This fact sounds utterly bizarre today (but yes, aside from Heisenberg, Born, and Jordan, plus the founder of "quantum theory" Max Planck, all the German-sounding founders of quantum mechanics tended to be Swiss or Austrian etc. – maybe this weakness of Germany was affected by the enhanced anti-Semitism and other ideologies in that country). He got his Nobel for cathode rays. They were streams of electrons – I think that you need this to be explained because the very phrase doesn't sound important today. Moreover, J.J. Thomson, Johann Hittorf, and Eugen Goldstein were arguably more vital and earlier discoverers of the cathode ray, in the same way in which Conrad Röntgen was the actual discoverer of the X-rays, even though Lenard wanted to take credit for those, too.
As the "Genius" series on National Geographic reminds us, Lenard was a top Nazi hater of Einstein – and a top warrior against modern physics which he called "Jewish physics". In 2015, Bruce Hillman wrote the book The Man Who Stalked Einstein: How Nazi Scientist Philipp Lenard Changed the Course of History which is extremely interesting because it reveals that the Šmoit-style criticism of modern physics which I considered to be a recent phenomenon isn't new, after all. It's just the crackpottery of the Aryan physics reloaded.
If you don't want to buy and read that book, you should at least read the 2015 Phys.org article When science gets ugly – the story of Philipp Lenard and Albert Einstein. The article reminds us of some basic facts, e.g.:
Lenard argued that Einstein's hyper-theoretical and hyper-mathematical approach to physics was exerting a pernicious influence in the field. The time had come, he argued, to restore experimentalism to its proper place. He also launched a malicious attack on Einstein, making little attempt to conceal his antipathy toward Jews.OK, so according to Lenard, relativity and modern physics in general was "hyper-theoretical" and "hyper-mathematical" and was exerting a pernicious effect on the whole field (of physics). Experimentalism had to be restored etc. Haven't you heard these things somewhere? Well, yes, it's exactly the anti-theoretical-physics garbage that was resuscitated by people like Woit and Smolin a decade ago.
Note that Lenard was "capable" of saying and writing this rubbish without any references to Karl Popper. Popper is just a redundant and worthless extra label that was recently glued on top of these anti-science ideas. The essence of the anti-theoretical-physics sentiment has always been the same: The people who criticize theoretical physics simply hate the idea that the mathematical reasoning becomes a key or the key portion of the physics research. They are just not talented enough for that.
So for some time, I was aware of the fact that the general philosophical tenets of the attacks against theoretical physics are very old. But only Hillman's book and some of the recent texts about the Einstein-Lenard animosity that I saw, e.g. this textbook of German physics by Lenard (written in the German Gothic fonts, of course, even though Hitler abandoned those fonts as ancient and reducing Germany's international influence 3 years prior to the publication of Lenard's book), a book about aether, and a presentation about aether theories have opened my eyes further.
It wasn't just the irrational hateful anti-theoretical physics philosophy that the Šmoits have copied from Aryan physics. The basic technical framework of "Smolin-style" alternative theories was pretty much plagiarized from the Aryan physics, too.
OK, let's look at the history a little bit. Lenard did some cathode ray work in 1888. Once the 20th century – and modern physics – began, he basically stopped doing anything new in physics that had value. That's a lot of time to do things like the German physics – he lived up to 1947. At any rate, there was a moment when Lenard was far more well-known than the young Einstein and these two men had a respectful relationship. It deteriorated soon and became terrible. My understanding is that the transformation took place quickly during the year 1909.
A big part of the sentiment boiled down to Lenard's visceral anti-Semitism. But I think that one can see that it didn't explain all the tension. It was at least equally important that Lenard was a full-blown crackpot when it came to anything that depends on modern theoretical physics. He was fighting against relativity, even in the 1930s, three decades after every usable physicist knew that relativity was a fact. You could dismiss this anti-relativity sentiment as a consequence of Lenard's anti-Semitism. It may have been primary for him to preserve the idea that a Jewish physicist couldn't have done any groundbreaking work – try to appreciate how indefensible this thesis became after the war when over 1/2 of the key advances in cutting-edge physics was done by Jewish physicists.
In some quotes, the influence of Lenard's racist sentiments on his opinions about physics (and the completely omnipresent yet incoherent mixing of scientific and political ideas, something that is so typical for the Smolins, Woits, and Hossenfelders of the present as well) was obvious. For example, Lenard once whined:
"Then the Jew came and caused an upheaval," he wrote at the time, "with his abolition of the concept of ether, and ridiculously enough, even the oldest authorities followed him. They suddenly felt powerless when confronted with the Jew. This is how the Jewish spirit started to rule over physics."But he also had his would-be "constructive" contributions to physics that were supposed to provide physics with alternatives. The 1944 textbook on German physics is basically just a textbook of classical physics. As far as I can say, the adjectives "German" and "classical" were basically synonymous if you looked at the content and basic axiomatic framework of physics. Well, "German" could have meant "classical and preferrably experimental", too. But aside from this outdated but basically uncontroversial physics, he was trying to promote concepts on the would-be cutting edge physics. And his proposals were main theories of the aether.
As this presentation tells us, Lenard wrote two books about aether:
- “Über Äther und Materie”, 1911
- “Über Äther und Uräther”, 1922
The first book, "On Aether and Matter", was mostly about the old electromagnetic aether. The second book, "On Aether and Fore-Aether" or "On Aether and Aether of Space", was partly a meme about some spin-network-like structure in the empty space similar to loop quantum gravity.
As the "Genius" series superficially sketches, Lenard had a young assistant named Jakob Johann Laub. Well, it turned out that Laub was a huge fan of Einstein's work (which implied that Laub felt certain about relativity and non-existence of aether) but Lenard ordered Laub to work to prove aether, anyway. And in 1909, as Hillman's book discusses in detail, Laub and Einstein exchanged some correspondence. Einstein was just exposed to a lecture by Lenard and he had compassion with Laub. Einstein wrote Laub:
Lenard must, however, in many things, be wound quite askew. His recent lecture on these fanciful ethers appears to me almost infantile. Further, the study he commanded of you... borders on the absurd. I am sorry that you must spend your time on such stupidity.It went so far that Einstein promised Laub to find a new job. Lenard didn't want to allow it, insisting that Laub continues with the infantile aether work ordered by Lenard up to the moment when Laub finds the new job. "This is really a twisted fellow, Lenard," Einstein pointed out after hearing this.
To write whole physics books about aether in 1911 or even 1922 is, well, plain retarded. These books are examples of the episodes in the history of physics that look chronologically wrong: some people happen to land into a later century than where they should have spent their lives and die. Einstein was surely convinced about the non-existence of aether years before 1905. But at any rate, in 1905, he clarified all the puzzling things about space and time related to the speed of light and it made sense. His special theory of relativity made it clear that all inertial frames are equally good to formulate the laws of physics – and not even in the vacuum, you can determine which of the inertial frames is privileged. None of them is.
It follows that the spacetime just cannot contain any substance or objects that could pick a privileged frame. Period. The question was settled. Nevertheless, Lenard continued to promote the meme that the electromagnetic phenomena required luminiferous aether. He did so even years after he "sort of" accepted general relativity. This attitude was extremely unnatural – when gravity could be described by fields in the otherwise empty vacuum, why should electromagnetism be completely different? They clearly look totally analogous. (Also, there was a sense in which Lenard accepted general relativity "more than" the special one. Just imagine how illogical this attitude was. Did he justify it in some way? Not really, political shields were already primary for him and they didn't care that general relativity is, well, a generalization of the special one so it requires the special one.) He was constructing this aether out of some pieces resembling "LEGO" – and that's probably the main reason why Einstein called it (and why I independently called loop quantum gravity and similar memes) "infantile".
Much more generally, the whole way of thinking of Lenard and the loop quantum gravity and other "spacetime built of pieces" champions is childish because it imagines that at the bottom of things, the simplest objects in Nature such as elementary particles or regions of the empty space are made of pieces or objects similar to those that kids may play with. What do adult modern physicists actually think? Well, the theories needed to understand the behavior of the vacuum or elementary particles are also made of pieces – but the pieces are terms in mathematical expressions, such as this Lagrangian of the Standard Model:
You know, the idea that is obvious to everyone who thinks like a modern physicist is that the mathematical structures and constraints are fundamental and primary; and "objects" that we can see are their consequences. Lenard and various "discrete physics" proponents that still exist have this basic point upside down. They are imagining that some "pictures" are primary and fundamental while mathematics is at most a "servant" that we use to describe this visualizable reality in a way that looks more credible. But mathematics cannot be just a "servant" in this sense. Fundamental laws of physics must be intrinsically formulated in the language of mathematics. The explanations "why this part of the theory works in one way or another" must be mathematical in nature, too.
Just compare the deep difference between the colorful picture of the spinfoam – which is basically equivalent to Lenard's infantile models of aether, at the level of detail that we follow in this text – and the Lagrangian. It's a difference between pictures and calculations, geometry and algebra. Now, I am not saying that geometry has no place in physics. All of physics may be phrased as "some generalized geometry". But if you need to understand the precise rules that govern Nature at the fundamental level, you simply need some algebra. You need to convert the pictures to mathematical structures or constraints.
It is extremely unnatural to imagine that at the bottom, Nature is constructed out of some pieces that actually need lots of parameters – similar to macroscopic pieces of "LEGO" – to describe their shape or interactions. There is really no reason to think that the fundamental pieces should resemble the macroscopic ones. Even though he remained an opponent of quantum mechanics, Einstein always understood the basic point that the fundamental laws must be different than the everyday life objects in many characteristics – and that the possible laws of physics should be searched in the "space of mathematically possible candidate theories" i.e. by a mathematical selection and classification, not e.g. according to some instinctive experience with everyday objects. Even the top quantum mechanical folks have really credited Einstein for his help to elucidate this conceptual point.
At the end, the transition from classical physics to modern physics – which involved both relativity and especially quantum mechanics – was a classic and perhaps the most profound example of a revolution in science. A revolution in science simply demolishes some assumptions that have been considered holy for a very long time. And some people are just too dogmatic and incapable of seeing that such a transition is necessary.
My reading of this history has filled me with some preliminary optimism. The recent decade isn't the first moment when theoretical physics was facing completely irrational and dishonest critics who love to mix science and politics in scientifically unacceptable ways and whose sermons are ultimately addressed to the least demanding audiences. Despite Nazi Germany's dominance over most of Europe by 1942, the world has recovered from this irrational political movement designed to cripple and enslave science. We have some chance that the society will recover from the recent revival of these ideas once again.