Bell's paradox

The most divisive issue in physics is Bell's inequality. Some say that it is one of the most profound discoveries in the entire history of science. Others say that it is a trivial observation of no great significance.

No Nobel Prizes have been given for any work related to Bell's inequality, altho a Wolf Prize was given in 2010.

Around 1930, Einstein and others thought that quantum mechanics was wrong, and needed a hidden variable theory. Bohr, John von Neumann, and others convinced everyone that hidden variable theories don't work, and that quantum mechanics is correct. The matter has been settled for 80 years.

In 1964, Bell proposed a way to prove that the hidden variable theories do not work. His plan succeeded, and affirmed what everyone had believed since 1930.

Variants of Bell's argument are published frequently. I mentioned one below.

So all Bell's inequality does is to demonstrate the wrongness of some long-discarded idea. It is like finding a new way to disprove the Plum pudding model of the atom, that was popular from 1904 to 1909. A more recent example is below.

Yet, entire books have been written on why Bell's inequality is so profound. I guess their point is that Bell somehow put his finger on what is strange about quantum mechanics, but it is only in comparison to some other (hidden variable) theory that is just as bizarre as quantum mechanics.

The quantum could be real

As mentioned below, a recent paper on quantum mechanics got a lot of attention for supposedly proving something about the reality of wave functions. Holger F. Hofmann (German name, Japanese address) explains precisely what is wrong with it, consistent with what I said here:

In a recent paper (arXiv:1111.3328), Pusey, Barrett and Rudolph claim to proof that statistical interpretations of quantum mechanics do not work. In fact, their proof assumes that all statistical interpretations must be based on hidden variable realism. Effectively, the authors demand from the start that reality must be decided by mathematics, and not by measurements. If this unjustified assumption is dropped, the quantum formalism has a natural statistical interpretation that fully explains the paradox presented by the authors. It is therefore possible to conclude that the paradox actually supports the statistical interpretation, demonstrating once more that quantum mechanics should not be explained by measurement independent realities that are never observed and therefore lie beyond the reach of empirical tests. ...

Although the paper also presents a nice little toy model that certainly has merit as a useful addition to the cabinet of quantum paradoxes, the analysis of the model does not really support the sweeping conclusions drawn fromit. Specifically, the authors merely analyze a hidden variable model, implicitly assuming that any statistical theory of quantum mechanics must also assume a measurement independent reality. ...

The explanations given by Bohr, Heisenberg, von Neumann and many others all assume that (a) quantum mechanics should be interpreted statistically, and (b) hidden variables do not work. ...

I would like to point out that the conclusions presented by the authors actually support the statistical interpretation of the quantum state, once the empirically unjustified assumption of dogmatic realism is dropped. In fact, the authors provide several arguments in favor of the statistical interpretation - mainly, that the collapse of the wavefunction is fully explained and loses its mystery. Likewise, entanglement loses much of its mystery.

That's right. It seems as if there is always some physicist arguing that some particular hidden variable theory does not work, and claiming that he has discovered something profound about quantum mechanics being contrary to reality. No, saying that hidden variable theory does not work has been conventional wisdom since 1932. That is what Einstein was complaining about in the 1930s, as well as Bohm and Bell later.

The faulty assumption is indeed that "reality must be decided by mathematics, and not by measurements." From that assumption, they claim to prove that there is no reality. But another possibility is that there is an objective physical reality, but we don't have a good mathematical representation of it. Quantum mechanics gives us a good mathematical theory of measurement, but there is no proof that all physical entities are amenable to our mathematical models.

Different philosophies of reality are possible, as there are different interpretations of quantum mechanics. But it is inexcusable to promote some particular view as being correct, because some hidden variable theory is wrong, without even mentioning the orthodox view that was proposed in 1925 and accepted in 1932. That 1932 view is still tenable today.

Twin paradox video

NewScientist has a new video explaining the relativity twin paradox in one minute.

The paradox is actually due to Paul Langevin in 1911. It should not be so surprising because a similar age difference occurs without relativity. In any realistic space travel scenario beyond our solar system, humans would have to be frozen to withstand the long travel times or the rapid acceleration. Frozen bodies do not age. So a space traveler returning from a long-distance trip would always be much younger than his twin back home.

Relativistic explanations get confusing when you ask whether the acceleration is causing the aging difference. The answer is yes in the sense that the acceleration defines the asymmetry between the twins, and without accelerating one twin back into the frame of the other, you would never notice the aging difference. But time dilation is caused by velocity, not acceleration. Understanding the effect of acceleration on clock synchronization is part of the paradox.

No other sentient life

The WSJ reviews a recent book, Alone in the Universe: Why Our Planet Is Unique by John Gribbin:

The author's conclusion: Earth is the sole abode of intelligent life in the galaxy, the product of a profoundly improbable sequence of cosmic, geologic and climatic events—some thoroughly documented, some inferable from fragmentary evidence—that allowed our planet to become a unique refuge where life could develop to its full potential.

Chief among these, paradoxically, was a near-cataclysmic planetary collision during Earth's infancy, which gave birth to the moon. Such encounters were relatively common in the harum-scarum chaos of an early solar system that teemed with veering planets and asteroids. In its suicidal blow against our world, the Mars-size impactor generated enough heat to liquefy both itself and Earth's exterior. Its dense, metallic core plunged inward to join our planet's existing metallic center, while the rest swept up part of the fiery terrestrial shell to form the moon.

One consequence of Earth's tumultuous youth was the thinning of its rocky crust. This has provided the planet with a lively tectonic existence, complete with vapor-spewing volcanoes, continents that divide and drift, and an ecologically advantageous global-temperature-regulation system. Earth's swollen metallic core remained liquid; its constant churning gives rise to electrical currents that generate a far-flung magnetic cocoon that shields us from dangerous solar particles. (The creation of Eden is far more complex than one might have heard.)

Another fortuitous coincidence on Mr. Gribbin's checklist is the moon's large size relative to Earth, a ratio unique in the solar system. Without such a gravitational partner to restrain the disrupting tugs of the sun and Jupiter, our planet might suffer paroxysms of axis-tilting. (Try to run a civilization when your once-temperate hemisphere suddenly heels over to an Arctic orientation.) Mr. Gribbin outlines how a series of climate-altering Ice Ages and tectonic shifts benefited human ancestors roaming the grasslands of East Africa. ...

Mr. Gribbin admits the possibility —even probability—that elementary life forms have arisen elsewhere in the galaxy. But the object of his scientific and statistical scrutiny is intelligent extraterrestrial life. While he cannot prove a galaxy-wide absence of other civilizations, he presents an array of modern, research-based evidence that renders that conclusion eminently reasonable.

I agree with this. Between science fiction stories and astronomy news, most people probably have the view that the scientific evidence favors the increased likelihood of sentient life on other planets. But there is a lot of evidence to the contrary, and I believe that it is likely that we are the only intelligent life in the Milky Way galaxy.

There are many other galaxies, and this leaves the possibility of sentient life in other galaxies. But even those science fiction stories do not suggest communication with other galaxies.

Einstein book finds new readers

Einstein just showed up on the NY Times list for ebook nonfiction bestsellers:

10 OUT OF MY LATER YEARS, by Albert Einstein. (Open Road.) A collection of essays from the years 1934-50 address social, religious and educational questions.

Einstein was an embarrassment during this period. He was a Communist fellow traveler who actively supported Communist front groups. He had an affair with a Soviet agent who had been sent to compromise him. He claimed to be a pacifist but he supported the development of nuclear bombs as long as the plan was to kill Germans.

He was a secular Jew and a Zionist. He denied believing in a personal God but also denied being an atheist. He identified with the Jewish people more than anyone else.

His scientific writings from this period were worthless. His work on relativity was mostly wrong. His main project was unified field theory, but his papers were nonsense. No one has ever been able to get any value out of anything he wrote on the subject. The hot subject in physics of the day was quantum mechanics, but he never understood or accepted it. The best that can be said of his work of this period is that quantum mechanics was clarified when other physicists explained how wrong Einstein was about the theory.

An Amazon reviewer writes:

Einstein is the greatest modern example of Keynes dictum of how it is 'ideas' that change the world. He is the example of how one man alone, thinking, transformed our understanding of nature, and our power to change it. In these essays the main interests of Einstein's life are touched upon. He writes with clarity and modesty.

No, Einstein did not write with modesty. He was an egomaniac who spent his whole life exaggerating his accomplishments, and scheming to get credit for the work of others.

It is a big myth that created relativity and transformed our understanding of nature by pure thought all by himself. Read my book how this myth is wrong in every detail. His work on relativity relied very heavily on others, and those others followed experiments and influenced the development of physics.

A lot of people read Einstein thinking that he was some sort of unique source of wisdom. Forget it. He wasn't.

Atheists against free will

Leftist-atheist-evolutionist Jerry Coyne writes in USA Today:

You may feel like you've made choices, but in reality your decision to read this piece, and whether to have eggs or pancakes, was determined long before you were aware of it — perhaps even before you woke up today. And your "will" had no part in that decision. So it is with all of our other choices: not one of them results from a free and conscious decision on our part. There is no freedom of choice, no free will. And those New Year's resolutions you made? You had no choice about making them, and you'll have no choice about whether you keep them.

The debate about free will, long the purview of philosophers alone, has been given new life by scientists, especially neuroscientists studying how the brain works. And what they're finding supports the idea that free will is a complete illusion.

He also brags that his fellow atheists agree with him. He says that atheist materialist philosophy requires physical determinism, and neuroscience research says we sometimes start making a decision a couple of seconds before we are consciously aware of it. (He says that brain scans show mental activity as much as seven seconds before a decision is completed.)

If this is depressing, Coyne assures us that there are two advantages to believing that we are mindless automatons; we have an increased appreciation for evolution and we gain empathy for all the other mindless automatons:

There's not much downside to abandoning the notion of free will. It's impossible, anyway, to act as though we don't have it: you'll pretend to choose your New Year's resolutions, and the laws of physics will determine whether you keep them. And there are two upsides. The first is realizing the great wonder and mystery of our evolved brains, and contemplating the notion that things like consciousness, free choice, and even the idea of "me" are but convincing illusions fashioned by natural selection. Further, by losing free will we gain empathy, for we realize that in the end all of us, whether Bernie Madoffs or Nelson Mandelas, are victims of circumstance — of the genes we're bequeathed and the environments we encounter. With that under our belts, we can go about building a kinder world.

No thanks. Those are not advantages to me. But ignoring the moral, religious, and psychological issues, my concern here is whether there is really proof of physical determination. It is a strange assumption considering that the overwhelming consensus among physicists is that the world is not deterministic. They say that probabilities are essential to quantum mechanics. Those probabilities do not necessarily settle the free will question; see the Free will theorem for a discussion.

Einstein did not believe in either quantum mechanics or free will. He was a determinist. Most physicists say that he was proved wrong.

I accept quantum mechanics, but I deny that it requires either a probabilistic or determinist view. It says nothing about free will. I think that it disproves Coyne's argument that a scientific worldview requires denying free will. Quantum mechanics is our most fundamental physical theory, and it does not require the sort of determinism that Coyne describes.

Update: Coyne now complains about new proposed laws about the teaching of evolution, because he sees them as a threat to his view of evolutionary science.

No unobservable superstructures are real

Lubos Motl writes:

What I finally want to emphasize is that all this redundant and "objectively real but totally unobservable" superstructure – from many worlds to extra invisible Bohmian positions of particles (which can't help in the case of spin or particle production, anyway) or other hidden variables to GRW collapses prescribed from above – is only being invented because certain people behave as bigots who are unable to admit that the physics research in the 20th century has irreversibly falsified all intrinsically classical models of the reality. All the new "fanciful stuff" with tons of choices and processes (superluminal communication, preferred frames, collapses, the length scale to which the GRW collapses shrink the wave function, the frequency of such flashes etc.) that can never be observed and with the infinite amount of fine-tuning and obfuscation that is needed for it to fake the real, relativistic quantum world (to guarantee that none of the new predictions is really observed) is only being proposed because some people's bigotry has no limits. Their dogmas about "realism" are more important for them than any amount of empirical evidence, more important for them than everything that science has actually found.

People, those bigots who are still denying that the insights of quantum mechanics inevitably force one to be careful about the positivist, instrumentalist principles and that forces us to understand science as a gadget to organize our observations rather than to promote the idea about an "independent real world": give up, apologize, shut up, and calculate!

I would not call them bigots, but it is a little strange that physicists are so bent on promoting a concept of reality that requires a totally unobservable superstructure. If that is what people mean by realism, then I am not a realist.

I go farther than Motl and say that quantum mechanics is a positivist theory. You can believe in many worlds interpretation if you want, but it is not part of quantum mechanics. I also say that probabilities are not part of (positivist) quantum mechanics. Probability is just one of those unobservable superstructures that has been tacked on to the theory to make people feel better. It has no scientific validity.

The probabilities give a way of thinking of waves as particles, but they do not help predict observations. Not directly, anyway. The realists would rather think about particles than waves. It seems to me that the realists ought to be willing to accept whatever is necessary, and the electrons are certainly not particles in the ordinary sense of the word. They are subject to Heisenberg uncertainty, and do not have definite positions and momenta.