Leonid Korogodski Posts

In 1972, Gerald Edelman (b. 1929) received the Nobel Prize in Physiology or Medicine for his discovery of somatic selection in the immune system of mammals. It was his answer to the question of how our bodies manage to produce so many different antibodies, each geared against a particular invader. Previously, it had been thought that the blueprints of all antibodies were encoded somewhere and were activated during an infection. But the number of all possible infectious agents that our species has encountered in the past and may yet encounter in the future is so staggering that this assumption strained…

Once upon a time, astronomers thought that the planets, the Sun, and the Moon all moved around the Earth in uniform circular motion. The heavens must be perfect, right? And what could be more perfect than a circle! One problem: every now and then, planets reverse the direction of their visible motion across the sky, which would be impossible if they turned around the Earth on circular orbits. This so-called retrograde motion of planets forced the introduction of epicycles. An epicycle was a smaller circle on which a planet would turn around a certain point, which itself would turn on…