On this day in 1905, Albert Einstein published an incredibly important physics paper. It was a very good year for him, but remarkably, not his best. In 1905, he published four papers — any one of which would have made him a huge figure in 20th century physics. He was 26 years old. And, as we know, working a day job. This is used by many people to claim that we don’t need to fund scientific research. Of course Einstein was working a government job. And the people who say that are idiots.
The first paper (9 June 1905) was, “On a Heuristic Viewpoint Concerning the Production and Transformation of Light.” This was the photoelectric paper that posited that energy is quantized. It is the most important paper in quantum mechanics. Interestingly, Einstein never did accept quantum mechanics of the Heisenberg and Schrödinger variety. That’s where the quote “God does not play dice” comes from. Even more interesting is that Max Planck, who did so much to further Einstein’s career, thought that this paper was total junk. And if anyone has the claim to being the father of quantum mechanics, it is Max Planck.
The second paper (18 July 1905) was, “On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat.” It’s a classic of statistical mechanics. It explained Brownian motion as a random walk. I’ll be honest, I’ve never paid much attention to the paper because it seems too obvious to me. Statistical mechanics have always just made sense to me. But it was a huge finding at the time.
The third paper (26 September 1905) was, “On the Electrodynamics of Moving Bodies.” That’s Special Relativity. There was a year of my life when I was quite literally obsessed with it. It made no sense whatsoever to me. I finally realized that the problem was not my understand of Special Relativity but with my expectations. It isn’t a theory meant to explain the universe as I know it. It is meant to explain the motion of bodies moving very fast relative to each other. There is no “intuition” that we humans will ever have for it.
The fourth paper (21 November 1905 — 110 years ago today) is the most important of the papers, “Does the Inertia of a Body Depend Upon Its Energy Content?” This is also about relativity. It is where we get the famous equation: E = mc². But what’s really important is that it is the first step toward Einstein’s greatest achievement, the General Theory of Relativity. And that, will have to wait for another time.