Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.
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To begin, let's start with a very apropos anecdote from Lorentz himself. At a conference on the Michelson–Morley experiment in 1927 at which Lorentz and Michelson were present, Michelson suggested that Lorentz was the initiator of the theory of relativity. Lorentz then replied: “I considered my time transformation only as a heuristic working hypothesis....


26

Not quite. Minkowski had the idea of representing special ralativity as geometry in 1907 under the direct influence of Einstein's 1905 paper, and he developed it in Raum und Zeit (1907) and Zwei Abhand lungen über die Grundgleichungen der Elektrodynamik (1909). See Minkowski on MacTutor. Before that only classical "spacetime" appeared, and only superficially....


21

Einstein himself told the story in his Kyoto address of 1922, which I quote from Pais's biography titled Subtle is the Lord: "If all systems are equivalent, then Euclidean geometry cannot hold in all of them. To throw out geometry and keep laws is equivalent to describing thoughts without words. We must search for words before we can express thoughts. ...


21

A good account is Weinstein, Max Born, Albert Einstein and Hermann Minkowski's Space-Time Formalism of Special Relativity. They did no have much of a relationship, what it was is well-summarized by Sommerfeld: "Strangely enough no personal contacts resulted between his teacher of mathematics, Hermann Minkowski, and Einstein. When, later on, Minkowski ...


18

The "movement" against relativistic mass was started by Adler in 1987 with Does Mass Really Depend on Velocity, Dad? (his answer, "actually no, but don't tell your teacher"). It got a boost from Okun's two 1989 papers. In 1990 American Journal of Physics solicited Okun's contribution on the relativistic mass to be published alongside Sandin's, who defended ...


14

It is often said that the reason why Einstein's Nobel Prize didn't mention Relativity Theory is the lack of sufficient evidence to the theory of relativity by 1922. But actually, by 1922, the special theory of relativity had been tested for almost all its major and pivotal predictions. The general theory of relativity had passed many highly significant tests ...


13

This seems a bit of a naive question to me. Einstein had been working on this problem for several years (starting as early as 1907), and had developed much of the physics by 1912. He greatly struggled to find the correct mathematical formulation of his theory, finally discovering the necessary tools from differential geometry during a collaboration with the ...


13

Who or what attracted Einstein's attention to Mercury, and when? What alerted him to the idea that Mercury's case was different from all those other cases, when a mundane explanation was involved? I know for sure that Henri Poincaré was aware of the problem and of its singularity - had he been in Kelvin's place, he would have added it to the list, and ...


13

It seems not. See: A.Douglas Stone, Einstein and the quantum: The quest of the valiant Swabian (2013): [page 6] Planck was the first major figure to recognize Einstein’s seminal 1905 work on relativity theory, and he became Einstein’s greatest champion in the world of science and one of his closest personal friends. [page 83] [Einstein's 1905 paper ...


12

The time when experimental evidence supporting relativity began to appear coincided with the rise of antisemitism in Germany following Germany's defeat in WWI. Antisemitism was on the rise in Germany; Jews were being scapegoated for the country's defeat in the war. As both Jew and pacifist, Einstein was an obvious target. The complexity of relativity ...


11

Let me clarify first that there are deep conceptual issues with what $E=mc^2$ means, and what it means to verify it. That energy contributes to inertial mass was known before Einstein. In 1900 Poincare showed that electromagnetic field has momentum, hence effectively mass, and implicitly gave it as $E/c^2$. Austrian physicist Hasenöhrl even wrote explicitly $...


10

Einstein is the one who removed the increments from the formula back in 1905, and one could say that the "historical reason" is his influence on theoretical physics. But his position was amply justified by subsequent experimental evidence. To explain, let us assume for now that energy and mass are considered in a frame where the object is stationary relative ...


9

Let's talk about special relativity (1905) first, then general relativity (1915). The motivation for special relativity is stated clearly in the first sentence of Einstein's paper "On the Electrodynamics of Moving Bodies": It is known that Maxwell's electrodynamics -- as usually understood at the present time -- when applied to moving bodies, leads to ...


8

There are several major ideas that went into general relativity: finite speed of gravity propagation, not necessarily Euclidean geometry of space, identification of inertia and gravity, mechanics as geometry, and uniformity of physical laws in all coordinate frames, even accelerated ones (general covariance). The last two ideas are specifically Einstein's, ...


8

Minkowski space time was considered by mathematicians before Einstein and before Minkowski. Of course the name "space-time" was not used. The reasons were purely mathematical, not physical. The most important application was the Klein model of the hyperbolic geometry (non-Eucludean geometry of Bolyai and Lobachevski). More presicely, Klein considered the ...


8

At the time of Newton, the scientists could NOT detect any deviation of the Newton's laws from reality. As we know now, the only visible effect of this deviation in the Solar system is the anomalous precession of Mercury's perihelion. It was detected only in the middle of 19th century; it makes about 43 seconds per century, and it was not known at Newton's ...


8

An influential figure in the later development of general relativity was John Archibald Wheeler (1911-2008). In the academic year 1952/53 he offered a yearlong course on special and general relativity at Princeton (the first such course there). According to Paul Halpern's book cited below, ``among the highlights of the spring session was a class trip on May ...


7

There is inherent vagueness in dating "predictions" and "confirmations" in many cases. For instance, who predicted heliocentrism? Copernicus, Kepler, Newton, perhaps Aristarchus? When was it confirmed? Another difficulty, also present in this example, is with predictions across major shifts in science (which happened about every 100 years since 17th century)....


7

You are guessing correctly. Riemann did not use $g$ for the metric tensor, he writes things like $ds^2$ or $\sum dx^2$ instead, see his 1854 lecture "On the Hypotheses which lie at the Bases of Geometry" (1854). Originally, "g" was for gravity. Einstein and Marcel Grossman, his mathematician friend who introduced him to tensor calculus and collaborated ...


7

First, to echo and elaborate on previous answers, Hilbert only appeared on the scene during the last few minutes of the last act, so to speak. Einstein made his first step towards the General Theory of Relativity (GR) in a 1907 paper "Relativitätsprinzip und die aus demselben gezogenen Folgerungen" (On the Relativity Principle and the Conclusions Drawn from ...


7

I emailed Matt Visser to ask for help, his reply is reproduced below with his permission: From: Matt Visser Sent: Saturday, March 21, 2015 11:49 PM I think the name "trace energy condition" was actually invented by Carlos Barcelo and myself; but the condition (without the explicit name) was used extensively --- for instance, in the neutron star ...


7

Here is a link to online version in German. As for the English translation, according to Milena Wazeck's Einstein's Opponents: The Public Controversy about the Theory of Relativity "nothing ever came of an English language version of 100 Autoren - no such book exists". This is despite the fact that Reuterdahl (one of the contributors) and Ruckhaber (one of ...


7

Not sure about "elementary" but, at least, he tried to reduce it to "the simplest and most intelligible form". He assumes the level of a graduating secondary school student, and warns of the "patience and force of will" required to get through. The linked article refers to the German 1916 publication of Über die spezielle und allgemeine Relativitätstheorie,...


6

To answer the question: "if Einstein did not exist": the special relativity was gradually developing independently of Einstein (by Lorentz and Poincare). If Einstein did not exist it would be developed at approximately the same time by the others. By the way, in the book of Whittaker, History of theories of electricity and magnetism, the chapter on special ...


6

I think the answer is rather anticlimactic, tl;dr is: The anomalous precession of Mercury was in fact a well-known problem amongst astronomers at that time. Correctly predicting the anomalous precession was a big and well-known test for any theory of gravitation which was not Newtons $1/r^2$ law. In the 1840's, Le Varrier, based on his calculations on the ...


6

I think Guido makes a good point in a comment that the analogue in math would be proving an old conjecture, and for this there are many examples that were settled after over 100 years. Besides Fermat's Last Theorem there is: the Poincaré conjecture, posed around 1900 and settled over 100 years later by Perelman, the prime number theorem, conjectured ...


6

Were there published suggestions, or otherwise discussed, that the universe could be expanding before Edwin Hubble observed that more distant galaxies indeed have higher redshift (1929)? Yes. De Sitter published expanding cosmological models in March 1917 in which there was a cosmological constant. Friedman published his models in 1922. People didn't take ...


5

Poincare's lecture given during the 1904 World's Fair was published in 1906. The Lorentz Festschrifft talk is discussed in this paper, which has a footnote to the original published version, and a translation: Poincaré, Henri, "La théorie de Lorentz et le principe de réaction", Archives néerlandaises des sciences exactes et naturelles. Recueil de travaux ...


5

The prime suspect for injecting Biblical references into cosmology would be Georges Lemaître, a cosmologist and... a Catholic priest. His "Cosmic Egg" and "Primeval Atom" lost to Hoyle's sarcastic "Big Bang" however, and it seems he passed up on introducing "dust". His 1927 Ph.D. thesis The Gravitational Field in a Fluid became the basis for the now famous ...


5

To have one man’s steps distilled into textbook form is a lot to ask: who teaches a course on that? The next best thing might be the proceedings and collections in Einstein Studies (with contributions of the same John Norton):    1. Einstein and the history of general relativity (1989),    3. Studies in the history of general relativity (1992),    5. The ...


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