DR. SALVADOR GONZALEZ
Professor of theoretical physics and the history of science
De La Salle University
In physics, one of the first questions asked by man was, what ultimately is the material world made of? And the one who first answered it scientifically, although he did not have much of a mathematical background at the time (around 5 BC) was Democritus, a Greek. He said that ultimately all material things are made up of atoms and these are very small particles.
But that was forgotten for a while. After the Greek civilization came the Roman Empire with its soldiers and lawyers, people who weren’t interested in science. It wasn’t until 1910 in England that John Dalton, a chemist, remembered the early teaching of the Greeks and he was able to explain nicely the laws of chemistry by saying that chemical substances are made up of atomic elements joined together.
At Cambridge, John Thompson wanted to know more about these atoms. He bombarded some materials with electrons and came to the conclusion that atoms are made up of a positive core surrounded on the surface by small negative electrons.
Thompson had a brilliant student from New Zealand, Ernest Rutherford, who, like many brilliant students, didn’t just accept his professor’s words. He conducted his own experiments. He got very thin gold foil and he bombarded this with helium. He found that most of the helium particles went through the gold foil, some were deviated slightly, while others behaved like they encountered large positive charges in the atom of the gold and were thus sent back. From which Rutherford concluded that the atom is made up of a nucleus, positively charged, surrounded by electrons, not on the surface, but away from the nucleus, and empty space between.
Rutherford, in turn, had a brilliant student, Niels Bohr, a Danish. Bohr continued the work and found that electrons go around the nucleus like planets go around the sun. That is the origin of our atomic picture.
In 1932 Chadwick of Cambridge discovered that in the nucleus there was not only the proton with positive charge, but also the neutron with zero charge. So now we picture the atom as having a nucleus with positive protons and neutral neutrons.
In 1935 a Japanese physicist said, ah yes, but why are they there? In other words, if the nucleus of the atom is made up only of positive charges, similar to each other, and neutral neutrons, what makes the positive neutrons stick together? Didn’t we learn in high school that opposite charges attract and similar charges repel? Why then are these protons with positive charges not repelling each other? So, he said, there must be another force inside the nucleus, greater than the electric force. This is the nuclear force.
In 1939 in Berlin two German chemists and an Austrian physicist stumbled upon nuclear fission. They were bombarding uranium ore with neutrons, hoping to make atoms bigger than uranium. (In the natural order of thins, uranium was the biggest atom, atomic number 92.) They thought that a uranium atom, if hit with a neutron, would become neptunium, and then plutonium, and lo and behold they’d be producing elements that are not found in nature. And while they were thus engaged in nuclear ballistics, they discovered that a certain type of uranium, about .7% of the uranium content of the ore, instead of getting bigger, fissions or splits.
And then Lisa Ratner, the Austrian physicist, had to run away from Berlin because she was a Jew. She fled to Copenhagen where she met with her nephew Otto Frisch, also a physicist, and together they performed the experiments, computed the results, then sent these to America, to Einstein and Fermi.
Einstein and Fermi again performed the experiments, again computed the results, and they agreed that indeed this was a tremendous amount of energy that could be produced and that this could become a weapon of war. And they knew that the Germans knew. Einstein then wrote to Roosevelt, suggested that the President see if a weapon could be produced ahead of the Germans. Fortunately the Germans never produced an atomic bomb. Heisenberg refused to give Hitler the knowledge he had (which is one of the nicest things about the German scientists of the time).
And so the war ended in Europe with Germany surrendering. But there was still Japan in the Pacific to tackle. The Americans had two bombs, a uranium-235 bomb and a plutonium-239 bomb. Whether wise or not, these two bombs were unloaded on Hiroshima and Nagasaki. One killed 80,000, the other 100,000. After that, people became horrified. In 1945 the Atomic Energy for Peace movement began.
But reactors were built anyway. The first ones to produce more bombs, the next ones for research. In the 1950s we were offered a research reactor by the Americans, the reactor we have now in Diliman, first put into operation in 1963. It produces radioactive substances needed for medicine, agriculture, and so on.
Mind you, at the time there was also a lot of protests against the reactor. They said it would blow up like a bomb, that it would cause radiation and kill everybody in the U.P., and we said it would not and it didn’t.
Question: You’re not against the nuclear power plant then?
In principle, no. But I would request for a clean bill of health. Let’s make sure it’s safe within reasonable risk. Then let’s have public hearings. We cannot avoid it any longer. And if we cannot convince our people of the safety of the reactor, then the people’s wishes must be followed.
[Source: “A Primer on Nuclear Power.” Alternative Futures. Vol II. No 1. 1985. 27-32]