Supposed advance in quantum computing

MIt computer scientist Scott Aaronson has finished defending himself against weirdo feminist attacks on his personal life, and is back to promoting quantum computing:

Within the last couple months, there was a major milestone in the quest to build a scalable quantum computer, and also a major milestone in the quest to figure out what you would do with a quantum computer if you had one. As I’ve admitted many times, neither of those two quests is really the reason why I got into quantum computing — I’m one of the people who would still want to study this field, even if there were no serious prospect either of building a quantum computer or of doing anything useful with it for a thousand years — but for some reason that I don’t fully understand, both of those goals do seem to excite other people.

I am pretty sure he is being sarcastic here. Yes, of course interest in quantum computing is based on the hope that such computers can be built and do useful things. He sounds like G.H. Hardy showing contempt for math doing anything useful.

Scott sure gets excited if someone like D-Wave claims that a quantum computer has been built, or someone like me claims that it is impossible.

I am wondering what these guys think about the possibility that we live in a computer simulation. Since I don't believe that scalable super-Turing quantum computing is possible, the simulator would be a classical computer. So if these quantum computing experiments are successful, then they would put an incredible computational strain on the simulator. What if they overload the simulator? We would all effectively die. This is a bigger threat to the world than the possibility of the LHC making a black hole that swallows the Earth.

Update: A comment says:

If the simulating computer of our world is resource scarce, what if we try to construct a quantum computer to apply Shor's algorithm? Do it for discrete logs or elliptic curve logs because they are uniformly hard. To pick a "hard" integer to factorize as a test, we pretty much have to come up with two large prime numbers first, and our simulator can just read off the prime numbers during generation, and then feed them into the output of the simulated quantum computer. But if we pick a random instance of a discrete log or an elliptic curve log, either Shor's algorithm would myseriously break down, or our simulator is at least partially a quantum computer on its own.

The answer is that it would deplete the resources of the simulator, and give us a cosmic blue screen of death. You have been warned.

Not accepting God playing dice

A reader comments:

Einstein was not the only one of the founders to have misgivings about intrinsic probability. This from Max Born’s Nobel lecture of December 1954:

“ ... when I say that the physicists had accepted the concepts and modes of thought developed by us at the time I am not quite correct. There are some very noteworthy exceptions, particularly among the very workers who have contributed most to building up the quantum theory. Planck, himself, belonged to the sceptics until he died. Einstein, De Broglie and Schrodinger have unceasingly stressed the unsatisfactory features of quantum mechanics and called for a return to the concepts of classical Newtonian physics while proposing ways in which this could be done without contradicting experimental facts. Such weighty views cannot be ignored.”

It is interesting that those he mentions were more the wave mechanics people, rather than the Copenhagen and Gottingen matrix crew. Waves evolve and interfere in a peculiarly local and causal manner, whereas the matrix approach was developed from a stance that ignored all possibility of underlying but unobservable deterministic processes. Yet matter and radiation are in some sense ultimately wave-like in behaviour.

For my money, it is far too early to be denying the possibility of a deterministic explanation of the Born rule. N. P. Landsman had it right I think in commenting in connection with that rule that the “notion of strictly ‘irreducible’ randomness ... which is only defined through negation ... quite possibly makes no philosophical sense at all”. ( arXiv:0804.4849v1 (quant-ph 30 Apr 2008 ). But in this of course he is philosophising!

I agree that irreducible randomness makes no philosophical sense at all.

Philosophy became useless in 1950

Here are some philosophers promoting the field:

Rebecca Newberger Goldstein -- philosopher, author, and Genius-grant recipient -- returns to the Rationally Speaking podcast to discuss her latest book, "Plato at the Googleplex: Why Philosophy Won't Go Away." Rebecca, Julia and Massimo argue over the value of philosophy in modern science, and whether it makes sense to designate "experts" in ethical reasoning.

They gripe about physicists saying that philosophers have been useless since about 1950.

They argue that philosophizing has been important to physics in the past, but all of their examples are before 1950.

These philosophers don't actually rebut the physicists. Sure philosophy can be important, and Plato was influential, but modern philosophers went nuts about 1950, and they have been useless since.

Goldstein is married to Steve Pinker, and also says:

The philosopher and mathematician AN Whitehead described the history of philosophy as a “series of footnotes to Plato”. Do you agree with him?

If that were the case, what a silly field philosophy would be! A 2,400-year-old man had all the answers? I would like to think that what he meant was that this methodology, this view of maximising coherence, was begun by Plato and that he also formulated questions from a wide range of different areas of inquiry — mathematics, epistemology, metaphysics and political theory — and saw their commonality. In that sense, you can say that all philosophy follows in Plato’s footsteps.

Was Plato a “Platonist” in the modern sense of being committed to a claim about the existence of abstract entities, numbers for example?

The one area of philosophy in which Platonism is constantly referred to is philosophy of mathematics. There was apparently a survey done by the American Mathematical Association and something like 98 per cent of mathematicians described themselves as “Platonists”. There is [in mathematics] very much a sense that you’re discovering rather than inventing. So this is a kind of commitment to the existence of the abstract, but necessarily in insolation [sic, isolation or insulation] from the physical — the structure of physical reality is given by the abstract, but the abstract can’t be reduced to sensory particulars. So it doesn’t have to involve a commitment to a kind of Platonic “heaven” that Russell, for example, makes fun of; it can be the claim that reality can’t be intelligible without referring to abstractions which cannot themselves be reduced to anything other than themselves.

Was Plato a Platonist? Well, there’s the Platonism of the forms which I think he gave up. In the Parmenides, he really criticises the theory of forms. It’s interesting that Socrates is a young man there and he can’t answer Parmenides’ questions. In the Timaeus, which is one of my favourite dialogues, it’s not the forms, it’s mathematics that is the key to intelligibility.

Every theoretical physicist I’ve ever known has believed that not only is reality given to us in the language of mathematics, but that when we have two empirically adequate theories, you go with the one that has the most beautiful mathematics — that’s in the Timaeus too. That’s a Platonism that’s still working. When my scientist friends say that the structure of reality is given in the most beautiful mathematics, I say to them, “That’s a metaphysical argument you’re using right there.” Steven Weinberg said of string theory, “Maybe it’s not true, but we’re going to find some application for it, because never in the history of science has it been the case that such beautiful mathematics didn’t somehow reveal reality.” Whoah! That’s Plato!

Those physicists are misguided. There is lots of beautiful math, such as p-adic numbers, that give a mathematical reality but not a physical reality.

There are hundreds of papers on P-adic quantum mechanics, so apparently some people believe in physical p-adics. I haven't read any of those papers, but I am going to go out on a limb here, and say that I am skeptical.

Established 500 years ago by observations

Leftist-atheist-evolutionist professor Jerry Coyne writes:

Dear Yiddish Girl,
Regardless of what “we Jews believe” — and I consider myself a secular Jew — you’re simply wrong about the Sun going around the Earth. The truth about that, which is the reverse, was established 500 years ago by observations, and only those blinded by adherence to ancient books of fiction could think otherwise. —Professor Ceiling Katz

As a matter of historical accuracy, this is not correct. Observations never established that the Earth went around the Sun, and early XX century relativity proved that such establishment was impossible.

Heliocentrism was proposed in ancient Greece over 2000 years ago, and by Copernicus in 1543. It became generally accepted in the 17th century based on theory, not observation. Proof that the Earth was not an inertial frame and that it moved relative to the distant stars did not come until much later.

Here is a new paper on 18th century Catholic scholarship:

The general prohibition of books advocating heliocentric theory put many progressive Jesuits in a difficult position. One of the most prominent Jesuit scientists of the 18th century, Rogerius Boscovich, was in particularly affected by conflicts between a beautifully simple theory of gravity by Newton, his Jesuit peripatetic education, Church doctrine and the lack of crucial experimental evidence for the motion of the Earth. I present the development of Boscovich's ideas prior to the lifting of the ban, and his retrospective considerations in later writings. These show that Boscovich's acceptance of the motion of the Earth was primarily driven by the existence of a working physical theory that also explained the motion of the Earth, and the lack of a consistent theory that supported any variation of a geocentric system.

So Newton had a heliocentric theory that was a lot more persuasive than any geocentric theory, but the observational evidence was more recnt.

Coyne also mocks the idea of a Biblical Adam and Eve, but again does not give science to back up his view. The academics have redefined hominid to include apes, to emphasize that humans and apes are all the same. But if we define human in a way that distinguishes us from apes, then there must have been a first human. It seems possible that there were two crucial genes that made us human, and a first Adam had one and mated with a first Eve with the other. Or perhaps there was a first Adam and Eve that made sudden progress in some non-genetic way, such as discovering tools or language or moral responsibility.

Admittedly a more gradualist view seems much more likely, with each generation barely distinguishable from the one before. And no one is going to dig up bones for Adam and Eve, so evidence for them will be very difficult.

The Bible itself is somewhat ambiguous about whether there were other people around with Adam and Eve, and most Bible students do not take a strictly literal interpretation.

I really don't mind Coyne and others launching scientific attacks on religious beliefs. I just think that they should get the science and the facts right. If science has ruled out certain religious views of Adam and Eve, I would like to see the explanation, with cites to the scientific literature.

Update: Coyne backtracks here, and asks readers whether the Earth goes around the Sun.

Inspired by Einstein to do meaningless theory

A SciAm writer interviews:

Horgan: Why did you become a physicist?

Smolin: I decided to become a physicist one spring evening when I was 17, as a result of reading Einstein’s autobiographical notes. He wrote that quantum mechanics needed a completion, which must include its unification with general relativity. At that moment I was a high school dropout planning to study architecture; but suddenly I was seized with the idea that I could follow Einstein, become a theoretical physicist and work on those two problems. That has defined my life.

How many physicists wasted their lives with such a delusion?

Most of what Einstein said on this topic was nonsense. He did not accept quantum mechanics, and there is no practical conflict between quantum mechanics and relativity. He induced a couple of generations of theorists to pursue untestable ideas according to a warped idea of what science is all about. This is largely why I wrote my book, How Einstein Ruined Physics. Smolin once gave this definition of science:

Science is not about what's true, or what might be true. Science is about what people with originally diverse viewpoints can be forced to believe by the weight of public evidence.

So if they convince the experts that we live in an 11-dimensional multiverse, then that is science whether it is true or not, according to Lee Smolin.

People think that Smolin has a reasonable view of science because he wrote a book critical of string theory. But if you read his book to the end, his beef is that he is much more radically anti-science than the string theorists. He and the multiverse proponents almost make the string theorists sound reasonable.

New 2015 FQXi essay contest

FQXi has announced a new essay contest"

The theme for this Essay Contest is: "Trick or Truth: the Mysterious Connection Between Physics and Mathematics".

In many ways, physics has developed hand-in-hand with mathematics. It seems almost impossible to imagine physics without a mathematical framework; at the same time, questions in physics have inspired so many discoveries in mathematics. But does physics simply wear mathematics like a costume, or is math a fundamental part of physical reality?

Why does mathematics seem so “unreasonably” effective in fundamental physics, especially compared to math’s impact in other scientific disciplines? Or does it? How deeply does mathematics inform physics, and physics mathematics? What are the tensions between them — the subtleties, ambiguities, hidden assumptions, or even contradictions and paradoxes at the intersection of formal mathematics and the physics of the real world?

This essay contest will probe the mysterious relationship between physics and mathematics.

I have submitted essays in the past. One of them was actually leading in the ratings at one point, but none of them won any prizes.

These are mainly physicists who are always going nuts with wild speculations about multiverses, quantum teleportation, and stuff like that. So they do not like my positivist and skeptical attitudes.

They do not give prizes to the more speculative essay either. You cannot say something that the judges think is false. Some of the winning essays are interesting, but most do not say much.

One question seems to be influenced by one of my essays:

What would it mean for something in the physical world to be NOT describable or model-able in terms of mathematics?

My 2012 essay said:

Much of modern theoretical physics assumes that the true nature of reality is mathematics. This is a great mistake. The assumption underlies most of the paradoxes of quantum mechanics, and has no empirical justification. Accepting that the assumption is wrong will allow physics and mathematics to progress as distinct disciplines. ...

The 2011 FQXi essay contest asked, “Is Reality Digital or Analog?” The answers accepted the premise that reality had to be one or the other, and no one admitted the possibility that it might be neither because both are mathematical.

I could be wrong, of course, but I seem to be the only one who seems to have considered the possibility that fundamental physics is not describable by math.

Doing without causal talk

Philosopher Massimo Pigliucci posted arguments against causal reductionism, whatever that is, and commented:

To begin with, because it is well established in philosophy of science that “special sciences” (i.e., everything but fundamental physics, including non-fundamental physics) do effectively deploy causal talk and cannot, apparently, do without it [9]. The puzzle of causal vs non-causal talk in science has always been at the fundamental level. ...< It simply means that explanation in the special sciences always invokes — or seeks to invoke — causality. This is not the case, or rarely so, in fundamental physics.

I replied:

SciSal, you have said before that fundamental physics has no use for causal talk, and yet it is shown to you that Einstein and the physics textbooks use causal language. Causality is indeed central to fundamental physics, and I defy you to show me some part of physics that does not use causality.

You say that it is "well established in philosophy of science" that fundamental physics can do without causality. Maybe so, but I doubt that you can find one physics textbook anywhere that agrees.

It is also false to say "the field equations of GTR do not explicitly include any causal talk". Those equations are hyperbolic partial differential equations, and solutions are causally determined by the Cauchy data. The GTR equations are as explicitly causal as any equations in all of science.

Maybe you are using some peculiar concept of causality. I do not see why P1 (no causation) would imply C (causal reductionism). I would say that all fundamental physics is based on causality, and that is the best basis for causal reductionism.

No one has to accept all solutions to GTR equations, such as time-like curves and backwards causation. It has always been understood that these equations constrain reality, but that lots of solutions are likely to be unphysical for other reasons.

I also disagree with your claim that "we know" that GTR is not a fundamental theory. It is as fundamental as anything in physics. Even the string theorists, who argue that string theory is the truly fundamental theory, take GTR as one of their premises.

SciSal, you say that there is no causality in fundamental physics, but then you say that none of the known theories are fundamental. So your statement is vacuous.

As Coel explained, quantum mechanics is causal. So is string theory. Both formally and in interpretation. The details are in any textbook.

I looked at your references, and only Raatikainen addresses it most directly:

... that there is genuine causation only at the fundamental micro-physical level. It would be important to note, though, that this is emphatically not how numerous distinguished philosophers of physics and experts in the theory of causation view the issue. ...

Now, in what follows, I do not want to commit myself to the view that there is no causation in fundamental physics – I do not even want to pretend that I am competent to judge the issue. However, it is important to keep in mind that many able philosophers have concluded this. But be that as it may, it just is not the case – contrary to what numerous physicalistic metaphysicians take for granted – that causation is uncontroversially present in fundamental physics. Therefore, such philosophers should perhaps think twice before declaring, from the armchair, that there is causation only at the fundamental physical level.

He is saying that people who understand physics say that causation is uncontroversially present in fundamental physics. Philosophers say the opposite. He does not understand physics, so he is not judging.

He also says:

To begin with, it is a historical fact that the notion of cause has disappeared from physics as the subject has developed (see Kuhn 1971; cf. Loewer 2001). More importantly, many philosophers who apparently know their physics have argued that the whole idea of causation is not even applicable to fundamental physics, or is incompatible with it. Very briefly, and roughly, one of the problems is that in some cases, one has to specify the entire state of the whole universe at one time in order to determine the state of even a small region at some later time. And in such a case, it is difficult indeed to consider anything as a cause (Latham 1987, Redhead 1990, Field 2003, cf. Loewer 2001, Hitchcock 2007, Elga 2007; this idea goes back, of course, to Russell 1912-13).

Yes, Russel said this, as I pointed out before. But this is crazy stuff. Almost every word of that paragraph is false. In particular, it is not true that "one has to specify the entire state of the whole universe at one time". It is akin to astrology to believe that things are affected by the distant universe. The physics textbooks say that this is impossible. I assure you that Nobel prizes would be given to anyone who could show that the entire state of the universe was needed to determine the state of a small region.

This is another example of how modern philosophy has diverged from science. Every single reference is over a century out of date in its understanding of science. It was foolish when Russell said it in 1913, and it is more foolish today.

I did not know Kuhn (Mr. Paradigm Shift) wrote an essay attacking causality. I could not find it online.

This is weird. I don't want to pick on Pigliucci, because he appears to be just reciting conventional wisdom among philosophers of science. But physics is all about causality, such as predicting the future from the present. I don't know how anyone could get any other impression. What do they think physics is about, if not causality?

Update: Pigliucci now says:

Let me try a different take: there are degrees of fundamentality, where, for instance quantum mechanics is more fundamental than relativity, and string theory (if true) would be more fundamental than QM. The point is that the further “down” one goes the less there seems to be need for talk of causality. ...

At the very least I don’t understand how a formalism (i.e., a set of equations) can be causal. It’s math, not physics. It becomes physics only once it is given a particular interpretation. Beyond that, QM for instance describes the probabilities of certain events without invoking talk of causes. When we predict the spontaneous decay of an atom or particle, for instance, we just say that it happens with probability X, we don’t say “and it is caused by Y.” ...

I don’t count nomological entailment as causation.

I have criticized him before on this point, and I am trying to figure out how he could be so wrong. He seems to be saying that if physics ever finds a truly fundamental theory, where everything is reduces to equations, then there will be just nomological entailment and not causality. Nomological means "relating to or expressing basic physical laws or rules of reasoning".

To me, this is like saying: "Energy does not arise in physics. In a fundamental theory, energy is described by formulas, and a formula is not the same as energy." It is just playing some stupid word game and pretending that it is profound.

Update: I posted:

I think that the argument is that if the laws of physics are explaining why "punching John in the face caused his nose to break", then we do not need causality anymore. That is, it is not really causality once it is understood. This reminds me of the philosophers who say that artificial intelligence (like playing chess) is not really intelligence once it becomes a cheap app on your smart phone.

QM for instance describes the probabilities of certain events without invoking talk of causes. When we predict the spontaneous decay of an atom or particle, for instance, we just say that it happens with probability X, we don’t say “and it is caused by Y.”

That was true a century ago. Physicists could measure the half-life of a radioactive element, and thereby say that the atom decays with probability X, but beyond that, spontaneous events were mysterious. Then quantum mechanics was discovered as a way to find causal explanations. Physical states are described by a wave function, time evolution is governed by a differential equation, and probabilities of (apparently spontaneous) events are given by a Hilbert space operators.

Quantum mechanics is routinely applied to explain and predict chemical reactions, silicon chips, lasers, and much of modern technology. The explanations are completely causal, or you would not be able to read this message. While it might seem that your computer is spontaneously sending a signal, every component is designed with a causal understanding of how a state at one time is causing a state at a nanosecond later.

I would go further, and say that incorporating causality into fundamental physics was the most important intellectual achievement in modern times. Before 1850, we did not have causal explanations for any of the four fundamental forces. Now we have fully causal theories for all four, and those theories have led to the most striking technological progress in the history of the planet.

Panu, I appreciate your clarification, but it does appear that all the physicists believe that causation is present in fundamental physics, and all the philosophers believe the opposite. This is a funny controversy, because it does not appear that any philosophers actually talk to any physicists. If they did, then no one would say "it is a historical fact that the notion of cause has disappeared from physics as the subject has developed".

As usual, Pigliucci says I am wrong.

Update: Here is a good page on why scientists disrespect philosophers.

Update: After I claim that the philosopher understanding of quantum mechanics was a century out of date, someone claiming to be a physicist tries to rebut me by citing an authority from 1916! Supposedly that 1916 theory showed that quantum mechanics was probabilistic and hence not causal. So he is only 99 years out of date. Here was my post:

Mathias Frisch does indeed say, "According to a view widely held among philosophers of science, the notion of cause has no legitimate role to play in mature theories of physics." He is not too interested in the opinions of physicists except to note that a popular modern textbook says that the principle of causality is "the most sacred tenet in all of physics". Elsewhere I found a philosophy book that said that physicists adhere to "causal fundamentalism, which claims that the job of all of physics is to uncover the prevalent causal relations in nature." So yes, there is a severe split between philosophers and physicists on this issue.

Dominik, in EM theory the fields at some spacetime point are caused by the fields and waves in the backwards light cone from that point, as per Maxwell's equations. And yes, that has commonly been called causation for 150 years.

You seem to be saying that causality in GR is not fundamental because gravity waves are emergent. However there is not any (relevant) distinction between fields and waves in GR. Not in EM either. The Sun causes the Earth to stay with a gravity field. You can think of it as the Sun sending gravity waves to the Earth, altho the ripples in the waves are not detectable. If you admit that the waves are causal, then you have to admit that the fundamental field is causal.

Marko, all of the sciences talk about probabilities, so that talk does not make anything "really spontaneous". And whether or not it is really spontaneous does not have anything to do with causality. Something can be caused whether spontaneous or not. Maybe there are philosophers of science who think that causality is restricted to deterministic systems, but not physicists.

You say that redshifts are caused, but that QM does not provide causal explanations. If you are really a physicist, then you surely know that those redshifts are displacements of spectral lines that are entirely explained by QM. So what are you trying to say, that there is no causal explanation for the lines, but there is one for the shifts in the lines? You will not find anything like that in a physics textbook.

Marko confirmed that I was stating his causality theory correctly.