Classical physics allows us to believe in the existence of a "meta-observer" who knows all the exact positions and velocities (or values of fields). This metaobserver may be called God. But in contrast with Sebens' claim, classical physics doesn't assert that God in this sense must exist.Yes, I agree with that. I would even go further, and say that there are not really particles in quantum mechanics. There is no particle in the sense of a specific position and momentum. The particle-like objects also have wave properties, and only truly look like particles in the instant of a particular observation.
The second sentence suggests that in quantum mechanics, a particle is in two places at once. But even though this language is often used in popular presentations and even physicists' sloppy formulations, it's not the case. When a particle is described by a wave function that is a superposition of "here" and "there", it doesn't mean that the particle is in two places at once. It means that the particle is "here OR there" (not "AND") and we can't know which is the right. But the locations "here" and "there" are only potential locations, not "objectively real locations" of anything, and they are mutually exclusive because the two position eigenstates are orthogonal to each other.
A quantum mechanical particle can't be in two places at once.
The double-slit experiment is often explained as the particle being in both slits at the same time. I guess you can think of it that way, but it is not helpful because the particles are never observed in both places at once.
After much more criticism, Lumo goes into full rant:
So "dreamers" not only want to "undo" the quantum revolution. They pretty much want to undo the transition of physics to "field theory" as well and claim that the world is described by a classical deterministic Newtonian mechanics. ...I would say only 100 years behind the times.
The only real problem, Mr Sebens, is the combination of complete stupidity and arrogance, values that you reconcile so smoothly and naturally.
I am totally infuriated by this junk because complete idiots who are, scientifically speaking, at least 300 years behind the times claim – and use similar idiots in the media to claim – that they are close to cutting-edge science.
Einstein is famous for saying quantum mechanics was all wrong. That was over 80 years ago. He had nothing better. Neither do any of the other quantum critics. At some point, you have to dismiss these people as crackpots.
Nature mag has a dose of common sense, endorsed by Peter Woit:
Scientific method: Defend the integrity of physicsI think that most scientists would agree with this. Not sure about Lumo, as he likes string theory, but even criticizes most of these untestable ideas as not scientific.
Attempts to exempt speculative theories of the Universe from experimental verification undermine science, argue George Ellis and Joe Silk.
This year, debates in physics circles took a worrying turn. Faced with difficulties in applying fundamental theories to the observed Universe, some researchers called for a change in how theoretical physics is done. They began to argue — explicitly — that if a theory is sufficiently elegant and explanatory, it need not be tested experimentally, breaking with centuries of philosophical tradition of defining scientific knowledge as empirical. We disagree. As the philosopher of science Karl Popper argued: a theory must be falsifiable to be scientific.
Chief among the 'elegance will suffice' advocates are some string theorists. Because string theory is supposedly the 'only game in town' capable of unifying the four fundamental forces, they believe that it must contain a grain of truth even though it relies on extra dimensions that we can never observe. Some cosmologists, too, are seeking to abandon experimental verification of grand hypotheses that invoke imperceptible domains such as the kaleidoscopic multiverse (comprising myriad universes), the 'many worlds' version of quantum reality (in which observations spawn parallel branches of reality) and pre-Big Bang concepts.
These unprovable hypotheses are quite different from those that relate directly to the real world and that are testable through observations — such as the standard model of particle physics and the existence of dark matter and dark energy. As we see it, theoretical physics risks becoming a no-man's-land between mathematics, physics and philosophy that does not truly meet the requirements of any.
In our view, cosmologists should heed mathematician David Hilbert's warning: although infinity is needed to complete mathematics, it occurs nowhere in the physical Universe.Also correct. Infinities come up a lot in physics, as in the unrenormalized charge of an electron, the center of a black hole, the initialization of the big bang, the infinite extent of space, etc. But none of these should be taken too seriously. They are mathematical models. Arguments about infinitely many universes are just silly.
Popper was the last philosopher of science that scientists took seriously. He is mainly liked for what he said about falsifiability as a criterion to demarcate what is or is not science in the 1930s. Peter Morgan responds:
There are limitations to a Popperian account of scientific methodology. The critique has been manifold and substantive at least since Quine. A simply stated criticism is that we don't falsify a theory, we only quantify how accurate it is in different ranges of application. We don't abandon a scientific theory, we find a new theory that is more accurate in part of the old theory's range of application (but there may be other issues, such as greater usability and tractability and good enough accuracy for practical purposes over a wide enough range, so that we are often happy, for example, to use classical mechanics instead of GR or QM).Popper did say some foolish things about scientific methodology. But he is being cited here for how he distinguished scientific theories, like relativity, from unscientific ones, like Freudian interpretations of dreams.
Freudians and other promoters of false or untestable or fringe theories have always hated Popper. He is also hated by leftists for writing The Open Society and Its Enemies, a political refutation of Marxism. So yes, people like to pretend that Popper has been discredited. I even criticize Popper's anti-positivism. But his basic idea of using falsification for science demarcation is sound.
String theorist Gordon Kane protests:
Ellis and Silk rely heavily on the absence of evidence of superpartners in the first LHC run. How will they respond if superpartners are found in the next run? Does that count as a successful test and reverse their opinion? The literature contains clear and easily understood predictions published before LHC from compactified string theories that gluinos, for example, should have been too heavy to find in Run 1 but willbe found in Run 2 (gluino mass of about 1.5 TeV). Third, it is common that some tests of theories at a given time are not technically possible but become possible later. Entanglement in quantum theory is an example.Yes, supersymmetry in the LHC energy ranges was a testable prediction. I think everyone agrees to that. So far the evidence shows that there is no such thing, but we will not know for sure for another couple of years.
I do not know why he says entanglement was not testable. Entanglement was essential to quantum mechanics going back to the 1920s, and was tested many times. Just about any multi-particle test of quantum mechanics is a test of entanglement.
Sure enuf, Lumo defends string theory:
String theory is known to be almost certainly right because it's the most elegant, explanatory, consistent, and unifying reconciliation of general relativity and quantum field theory. ...Jim Baggott writes:Chief among the 'elegance will suffice' advocates are some string theorists. Because string theory is supposedly the 'only game in town' capable of unifying the four fundamental forces, they believe that it must contain a grain of truth even though it relies on extra dimensions that we can never observe.They completely misrepresent that status of string theory. String theory is not "supposedly" the only game in town. It is the only game in town. And it doesn't contain just a "grain" of truth. It contains the whole truth. Due to its basic mathematical properties, it cannot be just another approximation that has to be deformed to obtain the right theory. It must be the right theory exactly.
However, scientists must learn to be willing to let go of Popper's principle of falsifiability. This lost support among philosophers of science quite some time ago, ...He is right that falsifiability lost support among philosophers of science, but those philosophers are unable to say anything worthwhile about that "escapist physics", and they will not stand up for the integrity of science. Falsifiability is still a useful concept for debunking that untestable physics speculation.
I agree with Ellis and Silk that the very integrity of science is at stake here. But I think that to deal with these issues properly, we must first understand why there has come to be such an appetite for what I have elsewhere referred to as 'fairy-tale' physics. In his critical 1987 review of John Barrow and Frank Tipler's book 'The Anthropic Cosmological Principle', Danish science historian Helge Kragh wrote: 'This kind of escapist physics, also cultivated by authors like Wheeler, Sagan and Dyson, appeals to the religious instinct of man in a scientific age.' It is also true that this kind of 'escapist' physics is now an integral part of the staple of some aspects of our contemporary culture - from Michio Kaku's 'Science Fantastic', to Morgan Freeman's 'Through the Wormhole' to Christopher Nolan's blockbuster 'Interstellar', not to mention the string of bestselling books that have appeared on string theory and multiverse in the last 10 years or so. We may worry that consumers are getting a very distorted impression of what science is all about, but we can only counter this by helping to make 'real' science at least equally accessible and entertaining.
Cliff makes a series of unsupported attacks on the testability concept, such as:
General relativity also flagrantly defies your standard: We did modify this theory after it failed to describe the rotation of galaxies, by postulating dark matter. GR+DM is still by far the most successful theory of galactic motion, so clearly any putative definition of science had better be able to accommodate this kind of tweaking that you want to exclude.No, this is a poor argument. Dark matter does not require any modification to general relativity. The observed galaxy rotation, combined with Newtonian gravity or GR, implies that the galaxies have more mass than what we directly see. Some people thought that it might be dust, black holes, neutrinos, or something like that, but the consensus is that these possibilities are not enuf. So the leading view is that there is some dark matter that is otherwise unknown to us. It is also possible that gravity is slightly distorted on galactic scales. But all these ideas are testable and falsifiable, so Cliff makes no sense.
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