A Jewish physicist, Lise Meitner, stumbled on nuclear fission by mistake. Back in the 5690s/1930s, few people dreamt that the powerful atom could ever be split in two.
The atom has a long history. Take a metal ball-bearing and cut it in half. Cut a half into two, repeat the process a few million times and what do you end up with? About five centuries before the Churban Bayis Sheni,
Demokritos of Ancient Greece theorized that everything from ants to elephants is made of tiny, indivisible “atoms,” a Greek term that means “unable to be divided.” He believed that your piece of iron would eventually become irreducibly tiny – the ultimate particle was the atom. Nothing smaller exists.
In modern terms, this idea makes perfect sense. If you take a sugar-cube sized speck of air and count its molecules (particles of a few atoms each), you will end up with a total of about 45 billion, billion particles. Does one need to get any smaller than that?
So matters stood for the next 2,000 years. In 5568/1808, an English scientist, Johan Dalton, was still writing in “A New System of Chemical Philosophy” that “We might as well attempt to introduce a new planet into the solar system or annihilate one already in existence, as to create or destroy a particle of hydrogen.”
If only he had been correct!
Even after scientists discovered that atoms consisted of even more minute protons and electrons, people thought that atoms were solid as marbles until Ernest Rutherford, of Cambridge University, literally smashed that illusion in 5670/1910. This was after he began shooting helium “bullets” at an incredibly thin sheet of gold foil. While most of the “bullets” punched right through, some of them bounced off as if the foil was studded with tiny, invisible rocks. If atoms were solid as marbles, this made no sense!
Rutherford concluded that atoms consist mostly of empty space. To illustrate his conception, imagine an atom the size of Lakewood Yeshivah. Somewhere in the middle you would find a tiny, dense nucleus the size of a fl y, while the whole beis medrash would be absolutely empty except for a few stray electrons whizzing near its outer walls. In other words, everything we see, including ourselves, consists overwhelmingly of a vacuum as empty as outer space.
Incidentally, Rutherford was also the conceptual grandfather of the atom bomb. Back in 5663/1903, after people discovered that unwieldy atoms, such as uranium and radium, are slowly disintegrating, releasing huge amounts of radiation in the process, he announced that “could a proper detonator be found, it was just conceivable that a wave of atomic disintegration might be started in matter, which would indeed make this old world vanish in smoke.”
Rutherford was not far off. Although atom bombs work not through slow disintegration but a sudden outburst of energy, they need the chain reaction he describes because without it, the most powerful atom bomb would fizzle out after splitting a few atoms and would kill no more than a couple of mosquitoes.
To sum up, Rutherford concluded that the protons of atoms are squeezed together inside a tiny nucleus. This raised a $70,000 question. Just as the positive poles of a magnet repel each other, the positively charged protons of an atom nucleus should repulse each other and fl y off in every direction. What keeps them glued together?
To solve this problem, physicists posited a new force, called the “strong nuclear force,” that binds the protons together and prevents them from wrenching apart. This is one reason many scientists thought no one would ever succeed in breaking an atom apart – what power could overcome the massive strong nuclear force that is billions of times stronger than gravity?
THE EXPLOSIVE PAPER CLIP
Near the beginning of the last century, Albert Einstein formulated an innocent-looking equation, E = mc2. In other words, the energy of matter equals the mass multiplied by the square of the speed of light (670 million miles per hour). This magnifies mass almost 450,000 million, million times. Beware the innocent-looking paper clip on your desk – transformed into pure energy it would deliver the same kick as the Hiroshima bomb!
Lise Meitner was the first person to extract energy from the heart of an atom in 5698/1938. Actually, someone else did it under her guidance – at the time, she was barred from setting foot in the physics laboratory where she had worked for thirty years.
Born in Vienna in 5638/1878, Meitner was raised to revere science and culture at the expense of her Jewish heritage. In 5667/1907, she moved to Germany and within twenty years, she was head of the theoretical physics division of the Kaiser Wilhelm Institute for Chemistry in Berlin. Thanks to her Austrian citizenship, she was allowed to retain her post after the Nazis began firing Jewish academics in 5693/1933, but after the 5698/1938 anschluss (takeover) of Austria, she became a German citizen and subject to its racial laws; the institute at which she had slaved for the past thirty years threw her out, and she fled to Stockholm.
After the war, she berated her former colleagues for their lack of resistance:
“You all worked for Nazi Germany. And you tried to offer only a passive resistance. Certainly, to buy off your conscience, you helped here and there a persecuted person, but millions of innocent human beings were allowed to be murdered without any kind of protest being uttered… First, you betrayed your friends, then your children in that you let them stake their lives on a criminal war.”
From her Stockholm exile, Meitner guided the research of her German colleagues, Otto Hahn and Fritz Straussman. Whenever Hahn hit a brick wall, he appealed to her for help and she informed him what to do next. At that time, Hahn and Straussman were busy shooting neutrons (part of the atom nucleus) at uranium atoms to see what would happen. Now Hahn wrote her yet another emotional appeal for help:
“…there is something about the ‘radium isotopes’ that is so remarkable that, for now, we are telling only you… Perhaps you can suggest some fantastic explanation… We know ourselves that [uranium] cannot burst apart into [barium]… If there is anything you could propose that you could publish, then it would still in a way be work by the three of us.”
Two days later, he sent her another appeal: “You see, you will do a good deed if you can find a way out of this.”
What was driving Otto Hahn insane? Ordinary barium (similar to calcium) used by Hahn during his experiments was becoming powerfully radioactive, and he could not figure out any reason for this.
Meitner came up with a revolutionary resolution to his problem: The radioactive barium was not the barium used by Hahn for his experiment but brand new barium. Where was it coming from? Unknowingly, Hahn was splitting his uranium atoms into smaller barium and krypton atoms.
As mentioned earlier, the nucleus is always in conflict – its protons try to pull apart while held together by the strong nuclear force. Large uranium atoms are so unstable that by shooting a neutron into them, Otto Hahn had wrenched them apart into two smaller atoms, releasing nuclear energy in the process. As Meitner’s nephew, Robert Frisch, explained, uranium atoms containing 238 protons and neutrons were actually expending less than a thousandth of their mass as energy:
“(My aunt) worked out that two nuclei formed by the division of a uranium nucleus would be lighter than the original uranium nucleus by about one-fifth the mass of a proton. Now whenever mass disappears, energy is created according to Einstein’s formula: E = mc2.”
Unwittingly, Hahn and Meitner had blasted clear the road to atomic fission.
News of the discovery spread, alerting Albert Einstein to send off the first of his four warning letters to President Franklin D. Roosevelt that he later called “the greatest mistake” of his life:
“Sir… In the course of the last four months, it has been made probable through the work of Joliot in France as well as Fermi and Szilard in America – that it may be possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of new radium-like elements would be generated… This new phenomenon would also lead to the construction of bombs, and it is conceivable – though much less certain – that extremely powerful bombs of this type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory…
“In view of this situation, you may think it desirable to have some permanent contact maintained between the Administration and the group of physicists working on chain reactions in America… Yours very truly, Albert Einstein.”
On the other hand, Meitner, described as the woman who left Germany with the bomb in her purse, refused to lift a finger in support of America’s nuclear project, declaring, “I will have nothing to do with a bomb!”
Einstein won out and today, as always, nothing saves between the world and destruction but Hashem’s will.
As the Medrash comments on the verse (Yeshayahu 33:14), “Sinners in Tzion are afraid… who among us shall dwell with devouring fire? Who among us shall dwell with the burners of the world” (mokdei olam)?
“Said Rabbi Yehuda, the son of Rabbi Shimon: ‘Why does Yeshayahu call the nations at the end of days, “Burners of the world?” Because, if Hashem gave the nations of the world permission, they would burn the entire world and its inhabitants in one instant.’”
(Source: E = mc2, David Bodanis, 2001 by Pan Books, Pan Macmillan, London)