Einstein's view of measuring rods

Here is a new paper:

The paper offers a historical overview of Einstein's oscillating attitude towards a "phenomenological" and "dynamical" treatment of rods and clocks in relativity theory.

This may sound like two obscure philosophical viewpoints, but it goes to the heart of why Einstein is credited for special relativity. Lorentz and Poincare had all the theory and equations and experiment interpretation before Einstein, so the only way to credit Einstein is to claim that there was something superior about his viewpoint.

But Einstein was not clear about what his viewpoint was, and he seemed to alternate between two viewpoints of Lorentz. Nobody cared much at the time, because the spacetime geometry viewpoint of Poincare and Minkowski is what became popular. Nevertheless, this paper explores Einstein's viewpoint in detail.

FitzGerald and Lorentz first deduced the length contraction as the logical consequence of interpreting Michelson-Morley as showing that the speed of light is constant even tho motion is relative. Then they gave an explanation in terms of the electromagnetic molecular forces. At the time, not everyone realized that solid objects are held together by electromagnetic molecular forces, so some people liked the way that Einstein skipped that part of the argument. He used rigid measuring rods, even tho the length contraction shows that there is no such thing.

Einstein's approach is often explained in positivist terms, altho Einstein's later philosophy disavowed such an approach.

Polchinsky defends non-empirical science

String theorist Joseph Polchinski has posted a preprint, Why trust a theory?

The meeting “Why Trust a Theory? Reconsidering Scientific Methodology in Light of Modern Physics,” which took place at the Ludwig Maximilian University Munich, Dec. 7-9 2015, was for me a great opportunity to think in a broad way about where we stand in the search for a theory of fundamental physics. ...

As the only scientific representative of the multiverse at that meeting, a major goal for me was to explain why I believe with a fairly high degree of probability that this is the nature of our universe. But an equally important goal was to explain why, contrary to what many believe, string theory has been a tremendous success, and remains a great and inspiring hope for our ultimate success in understanding fundamental physics. ...

I am coming at this as an active scientist trying to solve a scientific problem, in my case the theory of quantum gravity. ... In the end, my estimate simply came down to combining four factors of two. This led to the probability 94% that the multiverse exists. If I had quoted this in binary, probability 0.1111, the scientific content would have been exactly the same but it would have led to much less merriment.

My estimate uses a kind of analysis known as Bayesian statistics.

No, there is no scientific problem here, and there is nothing scientific about his approach.

He did not actually attend the meeting, as he was unable for unspecified health reasons.

His string theory is nutty enuf, but that is mainstream physics compared to his views about the multiverse, black hole firewalls, and the futility of experimental physics.

In effect we would be telling the experimentalists, who were spending billions of dollars and countless human-years of brilliant scientists, were essentially measuring random numbers, and I did not want to be the bearer of bad news. But for the most part Raphael’s point of view prevailed: we both agreed clearly on what the science was saying, and in the end one must be true to the science. I am not by nature a radical, but seem to have become one both with the multiverse and with the black hole firewall [26] just by following ideas to their logical conclusions. ...

Still my anxiety grew, until eventually I needed serious help. So you can say quite literally that the multiverse drove me to the psychiatrist.²

[footnote 2] In truth, I should have gotten help for anxiety sooner, and for more general reasons. One should not be reluctant to seek help.

Okay, maybe I should not call him nutty if he has a genuine psychiatrist problem. But he is a respected theoretical physicist, and people take him seriously.

He claims to address the critics of string theory, but his main argument is to deny that it is a non-empirical theory. He says:

If I just make the same crude counting of a factor of 2 for each, I end up with probability 98.5 [%] for string theory to be correct.

This is why Bayesians have a bad name.

He also attacks Peter Woit on the grounds that 10 years ago his blog had an anonymous comment that was rudely dismissive of a Steve Weinberg argument.

This must be a new low for ArXiv, the preprint server. I doubt that any real physics journal would publish such a complaint.

It is remarkable that the string theorists have done so little to rebut what Woit and other critics have said. You would think that big-shot professors would defend themselves, if everyone says that he is pursuing wrong and unscientific theories. Maybe they have no good defense.

Woit and Lubo have already posted their responses.

String theory could be described as something that was once a good idea that failed. The multiverse, black hole firewall, and Polchinsky's other ideas are unscientific nonsense from the start. And the philosophers at the German conference are clueless about what is scientific.

Update: Polchinski has moved his attack on Woit. He implies that Woit is not worthy of an attack on ArXiv. His attack on Woit is still online here.

Update: Separately, here is a Nature mag complaint that ArXiv has rejected some crappy papers that might be good enuf for a refereed journal.

Stewart on beauty and truth in relativity

I expect physicists to under-appreciate the fine points of a theory, and to under-credit the mathematical contributions. But I just stumbled across a 2007 book by a real mathematician who does a great job of explaining a lot of great mathematics, and then recites the same stupid Einstein myths as the physicists.

The book is Why Beauty Is Truth: The History of Symmetry, by Ian Stewart. Chap. 11 is on "the clerk from the patent office, and has a lot of Einstein idol worship. In particular:

The common theme here is symmetry. Changing from one frame of
reference to another is a symmetry operation on space-time. Inertial frames are about translational symmetries; rotating frames are about rotational symmetries. Saying that Newton's laws are the same in any inertial frame is to say that those laws are symmetric under translations at uniform speed. For some reason, Maxwell's equations do not have this property. That seems to suggest that some inertial frames are more inertial than others. And if any inertial frames are special, surely it should be those that are stationary relative to the aether.

The upshot of these problems, then, was two questions, one physical, one mathematical. The physical one was, can motion relative to the aether be detected in experiments? The mathematical one was, what are the symmetries of Maxwell's equations?

The answer to the first was found by Albert Michelson, a US Navy officer who was taking leave to study physics under Helmholtz, and the chemist Edward Morley. They built a sensitive device to measure tiny discrepancies in the speed of light moving in different directions, and concluded that there were no discrepancies. Either the Earth was at rest relative to the aether - which made little sense given that it was circling the Sun -- or there was no aether, and light did not obey the usual rules for relative motion.

Einstein attacked the problem from the mathematical direction. He didn't mention the Michelson-Morley experiment in his papers, though he later said he was aware of it and that it had influenced his thinking. Instead of appealing to experiments, he worked out some of the symmetries of Maxwell's equations, which have a novel feature: they mix up space and time. (Einstein did not make the role of symmetry explicit, but it is not far below the surface.) One implication of these weird symmetries is that uniform motion relative to the aether - assuming that such a medium exists - cannot be observed.

Einstein's theory acquired the name "relativity," because it made unexpected predictions about relative motion and electromagnetism. [p.189] ...

Einstein was not the only person to notice that the symmetries of spacetime, as revealed in Maxwell's equations, are not the obvious Newtonian symmetries. In a Newtonian view, space and time are separate and different. Symmetries of the laws of physics are combinations of rigid motions of space and an independent shift in time. But as I mentioned, these transformations do not leave Maxwell's equations invariant.

Pondering this, the mathematicians Henri Poincaré and Hermann Minkowski were led to a new view of the symmetries of space and time, on a purely mathematical level. If they had described these symmetries in physical terms, they would have beaten Einstein to relativity, but they avoided physical speculations. They did understand that symmetries of the laws of electromagnetism do not affect space and time independently but mix them up. The mathematical scheme describing these intertwined changes is known as the Lorentz group, after the physicist Hendrik Lorentz.

Minkowski and Poincare viewed the Lorentz group as an abstract expression of certain features of the laws of physics, and descriptions like "time passing more slowly" or "objects shrinking as they speed up" were thought of as vague analogies rather than anything real. But Einstein insisted that these transformations have a genuine physical meaning. Objects, and time, really do behave like that. He was led to formulate a physical theory, special relativity, that incorporated the mathematical scheme of the Lorentz group into a physical description not of space and a separate time, but of a unified space-time.

Minkowski came up with a geometric picture for this non-Newtonian physics, now called Minkowski space-time. It represents space and time as independent coordinates, and a moving particle traces out a curve - which Einstein called its world Line - as time passes. Because no particle can travel faster than light, the slope of the world line can never get more than 45° away from the time direction. The particle's past and future always lie inside a double cone, its light cone. [p.192]

No, it was Minkowski who introduced "world-point" for a spacetime point in his 1907 paper, and "world-line" in his more famous 1908 paper. Einstein did not use any of this spacetime terminology until after Minkowski's famous 1908 paper gained widespread acceptance.

On the bigger picture of who discovered special relativity, let's look at what Stewart gets right. The physical basis was the Michelson-Morley experiment, and the mathematical basis was the symmetry group of Maxwell's equations. Stewart gets this right, and acknowledges that Einstein did not explicitly mention either basis.

By comparison, Lorentz explicitly relied on Michelson-Morley in his papers of 1895, 1899, and 1904, Poincare did so in his 1904, short 1905, and long 1905 papers, and Minkowski in his 1907 and 1908 papers. Poincare and Minkowski explicitly described the Lorentz group as the symmetries of 4-dimensional spacetime and Maxwell's equations.

Thus Lorentz, Poincare, and Minkowski explicitly had the physical and mathematical bases of special relativity, and Einstein did not.

(I should note that the Michelson-Morley experiment by itself did not prove relativity. There were other possible explanations, such as a stationary Earth, aether drift, and emitter theory of light. Those explanations were rejected for other reasons. Historically, Michelson-Morley was the crucial experiment.)

So why does Stewart insist on crediting Einstein? The argument is that Poincare and Minkowski understood spacetime "on a purely mathematical level", and their transformations "were thought of as vague analogies rather than anything real."

Stewart is wrong. As you can see from the above papers, Lorentz, Poincare, and Minkowski are explicitly using their transformations to explain the Michelson-Morley experiment. There is no vague analogy. They are better grounded in real experiments than Einstein.

Minkowski's famous paper begins:

Gentlemen! The concepts about time and space, which I would like to develop before you today, have grown on experimental physical grounds. Herein lies their strength. Their tendency is radical. Henceforth, space for itself, and time for itself shall completely reduce to a mere shadow, and only some sort of union of the two shall preserve independence.

He is most emphatically saying that the Michelson-Morley experiment along with Maxwell's equations lead to a new understanding about the reality of space and time. He is transforming physical coordinates for space and time, and not just some vague mathematical non-real analogy.

Stewart says that Poincare and Minkowski did not understand that the symmetries mix up space and time. He is obviously wrong, as Minkowski emphasized that space and time were inseparable.

Again it is hard to understand how a mathematician like Stewart can get this so badly wrong. I can only assume that he never looked at any of the original papers, and relied on Einstein-idolizing accounts by physicists.

It is somewhat true that "Einstein attacked the problem from the mathematical direction." Philosophers who credit Einstein do so largely because he ignored experiments, and was just trying to give an alternative formulation of Lorentz's theory. As Lorentz later said, Einstein's 1905 innovation was to postulate what was previously proved. But Einstein failed to get to the mathematical heart of the theory that Poincare and Minkowski found -- that relativity is a 4D spacetime non-Euclidean geometry theory.

Covariance is an essential concept to XX century theoretical physics. Physicists commonly misunderstand this, and textbooks usually do not explain it correctly. It is what makes symmetry one of the most important concepts in all of physics. To Poincare and Minkowski, the heart of relativity is the covariance of Maxwell's equations under the Lorentz group. Einstein did not understand or appreciate the concept until 1915, as he wrote a paper against it in 1914.

The facts of relativity history are not in any serious dispute. It is amazing how many people get the facts and theory essentially right, and then idolize Einstein for work done by others, not Einstein.

Stewart is right that the history of relativity is a symmetry story. The Michelson-Morley experiment demonstrated symmetries in the physical world that were difficult to reconcile with the mathematical symmetries of Maxwell's equations. That is the issue that Lorentz squarely addressed and partially solved in 1895. This work ultimately led to Poincare and Minkowski discovering that all of these symmetries can be explained by a non-Euclidean geometry on 4-dimensional spacetime. That is the essence of special relativity. Einstein played no part in this story, except to help popularize work that had been published and accepted by experts years earlier.

Defending electrons with free will

I posted about a free will dispute between physicists Sabine Hossenfelder and Lubos Motl, and now Motl elaborates:

First, the human behavior is often unpredictable, random. People often look stubborn. These are the "external manifestations" of the free will of humans. But all the other people could very well be some machines or puppets that are controlled by some external puppet masters. The actual reason why I am sure about the existence of the free will (and I mean my free will) is that I feel it. I know that many if not all of my decisions were done by me and not dictated by any external people or data or mechanisms. At least, I have eliminated all conceivable influences that could operate within the spacetime by mechanisms that at least remotely resemble those that I consider allowed by physics.

This basic comment relies on my subjective perception, something that I cannot prove. I cannot prove that I am aware of myself, I am conscious, and I know that a given decision was really mine. Only I know it for sure.

That's right. I am convinced of my own free will in the same way that I am convinced of my consciousness.

This may not convince others. In fact, I am willing to believe that most people are not fully conscious, and do not have free will.

Now, does the quantum randomness play a role in the brain? You bet. Quantum randomness is everywhere and even if you applied decoherence and derived some effective classical equations of motion for the brain, they would have stochastic terms in them – which you could treat as classical stochastic terms, however (like the forces driving the Brownian motion).

Yes. It is possible that all randomness is attributable to quantum mechanicsF100.

Motl even defends electrons having free will:

1) An agent in possession of free will is able to perform an action that was possible to predict by nobody but the agent itself. ...

Conway and Kochen have proven that if we assume ..., then it follows that the elementary particles have a free will, too.

This is a "poetic" way of saying that the results of their measurements can't be predicted from the knowledge of any past or external data.

Now, if you think that the "free will of particles" sounds unusual if not comical, be sure that it sounds unusual or comical to me, Conway, and Kochen, too. It's simply not the kind of language we normally use – neither in everyday life nor in physics.

That's right, it sounds comical, but it is just as comical to say that humans do not have free will.

Finally, Lumo gets to the relationship between randomness and free will:

So Hossenfelder explicitly says things like:

If it is random, there is no agency to it, consequently there is no "will".

... It's just plain idiocy for someone to say that one's decision isn't free just because it has a random aspect – it's free exactly because it has it. It's totally hypocritical to call for equations and use the authority of physics – while rejecting every single important principle that physics has discovered and believing that the Universe may be described by some non-relativistic, fundamentally non-quantum, superdeterministic theory (and certain people promote these adjectives explicitly).

It's unbelievable for one individual to accumulate all these stupidities at the same moment. But Ms Hossenfelder has managed to get this 0.00% score in correctness about these conceptual issues, anyway.

Lumo is right about this, but he is a little hard on Hossenfelder. She is just parroting what has become conventional wisdom. 100% of modern philosophers are also wrong on this point. Leading physics expositors are also wrong. The textbooks are strangely silent on the issue.

PHysics books do not explain consciousness or free will, and that is reasonable as there is very little relevant scientific data, but they ought to explain randomness. Many physicists apparently think that randomness implies a lack of free will, or the splitting of a parallel universe, or an intrinsic physical entity like energy or temperature, or even a superdeterministic illusion. Each of these four ideas is crazy. They are only mentioned seriously because randomness is a gigantic hole in modern physics education.

Randomness sprinkled over the determinism

I posted yesterday about confusion over luck, and now I have another example.

Physicist Sabine Hossenfelder is also confused about randomness:

I wish people would stop insisting they have free will. It’s terribly annoying. Insisting that free will exists is bad science, like insisting that horoscopes tell you something about the future – it’s not compatible with our knowledge about nature. ...

There are only two types of fundamental laws that appear in contemporary theories. One type is deterministic, which means that the past entirely predicts the future. There is no free will in such a fundamental law because there is no freedom. The other type of law we know appears in quantum mechanics and has an indeterministic component which is random. This randomness cannot be influenced by anything, and in particular it cannot be influenced by you, whatever you think “you” are. There is no free will in such a fundamental law because there is no “will” – there is just some randomness sprinkled over the determinism.

In neither case do you have free will in any meaningful way.

Lubos Motl rebuts this, and endorses this comment:

Hossenfelder: "I wish people would stop insisting they have free will."

Stor: How could they, if they have no free will! :)

Motl cites the Free Will Theorem and argues for operational free will, but I don't think he gets to the heart of the matter.

People are really confused about probability and randomness.

Hossenfelder argues that our physical theories do not allow for free will. But if one did, what would it look like? For one thing, certain microscopic processes would be unpredictable. Just like quantum mechanics.

So how is quantum mechanics not the perfect theory for allowing a belief in free will?

Hossenfelder has her own proposal for a physical theory with free will. She says:

we need a time evolution that is neither deterministic nor random. ...

What we need in order for this evolution to not be random is a function F(ti) hat we can call the “free will function” that at any time ti returns a specific choice, ...

The function F should not be forward deterministic itself, otherwise we would be back in the block universe with Laplace’s demon. Neither should it be a random
process. ...

All examples that allow for free will have in common that the free will function cannot be a solution (at least piecewise) to a differential equation for if it was it could be evolved forward by use of this equation.

It is hard to make any sense of this. She seems to have in mind an F that is determined by knowledge that is only known to the person with the free will.

She writes:

The sensible consequence to draw from this "free will theorem" is of course that neither particles nor humans have free will. I don't know why you believe their argument implies I am wrong. The very opposite is the case, it supports my argument. Do you really want to argue that particles have free will? Seriously?

The authors of that theorem (Conway, Kochen) say that the sensible conclusion is that both humans and particles have free will. Electrons seem to have free will in the sense that if you align their spin in one direction, and then measure spin in a transverse direction, the electrons seem to decide on their own whether to have spin up or down. When we try to predict, all we can say is that we see a 50-50 chance of each possibility. Some people say that this is proof of true randomness, but it makes just as much sense to say that the electron has a mind of its own.

Saying that an electron has free will is essentially the same as saying that the electron appears to make choices that are not predictable by any external data. It does not mean that the electron has consciousness, and physicists do not know how to define that concept. Quantum mechanics textbooks do not say that the electron makes choices, because that would be anthropomorphizing it. But they make equivalent statements about it being unpredictable.

Update: More comments:

George Musser said: Many people may seek free will out of religious (not political) motivations, but in most cases I think it's simpler: we observe we have free will, and the purpose of science is to explain observations. Our observations might be illusory, but then we need to account for the illusion.

Hossenfelder: Since this comment section is suffering from an extraordinary influx of mostly ill-informed, impolite, and entirely superfluous submissions that clog my inbox, I am closing this comment section.

The answer may be luck

Brian Greene explained on RadioLab that there is no time, and we only have free will to choose alternate universes.

The most sensible comment is Lisa Randall saying that this is all speculation. But that suggests that it might be true. No, it is just an untestable fantasy that cannot possibly be true.

The episode appears to be a few years old, but I just heard it on my local NPR radio station.

To Greene, Kaku, and others, randomness means the universe is splitting into parallel universes.

A current ABC News story says time travel may be possible, according to scientists:

But physicists warn just because the feat may seem impossible, doesn't mean it is.

"We have a hard time perceiving how time can bend just like other dimensions, so Einstein's predictions seem strange," said J. Richard Gott, author of the book Time Travel in Einstein's Universe and a professor of astrophysics at Princeton University. "But this appears to be the world we live in." ...

Then again, even if we manage to bolt into the future, there remains the tricky issue of how to return by traveling to the past.

According to Einstein's theory, approaching the speed of light would theoretically slow time, traveling at the speed of light would make it stand still and traveling faster than the speed of light would reverse time.

But Einstein also showed that traveling at or faster than the speed of light is impossible because mass at these speeds becomes infinite. Does that mean traveling back in time is impossible? Some, like British theoretical physicist Stephen Hawking, have said so. But others think there may be a way to find "shortcuts" to the past.

In the late 1980's Kip Thorne of the University of California at Berkeley suggested that objects known as wormholes exist in space. These objects would essentially be two connecting black holes whose mouths make up a tear in the fabric of space-time.

By finding a wormhole and stretching it so one mouth extends light years away from the other, the wormhole could provide a passageway to a past or future point on the undulating river of time. ...

Hawking has suggested that time protects itself from such scenarios by preventing time travel to the past. Others suggest that the time traveler would simply enter a parallel universe that evolves along its own separate route in space. And others, like Halpern, say that past, present and future, might all exist and influence each other simultaneously in our universe.

Traveling to the future is nothing special, as freezing your body would have the same effect.

Here is another view, from Harvard psychology professor Steve Pinker:

But new studies looking for small effects of thousands of genes in large samples have pinpointed a few genetic loci that each accounts for a fraction of an IQ point. More studies are in the pipeline and will link those genes to brain development, showing that they are not statistical curiosities. The emerging picture is that most behavioral traits are affected by many, many genes, each accounting for a tiny percentage of the variance.

Biologists are solving a related mystery: What is the additional factor shaping us that cannot be identified with our genes or families? The answer may be luck. We’ve long known that the genome can’t wire the brain down to the last synapse, so there is tremendous room for unpredictable zigzags in development.

I quote this because of his attitude that "luck" might be some sort of answer to an unsolved problem.

Behavioral traits are attributable to genes, families, and possible additional factors. You can call those factors "luck" if you want, but that is just another way of saying that the factors are unknown or unpredictable with current knowledge.5

Most people think that the family environment is the most important, but research says that it is the least .

For another view from the other side of the world, see this 2012 article in an Iranian medical journal:

Deterministic thinking is one of the major cognitive distortions. This type of thinking ignores any possibility in making a conclusion about events. Any consequence of an event may be thought as: 2×2= 4. Equality is a dominant factor among all conclusions of this kind of distortion. Distortion emerges in cognitive rigidity in the mind and could be the source of all distortions. Cognitive rigidity is a main reason for depression and other psychosocial maladjustments. ...

for instance, divorce= misery; cancer = death or being informed of having a cancer = misery [20]. ...

Holy Quran: "sometimes an undesirable event may bring you luck and sometimes bad luck" [25] (Quran). Therefore, being too disappointed or too hopeful about events is not accepted in this perspective as prediction of events may not be possible. Even prediction of God's will is not promising in Shiite perspective -Arafeh praying, Imam Hossein [26]. This view is called "bada" in Shiite ideology which means everything can be initiated from the beginning. There is a phrase used most often by Moslems around the world when they are faced with different events and situations:”Insha Allah” which means “If God Wants”. This means that any consequence of events is due to will of God19, [27, 28]. Similarly, in the scientific approach, accepting or rejecting hypothesis by P value of zero is avoided despite possessing firm experimental reasons. The main reason for this approach is that some scientists believe in no absolute reality.

Apparently Moslems get diagnosed with cancer, and then have a hard time understanding that they have a chance of living, and a chance of dying. Islam teaches that all events are determined by the will of God, and deterministic thinking is depressing.

Moslem scientists can only do experiments by blocking out the Islamic teachings, and pretending that there is no absolute reality.

By contrast, Christianity teaches that people have free will.

Columbia statistician Andrew Gelman recently quoted this paper favorably, and says that "deterministic thinking" is "one of our favorite villains". Quantifying luck is the bread and butter of statisticians.

The West also has misunderstandings of luck and probability. One of the most widely praised and cited results in social science was a 1985 paper supposedly showing that basketball players do not have hot hands. It was recently shown to be based on an elementary probability error. But then the NY Times articles on the correction were hopelessly confused, as explained here:

The existence of "Hot Hands" and "Streaks" in sports and gambling is hotly debated, but there is no uncertainty about the recent batting-average of the New York Times: it is now two-for-two in mangling and misunderstanding elementary concepts in probability and statistics; and mixing up the key points in a recent paper that re-examines earlier work on the statistics of streaks. In so doing, it's high-visibility articles have added to the general-public's confusion about probability, making it seem mysterious and paradoxical when it needn't be.

The confusion is in phrases like "purely random situation". The Wall Street Journal made a similar error, but it posted a correction. The NY Times refused to post a correction.

Smolin draws lessons from Einstein and general relativity

Physicist Lee Smolin has some unusual views about science, and writes Lessons from Einstein's 1915 discovery of general relativity:

There is a myth that Einstein's discovery of general relativity was due to his following beautiful mathematics to discover new insights about nature. I argue that this is an incorrect reading of the history and that what Einstein did was to follow physical insights which arose from asking that the story we tell of how nature works be coherent.

No, he just switches from one incorrect myth to another.

All the characteristic phenomena that general relativity describes were unknown in 1915 when Einstein published his theory. These include the expanding universe, black holes, light bending in gravitational fields, gravitational lenses, time slowing down in gravitational fields, gravitational waves, dark energy. Not only were these phenomena not yet observed in 1915, most of them had not even been thought about. ...

Some people point to the shift in Mercury’s perihelion as a case of an anomaly that general relativity explained. The problem with this is that virtually nobody except Einstein thought this phenomena needed a new theory to explain it. The bulk of astronomical opinion was that this shift could be accounted for either by a new planet or by more precise calculations of the way the planets’ gravitational fields perturb each others orbits.

What should have been clear to anyone who followed physics was that Newton’s gravitational theory required revision in the light of special relativity. But why not introduce a field theory for gravity within the framework of special relativity?

Most of this is false. Einstein did not even believe in an expanding universe until around 1932, when Hubble convinced him of the evidence.

The possibility of black holes, where a star has collapsed to the point where gravity is too strong for light to escape, had been published a century earlier. Einstein rejected the concept, even after others showed that they were possible in GR.

Einstein did predict light bending, and that the amount should be greater than the Newtonian prediction. However some bending was expected in the Newtonian theory, as a result of light having inertia.

Einstein proposed gravitational lensing many years later, but that is just a consequence of bending light, and we would have it with or without GR.

Einstein also rejected gravitational waves and dark energy, even after advocated by others.

The theoretical cause for belief in dark energy comes from quantum mechanics, not GR. The GR physicists only embraced it after astronomical evidence was found in 1998.

Poincare was the leading mathematical physicists of the day in 1905 when he published a relativistic theory of gravity and explained why such a theory was necessary. He also proposed using it to explain gravity waves. A couple of years later, he proposed using it to explain the anomaly in Mercury's orbit. It is not true that this was Einstein's original idea; he got it directly from Poincare.

Einstein was neither very well educated in mathematics, nor very good at it. He depended on friends
\such as Marcel Grossman [Grossmann] to explain to him the mathematics on which general relativity is based. And he depended on other friends, such as Michael Besso, to find the correct interpretation of the mathematics. Indeed, contemporaries noted that there were many colleagues who were much better at mathematics, such as John von Neumann.

Unlike Newton, Einstein did not invent any of the mathematics he used to express his new theories. General relativity employs mathematics that was advanced for the timethe mathematics of curved surfaces and general geometries which had been developed by mathematicians in the second half of the 19th Century. Einstein was the first physicist to use this new approach to geometry to describe physical systems. But he followed the tuition [intuition?] of Marcel Grossman [Grossmann] in learning and applying the mathematics.

Indeed, Einstein was not very good at using this new mathematics. Once he had written down and published the equations of general relativity, solutions which describe simple examples were quickly found. These describe very symmetric situations such as spherically symmetric stars and homogeneous, expanding universes. To derive these solutions are now homework exercises in undergraduate courses in general relativity. But Einstein didn’t find any of these simple solutions, indeed there is no evidence he even looked for them. They were found by others within weeks of his papers being published.

If Einstein did not do the math, what did he do?

The essence of GR is to reconcile gravity with special relativity. It was primarily a mathematical problem, and Einstein was lucky to have mathematician friends (Grossmann, Levi-Civita, Hilbert) who understood the necessary tools.

SR uses a flat spacetime metric, and works great as long as everything is linear. As soon as you have an accelerating frame of reference, then some nonlinearities become puzzle. A covariant theory based on a curved spacetime metric is needed. Grossmann figured out that the key condition for a pure gravitational field is that the Ricci tensor is zero.

Einstein deduced the starlight deflection, Mercury precession, and Doppler red-shift. He also deduced the gravitational slowing of clocks, but that was based on SR, in 1907. The Mercury precession was the only one that really used the nonlinear curviture of GR.

Why did Einstein weave a myth around his creation of general relativity? What was his motive for telling a fable about the role of mathematical beauty in his creation of general relativity?

The reason may be that he was making propaganda to promote interest in work he was doing to follow up on general relativity. This was aimed to go beyond general relativity to a theory he hoped would be his masterpiece, a unified theory of all phenomena, incorporating not just gravity but also electromagnetism. He called this the unified field theory.

Einstein weaved a myth about everything he did. No need to explain much. His famous GR paper did not cite any sources or credit any of his collaborators. His previous famous papers did the same thing.

All of this would only be of interest to historians, except that theoretical physicists and philosophers are always looking to Einstein and the relativity story as justification for how things ought to be done.

Smolin is a big believer in quantum gravity, and argues that string theory is the wrong approach.

One principle that seems reliable is background independence[6]. This says that the laws of nature should be statable in a form that does not rely on the specification of a fixed geometry of spacetime. Einstein’s theory of general relativity satisfies this principle, and it has been a useful heuristic for the search for quantum gravity. ...

One implication of this principle is that there can be no fundamental symmetries in the laws of nature. Every event in the history of the universe must be describable uniquely in terms of the relational degrees of freedom. This means that the closer we are to a fundamental theory, the fewer symmetries we should have. This may be why our search for larger and larger symmetries is no longer working. ...

The search for quantum gravity has produced one candidate for a new physical principle, which is the holographic principle. ...

Leonard Susskind[12] and Juan Maldacena[13] have applied the holographic principle to string theory, where it turned out to be extremely illuminating. It has other applications beyond string theory which suggest it is a truly general principle. Unfortunately, these so far do not apply to our world, because they require the dark energy be negative when, in nature, it is positive. Still, this is one of the very best idea [ideas] we have so far and it shows we can get further if we start with insights and principles, as ’t Hooft did.

My sense is that the hAs [???] so far stated, the holographic principle fails to have the direct physical content of the principles of relativity and equivalence. It cannot be expressed or tested in a single experiment.

We also so far lack a formulation of the holographic principle which is consistent with the principle of background independence that grounds general relativity[14].

His notion of background independence is not really testable either. I am not sure the concept even makes sense, as the GR equations have solutions that are not physically realizable.

Science news is about what is being hyped

Scott Aaronson answers the annual Edge question:

2015 marked a turning point. For the first time, the most hard-nosed experimentalists are talking about integrating 40 or more high-quality quantum bits (“qubits”) into a small programmable quantum computer—not in the remote future, but in the next few years. ...

They’ll suffice to disprove the skeptics, to show that nature really does put this immense computing power at our disposal ... And if quantum computing turns out not be possible, ...

So quantum computing has still not been proved possible, but hard-nosed experimentalists are talking about it, and that is exciting.

Gordon Kane on how the big news is that the LHC should soon see superparticles. (This would actually be fine except that Kane omits the crucial context, that he’s been predicting superparticles just around the corner again and again for the past twenty years and they’ve never shown up)

Just as the quantum computing folks have been predicting quantum computers for 20 years and they've never shown up.

Krauss tries to minimize Muslim terrorism

Physicist Lawrence M. Krauss seems to be regularly contributing essays to the New Yorker mag, and his latest is Thinking Rationally About Terror:

“Panic” is not too strong a word. According to a New York Times poll conducted earlier this month, people are as terrified about terrorism today as at any time since September 11, 2001. Donald Trump called for the closing of borders to Muslims; John McCain said, in response to the President’s address on the San Bernardino shooting, that “this is the war of our time.” ...

After the religious extremism of the young couple had been established, the anxiety level skyrocketed. Nothing had changed about the substance of the crime. Still, one minute, we were debating legislation; the next, we were talking about war.

Indeed, all around the world, when violence is perpetrated by terrorists instead of by other criminals, governments respond in extraordinary ways. ...

Exactly how much more dangerous has terrorism made our lives? To answer this question, it helps to run the numbers. ...

And, in the process, we need to distinguish policies that can realistically improve the safety of the public from those that only appear to do so.

This is mostly a political rant from a leftist atheist evolutionist multiculturalist, and most of his opinions are off-topic for this blog.

But Krauss uses his status as a scientist to argue that a rational person would not worry much about terrorism because the total number of murders in France and USA are relatively small so far.

He radically underestimates the cost. There is a large segment of the Islamic world that is in a long-term war with Western Civilization. This war has already cost us trillions of dollars with wars in Kuwait, Bosnia, Kosovo, Afghanistan, Iraq, Somalia, Yemen, Libya, and Syria. It has retricted our travel freedoms with TSA airport procedures. It has emboldened the Left to cut back our First and Second Amendment rights.

More seriously, if Europe does not find the will to resist, it will be subjugated under Sharia Law in a couple of generations.

A rational approach would at least compare the alternatives. What if we let 5M Muslim migrants into the USA, and only 1% are terrorists? Japan does not let any Muslims in, and it does not have any terrorism.

Krauss hates Republicans and anyone else who is against same-sex marriage, so he is against the Muslims also, but he writes an essay minimizing their terrorist threats.

Stock exchange is a quantum computational virtual reality

At first, I thought that this essay was a joke:

Recently, quantum gates and quantum circuits have been found when portfolios of stocks were simulated in quantum computation processes. This astonishing discover might be pointing out to the existence of a bizarre quantum code that rules the stock market transactions.

To take an advantage over the competition, financial institutions must adopt new scientific ideas and advanced technologies very early in their development. This is the case of quantum computers too.

Promised to be more powerful and faster than their classical counterparts, quantum computers captured the total attention of financial players lately. ...

Briefly, financial problems can be solved, in an adiabatic quantum computation, by initializing a system of particles into the ground state of a simple Hamiltonian, and then adiabatically evolving the Hamiltonian to one whose ground state encodes the solution to the problem.

The amazing thing here is that changing the quantum states of tiny particles can solve exclusively human related problems, like selecting an optimum portfolio of assets in the financial markets.

There is another angle to view the applicability of quantum computation to financial markets that refers to simulation of price movements of stocks in the portfolios. A recent paper [Quantum Gates and Quantum Circuits of Stock Portfolio] in applying quantum computation to model the stock price movements surprisingly suggests that the stock market itself is a complex quantum algorithm. ...

In topological quantum computation, quantum gates are simply implemented by braiding the quasi-particles trajectories in a predefined sequence.

What these quasi-particles and braided trajectories had to do with financial markets?

Here is the catch. The time series of prices of stocks in the portfolios are exhibiting the same braiding behavior, just like the collection of quasi-particles. From here to the idea of simulating the prices of stock movements in a portfolio on a quantum simulation is just a small step to take.

The astonishing thing is that, when simulating in topological quantum computation environment the time series of stock prices realize, in their braiding movement, elementary quantum gates. The quantum gates that prices of stocks in a portfolio are realized can be chained in quantum circuits.

It is absolutely fascinating to see how stocks of reputable companies like McDonalds or Walt Disney Company are literally realizing quantum gates in their New York Stock Exchange daily evolution.

Selecting a stock portfolio, from the shares of companies listed on Dow Jones Industrial Average market index, composed of McDonald's Corp. (MCD), The Walt Disney Company (DIS), American Express Company (AXP), and United Health Group Incorporated (UNH),an astonishing chain of quantum gates is recovered. Hadamard gate, Pauli gates and S-phase gate are all acting concerted in 1-qubit quantum circuit.

More complex quantum code structures arise considering increasing the number of stocks in the portfolio. 2-qubit quantum circuits are realized by adding Nike Inc. (NKE) and The Home Depot, Inc. (HD) to the initial portfolio of stocks.

Fragment of the Stock Market Quantum Algorithm realized by quantum computing simulation of a stock portfolio composed of: The Walt Disney Company (DIS), Nike Inc. (NKE), McDonald's Corp. (MCD), American Express Company (AXP), UnitedHealth Group Incorporated (UNH), The Home Depot, Inc. (HD)

Extended the process to the whole Dow Jones Industrial Average market index a mysterious quantum code of the stock market is revealed.

Here is the link to the quantum computational universe. This strange quantum code laying beneath the stock market transactions may be a small fragment of the universal code the entire Universe acts according with. This result may point out the shocking conclusion that New York Stock Exchange is perhaps a quantum computational virtual reality.

From the way that specific stocks are mentioned, I think that somebody is doing some serious conning. Somebody is claiming to be able to manage a stock market portfolio based on quantum computation. The author of this essay may not even realize that this is all BS.