Roentgen and Becquerel were exploring what they thought was an untrodden path in the forest and came upon a new road that led their successors to the very citadel of the material universe. Young Enrico Fermi was curious to find out what would happen if he fired a neutron into the nucleus of uranium, hoping only to create a heavier isotope of uranium, or at best a new element. His rather modest goal led five years later to the fission of uranium, and in another six years to the atomic bomb.
Yet, as we have seen, in both fission and fusion only a very small fraction of the mass of the protons and neutrons in the nuclei of the elements used is liberated in the form of energy, while 99.3 to 99.9 per cent of their substance remains in the form of matter. We know of no process in nature which converts 100 per cent of the matter in protons and neutrons into energy, but scientists are already talking about finding means for bringing about such a conversion. They are seeking clues for such a process in the mysterious cosmic rays that bombard the earth from outer space with energies billions of times greater than those released by fission or fusion, great enough to smash atoms of oxygen or nitrogen, or whatever other atoms they happen to hit in the upper atmosphere, into their component protons and neutrons. Luckily, their number is small and most of their energy is spent long before they reach sea level.
But we have already learned how to create secondary cosmic-ray particles of relatively low energies (350,000,000 electron-volts) with our giant cyclotrons. The creation of these particles, known as mesons, which are believed to be the cosmic cement responsible for the nuclear forces, represents the actual conversion of energy into matter. This is the exact reverse of the process taking place in fission and fusion, in which, as we have seen, matter is converted into energy. And we are now about to complete multibillion-volt atom-smashers that will hurl atomic bullets of energies of from three to ten billion volts at the nuclei of atoms. With these gigantic machines, known as the cosmotron (at the Brookhaven National Laboratory of the Atomic Energy Commission) and the bevatron (at the University of California), we shall be able to smash nuclei into their individual component protons and neutrons and thus get a much more intimate glimpse of the forces that hold the nuclei together. What is more, instead of creating only mesons, particles with only 300 electron masses, we shall be able for the first time to convert energy into protons and neutrons, duplicating, as far as is known, an act of creation that has not taken place since the beginning of the universe. Man at last will be creating the very building blocks out of which the universe is made, as well as the cosmic cement that holds them together.
What new continents will our first glimpse into the mechanism of the very act of creation of matter out of energy reveal? What new secrets will be uncovered before the dazzled eyes and mind of man when he takes the nucleus of the atom completely apart at last? Not even Einstein could tell us. But, as Omar Khayyám divined, “a single Alif” may provide “the clue” that, could we but find it, leads “to the Treasure-House, and peradventure to the Master too.” The fact is that we already have opened the door to the anteroom of the treasure-house, and we are about to unlock the door to one of its inner chambers. What shall we find there? No one as yet knows. But we do know that every door man has opened so far has led to riches beyond his wildest dreams, each new door bringing greater rewards than the one before. On the other hand, we also know that the treasure-house has many mansions, and that no matter how many chambers he may enter, he will always find new doors to unlock. For we have learned that the solution of any one secret always opens up a thousand new mysteries.
We also have learned, to our sorrow, that any new insight gained into nature’s laws and forces can be used for great good and for equally great evil. The greater the insight, the greater the potentialities for good or evil. The new knowledge he is about to gain by his deeper insight into the heart of matter, and by his ability to create it out of energy, may offer man the means to make himself complete master of the world he lives in. It is equally true, alas, that he could use it to destroy that world even more thoroughly than with the hydrogen bomb.
As already stated, scientists are even now discussing the possibility of finding means for the complete annihilation of matter by the conversion of the entire mass of protons and neutrons into energy, instead of only 0.1 to 0.7 per cent. And while the total annihilation of protons and neutrons still seems highly speculative, we already know that such a process actually does take place in the realm of the electron. This is the phenomenon already achieved numerous times on a small scale in the laboratory, in which a positive electron (positron) and an electron with a negative charge completely destroy each other, their entire mass being converted into energy. Luckily, this is at present only a laboratory experiment, in which each positron must be individually produced, since there are hardly any positive electrons in our part of the universe. But suppose the new knowledge we are about to pry loose from the inner citadel of matter reveals to us a new process, at present not even suspected, that would release positrons in large numbers, just as the fission and fusion processes made possible for the first time the liberation of large quantities of neutrons. Such an eventuality, by no means beyond the realm of the possible, would open potentialities of horror alongside which those of the H-bomb, even the rigged one, would be puny. For any process that would release large numbers of positrons in the atmosphere, in a chain reaction similar to the one now liberating neutrons, may envelop the earth in one deadly flash of radioactive lightning that would instantly kill all sensate things. And although this is admittedly purely speculative, no one dare say that such a discovery will not be made, not when one remembers how remote and unlikely a process such as fission seemed to be just before it was made.
Though many of the great discoveries came about as the result of chance, they came because, as Pasteur said, “chance favors the prepared mind.” Actually they came largely through the intellectual synthesis of what had originally appeared as unrelated phenomena or concepts. When Faraday discovered the principle of electromagnetic induction, he established for the first time that electricity and magnetism, looked upon since prehistoric times as two separate and distinct phenomena, were actually only two aspects of one basic natural force, which we know today as electromagnetism. This great intellectual synthesis led directly to the age of electricity and all its wonders. About thirty years later the great Scottish physicist James Clerk Maxwell demonstrated that electromagnetic action traveled through space in the form of transverse waves similar to those of light and having the same velocity. This revealed the existence in nature of electromagnetic waves, better known to us today as radio waves. About a quarter century later the great German-Jewish physicist Heinrich Hertz not only produced these electromagnetic waves but showed that they are propagated just as waves of light are, possessing all other properties of light, such as reflection, refraction, and polarization. This led directly to wireless telegraphy and telephony, radio and television, radiophotography and radar.
When Einstein, in his special theory of relativity of 1905, united matter and energy in one basic cosmic entity, the road was opened to the atomic age. Yet Einstein was never satisfied and has devoted more than forty-five years of his life to the search for a greater, all-embracing unity underlying the great diversity of natural phenomena. In his general theory of relativity of 1915 he formulated a concept that encompasses the universal law of gravitation in his earlier synthesis of space and time, of which matter and energy were an integral part. This synthesis, wrote Bertrand Russell in 1924, “is probably the greatest synthetic achievement of the human intellect up to the present time. It sums up the mathematical and physical labors of more than two thousand years. Pure geometry from Pythagoras to Riemann, the dynamics and astronomy of Galileo and Newton, the theory of electromagnetism as it resulted from the researches of Faraday, Maxwell, and their successors, all are absorbed, with the necessary modifications, in the theories of Einstein, Weyl, and Eddington.
“So comprehensive a synthesis,” he continued, “might have represented a dead end, leading to no further progress for a long time. Fortunately, at this moment quantum theory [the theory applying to the forces within the atom] has appeared, with a new set of facts outside the scope of relativity physics [which applies to the forces governing the cosmos at large]. This has saved us, in the nick of time, from the danger of supposing that we know everything.”
Yet Einstein, working away in majestic solitude, has been trying all these years to construct a vast intellectual edifice that would embrace all the laws of the cosmos known so far, including the quantum, in one fundamental concept, which he designates as a “unified field theory.” Early in 1950 he published the results of his arduous labors since 1915. This he regards as the crowning achievement of his life’s work, a unified theory that bridges the vast gulf that had existed between relativity and quantum, between the infinite universe of the stars and galaxies and the equally infinite universe within the nucleus of the atom. If he is right, and he has always been right before, his latest contribution will prove to be a greater synthetic achievement of the human intellect than ever before, embracing space and time, matter and energy, gravitation and electromagnetism, as well as the nuclear forces within the atom, in one all-encompassing concept. In due time this concept should lead to new revelations of nature’s mysteries, and to triumphs even greater than those which followed as a direct consequence of all earlier intellectual syntheses.