Wednesday, March 14, 2012
Monday, March 12, 2012
New spacetime conception in 1905
Mario Bacelar Valente just posted Did the concepts of space and time change that much with the 1905 theory of relativity?, saying:
Valente relegates Lorentz and Poincare to a footnote:
Valente credits Einstein for abolishing the aether (ether):
The answer to Valente's question is the Lorentz changed our conception of space and time in 1895, and Poincare changed it again in 1905. Einstein's 1905 paper was mostly an explanation of Lorentz's theory, and did not have any significant new conceptions.
The advent of the 1905 theory of relativity is rightly considered as a breakthrough moment in the history of physics; in particular. it is widely accepted that it brought a new conception of space and time. The purpose of this work is to reevaluate to what point and in what sense can we consider that the conception of space and time went through a transformation when going from Newtonian mechanics to the theory of relativity.It is widely accepted that the new conception of space and time became popular from Minkowski's 1908 paper. As explained in How Einstein Ruined Physics, Minkowski got his ideas from Poincare's 1905 paper, not Einstein's.
Valente relegates Lorentz and Poincare to a footnote:
53 Let us not forget that to Lorentz the so-called local time was just a mathematical artifact to help in calculations (see, e.g. Lorentz 1916, 57-8 and 187-9; Darrigol 2006, 11). Poincaré did notice that the local time had operational meaning since actually this is the time measured by an observer in absolute motion in relation to the ether; However Poincaré still considered a sort of absolute time (‘le temps réel’), the time measured by an observer in absolute rest in relation to the ether (see, e.g., Poincaré 1913, 43-6; Darrigol 2006, 17-9). It was Einstein who for the first time presented a truly relativistic notion of time in which physical time has to be defined and ‘spread’ within an inertial reference frame, and there is no preferred reference frame (see, e.g., Einstein 1905; Paty 1993, 148-52).Like other modern historians, Valente is criticizing Lorentz and Poincare for their terminology in later years. The criticism is silly and misinformed. And it proves nothing, because even if they did use inferior terminology in 1913 and 1916, it would not have anything to do with who had the new space-time theory in 1905.
Valente credits Einstein for abolishing the aether (ether):
In 1905, in his criticism of Lorentz's electron theory Einstein, like others (see, e.g., Darrigol 2000, 366-72), defended the view that we must “give up [on] the ether” (Einstein 1910, 124). Einstein argument is based on the idea that the ether seems to enable a special reference frame in relation to which things might still be said to be in 'absolute' rest or motion. Since it turns out that it is not possible to determine experimentally the velocity of material things in relation to the ether, there is no way to distinguish the ether's reference frame from other inertial reference frames. Accordingly, Einstein considers that one should “give up the notion of a medium filling all of space” (Einstein 1910, 124). ... Later, within his theory of gravitation, Einstein put forward the idea that the curved space-time is a sort of ether (Einstein 1920).Note that Valente is crediting Einstein for what he said about the aether in 1910, in spite of what he said in 1905 and 1920. Einstein did not criticize Lorentz's theory in 1905, and in succeeding years, Einstein and others called it the Lorentz-Einstein theory.
The answer to Valente's question is the Lorentz changed our conception of space and time in 1895, and Poincare changed it again in 1905. Einstein's 1905 paper was mostly an explanation of Lorentz's theory, and did not have any significant new conceptions.
Friday, March 9, 2012
Goldreich is also a QC skeptic
I explained how I can believe that quantum mechanics (QM) is true while quantum computing (QC) is false, while Scott Aaronson argues that the burden of proof is on me to show that QC is false. Computer science professor Oded Goldreich explained in 2005 what is wrong with Aaronson's position:
I agee with Goldreich. Experiments have confirmed aspects of QM to fantastic accuracy, but QC may still be completely false. Aaronson wants to dismiss because I wrote a book on How Einstein Ruined Physics, but Oded Goldreich even more of a big-shot computer science professor than Aaronson, and he is also a QC skeptic.
Goldreich has written papers on one-way functions, even tho no one has proved that they exist. So his situation is somewhat analogous to Aaronson, who has written most of his papers assuming QC, even tho QC may not exist. The difference is that Goldreich admits that his position is speculative.
Goldreich also says that he sees no point in arguing, so I guess that is why he does not argue in the comments on Aaronson's blog. My guess is that there are a lot of professors who are skeptical about QC, but consider it rude to badmouth a huge source of research grant money.
Update: Aaronson just got to be more of a big-shot with today's announcement:
No wonder no one wants to admit that quantum computers can only do what regular computers can do. Another physicist has already remarked:
Some (but I'm told that not all of the) believers of Quantum Computing (QC) assert that its possibility is ensured (or even required) by the Laws of Quantum Mechanics (QM). In my opinion, such an assertion is based on two fundamental confusions.Goldreich argues that QC is based on an idealized model that has been extrapolated far beyond what has ever been established in QM, and any such model has to be considered speculative, especially when it makes surprising or counter-intuitive predictions. So he says that "Being skeptic of this [QC] speculation seems to be the default and natural position."
Firstly, the Laws of QM are merely a refutable model (or assumption) about the real world, they are not the reality itself nor can they ever be proved to provide a full description of reality. (This is indeed a generic remark that applies to any model of reality, but it is good to bear it in mind when one wants to talk about ``lack of assumptions'': The assumption that QM provides a ``correct'' description of reality is no less an assumption than the conjecture that one-way functions exist. On the contrary, it seems that the latter assumption may be proved correct whereas the former can only be refuted (and can never be proved correct).) [See further discussion (Nov. 2011).]
Secondly, as far as I know (and here I may be wrong), QM says that certain things are not impossible, but it does not say that every thing that is not impossible is indeed possible. For example, it says that you cannot make non-Unitary transformations, but this by itself does not mean that you can effect any Unitary transformation that you want. ... [I have held the aforementioned opinions since I first heard of QC in the early 1990's.]
I agee with Goldreich. Experiments have confirmed aspects of QM to fantastic accuracy, but QC may still be completely false. Aaronson wants to dismiss because I wrote a book on How Einstein Ruined Physics, but Oded Goldreich even more of a big-shot computer science professor than Aaronson, and he is also a QC skeptic.
Goldreich has written papers on one-way functions, even tho no one has proved that they exist. So his situation is somewhat analogous to Aaronson, who has written most of his papers assuming QC, even tho QC may not exist. The difference is that Goldreich admits that his position is speculative.
Goldreich also says that he sees no point in arguing, so I guess that is why he does not argue in the comments on Aaronson's blog. My guess is that there are a lot of professors who are skeptical about QC, but consider it rude to badmouth a huge source of research grant money.
Update: Aaronson just got to be more of a big-shot with today's announcement:
Today the National Science Foundation (NSF) named two young scientists, Robert Wood of Harvard University and Scott Aaronson of the Massachusetts Institute of Technology (MIT), to receive this year's Alan T. Waterman Award.Wow, he offers a $0.1M prize in an attempt to prove me wrong, and then a couple of weeks later the feds give him a $1.0M prize for being such a visionary. He could be proved wrong and have to pay that $0.1M, and still make a $0.9M profit on the deal!
The annual award recognizes an outstanding researcher under the age of 35 in any field of science or engineering NSF supports.
In addition to a medal, each of this year's awardees will receive a $1 million grant--twice the amount of last year's award--over a five year period for further advanced study in his field.
"Robert and Scott embody the best in young, bold and talented researchers," said NSF Director Subra Suresh noting that computing is central to both of their research pursuits. "I have no doubt that these two researchers will continue to have an extraordinary impact on our nation and the world in the years to come." ...
Scott Aaronson is an associate professor of Electrical Engineering and Computer Science at MIT, affiliated with MIT's Computer Science and Artificial Intelligence Laboratory, the largest Interdepartmental lab at MIT. Aaronson, a theoretical computational scientist, pursues research interests that focus on the limitations of quantum computers and computational complexity theory more generally. ...
"By illuminating the fundamental limits on what can be computed in the physical world, and the potential implications of those limits, Scott Aaronson has staked out important new ground in computational theory," said MIT President Susan Hockfield, "I am delighted that the National Science Foundation has recognized his dual abilities, both to articulate key research questions and to offer new methods and ideas for addressing them, with the Alan T. Waterman Award."
No wonder no one wants to admit that quantum computers can only do what regular computers can do. Another physicist has already remarked:
Not only is this great news for Scott, but a rising tide lifts all boats: the entire field of quantum computing benefits when our talented researchers get recognition for their achievements.
Wednesday, March 7, 2012
Wigner on Einstein
Famous physicist Eugene Wigner said:
I would take Wigner seriously if he had some first-hand experience of Einstein's originality. Instead, Wigner is only crediting Einstein for originality that was reported in textbooks. As I explain in How Einstein Ruined Physics, very little of relativity was original to Einstein. Special relativity was due to Maxwell, FitzGerald, Lorentz, Poincare, and Minkowski. General relativity was due to Poincare, Grossmann, Hilbert, and Schwarzschild, with cosmological applications done by others. For more info, see Relativity priority dispute.
John von Neumann did invent ordinals (for use in axiomatic set theory), the Hilbert space formulation of quantum mechanics, operator algebras, game theory, and computers (for use in numerical simulations). A recent WSJ review of Turing's Cathedral: The Origins of the Digital Universe says:
Update: Steve Hsu is another von Neumann fan.
I have known a great many intelligent people in my life. I knew Planck, von Laue and Heisenberg. Paul Dirac was my brother in law; Leo Szilard and Edward Teller have been among my closest friends; and Albert Einstein was a good friend, too. But none of them had a mind as quick and acute as Jansci [John] von Neumann. I have often remarked this in the presence of those men and no one ever disputed me.Wigner was born in 1902 and probably did not even meet Einstein until the 1930s. Those two "greatest inventions" were in 1905 and 1915. Wigner is famous for his contributions to quantum mechanics, which Einstein never appreciated. Einstein never accomplished anything after about 1920.
... But Einstein's understanding was deeper even than von Neumann's. His mind was both more penetrating and more original than von Neumann's. And that is a very remarkable statement. Einstein took an extraordinary pleasure in invention. Two of his greatest inventions are the Special and General Theories of Relativity; and for all of Jansci's brilliance, he never produced anything as original.
I would take Wigner seriously if he had some first-hand experience of Einstein's originality. Instead, Wigner is only crediting Einstein for originality that was reported in textbooks. As I explain in How Einstein Ruined Physics, very little of relativity was original to Einstein. Special relativity was due to Maxwell, FitzGerald, Lorentz, Poincare, and Minkowski. General relativity was due to Poincare, Grossmann, Hilbert, and Schwarzschild, with cosmological applications done by others. For more info, see Relativity priority dispute.
John von Neumann did invent ordinals (for use in axiomatic set theory), the Hilbert space formulation of quantum mechanics, operator algebras, game theory, and computers (for use in numerical simulations). A recent WSJ review of Turing's Cathedral: The Origins of the Digital Universe says:
The mathematician John von Neumann, born Neumann Janos in Budapest in 1903, was incomparably intelligent, so bright that, the Nobel Prize-winning physicist Eugene Wigner would say, "only he was fully awake." One night in early 1945, von Neumann woke up and told his wife, Klari, that "what we are creating now is a monster whose influence is going to change history, provided there is any history left. Yet it would be impossible not to see it through." Von Neumann was creating one of the first computers, in order to build nuclear weapons. But, Klari said, it was the computers that scared him the most.After von Neumann died, his Princeton IAS employer shut down the project and resolved to never do anything so practical again.
Update: Steve Hsu is another von Neumann fan.
Monday, March 5, 2012
No prizes for theoretical physics
A reader commented that proving the impossibility of quantum computers would surely win a Nobel Prize. I doubt it.
I cannot think of an example of a Nobel prize for something similar. The prize usually goes to experimental discoveries of various sorts. Here is a list of some of the more important advances in theoretical physics of the 20th century.
I cannot think of an example of a Nobel prize for something similar. The prize usually goes to experimental discoveries of various sorts. Here is a list of some of the more important advances in theoretical physics of the 20th century.
- Lorentz covariance
- Minkowski space
- Spinors
- Noether's theorem
- Chaos theory
- Impossibility of hidden variable theory
- The stability of matter in quantum mechanics
- CPT symmetry
- Spin-statistics theorem
- Gauge theory, lattice models
- Higgs mechanism
- Penrose–Hawking singularity theorems
Without the Higgs to spur spontaneous symmetry-breaking, it turns out, the edifice of fundamental physics — and no fewer than eight of the Nobel prizes awarded to 20 physicists over 35 years — would stand on shaky ground. No wonder boffins have their eye on the news from Geneva.I am deliberately omitting the supposed great breakthrus of the last 30 years, such as String theory, Supersymmetry, Multiverse, and cosmological inflation. These are very unlikely to ever win Nobel prizes.
Saturday, March 3, 2012
Life of Galileo
NPR Science Friday had a program on Life of Galileo, a play by Bertolt Brecht. They kept making analogies between Galileo and global warming alarmists and others.
They should have explained that this was a fictionalized play by a German Marxist, that the arguments given by Galileo about telescopes and tides were fallacious, and that his conflict did not really destroy his daughter's marriage.
I can see the appeal of a story about a scientist who stands up to authority to tell the truth about his discoveries. But when the story does not tell the truth about the science, then it defeats the point.
They should have explained that this was a fictionalized play by a German Marxist, that the arguments given by Galileo about telescopes and tides were fallacious, and that his conflict did not really destroy his daughter's marriage.
I can see the appeal of a story about a scientist who stands up to authority to tell the truth about his discoveries. But when the story does not tell the truth about the science, then it defeats the point.
Friday, March 2, 2012
Weak mathematical universe hypothesis
The Mathematical universe hypothesis is:
For example, if we had a faithful mathematical representation (model) of an electron, then that would qualify. We do not. By faithful, I mean that some set of numbers, formulas, and other mathematical entities fully capture all aspects of the electron.
Tegmark seems to assume that our universe has a perfect mathematical representation, so he thinks that related models could correspond to other universes. But the statement that our own universe can be so mathematized requires a huge leap of faith. As far as I know, there is no known way to do it, and no good reason to believe that it is possible.
If an electron were a (classical) particle, then it could be faithfully represented by its position, velocity, mass, electric charge, and maybe its spin (angular momentum). This is impossible for a quantum particle, because of the uncertainty principle.
Tegmark argues:
The belief that physical reality has an objective mathematical structure has been known as hidden variable theory for most of the 20th century. It has been a complete failure, and the consensus is that these theories are wrong.
Tegmark also confusingly calls his view an “extreme shut-up-and-calculate approach to physics”. This terminology refers to using quantum mechanics to predict experiments, without having a realistic model of the underlying physics. The "shut up" is an admonition to ignore the underlying physics as long as you can calculate answers. So the shut-up-and-calculate approach is directly contrary to the mathematical universe hypothesis, because it disavows any need for the physical universe to be a mathematical structure.
I think that Tegmark's MUH is at the core of many misunderstandings of modern physics. The WMUH is implicitly assumed by most physicists, in spite of decades of evidence to the contrary. It is time to recognize it as the implausible hypothesis that it is, and to only use it when it is explicitly stated as a dubious assumption.
When physicists are presented evidence against the WMUH, they will often despair that reality does not exist, or that nature is incomprehensible, or some such nonsense. None of that follows. We just have to reject Tegmark's extreme views.
In physics and cosmology, the mathematical universe hypothesis (MUH), also known as the Ultimate Ensemble, is a speculative "theory of everything" (TOE) proposed by the theoretical physicist, Max Tegmark.This seems silly to me. I am more interested in what I call the weak mathematical universe hypothesis (WMUH). It merely says that there exists at least one structure that exists both mathematically and physically.
Tegmark's sole postulate is: All structures that exist mathematically also exist physically. That is, in the sense that "in those [worlds] complex enough to contain self-aware substructures [they] will subjectively perceive themselves as existing in a physically 'real' world". The hypothesis suggests that worlds corresponding to different sets of initial conditions, physical constants, or altogether different equations should be considered equally real.
For example, if we had a faithful mathematical representation (model) of an electron, then that would qualify. We do not. By faithful, I mean that some set of numbers, formulas, and other mathematical entities fully capture all aspects of the electron.
Tegmark seems to assume that our universe has a perfect mathematical representation, so he thinks that related models could correspond to other universes. But the statement that our own universe can be so mathematized requires a huge leap of faith. As far as I know, there is no known way to do it, and no good reason to believe that it is possible.
If an electron were a (classical) particle, then it could be faithfully represented by its position, velocity, mass, electric charge, and maybe its spin (angular momentum). This is impossible for a quantum particle, because of the uncertainty principle.
Tegmark argues:
So here is the crux of my argument. If you believe in an external reality independent of humans, then you must also believe in what I call the MUH: that our physical reality is a mathematical structure. In other words, we all live in a gigantic mathematical object – one that is more elaborate than a dodecahedron, ... Everything in our world is purely mathematical – including you.I say that we should start with the weak MUH hypothesis that something in our world is purely mathematical. I do believe in an external reality independent of humans, but I don't see any reason to believe in the weak MUH. I prefer to reject it, until someone shows how it can be true.
The belief that physical reality has an objective mathematical structure has been known as hidden variable theory for most of the 20th century. It has been a complete failure, and the consensus is that these theories are wrong.
Tegmark also confusingly calls his view an “extreme shut-up-and-calculate approach to physics”. This terminology refers to using quantum mechanics to predict experiments, without having a realistic model of the underlying physics. The "shut up" is an admonition to ignore the underlying physics as long as you can calculate answers. So the shut-up-and-calculate approach is directly contrary to the mathematical universe hypothesis, because it disavows any need for the physical universe to be a mathematical structure.
I think that Tegmark's MUH is at the core of many misunderstandings of modern physics. The WMUH is implicitly assumed by most physicists, in spite of decades of evidence to the contrary. It is time to recognize it as the implausible hypothesis that it is, and to only use it when it is explicitly stated as a dubious assumption.
When physicists are presented evidence against the WMUH, they will often despair that reality does not exist, or that nature is incomprehensible, or some such nonsense. None of that follows. We just have to reject Tegmark's extreme views.
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