Wednesday, January 16, 2019

Atomic laws are not deterministic

Evolutionist Jerry Coyne is on a free will rant again:
[Scott] Aaronson thinks there’s a real and important question in the free-will debates, but argues that that question is not whether physical determinism of our thoughts and actions be true, but whether they are predictable. ...

What I meant was “physical determinism” in the sense of “our behavior obeys the laws of physics”, not that it is always PREDICTABLY determined in advance. ...

As he says at 4:15, “My view is that I don’t care about determinism if it can’t be cashed out into actual predictability.”

This seems to me misguided, conflating predictability with the question of determinism. ...

What I care about is whether determinism be true. And I think it is, though of course I can’t prove it. All I can say is that the laws of physics don’t ever seem to be violated, and, as Sean Carroll emphasizes, the physics of everyday life is completely known. ...

What I meant was “physical determinism” in the sense of “our behavior obeys the laws of physics”, not that it is always PREDICTABLY determined in advance. ...

I’m doing my best to explain what seems obvious to me: we are material creatures made of atoms; our behaviors and actions stem from the arrangement of those atoms in our brains, and those atoms must obey the laws of physics. Therefore, our behaviors and actions must obey the laws of physics, and are “deterministic” in that sense. We are, in effect, robots made of meat, with a really sophisticated onboard guidance system. I know many people don’t like that notion, but I think that, given the laws of physics, it’s ineluctable.
I have to side with Aaronson here, and wonder what Coyne even means by "the laws of physics".

Of course the laws of physics are not violated. If they were, then they would not be laws of physics. Saying that does not tell us anything about free will.

Saying that we are made of atoms that obey the laws of physics is an odd argument for determinism. Our best theories about atoms are not deterministic.

Carroll has his own problems, as he believes in many-worlds.

Monday, January 14, 2019

IBM announces quantum computer

ExtremeTech reports:
At CES 2019, IBM Research has made what it hopes is a big step in that direction with what it calls the “first fully-integrated commercial quantum computer,” the Q System One. ...

IBM will be adding the Q System One to its arsenal of cloud-accessible quantum computers, first at its existing quantum data center, and at a new one planned for Poughkeepsie, New York. So for those who aren’t Fortune 500 companies with a budget to purchase their own (IBM hasn’t announced a price for the unit, but if you have to ask…), they’ll be able to make use of one. The current version reportedly “only” supports 20 Qubits, so the breakthrough isn’t in processing power compared with other research models, but instead in reliability and industrial design suitable for use in commercial environments.
This computer will be outperformed by your cell phone.

If the computer could actually do anything useful or have any performance advantage, you can be sure that IBM would be bragging about it. If they could achieve quantum supremacy, there would be academic papers and lobbying for a Nobel Prize.

Friday, January 11, 2019

Brian Greene still plugging string theory

Sam Harris interviews Brian Greene in this two-hour video.

Greene is indignant when Harris says that string theory has failed to deliver the goods. Greene says that the theory has made great progress, and has merged gravity and quantum mechanics. The only trouble is that we do not know what that merged theory is, and it has made any testable predictions. That is not much of a criticism, he says, because no quantum gravity theory will ever make any testable predictions.

Someone asked about Bohr saying that physics is about observables. Greene prefers a wider view, and says that physics should look behind the curtain and tell us what is really going on.

So Greene can justify a string theory with no testable predictions.

Greene also defended many-worlds theory and Bohmian mechanics, altho he has not fully adopted them because the measurement problem is unsolved.

Harris points out that Bohmian mechanics is nonlocal, so doing something in one place can have an instantaneous distant effect. Greene agreed, but said that quantum mechanics is nonlocal anyway.

Greene is very misleading here. It is true that in textbook QM, if you make a measurement and collapse the wavefunction, then your knowledge of some distant particle can be immediately affected. You can say that is nonlocal, but classical mechanics is nonlocal in the same way. Bohmian mechanics is different in that it says that an electron is in one place, but its physical effects are in another place. That is a fatal flaw, since no such nonlocality has ever been observed in nature.

And any defense of many-worlds is nutty.

He gives this argument, common among many-worlds advocates, that it is a simpler theory, and thus preferable under Occam's Razor. He gives an example. Suppose a simple quantum experiments results in an electron being in one of two places, symbolized by his left hand and right hand. Suppose you then find the electron in his left hand. Under Copenhagen, you would deduce that the electron is not in his right hand. But that deduction is an extra step, and the many-worlds theory is more parsimonious because it skips that step and posits that the electron is in his right hand in a parallel universe.

It is amazing to see an educated man make such a silly argument with a straight face. The argument really doesn't even have much to do with quantum mechanics, as you could use it with any theory that makes predictions, and concoct a many-worlds variant of the theory that does not make any predictions.

Besides many-worlds, Greene defends physical theories in which anything can happen. If you assume infinite space, infinite time, infinite universes, etc., then pretty much anything you can imagine would be happening somewhere, and happening infinitely many times. In particular, Jesus rose from the dead.

Greene agrees with Harris that humans have no free will. Greene rejects Harris's determinism, but says that the laws of physics have no room for free will.

At least Greene did not go along with Harris's wacky consequentialist vegetarian philosophy.

It is too bad that Physics does not have better spokesmen.

Wednesday, January 9, 2019

Paper argues QM is about determinables

I posted on the characteristic trait of quantum mechanics. Now David Albert wrote a paper with his own novel view:
I distinguish between two conceptually different kinds of physical space: a space of ordinary material bodies, which is the space of points at which I could imaginably place (say) the tip of my finger, or the center of a billiard-ball, and a space of elementary physical determinables, which is the smallest space of points such that stipulating what is happening at each one of those points, at every time, amounts to an exhaustive physical history of the universe. In all classical physical theories, these two spaces happen to coincide – and what we mean by calling a theory “classical”, and all we mean by calling a theory “classical”, is (I will argue) precisely that these two spaces coincide. But once the distinction between these two spaces in on the table, it becomes clear that there is no logical or conceptual reason why they must coincide – and it turns out (and this is the main topic of the present paper) that a very simple way of pulling them apart from one another gives us quantum mechanics.
He presents this as how to teach quantum mechanics, as he says it is the essence of the quantum mysteries.

To explain his artificial examples, he has to use non-local Hamiltonians, and refer to kooky interpretations like many-worlds and Bohmian pilot waves. His whole idea of determinables is based on thinking of particles as existing as points in space.

I don't think his approach helps to understand quantum mechanics at all. I am just posting this as another opinion of how quantum mechanics differs from classical mechanics.

Monday, January 7, 2019

The characteristic trait of quantum mechanics

Erwin Schroedinger introduced the term "entanglement" with this 1935 paper:
1. When two systems, of which we know the states by their respective representatives, enter into temporary physical interaction due to known forces between them, and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives (or ψ-functions) have become entangled. To disentangle them we must gather further information by experiment, although we knew as much as anybody could possibly know about all that happened.
This is an important insight, but I don't agree that this is really "the characteristic trait of quantum mechanics.

How is it that quantum mechanics allows creating systems where we could know "as much as anybody could possibly know", and still leave some questions unanswered?

In order for entanglement to seem so mysterious, it has to be combined with some other quantum mystery.

I have argued here that the the characteristic trait of quantum mechanics is the non-commuting observables.

Sure enough, Schroedinger’s argument in the next few pages depends on non-commuting observables. That is where the quantum weirdness is. It is not so weird that our knowledge of a system could depend on a system with which it previously interacted.

Thursday, January 3, 2019

The Mind Body Problems

SciAm writer John Horgan is plugging his latest book, Mind-Body Problems: Science, Subjectivity and Who We Really Are. You can read it online for free.

It does not actually solve the mind-body problem, but rather tells you about an assortment of characters who are trying.

Check out his website, or an EconTalk interview of him.

Machines appear deterministic (until chaos, at least), while human minds do not. If you believe in the reductionist scientific program, then it should be possible to look at smaller and smaller scales until determinism disappears.

That is exactly what we see, of course. Mechanistic determinism disappears at the atomic level.

When you point this out to anti-free-will advocates, they say you are looking at randomness, not free will. You are supposed to recognize it as random because you cannot predict it.

Isn't that how you are supposed to recognize free will? The hallmark of free will is that someone else cannot predict the action.

One of Horgan's arguments is that the existence of free will is implied by the observation that some people have more of it than others. Okay, I accept that. But then he cites babies as having not very much free will.

No, I think toddlers have more free will than adults. Maybe not newborn babies, but by age 1.5, they make dozens of decisions a day, completely autonomously.

Horgan's main argument is that free will is essential for his entire outlook on life. He has figured out how to dispense with God and religion, but not free will.

Sabine Hossenfelder rips into one of the ideas that Horgan is pursuing:
I recently discovered panpsychism. That’s the idea that all matter – animate or inanimate – is conscious, we just happen to be somewhat more conscious than carrots. Panpsychism is the modern elan vital.

The particles in the standard model are classified by their properties, which are collectively called “quantum numbers.” The electron, for example, has an electric charge of -1 and it can have a spin of +1/2 or -1/2. ...

Now, if you want a particle to be conscious, your minimum expectation should be that the particle can change. It’s hard to have an inner life with only one thought. But if electrons could have thoughts, we’d long have seen this in particle collisions because it would change the number of particles produced in collisions.

In other words, electrons aren’t conscious, and neither are any other particles. It’s incompatible with data.
A comment relates this to an ancient argument:
I think it's interesting to relate it to Galen's argument against atomism. He claimed that (i) atoms cannot be conscious, since they are unchanging, (ii) no combination of unconscious parts can be conscious, (iii) we are conscious. Therefore, we cannot be combinations of atoms.
This issue drew a surprisingly large number of comments, with some defending panpsychism.

Some view consciousness and free will as mere illusions. I think that view degenerates into life being meaningless, but some intelligent folks say it anyway.

If you believe in consciousness and free will, it seems plausible to me that the quantum mechanics of electrons and other particles could play an essential role. Otherwise, consciousness and free will would have to arise in classical deterministic machines, and that is even harder to imagine. I think that Bee has fallen for a version of Galen's fallacy.

Update: Lubos Motl sides with panpsychism. His argument is that if there is human consciousness, and if we are all made of atoms, then those atoms must have tiny bits of whatever consciousness is.