Saturday, February 24, 2024
Thursday, February 22, 2024
In short, quantum computing researchers have been claiming quantum supremacy for years. Some call it quantum advantage. However, there has never been any convincing demonstration that quantum computers have any speedup at all over conventional computers.
The latest is that IBM claimed last year to do a quantum calculation on a "noisy" quantum computer. Some thought that they had outdone Google. But a Chinese group outdid them by doing the calculation faster and better on a classical computer.
The quantum enthusiasts will argue, as usual, that this does not disprove quantum computing, and maybe a more clever experiment would show an advantage. I am waiting.
Monday, February 12, 2024
The starting idea of the natural sciences is that the world operates by rules that can be discovered by observations on scales large or small, depending on what interests you. In fundamental physics, the subject of this essay, the idea is narrowed to four starting assumptions.These sound reasonable, but they leave no room for many-worlds theory, string theory, simulation hypothesis, superdeterminism, or many of the ideas that are now fashionables.
A: The world operates by rules and the logic of their application that can be discovered, in successive approximations.
B: A useful approximation to the rules and logic, a theory, yields reliably computed quantitative predictions that agree with reliable and repeatable mea- surements, within the uncertainties of the predictions and measurements.
C: Fundamental physical science is growing more complete by advances in the quantity, variety, and precision of empirical fits to predictions, and by occa- sional unifications that demote well-tested fundamental physical theories to useful approximations to still better theories.
D: Research in fundamental physical science is advancing toward a unique mind-independent reality.
The essay gives way too much attention to philosopher Thomas Kuhn.
It quotes Einstein:
The supreme task of the physicist is to arrive at those universal elemen- tary laws from which the cosmos can be built up by pure deduction.This sounds a little like Weinberg's mythical Final Theory, also discussed.
No, trying to build the cosmos from pure deduction is foolishness.
Thursday, February 8, 2024
Albert Einstein asked that when he died, his body be cremated and his ashes be scattered in a secret location. He didn’t want his grave, or his body, becoming a shrine to his genius. When he passed away in the early morning hours of April, 18, 1955, his family knew his wishes. There was only one problem: the pathologist who did the autopsy had different plans.Later in the show, it discussed theories for the origin of Einstein's most brillian idea -- special relativity. Besides his extra-smart brain, it mentioned his physicist wife and a philosopher. It even had professor Galison explaining how train schedules causes people to rethink time.
In the third episode of “G”, Radiolab’s miniseries on intelligence, we go on one of the strangest scavenger hunts for genius the world has ever seen. We follow Einstein’s stolen brain from that Princeton autopsy table, to a cider box in Wichita, Kansas, to labs all across the country. And eventually, beyond the brain itself entirely. All the while wondering, where exactly is the genius of a man who changed the way we view the world?
Okay, but there was no mention of Lorentz and Poincare, or the fact that they had published the entire theory ahead of Einstein.
Galison is unusual because he does not recite crazy stories about Einstein's originality, like other Einstein scholars. He read Lorentz and Poincare and obviously understands that they did it all first, but he refuses to comment on the priority dispute.
Monday, February 5, 2024
In the 1960s Friedrichs met Heisenberg and used the occasion to express to him the deep gratitude of mathematicians for having created quantum mechanics, which gave birth to the beautiful theory of operators on Hilbert space. Heisenberg allowed that this was so; Friedrichs then added that the mathematicians have, in some measure, returned the favor. Heisenberg looked noncommittal, so Friedrichs pointed out that it was a mathematician, von Neumann, who clarified the difference between a self-adjoint operator and one that is merely symmetric. "What's the difference," said Heisenberg.There is the difference between a physicist, and a mathematical physicist.
- story from Peter Lax, Functional Analysis (slightly edited for length)
To a physicist, an observable is a symmetric operator, because those are the ones that give real values, and only real values are observed. To von Neumann, an observable is a self-adjoint operator on a Hilbert space, where some additional technical requirements are needed in order to prove the spectral theorem.
I am not trying to say that Heisenberg was stupid. But it is striking that a world-famous physicist could get a Nobel Prize for using operators as observables, and still be oblivious to the formal mathematical definition found in textbooks. We cannot expect physicists to understand mathematical subtleties.
Thursday, February 1, 2024
Apparently this is not true. We know that the weak force is chiral, ie, it violates mirror reflection symmetry. Neutrinos are left-handed in the Standard Model.
From the Scott Aaronson blog:
“There is currently no fully satisfactory way of evading the Nielsen-Ninomiya theorem. This means that there is no way to put the Standard Model on a lattice. On a practical level, this is not a particularly pressing problem. It is the weak sector of the Standard Model which is chiral, and here perturbative methods work perfectly well. In contrast, the strong coupling sector of QCD is a vector-like theory and this is where most effort on the lattice has gone. However, on a philosophical level, the lack of lattice regularisation is rather disturbing. People will bang on endlessly about whether or not we live “the matrix’”, seemingly unaware that there are serious obstacles to writing down a discrete version of the known laws of physics, obstacles which, to date, no one has overcome.”There is a whole industry of physicists doing lattice approximations to the SM, but the SM is chiral and the approximations are not, so there is no hope that the approximations converge to the SM.
Aaronson is commenting on the silly idea that we live in a computer simulation. If we did, it would raise another silly idea that we could overwork the simulator by doing certain experiments.
Monday, January 29, 2024
The quantum computer revolution may be further off and more limited than many have been led to believe. That’s the message coming from a small but vocal set of prominent skeptics in and around the emerging quantum computing industry.Compare to the hype surrounding Artificial Intelligence (AI). It is also over-hyped by its enthusiasts, but it has also delievered a lot of very impressive demonstrable results. Quantum computing has delivered nothing, and may never deliver anything.
The problem isn’t just one of timescales. In May, Matthias Troyer, a technical fellow at Microsoft who leads the company’s quantum computing efforts, co-authored a paper in Communications of the ACM suggesting that the number of applications where quantum computers could provide a meaningful advantage was more limited than some might have you believe.
“We found out over the last 10 years that many things that people have proposed don’t work,” he says. “And then we found some very simple reasons for that.” ...
Even in the areas where quantum computers look most promising, the applications could be narrower than initially hoped. In recent years, papers from researchers at scientific software company Schrödinger and a multi-institutional team have suggested that only a limited number of problems in quantum chemistry are likely to benefit from quantum speedups. ...
“In the public, the quantum computer was portrayed as if it would enable something not currently achievable, which is inaccurate,” he says. “Primarily, it will accelerate existing processes rather than introducing a completely disruptive new application area. So we are evaluating a difference here.” ... “Most problems in quantum chemistry do not scale exponentially, and approximations are sufficient,” he says. “They are well behaved problems, you just need to make them faster with increased system size.”
Someday we really will have personal robots and self-driving cars, but we may never have a useful quantum computer.
Google Research just released a video:
Quantum Computing - Hype vs. reality | Field NotesIt says quantum computers could become useful by 2030, or maybe a few years later.
25,188 views Jan 22, 2024 #GoogleAI #GoogleResearch
As the race to build the world's first truly useful quantum computer intensifies, so too does the need for clear-eyed assessment. This Field Notes episode brings in the Google Quantum AI team to help answer a few fundamental questions to drive understanding of its impact now and in the future.
the group is called "Quantum AI", but the video said nothing about AI. Just combining buzzwords, I guess.
The most touted application was fusion simulations, in order to help bring fusion power plants to market. Othere were discuvering drugs, and making the planet greener with chemistry for better batteries and fertilizer.
No mention of breaking everyone's cryptosystems. That is the only think quantum computer enthusiasts are sure about.
I am amazed that Google keeps funding this pipe dream. It has canceled hundreds of really useful products. It has developed some really good AI, but is checken to market it like OpenAI and Microsoft. Elsewhere Google touts quantum machine learning, but I doubt this will ever be practical. The non-quantum methods are progressing rapidly, and there is no sign that quantum computers would be useful.
Self-driving cares are over-hyyped, but I believe we are making progress and will get there. I do not think that that we are getting any closer to quantum computing.
Friday, January 26, 2024
How do we know climate change is caused by humans?She says this info is hard to find, but I found the same info as the first link from a search, a 2009 artucke:
In this video I summarize the main pieces of evidence that we have which show that climate change is caused by humans. This is most important that we know in which frequency range carbon dioxide absorbs light, we know that the carbon dioxide ratio in the atmosphere has been increasing, we know that the Ph-value of the oceans has been decreasing, the ratio of carbon isotopes in the atmosphere has been changing, and the stratosphere has been cooling, which was one of the key predictions of climate models from the 1960s.
How Do We Know that Humans Are the Major Cause of Global Warming?YouTube also slaps an obnoxious "context" link on the video, with some info. You also get the same info from ChatGPT.
The evidence is that humans burning fossil fuels emit CO2, and the increases in atmospheric CO2 have caused warming. Probably most of the warming observed in recent decades.
My quibble is when they leap from this to saying that humans cause most of the climate change. The climate is changing a lot of different ways, in different places. I do not see anyone even trying to quantify climate change. Just CO2 and temperature.
Monday, January 22, 2024
David Albert - What Does Quantum Theory Mean?Albert is a physicist-turned-philosopher, and he explains this pretty well.
Quantum theory may be weird—superposition and entanglement of particles that in our normal world would make no sense—but quantum theory is truly how the microworld works. What does all this weirdness mean? How to go from microworld weirdness to macroworld normalcy? Will we ever make sense out of quantum mechanics?
He goes on to say that more and more physicists are adopting the many-worlds interpretation. He says it is counter-intuitive, but does not reject it for that reason. He rejects it because it does not explain the world.
In his opinion, it does not really solve the measurement problem, for two reasons.
(1) it tries to explain the definite outcomes as an illusion. Maybe this position could be justified some day.
(2) it cannot explain the probabilities we see, as many-worlds says all outcomes are determined.
He admits that physicists have done a lot of contortions to try to get around these issues, but they have failed.
"At the end of the day, it does not account for our experience."
I agree with him on these points. Perhaps mathematical physicists will develop a decoherence theory showing that the wave function branching resembles what we see. It hasn't happened yet, but it is possible.
But many-worlds will never explain the probabilities, because the whole point of many-worlds is to reject probabilities. The parallel worlds arise because probabilities are interpreted as world splittings, and all possibilities are realized in inaccessible alternate worlds.
So why are more and more physicists adopting such a wrong theory? No answer given. Physicists are losing their grip on reality.
Thursday, January 18, 2024
The discovery was announced; the story reported; and then there was silence. Physicists endeavoured, of course, to maintain the impression that they had discovered something of inestimable value. They were game. Writing in The Daily Beast, Sean Carroll predicted that the Higgs Boson would “revolutionize physics,” and if this is what physicists always say, then at least they seem never weary of saying it.From what I have found, calling everything a revolution stems from calling the Copernicus heliocentric model the Copernican Revolution, because the Earth revolved around the Sun. It was a weak pun. And then that was so important, it became the Scientific Revolution.
Lawrence Krauss, writing in The Daily Beast as well, gave it his best. Many years ago, Leon Lederman had designated the Higgs Boson as the God particle. No one can today remember why. The God particle? “Nothing could be further from the truth,” Krauss remarked. In this, of course, he was entirely correct: Nothing could be further from the truth.
In the end, Krauss, like Carroll before him, could do no better than an appeal to the revolution. The discovery of the Higgs Boson “validates an unprecedented revolution in our understanding of fundamental physics …” Readers of The Daily Beast are always pleased to uphold the revolution, no matter how revolting. Yet, the Standard Model was completed in the early 1970s,
Finding the Higgs Boson just confirmed what people thought 50 years earlier. Not a revolution.
Monday, January 15, 2024
“Tell me,” the great twentieth-century philosopher Ludwig Wittgenstein once asked a friend, “why do people always say it was natural for man to assume that the sun went around the Earth rather than that the Earth was rotating?” His friend replied, “Well, obviously because it just looks as though the Sun is going around the Earth.” Wittgenstein responded, “Well, what would it have looked like if it had looked as though the Earth was rotating?”For example, he tells it in this interview, where he attributes it to a play, so it might be fiction. He tells it again here, plugging his latest book.
It is a good story. Just because your data fits your model, you cannot conclude that your model is right. There could be a completely different model that fits just as well.
I am not sure what point Krauss was making. He seems to be saying that the many-worlds theory would look just like the Copenhagen interpretation of quantum mechanics. This is not a great example, because in our world we see more probable events as more likely. In many-worlds theory, there is no known reason for that happening. It is like saying the world is a simulation. It does not look like a simulation unless you also assume that the simulator has replicated natural laws very accurately.
Wednesday, January 10, 2024
Does information work at the deep levels of physics, including quantum theory, undergirding the fundamental forces and particles? But what is the essence of information—describing how the world works or being how the world works. There is a huge difference. Could information be the most basic building block of reality?Okay, but he is challenged for a proton, and says that a proton is fully described by 50-60 bits for its location in the universe, and 1 bit for spin up or down.
Seth Lloyd is a professor of mechanical engineering at the Massachusetts Institute of Technology. He refers to himself as a “quantum mechanic”.
What? The diameter of the observable universe is about 4x1028 cm. So that is about 6x1084 cm3 in volume, so it would take that many bits to specify location to the nearest cubic cm.
A cubic cm is a lot of space for a proton. We need at least 100 bits to specify a proton location to some small region. And the universe could be bigger than what is observable.
But that is not my issue here. The proton could have velocity. Need many more bits for that.
And spin is not just one bit. Spin could point in any direction, not just up or down.
None of these proton parameters can be specified precisely, because of Heisenberg Uncertainty. A proton can have a wave function, and not position and momentum at the same time. So how many bits are needed for a wave function?
But then the wave function is not even real, so I don't know if it makes sense to ask how many bits are needed for a wave function.
So if a proton is equivalent to some number of bits of information, I don't know how to calculate that number. Lloyd is underestimating them.
Monday, January 8, 2024
Voigt transformations in retrospect: missed opportunities? ...Voigt's paper was not appreciated. The paper moves on to "the pointless Einstein-Poincar´e priority dispute."
Nearly two decades before the vigorous development of special relativity has started, in 1887 Woldemar Voigt published an article on the Doppler effect in which some fundamental principles underlying the relativity theory were anticipated. Namely, he was the first who used Einstein’s second postulate (universal speed of light) and the restricted form of the first postulate (invariance of the wave equation when changing the inertial reference system) to show that the Doppler shift of frequency was incompatible with Newtonian absolute time and required a relative time identical with the Lorentz’s local time introduced later.
In particular we are interested in to find out why the role played by Poincar´e was not properly acknowledged at that time by his contemporaries. Our hypothesis is that this happened because Poincar´e’s approach required a higher level of mathematical education than the majority of physicists had at that time. Minkowski belonged to a few who were in a position to duly appreciate Poincar´e’s contribution.Poincare and Minkowski died in the next several years, so that partially explains why they did not take part in a priority dispute with Einstein. The paper acknowledges that Einstein lied about his sources all his life.
Many credit Einstein for discovering clock synchronization and the relativity of simultaneity in 1905, but that is clearly false:
Already in 1898, “Poincar´e had presented exactly the same light signaling and clock synchronization thought experiment that would later be found in Einstein’s 1905 relativity paper” , although Poincar´e’s presentation is without any mention of the relativity principle and Lorentz’s local time. Two years later in his lecture “Lorentz’s theory and the principle of reaction” Poincar´e used his light signaling and clock synchronization thought experiment to explain the physical meaning of the Lorentz’s local time . ...Minkowski was the much bigger influence on acceptance of relativity:
In 1902 letter to the Nobel committee to nominate Lorentz for the Nobel prize in Physics, which he indeed was awarded, Poincar´e praises very highly Lorentz’s “most ingenious invention” of “local time” and writes: “Two phenomena happening in two different places can appear simultaneous even though they are not: everything happens as if the clock in one of these places were late with respect to that of the other, and as if no conceivable experiment could show evidence of this discordance” .
Minkowski’s September 21st, 1908, lecture “Space and Time” was a crucial event in the history of relativity 1. ...The geometry of special relativity was only appreciated by mathematicians:
The influence of the Cologne lecture was enormous. Its published version “sparked an explosion of publications in relativity theory, with the number of papers on relativity tripling between 1908 (32 papers) and 1910 (95 papers)” . The response to the Minkowski’s lecture was overwhelmingly positive on the part of mathematicians, and more mixed on the part of physicists — only in the 1950s their attitude began to converge toward Minkowski’s space-time view . ...
However, in our opinion, to make the decision to exclude Poincar´e’s name from the Cologne lecture Minkowski needed some serious reason to psychologically justify such an unfair omission.
A surprising fact about Minkowski’s “Raum und Zeit” lecture is that it never mentions Klein’s Erlangen program of defining a geometry by its symmetry group . A link between Minkowski’s presentation of special relativity and Erlangen program was immediately recognized by Felix Klein himself  who remarked: “What the modern physicists call the theory of relativity is the theory of invariants of the 4-dimensional space-time region x, y, z, t (the Minkowski ’world’) under a certain group of collineations, namely, the ’Lorentz group’ ”. Untimely death of Minkowski presumably hindered the appreciation of this important fact by physicists.It concludes:
In parallel to the advance in modern physics, in the middle of the twentieth century it became increasingly evident that Poincar´e’s contribution to relativity was unjustly downplayed. As a result, some attempts to restore the justice followed. ...Did the authors of this paper think that they were going to write the last word on the subject?
Most succinctly this difference was expressed by Lorentz himself: ‘the chief difference being that Einstein simply postulates what we have deduced, with some difficulty, and not altogether satisfactorily, from the fundamental equations of the electromagnetic field” .
Poincar´e’s objective was much more ambitious than Einstein’s as he wanted to derive special relativity as an emergent phenomenon. It is quite possible therefore that Poincar´e simply considered Einstein’s contribution as being too trivial in light of this bigger goal. “To Poincar´e, Einstein’s theory must have been seen as a poor attempt to explain a small part of the phenomena embraced by the Lorentz theory” .
There is still another aspect which makes Einstein-Poincar´e priority dispute pointless. Modern understanding of relativity is significantly different from the one that was cultivated at the beginning of the twentieth century. Two examples are the notions of æther and relativity of simultaneity which are often used in the priority dispute. ...
Usually this stubbornness of Poincar´e with respect to the æther is considered as his weak point, as an evidence that he didn’t really understand relativity. It is historically true that the abolishment of the æther by Einstein played a crucial role and revolutionized physics. However, frankly speaking, in retrospect, when this revolution came to its logical end in modern physics, we can equally well consider Poincar´e’s attitude as prophetical.
As modern physics has progressed in the twentieth century, it became increasingly evident that the vacuum, the basic state of quantum field theory, is anything but empty space. In fact, at present an æther, “renamed and thinly disguised, dominates the accepted laws of physics” . It is clear that only “intellectual inertia”  prevents us from using historically venerable word “æther” instead of “vacuum state” when referring to the states with such complex physical properties as vacuum states of modern quantum theories.
Poincar´e proponents in the priority dispute argue that Einstein synchronization, which Einstein himself considered as the crucial element of special relativity, has in fact originated from Poincar´e’s work.
In light of this immense and still continuing progress of modern physics, attempts to retrospectively induce an artificial Poincar´e-Einstein priority dispute and rewrite the history seem minute. We will be happy if this arid and futile dispute will come to its end. There is nothing scientific in it and its presence only emphasizes hideous traits of human nature.
This paper is convincing that Lorentz and Poincare had all of relativity theory before Einstein, that Einstein lied about his sources to get more credit for himself, and that in retrospect the Poincare-Minkowski view was superior to Einstein's.
However the authors think that it is unfair to judge Einstein in retrospect, as no one could have known which ideas would be more important later. It took 50 years, the authors say, for the Physics community to come around to the Poincare-Minkowski geometric view. The paper puts a lot of weight on the opinion of Max Born, who was a friend of Einstein, and who was greatly influenced by Einstein's 1905 paper. But there is not much substance to Born's opinion. Many people are greatly influenced by a textbook, but that does not mean that the textbook is original. While Born was a relativity expert, it is not clear that he understood Poincare's papers.
I might agree that the priority dispute is tiresome and settled, except that the Physics community continues to idolize Einstein as the greatest genius ever, for how he discvoered relativity. For example, see this recent Discover magazine list of the ten greatest scientists of all time, where Einstein is number one, mainly for relativity work. (Three of the other nine are women, but that is another story.)
Friday, January 5, 2024
Rosalind Franklin was not a ‘wronged heroine’, she was an equal contributor to the discovery.No, she was not an equal contributor. She had little contact with Crick and Watson.
I am all for crediting her for what she did. She did valuable work on DNA that got used by Crick and Watson. But this Nature article added nothing new. The story is well-known, and can be found on Wikipedia.
This story is politicized, because people hate Watson for saying that people have genetic difference, and love to put Franklin on lists of great XX century scientists, because she was a woman.
Wednesday, January 3, 2024
Determinism ... Indeterminism, though, is just as bad because if you do something by chance, that doesn't mean it is done by you freely. This is a point made many years ago. It looks like both determinism and indeterminism are incompatible with free will, which shows there is something wrong with the concept.Yes, the argument has been made many times, and it is nonsense.
Saying that someone's choices are indetermined is essentially the same as saying that he is free to make a choice.
If you can predict my choice, then it is apparently determined by past events. But if I make a free choice, then you cannot predict it, and it seems like random chance.
His argument is like saying electrons do not exist. An electron is a charged particle, so its charge must be positive or negative. If the charge is positive, then it is not an electron. A negative charge is just as bad, because then it would be a negative charge carrier, instead of an electron.
The argument does not say anything.
It is amazing how many philosophers and other scholar swallow this nonsense argument.