Today is the 120th anniversary of the discovery of the electron by J.J. Thomson in 1897, for which he received the Nobel prize in 1906. The results were published in Philosophical Magazine 44 (269): pages 293–316. I don't know the precise date of publication, but the paper itself is bylined at the end: Cambridge, Aug. 7, 1897 The work was done at the Cavendish Laboratory, probably just a few dozen yards from the Computer Laboratory where I spent a large part of my last year as an undergraduate. The paper is reprinted in Classical Scientific Papers, Physics (Mills & Boon, 1964). Now that is not exactly the type of book I associate with that publisher! Thomson didn't name the particle, in his paper he called them "corpuscles." Discovery of the Electron When J.J. Thomson started his experiments, the lightest particle known was a hydrogen ion (we now know that is a proton). Thomson found a particle with a charge-to-mass ratio 2000 times higher. Thomson showed that cathode rays were particles, that the particle didn't depend on the material used for the cathode, that the particles could pass through films of aluminum and gold. By deflecting the beam, he could estimate the mass-to-charge ratio. We now know that the charge on a proton and an electron are the same, so that this ratio is entirely the difference in mass between the proton and electron (the modern number is 1836.152... so 2000 is pretty close) although there was certainly a possibility in Thomson's day that there was a difference in charge. One thing that I find surprising about this is that 1897 is the year that one of my grandparents was born. So the electron was only discovered in the year my grandfather was born. It is easy to overlook that what we now consider high-school science was on the cutting edge of research in the lifetime of people I knew well. Since I ended up in semiconductors as a career, I am aware that various aspects were invented during my lifetime or shortly before. Of course, programmable computers were only invented during and shortly after the second world war. But back in, say, the age of the civil war, it would be another 30 years before the electron would be discovered. Perhaps more amazingly, the neutron was not discovered until 1932, also at the Cavendish, when my father was already a toddler. Electrons and Semiconductors In the world of semiconductors, and thus EDA and IP, there can't be anything more important than electrons. A lot of what Cadence's customers do with our products is work out elaborate schemes for moving electrons around. At the very basic level, electrons on the gate of a MOSFET turn the channel on, and electrons flowing through the interconnect make this scalable to billions of transistors. DRAM and flash depend on the charge of electrons to hold the data bit values for a few dozen milliseconds (DRAM) or a decade or more (flash). Of course, modern ICs won't work without silicon, copper for the interconnect, Hafnium for HKMG, and more. In fact, a surprisingly large portion of the periodic table is used in semiconductor manufacture, and even more of it is used occasionally for esoteric purposes in specialized processes. But despite silicon being the element in the name Silicon Valley, it is really about the electrons. And by the way, there is no silicon in Silicon Valley, in the sense that there are no longer fabs. I believe the last manufacturing fab was an Intel fab that closed in 2008, leaving a few research fabs that hardly count as fabs, just clean rooms, some at semiconductor companies and some at equipment manufacturers like Applied Materials. Einstein's Nobel Prize Talking of early 20th century Nobel prizes, you would guess, even if you didn't know, that Einstein won a Nobel prize for physics. You would be right, the 1921 prize. But not for special relativity, for the discovery of the photoelectric effect. This laid some of the groundwork for quantum mechanics by showing that light itself was quantized. This was important, but not really as big a leap (ironically, I almost wrote "quantum leap") as relativity. Einstein had been proposed year after year for the physics prize for special relativity. This was another of the four ground-breaking papers published in Einstein's annus mirabilis, 1905 (photoelectric effect, special relativity, brownian motion, and mass-energy equivalence). However, special relativity remained an elegant theoretical concept that hadn't actually made any testable predictions. That changed in 1919 when physicist Eddington showed that the stars positions behind and close to the sun were just where they should be as predicted by the theory. Normally, close to the sun, stars are not visible because the sun overwhelms everything, but Eddington used the opportunity of a total eclipse to make the measurements. Another wrinkle was that Einstein, as part of his divorce settlement, had promised any eventual Nobel winnings to his wife as part of the settlement. But still, year after year, the Nobel committee didn't award the prize to Einstein. The theories I've seen as to why not are: Anti-semitism The Nobel committee doesn't like theoretical physics and almost always it goes to an experimental physicist The Nobel committee really did want to make sure that the ideas were validated by multiple experiments. They really hate making an award in a scientific discipline that gets refuted (they don't seem to care in Peace or Literature, where they seem to get it wrong as often as not) The Nobel committee were all the previous generation of physicists on the wrong side of the paradigm shift, and so never accepted relativity ("science advances one funeral at a time") In fact, in 1921, the Nobel committee was so screwed up that they decided not to award the prize at all. They wouldn't award it to Einstein for special relativity, and they would look like idiots if they awarded it to anyone else. Eventually, a compromise was brokered and Einstein was awarded the deferred 1921 prize, but not for relativity, for the photoelectric effect. Even the compromise couldn't avoid the elephant in the room of relativity and the committee went out of their way to emphasize that the prize was not for relativity. The prize was awarded for: services to theoretical physics, and especially for his discovery of the law of the photoelectric effect but then they continued that the prize was awarded: without taking into account the value that will be accorded your relativity and gravitation theories after these are confirmed in the future A more generous reading of that last sentence would be that the Nobel committee was leaving the door open to give him another award for special relativity, or general relativity later...but that never happened (but both totally should have). So Einstein got his Nobel, his ex-wife got her money, and the Nobel committee could continue to pretend that relativity was an unproven theoretical idea with promise. And the answer to the trivia question "In what year did Einstein win the 1921 Nobel prize for physics?" is 1922. Nobel Prize Pop Quiz Back in semiconductor-land, John Bardeen, along with Shockley and Brattain, won the 1956 Nobel prize in physics for the invention of the transistor, which changed my life, and yours, too. He won a second physics Nobel prize in 1972 (for superconductivity). Frederick Sanger won two in chemistry (1958 and 1980). Who is the only person to win two Nobel prizes in two different scientific disciplines? Hint: She's a woman. The answer is Marie Curie (for physics in 1903, and chemistry in 1911). Linus Pauling won two different prizes, but but only one was in science (chemistry in 1954 and peace in 1962). Sign up for the weekly Breakfast Bytes email:![]()
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