Wednesday, July 7, 2010

God as quantum observer

Today we will look at the intersection of quantum nonsense and terrible arguments for God.  How fun!

This argument is based on something Michio Kaku said to Deepak Chopra in an interview. It wasn't very clearly stated, so I'm filling in the blanks.
  1. Quantum mechanics says that things do not exist unless there is an observer to observe them.
  2. The universe exists.
  3. There must be an omniscient conscious being to observe the universe.
  4. That being is God.
 As with most arguments for God, the last step is troublesome, because there are all sorts of things the being could be.  There's no compelling reason to think that the object in question can appropriately be called "God", much less the Judeo-Christian god.  For example, why should we think that it's a single object observing the entire universe rather than multiple objects?  But since Deepak Chopra is not part of any western religion, he would skip step 4, thus avoiding the problem.  Unfortunately for him, the rest of the argument is crap too.

Rebutting the rest of the argument is really an exercise in applying the advice in my presentation on Quantum Mechanics for Skeptics.

Error #1: Elementary misunderstanding of what Quantum Mechanics actually says

According to step 1, things don't exist until we observe them.  This is incorrect.   Observation does not cause things to come into existence, it just causes a mixed state to become a definite state.  For example, if we have an electron in two places at once, and we observe its position, then it "collapses" into a single position.  The electron existed before you observed it.  The mixed state existed before you observed it.

Getting a little more advanced: Even after you observe an object, in some sense it's still in a mixed state.  This is because all states are mixed states.  So even if you mistakenly believed that "mixed state" = "does not exist", then you would be forced to conclude that nothing exists with or without observers.

Error #2: Misunderstanding observers

Step 1 just talks about observers, while step 3 suddenly jumps to conscious observers.  Observers do not need to be conscious.  The chair I'm sitting on functions as an observer.  A piece of white paper functions as an observer.  Anything with enough atoms to be visible to the naked eye probably functions as an observer.  When you realize the banality of observers, it makes much more sense to conclude that the universe is full of non-conscious observers, none of which need be omniscient.

Error #3: Misunderstanding quantum interpretations

This whole time we've been talking about observers.  But observers are specific to one interpretation of quantum mechanics, the Copenhagen interpretation.  Under many other interpretations, there is no such thing as an observer.

The thing is with quantum interpretations, they're all or nothing.  All interpretations make the same predictions.  Therefore, all of them predict God, or none of them do.  If you've formulated an argument that only works for the Copenhagen interpretation, but not for others, then this is a sign that you made an error somewhere.  I already showed errors in the argument, so the problem is resolved.

A summary:
#1: The universe does not need to be observed to exist.
#2: There are probably non-conscious observers all over the universe.
#3: A valid argument would make sense under all quantum interpretations, but this one does not.

I've also heard an argument from quantum mechanics that God does not exist.  It is also a crap argument.  I will cover it next time.


Milan H said...

The crap that people try to pull with the implications of quantum theory is pretty disappointing. In fact, if we were to take their interpretation of God 'observing' everything, than wave functions wouldn't exist. QED, God isn't real! :D

IhateNOAMchomsky said...

This doesn't make sense to me (I came here to debunk on of my friends claims). Can you please clarify this point: You sed something along the lines of anything with enough mass is an observer. But how come the components of the double slit experiment (the material the slits were made out of, ect) and say, the ceiling of the laboratory or lid of the box, didn't act as observers?

miller said...

The slits are not made out of anything. They're just holes in a screen. So they can't act as observers.

The screen is made of something, and can indeed act as an observer. Some photons, rather than going through the slits, will hit the screen instead. And since the screen is an observer, it will hit only one spot on the screen.

valerian texeira said...

I may not agree the ultimate observer to be God (I am not a believer either) however your argument to challenge, riddled with many loopholes.
1. It is not mixed states but wave function collapsing into a definite mater (particle) state. Vast difference between
2. Chair becoming a quantum observer? Hearing it for the first time I am not sure! If the double slit apparatus etc becomes a observer No interference pattern possible at all!
3 Copenhagen Interpretation put forward by the founding fathers of quantum mechanics extremely indeterminist most important among, other interpretations more deterministic like God!

miller said...

Valerian Texeira,

1. It seems that you lost part of this point, since you stopped mid-sentence! In any case, it's been pointed out to me that I've been misusing the term "mixed state". What I should have said is that the wavefunction is in a superposition of multiple eigenstates, and collapses into a single eigenstate (ie a state where the observed quantity has a definite value).

However, when the particle is in an eigenstate of position, it is not an eigenstate of momentum and vice versa. So there's no real distinction between eigenstates and superpositions of eigenstates.

2. As I've explained in a previous comment, the reason the double slit itself does not act as observer is because slits are just empty space.

An observer is any system that is complicated enough that it behaves classically. The biggest quantum system I know of was 40 microns in length, and at temperature 0.1 K. A chair is bigger and hotter than that, and therefore would act as an observer.

3. I am not sure what you are trying to say. QM does not stand or fall on the opinions of its "founding fathers". And there is nothing wrong with a theory having one particular similarity to God.

odrareg said...

You should have invited a quantum mechanics expert already recognized by fellow peer quantum experts,instead of talking all alone, unless you are an already quantum mechanics expert recognized internationally by peer experts.

As the situation stands, you are talking to yourself.


miller said...

I am in fact a quantum mechanics expert, but I don't need to be to write this stuff. Ideally, even non-experts should learn how to recognize quantum nonsense.

odrareg said...

You are a quantum mechanics expert on literature or in actual experiments with quantum mechanics events and its queerness?

I mean you regularly look at the particles and/or waves behaving before your eye even though not directly but through instrumentation?

If you do regularly look at particle and waves behaving before your eye, please tell me what queerness do you observe at any one time with the same physical identical one particle or, say, one wave, like with particle, say, numbered (imaginary number)48774958, or wave?

Forgive me for I am not any quantum mechanics expert at all.

But I am very keen to delve seriously into quantum mechanics queerness, like a particle spinning up and down at the same physical point of time duration and in the same point of space extension occupied by the particle.

Or is the queerness out of sight but is based on a conclusion on human reasoning, grounded on what has transpired before or elsewhere and what is happening actually as witnessed by the eye of the experimenter of quantum mechanics event?

miller said...

"Quantum mechanics" isn't really a field of physics, because it's already well-understood and it's an important part of nearly every field of physics. It's a part of every physicist's undergraduate education. If you seriously want to learn about it, I recommend Griffiths.

I work in condensed matter, which is all about quantum mechanics applied to very large numbers of particles. It's not nearly as straightforward as you're imagining, with looking at particles/waves before my very eyes. But I do in fact shoot lasers at electrons, which are modeled as waves.

To be fair, when I wrote this in 2010, I was not doing research at the time. But this is pretty basic stuff that anyone can understand. I want my readers, who are not necessarily physicists, to be able to recognize quantum nonsense, even if they don't understand modern physics research.

odrareg said...

Thanks for your accommodation.

Please, tell me your experience in regard to my inquiry:

[quote]Forgive me for I am not any quantum mechanics expert at all.

But I am very keen to delve seriously into quantum mechanics queerness, like a particle spinning up and down at the same physical point of time duration and in the same point of space extension occupied by the particle.

Or is the queerness out of sight but is based on a conclusion on human reasoning, grounded on what has transpired before or elsewhere and what is happening actually as witnessed by the eye of the experimenter of quantum mechanics event?

Between you and me, I am a blind man in an alien environment.

In brief, what exactly is the quantum mechanics experimenter seeing with his eye even though already indirectly by instrumentation, and what is his conclusion of what transpired and is still transpiring outside the range of his eye sight?

For I just want to know whether, and forgive me again, in a quantum mechanics event the law of contradiction no longer prevails, and the law of causality no longer prevails, so that in its most grievous transgression, a particle is not a particle, and a particle comes forth from nothing at all and from no agent whatever as its source of existence.

Or, expounders of quantum queerness take liberty with speculation that is not founded on actual reality: even though his contact with reality is already limited to what his eye can only indirectly by instrumentation ascertain what is taking place within his immediate time and space of his observation range, which range is very much circumscribed vis a vis all the scope of existence not captured within his eye range, already only indirectly accessible to his eye through instrumentation.

miller said...

As I said before, if you seriously want to learn about quantum mechanics, you should read a textbook. Or take a course. It's not something you can really learn from a blog.

But if you insist, I have some really old stuff I've written on the topic (1, 2, 3, 4). I don't know if it's any good. Honestly, you may be better off googling it. For instance

In response to specific comments...

Quantum mechanics has never denied the law of non-contradiction. It is possible for a particle to be in a superposition of state X and state Y. Sometimes people say this means it is in state X and state Y at the same time, which sounds like a contradiction. But it's really just a language limitation.

Particles don't come forth from nothing (at least, not in basic quantum mechanics). Rather, there is a particle, and its position is uncertain. But when you measure its position, you get a single value.

miller said...

With regards to the screen or the chair being an observer:

"An obvious question is why one needs to talk about knowledge and minds at all. Couldn’t an inanimate physical device (say, a Geiger counter) carry out a “measurement”? That would run into the very problem pointed out by von Neumann: If the “observer” were just a purely physical entity, such as a Geiger counter, one could in principle write down a bigger wavefunction that described not only the thing being measured but also the observer. And, when calculated with the Schr√∂dinger equation, that bigger wave function would not jump! Again: as long as only purely physical entities are involved, they are governed by an equation that says that the probabilities don’t jump.

That’s why, when Peierls was asked whether a machine could be an “observer,” he said no, explaining that “the quantum mechanical description is in terms of knowledge, and knowledge requires somebody who knows.” Not a purely physical thing, but a mind."

miller said...

Your entire comment is a quote without citation. :-[ Why bother commenting at all?

I disagree with Steven Barr, because the wavefunction cannot be interpreted as an epistemic probability. Look up the PBR theorem. Also look up decoherence, which is the process by which probabilities can apparently "jump" regardless of whether there are observers or not.

miller said...

I am not an expert in this field and my intention of posting that was not to argue for either side, hence the lack of citation. I just put that there to show that there are other experts who are of the opinion that the observer is required to have a "mind". Where people go from these two differing schools of thoughts is up to them, my intention was just to stimulate investigation into why there are experts on both sides. By the way, have either of you heard of the pilot-wave theory? If that one turns out to be correct (albeit in many many decades yet if at all), it would throw a huge spanner to both sides of the argument anyway.

miller said...

There's a problem with that: by not citing the source, nobody even knows that you're quoting an expert!

In any case I strongly disagree with Steven Barr on substantive grounds. Generally his arguments aren't very good and seem to emphasize the opinions of "great scientists" in the 30s. The most important work on quantum interpretations was done in the 50s (e.g. Bell's theorem, decoherence, Bohmian mechanics). It's also unclear what the problem is with writing down a bigger wavefunction, and even if that is a problem, what minds could possibly do to solve it. But no it does not surprise me to hear experts disagree with me; I work with scientists after all.

I know about pilot wave theory (specifically Bohmian mechanics), and well these interpretations aren't things you can prove, exactly. In any case, my argument does not depend on any specific interpretation. What I'm saying is that if you make a claim which is based on a specific interpretation, then your claim must not create empirical differences, because there is no empirical difference between the interpretations.

miller said...

"there is no empirical difference between the interpretations."

I don't know that we should accept this statement a priori. It would be nice to find a real empirical difference between the interpretations, so we could actually test them.

miller said...

Point taken. Oh and here is the article I had in mind when I brought up pilot wave theory, in case you are interested:

miller said...

Well if you find an empirical difference in some sense it's a different interpretation. So the way to "prove" Bohmian mechanics is to really disprove all the major interpretations in favor of a new interpretation, one which is very much like Bohmian mechanics and very unlike MWI or Copenhagen. But yeah I'm all for that.