Impossibility of quantum computers

MIT computer scientist Scott Aaronson is betting that quantum computers are possible, while he concedes that they have not yet been built, while others argue that they are impossible. Now Jo˜ao N. C. Especial has added a comment:

Entanglement is consequently the indispensable resource for relevant Quantum Computation and the viability of such Quantum Computation rests on whether this predicted phenomenon does indeed exist in the real world.

It happens that a terrible mistake has been made in the interpretation of experimental Bell tests (experiments which aim to demonstrate Entanglement): The inequalities used to interpret the experiments’ results did not adequately take into account the non-idealities present in the real experimental setups, and hence, the wrong inequalities were used and the wrong conclusion, that Entanglement had been observed, was drawn.

In fact, when the correct inequalities are used to interpret them, all experimental results to this date are found compatible with local-realism and, hence, no evidence presently exists that Entanglement is a real phenomenon.

Aaronson replies on his blog:

(1) The author never really comes out and says which tests would convince him that entanglement is there. ...

(2) The broader point is that quantum mechanics is a wildly-successful framework that, if it’s wrong at all, has to be replaced by something radically different. Yes, it’s important that physicists continue to perform better and better experimental tests of whatever aspects of QM they can, looking for deviations between theory and experiment. But ultimately, I’d say the burden lies with the people who deny some aspect of QM — whether it’s quantum computing, or something even more basic like 2-particle entanglement — to suggest an alternative picture of reality that recovers QM’s century of experimental successes, but in which the aspect in question doesn’t appear. Indeed, that was precisely the point of my bet: that I’m tired of the “defense attorneys” who think they win if they can raise a single point that the prosecution can’t immediately answer, and who don’t acknowledge any need to offer their own alternative picture of the world.

Yes, QM is wildly successful, and some interpretations say that on the smallest scales the math predicts:

• energy is not conserved
  
• particles go backwards in time
  
• particles can be in 2 places at once
  
• nonlocal action-at-a-distance
  
• entangled qubits
  
• super-Turing computation

And yet none of this is ever observed on a macroscopic level. The closest is that the Bell test experiments are given as evidence for nonlocality, but they have loopholes, and there is no convincing demonstration of nonlocality.

I am one of the “defense attorneys” that Aaronson is tired of. I cannot prove that quantum computing is impossible any more than I can prove that perpetual motion machines, psychic telekinesis, and backwards time travel is impossible. I reject those ideas because they are contrary to common sense, contrary to established science, and because a lot of smart people have spent a lot of time and money on them and failed. Extraordinary claims require extraordinary evidence.

The math of QM involves idealizations that are not meant to be taken literally. Eg, an electron is sometimes a particle and sometimes a wave, according to complementarity. But a particle is not a wave and a wave is not a particle. If you take either the particle model or wave model too literally, you will get some false conclusions. These are just conceptual tricks. The observations are what is real, and QM predicts those well.

The quantum computing enthusiasts cite the wild success of QM experiments, but those experiments do not really justify quantum computing. For that, they resort to extrapolations of those mathematical idealizations that have never been confirmed. But none of those idealizations are real. They are just mathematical shortcuts for explaining observations.

There are experiments that claim dozens of qubits, but there is a Nobel Prize waiting for anyone who can convincingly demonstrate a single qubit.

Aaronson asks what would convince me. All it takes is an experiment that demonstrates a computation that is greater than what is possible with a Turing machine. I don't see much chance of that.

Update: Aaronson just posted a diatribe against Joy Christian, a (male) skeptic about Bell nonlocality, and concludes:

But let’s forget about money for now. Over the past few months, I’ve had a real insight: the most exciting potential application of scalable quantum computers is neither breaking RSA, nor simulating quantum physics, nor Grover’s algorithm, nor adiabatic optimization. Instead, it’s watching the people who said it was impossible try to explain themselves. That prospect, alone, would more than justify a Manhattan-project-scale investment in this field.

Aaronson is saying that he cannot prove that quantum computing has any validity, but he will settle for trying to show that there are flaws in Christian's argument that quantum computing is impossible.

Christian's mathematical models probably are wrong. But Christian being wrong does not make quantum computing possible. Only an experiment can prove quantum computing possible, and no one has been able to do that.

Update: Lumo piles on. Update: Aaronson says he will continue to be a unabashed doofus and admit when he doesn’t know something or makes a mistake.

Why There Is Something Rather Than Nothing

Lawrence Krauss's book, A Universe From Nothing: Why There Is Something Rather Than Nothing, continues to cause controversy, as noted below. Peter Woit writes:

In this morning’s developments, we have prominent skeptic Michael Shermer, in Much Ado About Nothing, making the case that the Multiverse finishes off that “God” business, using “multiverse hypotheses predicted from mathematics and physics”.

Krauss doubles down against bad reviews with his Atlantic interview:

Philosophy is a field that, unfortunately, reminds me of that old Woody Allen joke, "those that can't do, teach, and those that can't teach, teach gym." And the worst part of philosophy is the philosophy of science; the only people, as far as I can tell, that read work by philosophers of science are other philosophers of science. ... [philosophy] hasn't progressed in two thousand years. ...

Well, I read a moronic philosopher who did a review of my book in the New York Times ...

But if you can show how a set of physical mechanisms can bring about our universe, that itself is an amazing thing and it's worth celebrating. I don't ever claim to resolve that infinite regress of why-why-why-why-why; as far as I'm concerned it's turtles all the way down. The multiverse could explain it by being eternal, in the same way that God explains it by being eternal, but there's a huge difference: the multiverse is well motivated and God is just an invention of lazy minds. ...

The religious question "why is there something rather than nothing," has been around since people have been around, and now we're actually reaching a point where science is beginning to address that question. And so I figured I could use that question as a way to celebrate the revolutionary changes that we've achieved in refining our picture of the universe. ...

"the remarkable revolutions that have taken place in our understanding of the universe over the past 50 years -- revolutions that should be celebrated as the pinnacle of our intellectual experience." ...

If I'd just titled the book "A Marvelous Universe," not as many people would have been attracted to it.

So his title is flamebait, but it suckered Dawkins into endorsing the book by saying that it is the "deadliest blow to supernaturalism" since Darwin.

Krauss continues to defend himself, and attack philosophers, in a comment to Coyne's blog

I haven’t responded to the review by Albert simply because it seemed to me not worthy of response.. and nothing has changed my mind about that.

and now in a SciAm article:

Which brings me full circle to the question of nothing, and my own comments regarding the progress of philosophy in that regard. When it comes to the real operational issues that govern our understanding of physical reality, ontological definitions of classical philosophers are, in my opinion, sterile. ...

That question can be phrased as follows: How can a universe full of galaxies and stars, and planets and people, including philosophers, arise naturally from an initial condition in which none of these objects—no particles, no space, and perhaps no time—may have existed? Put more succinctly perhaps: Why is there ‘stuff’, instead of empty space? Why is there space at all?

About the only philosopher Krauss credits is Peter Singer, the wacky animal rights guru.

I attack philosophers myself on this blog, and in my book. But the NY Times reviewer, David Z. Albert, was a legitimate physicist before he turned to philosophy, and his criticisms are never directly addressed by Krauss. Albert wrote a book on the many-minds interpretation of quantum mechanics, which is pretty goofy, but not directly relevant.

The core of the problem is that modern physics has nothing to say about nothingness. There is no such thing, as far as we know. The closest we can get to empty space is the luminiferous aether, also called the quantum vacuum state. Our best quantum theories, such as quantum electrodynamics (QED), are really perturbation theories of the aether. That is, what seems like empty space to us is really a complicated set of fluctuating relativistic quantum fields.

A few decades ago, cosmologists proposed that the observable galaxies are the remnants of quantum fluctuations during the first nanosecond of the big bang. Krauss elaborations on this, and says that the whole universe might be the result of quantum fluctuations. As he tacitly admits, he is not really telling us Why There Is Something Rather Than Nothing, but rather giving a modern variant of Turtles all the way down.

All of this nonsense would be hardly worth commenting on, except that Krauss and Dawkins are two of our leading science expositors, and they are peddling nonsense. They should know better. I don't bother attacking crackpots. I started this blog when I realized that our leading academic scholars were promoting ideas about science that are entirely mistaken. The current May SciAm cover story is a wildly speculative story about combining supersymmetry and gravity into supergravity:

More profoundly, the novel methods breathe new life into a unified theory that physicists left for dead in the 1980s. The force of gravity looks like two copies of the strong subnuclear interactions working in unison.

The tipoff is that the authors keep talking about how radical and revolutionary their approach is, but cannot point to any substantive progress since the 1980s when many experts decided that it was a dead-end. The same issue has a separate article explaining why supersymmetry is dead. While there is some debate about that, supergravity is surely dead and not worthy of a SciAm cover story.

Quantum steering into the past

A Nature paper claims:

Physicists have demonstrated that making a decision about whether or not to entangle two photons can be made after you've already measured the states of the photons."

There is more explanation here and here.

If they really found an experiment that reverses cause and effect, it would be headline news. Nobel prizes would be given. It would be hailed as the most profound discovery of the last century, if not the last millennium. Like paychic telekinesis, or perpetual motion machines. I don't doubt that they have a clever experiment for confirming some quantum mechanics formula, but quantum mechanics has no way to reverse cause and effect.

Using quantum mechanics to attack religion

Many leftist-atheist-evolutionists follow Einstein and have a quasi-religious belief in determinism. One of them, Jerry Coyne now backtracks:

2. Determinism. Lou Jost and other readers on this site have argued that behavior (and evolution) might not be deterministic because they’re affected by quantum-mechanical considerations. When I used the word “determinism” in the past, I suppose I was a bit inaccurate: what I meant was that behavior is determined by physical processes, both deterministic and quantum-mechanical, i.e., that there is nothing to our behavior beyond physics. I should have used “materialism” rather than “determinism”!

Now I’m not quite convinced that quantum mechanics plays a real role in both our decision-making or in the course of evolution. Can our “choices” really be affected by nondeterministic motions of molecules? And is mutation, a crucial factor in setting the course of evolution, really affected by quantum mechanics? I remain agnostic on these issues and am doing some reading to get up to speed.

Stenger does some interesting calculations to show that neurotransmission in the brain cannot be affected by quantum-mechanical events, and so in that respect the operation of our brain is truly deterministic

They are doubting the role of quantum mechanics. There is no understanding of molecular biology without quantum mechanics, and there hasn't been for nearly a century.

I don't think it helps his argument to replace the word “determinism” with “materialism”. I guess that he trying to imply that he accepts quantum mechanics but not religion, because common interpretations of quantum mechanics are not deterministic. But they are not materialist either! Physicists even call them "spooky" to emphasize how they are contrary to materialist intuition.

I am not religious, but these attacks on religion are not grounded in legitimate science. I agree with John Horgan, who writes:

I’m nonetheless going out on a limb and guessing that science will never, ever answer what I call “The Question”: Why is there something rather than nothing? You might think this prediction is safe to the point of triviality, but certain prominent scientists are claiming not merely that they can answer The Question but that they have already done so. ...

But Krauss asks us to take the quantum theory of creation seriously, and so does evolutionary biologist Richard Dawkins. “Even the last remaining trump card of the theologian, ‘Why is there something rather than nothing?,’ shrivels up before your eyes as you read these pages,” Dawkins writes in an afterword to Krauss’s book. “If On the Origin of Species was biology’s deadliest blow to supernaturalism, we may come to see A Universe From Nothing as the equivalent from cosmology.”

Whaaaa…??!! Dawkins is comparing the most enduringly profound scientific treatise in history to a pop-science book that recycles a bunch of stale ideas from physics and cosmology. This absurd hyperbole says less about the merits of Krauss’s derivative book than it does about the judgment-impairing intensity of Dawkins’s hatred of religion. ...

Science has told us so much ... But when scientists insist that they have solved, or will soon solve, all mysteries, including the biggest mystery of all, they do a disservice to science; they become the mirror images of the religious fundamentalists they despise.

In the comments, Krauss protests that he "didn’t make any definitive claims", as if that excuses him from trying to write a scientific book on a religious subject.

No final theory in sight

Famous physicist Steven Weinberg writes The Crisis of Big Science:

So now we are waiting for results from a new accelerator at CERN that we hope will let us make the next step beyond the Standard Model. This is the Large Hadron Collider, or LHC. ...

The discovery of the Higgs boson would be a gratifying verification of present theory, but it will not point the way to a more comprehensive future theory. We can hope, as was the case with the Bevatron, that the most exciting thing to be discovered at the LHC will be something quite unexpected. Whatever it is, it’s hard to see how it could take us all the way to a final theory, including gravitation.

That is his plea to build a new particle accelerator. This is the first article like this that I have seen that does not mention Einstein. There are more comments here.

I suspect that Weinberg does not mention Einstein because Einstein is famous for revolutionizing physics while working at a day job. Weinberg wants $100B of funding for a project to find the Einsteinian final theory, but it doesn't help to mention Einstein because people might say that it would be better to wait for some genius like Einstein to solve the theory in his spare time.

No amount of money is going to “take us all the way to a final theory”, as Weinberg advocates. As long as he states his goals in terms of these unachievable fantasies, the congressman is right to say “No”.

He concludes:

It seems to me that what is really needed is not more special pleading for one or another particular public good, but for all the people who care about these things to unite in restoring higher and more progressive tax rates, especially on investment income. I am not an economist, but I talk to economists, and I gather that dollar for dollar, government spending stimulates the economy more than tax cuts. It is simply a fallacy to say that we cannot afford increased government spending.

This is crazy left-wing nonsense. The USA has vastly increased govt spending in the last 3 years, with stimulus bills, bail-outs, war escalations, new social programs, expanded food stamps, and quantitative easing, and the result has been the longest recession that anyone can remember. Government spending does not stimulate the economy. The Great Depression proved that.

Explaining the Fizeau experiment

Galina Weinstein is writing an Einstein book, as noted below, and is pre-publishing his research in pieces. He She just posted Albert Einstein and the Fizeau 1851 Water Tube Experiment:

When Robert Shankland asked Einstein how he had learned of the Michelson-Morley experiment, Einstein told him that he had become aware of it through the writings of Lorentz, but only after 1905 had it come to his attention. "Otherwise", he said, "I would have mentioned it in my paper". He continued to say that the experimental results which had influenced him most were stellar aberration and Fizeau's water tube experiment. "They were enough". Indeed the famous Michelson-Morley experiment is not mentioned in the 1905 relativity paper; but curiously Einstein did not mention Fizeau's experimental result either, and this is puzzling in light of the importance of the experiment in Einstein's pathway to his theory.

No, the stellar aberration and Fizeau experiments were not enough, as Einstein explained in his 1909 review paper:

This contradiction was chiefly eliminated by the pioneering work of H. A. Lorentz in 1895. Lorentz showed that if the aether were taken to be at rest and did not participate at all in the motions of matter, no other hypotheses were necessary to arrive at a theory that did justice to almost all of the phenomena. In particular, Fizeau's experiments were explained, as well as the negative results of the above-mentioned attempts to detect the Earth's motion relative to the ether. Only one experiment seemed incompatible with Lorentz's theory, namely, the interference experiment of Michelson and Morley.

It was because of the Michelson–Morley experiment that Lorentz and Poincare improved the 1895 theory to a full relativity theory during 1899-1904, and they said so in their papers before Einstein wrote anything.

So Einstein certain knew in 1905 that Michelson-Morley was the crucial experiment for special relativity, but he may not have understood exactly why.

The one relativity formula that Einstein had in 1905 that had not been published by Lorentz in 1904 or earlier was the velocity-addition formula. (Poincare had it before Einstein, and included it in a letter to Lorentz, so Lorentz knew it before Einstein.) Weinstein says:

In 1907 Max Laue showed that the Fresnel dragging coefficient would follow from a straightforward application of the relativistic addition theorem of velocities. This derivation is mathematically equivalent to Lorentz's derivation of 1895. From 1907 onwards Einstein adopted Laue's derivation.

When the Einstein fans praise his 1905 work, they often argue that the previous work of Lorentz and Poincare was just mathematical, while only Einstein truly appreciated the physical significance of relativity. Others say the opposite, and argue that Einstein paid no attention to the physical experiments, and that his contribution was to turn relativity into a mathematical theory with postulates. I think that both views are desperate and misinformed attempts to over-credit Einstein.

Weinstein wonders why Einstein did not use the velocity addition formula to explain Fizeau:

John Norton writes, "It might seem surprising that Einstein could devise and publish the relativistic rule of velocity composition in his 1905 paper (§5) without recognizing that the result of the Fizeau experiment is a vivid implementation of the rule." ... Stachel explains that Einstein was under the spell that everything could be solved using Maxwell's equations that he failed to notice the kinematic nature of Fresnel’s formula, resulting from direct application of the relativistic law of combination of relative velocities; it was left for Laue to make this observation in 1907.

These are all big Einstein idolizers who have looked really hard for originality in Einstein's work. They say that Einstein had a superior understanding of relativistic kinematics, so they are baffled he was unable to apply that understanding to Fizeau, as Laue did. The simple explanation is that Einstein did not have a superior understanding.

Weinstein also posts Did Mileva Maric assist Einstein in writing his 1905 path breaking papers?

Writers read Einstein's letter to Maric from 1901 in which he wrote: "bringing our work on relative motion to a successful conclusion!" What came afterwards was boosted by a claim that Joffe had seen the original relativity paper manuscript, and that it was signed "Einstein-Marity" (i.e., "Maric"). This drew the attention of some writers to develop a theory according to which Mileva Maric assisted Albert Einstein in solving his physics problems, but her name was left out of the published article and only Einstein's name appears in the journal as author. Historical and primary sources do not support this scenario.

Mileva was a physics grad student, was married to Einstein, and did read and discuss his papers with him. So she surely had some influence. The question is how much.

The main argument against Mileva's influence is that she never again did anything so original. But some of Einstein's strongest admirers also say that he never again did anything so original as that 1905 relativity paper. My view is that the 1905 was not very original at all, and that we cannot trust Einstein about his sources because he did not believe in crediting his sources. So the amount of her influence is a mystery, but not a very interesting one. Even if it were somehow shown that she came up with the main ideas, it would not change my opinion of him very much because it would just mean that she stole them from Lorentz and Poincare instead of him stealing them.

Einstein contemplation

Non Sequitur by Wiley Miller, April 19,2012.