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Galina Weinstein

Publications and source records attributed to Galina Weinstein.

At least 37 records · Page 2Linked to original sources
arXiv2023

The Neverending Story of the Eternal Wormhole and the Noisy Sycamore

There has been a great buzz surrounding Daniel Jafferis et al.'s latest Nature paper, "Traversable wormhole dynamics on a quantum processor". The Nature paper discusses an experiment in which Google's Sycamore quantum processor is used to simulate a sparse N = 7 SYK model with 5 terms (a learned Hamiltonian). The Nature paper shows that the learned Hamiltonian preserves the key gravitational characteristics of an N = 10 SYK model with 210 terms and is sufficient to produce a traversable wormhole behavior. I will examine the experiment and discuss some philosophical challenges concerning the experiment in memory of Ian Hacking. Recently, Norman Yao and two graduate students discovered multiple flaws in Jafferis et al.'s learned Hamiltonian and uploaded a comment on the Nature paper. As expected, Jafferis and his team found a simple way to clarify the misunderstanding. They found a physical justification that allowed them to avoid the problem. In this paper, I elucidate the main arguments Yao and his students raised and the way Jafferis et al. found to save their learned Hamiltonian. I will end this paper with a philosophical comment on this recent development in the context of the learned Hamiltonian.

gr-qc↗
arXiv2023

Retrospectively Diagnosing Einstein with Asperger's Syndrome and the Dismal Failure of Debunking Myths

In 2003, Simon Baron-Cohen, a world expert on autism, diagnosed Einstein posthumously with Asperger's syndrome. I think we cannot diagnose a dead person. Historians of science have fiercely objected to this trend of diagnosing deceased scientists by reconstructing from scant evidence, calling these diagnoses myths. Despite the historians' efforts at demolishing myths, Einstein has been constantly diagnosed with Asperger's syndrome. I will stick my neck out and suggest in this paper that although historians' critique of Baron-Cohen and others includes debunking myths, it piggybacks on another myth that uses the following metaphors: a dull and socially adept Einstein who worked at Zurich, Prague, Berlin, and Princeton, an industrious scientist who earned his living through his work as a professor at the university; he had a special gift of friendship and collegiality, and he was deeply embedded in the academic community. These explanations do not make sense from the perspective of Einstein sitting in his office at Princeton, let alone Einstein sitting in the patent office. This perhaps explains the tendency of people to find counterclaims and myths more persuasive than historians' explanations which seem deeply problematic.

physics.hist-ph↗
arXiv2022

A comment on: Adam R. Brown and Leonard Susskind's paper "A holographic wormhole traversed in a quantum computer"

Adam Brown and Leonard Susskind write in their new paper, "A holographic wormhole traversed in a quantum computer": "The idea of a wormhole dates back to 1935, when Albert Einstein and his collaborator, Nathan Rosen, studied black holes in the context of Einstein's general theory of relativity. [...] In the same year, Einstein and Rosen wrote another paper, this time in collaboration with Boris Podolsky. [...] At the time, these two ideas - wormholes and entanglement - were considered to be entirely separate". I will show in this comment that for Einstein the Einstein-Rosen (ER) bridge and the EPR argument were not "entirely separate".

physics.hist-ph↗
arXiv2022

Maxwell's demon and impossibility statements: Einstein on perpetuum mobile of the second kind

This paper discusses Maxwell's demon thought experiment. In recent years, there has been extensive research on Maxwell's demon. I first provide a detailed overview of important historical milestones of Maxwell's demon thought experiment. Einstein would often write about both relativity and thermodynamics. In this paper, I first argue that: 1. Einstein spoke of Perpetuum mobile of the second kind (a Maxwell's demon) in the context of the discovery of his relativity theory, the famous chasing a light beam thought experiment, and the contraction of lengths. 2. He would often compare relativity with thermodynamics. 3. When doing so, he would say that perpetual motion machines cannot exist. In the same category, no signal transmission faster than light is possible. 4. Einstein's approach in speaking of the principles of thermodynamics and relativity suggests that he was occupied with "impossibility statements". After discussing the essential aspects of Maxwell's demon and the different ways of excorcising the demon, I examine the role of "impossibility statements" in Maxwell's demon thought experiment.

physics.hist-ph↗
arXiv2022

Einstein and the problem of confirmation by previously known evidence: A comment on Michel Janssen and Jürgen Renn's "Einstein and the Perihelion Motion of Mercury"

In this paper, I comment on a recent paper by Michel Janssen and Jürgen Renn. In his published paper of November 18, 1915, Einstein presented a solution to the problem of the perihelion motion of Mercury and obtained the correct result of 43 seconds of arc per century. Before 1915, Einstein had established non-covariant field equations (the Entwurf field equations). But in 1915, he changed his mind and dropped these equations and was led to general covariance. In a manuscript written in 1913, Einstein and his best friend Michele Besso tried to solve the Entwurf field equations to attain the perihelion advance of Mercury. The end result arrived at by Einstein was 1821 seconds of arc per century. To make a long story short, the field of a static Sun produced an advance of the perihelion of Mercury of 18 seconds of arc per century. Einstein kept quiet about this result and continued to work on the Entwurf theory. Janssen and Renn ask: If we follow the prescriptions of Karl Popper, why did Einstein not accept that his Entwurf theory had been falsified? They further ask: Given the undeniable importance of Besso's earlier calculations, why did Einstein not invite Besso as a co-author of his November 1915 paper on the perihelion motion of Mercury? Besso did not even get an acknowledgment in Einstein's paper. After a brief review of Einstein's and Besso's early attempts at calculating the advance of the perihelion of Mercury, I discuss falsification and confirmation by previously known evidence and then propose an answer to the above two questions.

physics.hist-ph↗
arXiv2021

Do gravitational waves confirm Hawking's area law?

Recently an experiment has been performed for the purpose of "testing the area law with GW150914". As the experimenters put it, the experiment presents "observational confirmation" of Hawking's area law based on the GW150914 data. It is the purpose of this paper to philosophically examine the test of the area law and to show that the area law is not confirmable yet is falsifiable. Accordingly, the GW150914 data do not confirm Hawking's area law. What has been tested with positive results was the hypothesis A3 > A1 + A2, where A3 = GW150914 remnant and A1 + A2 = GW150914 merger. But this single instance does not provide observational confirmation of Hawking's area law.

physics.hist-ph↗
arXiv2021

Demons in Black Hole Thermodynamics: Bekenstein and Hawking

This paper comprehensively explores Stephen Hawking's interaction with Jacob Bekenstein. Both Hawking and Bekenstein benefited from the interaction with each other. It is shown that Hawking's interaction with Bekenstein drove him to solve the problems in Bekenstein's black hole thermodynamics in terms of a new thermal radiation mechanism. Hawking derived the thermal radiation using a semiclassical approximation in which the matter fields are treated quantum mechanically on a classical spacetime background. Hawking's semiclassical approximation yielded a simple formula for the entropy of the black hole, which turned out to be equivalent to Bekenstein's equation for entropy.

physics.hist-ph↗
arXiv2021

Why Do You Think It is a Black Hole?

This paper analyzes the experiment presented in 2019 by the Event Horizon Telescope (EHT) Collaboration that unveiled the first image of the supermassive black hole at the center of galaxy M87. The very first question asked by the EHT Collaboration was: What is the compact object at the center of galaxy M87? Does it have a horizon? Is it a Kerr black hole? In order to answer these questions, the EHT Collaboration first endorsed the working hypothesis that the central object is a black hole described by the Kerr metric, i.e. a spinning Kerr black hole as predicted by classical general relativity. They chose this hypothesis based on previous research and observations of the galaxy M87. After having adopted the Kerr black hole hypothesis, the EHT Collaboration proceeded to test it. They confronted this hypothesis with the data collected in the 2017 EHT experiment. They then compared the Kerr rotating black hole hypothesis with alternative explanations and finally found that their hypothesis was consistent with the data. In this paper, I describe the complex methods used to test the spinning Kerr black hole hypothesis. I conclude this paper with a discussion of the implications of the findings presented here with respect to Hawking radiation.

physics.hist-ph↗
arXiv2019

Why did Einstein Reject the November Tensor in 1912-1913, only to Come Back to it in November 1915?

The question of Einstein's rejection of the November tensor is re-examined in light of conflicting answers by several historians. I discuss these conflicting conjectures in view of three questions that should inform our thinking: Why did Einstein reject the November tensor in 1912, only to come back to it in 1915? Why was it hard for Einstein to recognize that the November tensor is a natural generalization of Newton's law of gravitation? Why did it take him three years to realize that the November tensor is not incompatible with Newton's law? I first briefly describe Einstein's work in the Zurich Notebook. I then discuss a number of interpretive conjectures formulated by historians and what may be inferred from them. Finally, I offer a new combined conjecture that answers the above questions.

physics.hist-ph↗
arXiv2016

Einstein and Gravitational Waves 1936-1938

Around 1936, Einstein wrote to his close friend Max Born telling him that, together with Nathan Rosen, he had arrived at the interesting result that gravitational waves did not exist, though they had been assumed a certainty to the first approximation. He finally had found a mistake in his 1936 paper with Rosen and believed that gravitational waves do exist. However, in 1938, Einstein again obtained the result that there could be no gravitational waves!

physics.hist-ph↗
arXiv2016

Einstein's Discovery of Gravitational Waves 1916-1918

In his 1916 ground-breaking general relativity paper Einstein had imposed a restrictive coordinate condition, his field equations were valid for coordinate systems which are unimodular. Later, Einstein published a paper on gravitational waves. The solution presented in this paper did not satisfy the above restrictive condition. In his gravitational waves paper, Einstein concluded that gravitational fields propagate at the speed of light. The solution is the Minkowski flat metric plus a small disturbance propagating in a flat spacetime. Einstein calculated the small deviation from Minkowski metric in a manner analogous to that of retarded potentials in electrodynamics. However, in obtaining the above derivation, Einstein made a mathematical error. This error caused him to obtain three different types of waves compatible with his approximate field equations: longitudinal waves, transverse waves and a new type of wave. Einstein added an Addendum in which he suggested that in systems in unimodular coordinates only waves of the third type occur and these waves transport energy. He became obsessed with his unimodular coordinates. Einstein's colleagues demonstrated to him that in the coordinate system in unimodular coordinates the gravitational wave of a mass point carry no energy, but Einstein tried to persuade them that he had actually not made a mistake in his gravitational waves paper. Einstein, however, eventually accepted his colleagues results and dropped the restrictive unimodular coordinates. This finally led him to discover plane transverse gravitational waves.

physics.hist-ph↗
arXiv2015

Two-body problem in general relativity: A heuristic guide for the Einstein-Rosen bridge and EPR paradox

Between 1935 and 1936, Einstein was occupied with the Schwarzschild solution and the singularity within it while working in Princeton on the unified field theory and with his assistant Nathan Rosen, on the theory of the Einstein-Rosen bridges. He was also occupied with quantum theory. He believed that quantum theory was an incomplete representation of real things. Together with Rosen and Boris Podolsky he invented the EPR paradox. I demonstrate that the two-body problem in general relativity was a heuristic guide in Einstein's and collaborators' 1935 work on the Einstein-Rosen bridge and EPR paradox.

physics.hist-ph↗
arXiv2015

Einstein's Uniformly Rotating Disk and the Hole Argument

Einstein's first mention of the uniformly rotating disk in print was in 1912, in his paper dealing with the static gravitational fields. After the 1912 paper, the rotating disk problem occurred in Einstein's writings only in a 1916 review paper, "The Foundation of the General Theory of Relativity". Einstein did not mention the rotating disk problem in any of his papers on gravitation theory from 1912 until 1916. However, between 1912 and 1914 Einstein invoked the Hole Argument. I discuss the possible connection between the 1912 rotating disk problem and the Hole Argument and the connection between the 1916 rotating disk problem and the Point Coincident Argument. Finally, according to Mach's ideas we see that the possibility of an empty hole is unacceptable. In 1916 Einstein replaced the Hole Argument with the Point Coincidence Argument and later in 1918 with Mach's principle.

physics.hist-ph↗
arXiv2014

Did Einstein "Nostrify" Hilbert's Final Form of the Field Equations for General Relativity?

Einstein's biographer Albrecht Fölsing explained: Einstein presented his field equations on November 25, 1915, but six days earlier, on November 20, Hilbert had derived the identical field equations for which Einstein had been searching such a long time. On November 18 Hilbert had sent Einstein a letter with a certain draft, and Fölsing asked about this possible draft: "Could Einstein, casting his eye over this paper, have discovered the term which was still lacking in his own equations, and thus 'nostrified' Hilbert?" Historical evidence support a scenario according to which Einstein discovered his final field equations by "casting his eye over" his own previous works. In November 4, 1915 Einstein wrote the components of the gravitational field and showed that a material point in a gravitational field moves on a geodesic line in space-time, the equation of which is written in terms of the Christoffel symbols. Einstein found it advantageous to use for the components of the gravitational field the Christoffel symbols. Einstein had already basically possessed the field equations in 1912, but had not recognized the formal importance of the Christoffel symbols as the components of the gravitational field. Einstein probably found the final form of the generally covariant field equations by manipulating his own (November 4, 1915) equations. Other historians' findings seem to support the scenario according to which Einstein did not "nostrify" Hilbert.

physics.hist-ph↗
arXiv2014

Einstein, Schwarzschild, the Perihelion Motion of Mercury and the Rotating Disk Story

On November 18, 1915 Einstein reported to the Prussian Academy that the perihelion motion of Mercury is explained by his new General Theory of Relativity: Einstein found approximate solutions to his November 11, 1915 field equations. Einstein's field equations cannot be solved in the general case, but can be solved in particular situations. The first to offer such an exact solution was Karl Schwarzschild. Schwarzschild found one line element, which satisfied the conditions imposed by Einstein on the gravitational field of the sun, as well as Einstein's field equations from the November 18, 1915 paper. On December 22, 1915 Schwarzschild told Einstein that he reworked the calculation in his November 18 1915 paper of the Mercury perihelion. Subsequently Schwarzschild sent Einstein a manuscript, in which he derived his exact solution of Einstein's field equations. On January 13, 1916, Einstein delivered Schwarzschild's paper before the Prussian Academy, and a month later the paper was published. In March 1916 Einstein submitted to the Annalen der Physik a review article on the general theory of relativity. The paper was published two months later, in May 1916. The 1916 review article was written after Schwarzschild had found the complete exact solution to Einstein's November 18, 1915 field equations. Einstein preferred in his 1916 paper to write his November 18, 1915 approximate solution upon Schwarzschild exact solution (and coordinate singularity therein).

physics.hist-ph↗
arXiv2013

Einstein's 1916 derivation of the Field Equations

In his first November 4, 1915 paper Einstein wrote the Lagrangian form of his field equations. In the fourth November 25, 1915 paper, Einstein added a trace term of the energy-momentum tensor on the right-hand side of the generally covariant field equations. The main purpose of the present work is to show that in November 4, 1915, Einstein had already explored much of the main ingredients that were required for the formulation of the final form of the field equations of November 25, 1915. The present work suggests that the idea of adding the second-term on the right-hand side of the field equation might have originated in reconsideration of the November 4, 1915 field equations. In this regard, the final form of Einstein's field equations with the trace term may be linked with his work of November 4, 1915. The interesting history of the derivation of the final form of the field equations is inspired by the exchange of letters between Einstein and Paul Ehrenfest in winter 1916 and by Einstein's 1916 derivation of the November 25, 1915 field equations.

physics.hist-ph↗