."

UPDATE:

 _Experimental loophole-free violation of a Bell inequality using entangled
electron spins separated by 1.3 km_ 2015

[https://arxiv.org/abs/1508.05949v1](https://arxiv.org/abs/1508.05949v1)

"For more than 80 years, the counterintuitive predictions of quantum theory
have stimulated debate about the nature of reality. ... In the past decades,
numerous ingenious Bell inequality tests have been reported. However, because
of experimental limitations, all experiments to date required additional
assumptions to obtain a contradiction with local realism, resulting in
loopholes. Here we report on a Bell experiment that is free of any such
additional assumption and thus directly tests the principles underlying Bell's
inequality. ... This result rules out large classes of local realist theories,
and paves the way for implementing device-independent quantum-secure
communication and randomness certification."

I'm not aware of any significant challenges to these studies.

~~~
testvox
Why do you think this disproves pilot wave theory?

> Physicists also compulsorily reject Bohm’s construction because it
> explicitly builds nonlocality into its framework—even though violations of
> Bell’s inequality have conclusively shown that the stage of our universe is
> nonlocal. This is perplexing. Nonlocality is unavoidable in any theory that
> recovers the predictions of quantum theory. Therefore, any criticism of a
> theory that displays Nature’s nonlocal feature in an obvious way is both
> unfounded and counterproductive. Despite this, Bohm’s inherent explication
> of nonlocality continues to be obnoxiously mistaken as a strike against it
> instead of for it.

~~~
codethief
> even though violations of Bell’s inequality have conclusively shown that the
> stage of our universe is nonlocal

They have not. What they have shown is that the universe cannot be local _and_
deterministic at the same time.

~~~
tezthenerd
Bell's theorem rules out locality even for non-deterministic theories as well.
Don't get determinism and realism confused...

~~~
codethief
I might not be using the same definitions as you are or maybe I'm getting
something mixed up, so I'd be glad if you could elaborate on what exactly you
mean by "determinism", "realism" and especially "locality".

(In my book, the Copenhagen interpretation is a non-realistic(∆), non-
deterministic and local theory, which would contradict your statement.)

(∆) Assuming, of course, that the wave function is _not_ an object of reality,
as I think is standard.

~~~
tezthenerd
Many would argue that Copenhagen is not local, but its very hard to even
define locality if you are genuinely non-realist about _everything_.

Regardless, if it was possible to be "local + non-deterministic" many of us
would be fine with that. But its not - Bell rules out "locality + realism",
regardless of whether the realistic theory is deterministic or non-
deterministic.

~~~
codethief
> Many would argue that Copenhagen is not local

Who? I believe the point of view that the Copenhagen interpretation is local
is the standard one.[1]

> but its very hard to even define locality

How so? There are various definitions of locality—in terms of no faster-than-
light transmission of information, in terms of commutators of field operators
at spacelike distances vanishing as well as in terms of C* algebras—and the
Copenhagen interpretation fulfills them all.

> if you are genuinely non-realist about _everything_

I'm being non-realist only about things whose existence we can't prove, e.g.
the wave function.

> Regardless, if it was possible to be "local + non-deterministic" many of us
> would be fine with that. But its not - Bell rules out "locality + realism"

I don't see how this disproves anything of what I said. While I think you're
right[2] about the fact that the violation of Bell's inequality rules out
local realism—irrespective of determinism—, I already said that, in my book,
Copenhagen is not a realistic theory because the wave function is not an
object of reality.

[1]:
[https://en.wikipedia.org/wiki/Principle_of_locality#Copenhag...](https://en.wikipedia.org/wiki/Principle_of_locality#Copenhagen_interpretation)

[2]: _" However, Fine's theorem shows that, this deterministic assignment of
properties is not required to prove Bell's theorem. This is because the set of
statistical distributions for measurements on two parties, once locality has
been assumed, are independent of whether or not determinism is also assumed."_
([https://en.wikipedia.org/wiki/Principle_of_locality#Local_re...](https://en.wikipedia.org/wiki/Principle_of_locality#Local_realism))

~~~
codethief
s/realistic/realist, sorry for the typo.

------
MichaelAO
Interesting interview with Basil Hiley (collaborator with David Bohm) on this
topic:
[https://www.youtube.com/watch?v=wayQn0uVIvE](https://www.youtube.com/watch?v=wayQn0uVIvE)

------
beautifulfreak
I wonder if anyone here would be so kind as to explain Schrodinger's argument.
I'm not grasping it. Is he making a fundamental point about the degrees of
freedom an electron can have, delimiting ideas about how a brain can process
thought with the help of self-willed electrons? Or is it confined to whether
an electron itself can have thought. What point is he making in the debate
about whether humans are automata? I'll read it again, but it's subtle and I
might not understand quantum mechanics sufficiently to understand it.

~~~
Tomminn
He's saying that just because the movements of particles are not predictable
doesn't mean you all of a sudden get to claim "free will"\-- the ability to
somehow impose an arbitrary desire in the chain of causality between your
sense experiences and your actions. In order for you to have "free will" in
this classical sense, you'd have to control the "slit" the electrons "swerve"
through. But you don't. They just act randomly. They're not the things that
impose your will. Your will is still an illusion.

------
panic
I wonder what Schrödinger would have thought of the Free Will Theorem:
[https://arxiv.org/pdf/quant-ph/0604079.pdf](https://arxiv.org/pdf/quant-
ph/0604079.pdf)

~~~
effie
I think he would not like it. The theorem is underwhelming and uses misleading
attention-seeking terminology. A more appropriate way to state it is, I think,
this: if experiment settings violate determinism, its results have to violate
determinism as well. To the author's credit, they say as much in the
introduction themselves - "I saw you put the fish in".

------
mentos
If electrons are the lowest level of granularity when it comes to determining
state in computers then maybe it is the same in the mind?

I imagine a computer made of silicon with the trillions of grooves that the
mind has in biological form would find itself to have a conscious just the
same. Remove the silicon from the computer or biomass from the brain leaving
just electrons behind and you would have a network I would argue gives rise to
the seat of consciousness.

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edem
From what I understand "seeing" is an active proccess, since it needs light.
If we want to observe small things we need more precise light, which means
more energy. The problem is not that small particles are somehow become aware
when we observe, but the observation itself adds energy to the system, thus
alters it. Is this correct?

~~~
stephengillie
"Observing" means entangling with photons which have previously been entangled
with the observed object. Thus, viewing an object means changing its state in
such a way that you're temporarily also part of its state, forming an entropy
gradient to gain energy/information from it.

~~~
IAmGraydon
That is completely incorrect.

------
Koshkin
[Meta] A light, hard to read shade of gray. (Never understood why would anyone
want to do that to the reader.)

~~~
stephengillie
HN uses the same poor text contrast to highlight unpopular opinions.

------
macmac
No.

~~~
amelius
From the article:

> To think that such a particle can think is so absurd, that I might give the
> answer “No” and have my talk over. However, (...)

