Quantum Labyrinth
It was a monumental match of highly original thinkers who had the gumption to rebuild quantum physics from the ground up, based on novel principles. Introduced by Feynman and named by Wheeler, this approach sees reality as a composition of all possibilities, like a song with multiple tracks blended together. How does one electron cross the road? The correct quantum answer is that it takes every physically possible path- with reality a combination of them all. The two physicists would prove the perfect team; honing and reworking bizarre hypotheses into workable solutions would become their joint specialty.
Elementary particles interact with each other in pairs through a kind of exchange. Particle interactions have only a few fundamental kinds. Today we know that nature offers four basic types: gravitation, electromagnetism, and the strong and weak nuclear forces. At the time of Feynman’s graduate studies, the latter two- referring to ways nuclei bind or decay- were little understood; he would hep decipher them later in life. Physicists didn’t even know if these were separate interactions or the same force. Rather, they spoke of the “meson force” as the means by which protons and neutrons- the nuclear particles, or “nucleons”- cluster together by exchanging mesons. Today we know that other particles called “gluons”, do the sticking together and that yet other particles called the W^+, W^-, and Z^0, convey the decay-inducing weak force.
Compton Scattering: a quantum process on the subatomic level not readily explained by Newtonian physics. Identified by American physicist Arthur Compton, who won the Nobel Prize for his discovery, the Compton effect involves light scattered by an electron. Shine light on an electron, and the electron acquires energy and momentum [mass times velocity] which hoist it in a certain direction like a hurled javelin. In the process it emits light of a longer wavelength [distance between peaks] than the original, aimed at an angle different from that of the electron. For visible light, wavelength corresponds to color, so the emitted light will have a different hue from the original, skewing toward the redder end of the spectrum. Normally though, Compton scattering uses invisible X-rays, in which case the emitted light will be X-rays of a longer wavelength. The importance of the Compton effect is that quantum theory precisely predicts the difference between the initial and final wavelengths, along with the scattering angles of the electron and the emitted light. How it performs that feat reveals the essence of the quantum idea, first proposed by Planck and refined by Einstein in what is called the photoelectric effect.
After several physicist sounded the alarm about the possibility of Nazi weapon development after Germany discovered nuclear fission the immediate answer was silence. Washington can move very slowly. Although Fermi contacted the Navy department in March 1939 and Einstein first wrote to Roosevelt in August of the same year, the president saw little urgency. Prodded again Szilard, Einstein sent two more letters in 1940. That year the US allocated about $6,000 for nuclear fission research [about $100,000 in today’s dollars, adjusted for inflation] Only on December 6, 1941, the day before the Japanese bombed Pearl Harbor and the United States entered the war, did the American atomic program, later code-named the Manhattan Project. Begin in earnest with much greater funding.
