From Earth to Heaven
Asimov's essays in From Earth to Heaven contrast mythical lost lands with scientific wonders, finding true romance in physics, statistics, and the universe's puzzling nature.
Isaac Asimov, a writer whose mind seems to leap from Earth to Heaven and back again, often finds profound wonder in the most unexpected places. He is a man who sees poetry not just in the grand sweeps of imagination but sometimes even in the cold, hard world of statistics. In one chapter, nestled amongst essays on everything from the certainty of uncertainty to the sheer density of dead stars, he takes us on a journey that begins with a forgotten myth and ends deep within the puzzling heart of modern physics. This particular exploration is titled "The Land of Mu".
The journey starts not with equations or lab coats, but with a book the author encountered in his youth – James Churchward's The Lost Continent of Mu. Asimov, with his characteristic straightforwardness, recounts how this book about a hypothetical continent that supposedly sank beneath the Pacific struck him immediately as nonsense. He contrasts this kind of imaginative but unfounded tale with what he considers "honest science fiction". He even points to another book, Lost Continents by L. Sprague de Camp, as a rational and amusing resource for those curious about such legends. So, one might expect the chapter to simply dismiss the idea of Mu as utter "bilge".
However, Asimov, ever the connector of disparate ideas, notices a "queer coincidence". The word "Mu" has, in fact, gained a certain significance in science, particularly in the field of nuclear physics. This is where the true romance lies for him, not in sinking continents, but in the "dainty and most succulent enigmas" that rest on this scientific "Mu". He promises to tell us about this real Land of Mu.
To understand this scientific connection, Asimov logically builds upon concepts discussed in earlier chapters, specifically the structure of atomic nuclei and the uncertainty principle. We are reminded of the efforts to understand what holds the nucleus together. He recalls the theoretical work of Yukawa, who in 1935, used Einstein's version of the uncertainty principle to suggest the existence of an "exchange particle" that would mediate the strong nuclear force, binding protons and neutrons together. This particle was predicted to have a mass intermediate between that of an electron and a proton/neutron.
The excitement arises when a particle with approximately the predicted mass was actually discovered. It had a mass about 207 times that of an electron. This particle was initially named "mesotron," later abbreviated to "meson," derived from the Greek word "meso" meaning "intermediate". For a dozen years, this discovery caused irritation among physicists. Why? Because this particle, the "mesotron," did not behave like the predicted particle. Yukawa's particle needed to interact very rapidly and strongly with atomic nuclei to act as the nuclear "cement". But this discovered meson did not; it could pass through inches of lead, barely interacting with nuclei.
The puzzle persisted until 1948, when a second, slightly more massive meson was found. This second particle did react virtually instantaneously with nuclei, fulfilling the role of Yukawa's predicted particle perfectly. Now, there were two mesons. To distinguish them, scientists adopted the common practice of using Greek letter prefixes. Since the first meson had precedence, it was associated with the Greek letter corresponding to "m," which is μ (mu). Thus, the first-discovered, but not the predicted, meson became known as the "mu" meson, or simply the muon.
And here we find the unexpected connection back to the chapter's title and the mythical lost continent. The scientific world has its own "Land of Mu," not a geographical one, but a realm of fundamental particles, specifically the muon. Asimov emphasizes the contrast between Churchward's imaginary land and this scientific one, asking us to consider where the "true romance lies". For him, it is unquestionably in the tangible, albeit puzzling, discoveries of science.
This scientific "Land of Mu" represents not the resolution of a mystery but a deepening one. The muon exists, it is a fundamental particle, but it is the wrong particle to explain the nuclear force. This leads into new questions and enigmas that occupy nuclear physicists. Asimov, in his typical fashion, uses this example to illustrate the dynamic nature of science – prediction, discovery, unexpected results, and the constant pursuit of deeper understanding.
The chapter serves as a beautiful example of Asimov's talent for making complex science accessible and engaging. He doesn't just present facts; he presents the story of scientific discovery, complete with human curiosity, frustration, and the unexpected turns it can take. He takes a term that might otherwise be dismissed as pseudoscientific fancy and reveals its surprising, real-world scientific counterpart, using it as a springboard to explain fundamental physics. The chapter builds upon the idea that our understanding of the universe, even at the smallest scales, is filled with uncertainty and requires constant investigation, a theme touched upon in previous discussions of the uncertainty principle. It also implicitly sets the stage for further explorations into the strange properties of matter at extreme conditions, as hinted at by the subsequent chapter title, "Squ-u-u-ush!". Through the lens of "The Land of Mu," Asimov reminds us that the universe's deepest mysteries are often more fascinating than any fictional myth, and the pursuit of understanding them is a truly romantic endeavor.
