Interview with Thomas A. Tombrello - Caltech Oral Histories

Tombrello–73
groups at Chicago, and that was part of the vision of Robert Sharp. The two people that I
consider the great visionaries of that period were Robert P. Sharp [Sharp Professor of Geology;
d. 2004] and Robert Bacher. When Sharp took over the geology division [in 1952], they were
strong in geology, geophysics, and paleontology. They got out of paleontology—they gave the
bone collection to the Los Angeles County Museum of Natural History—and he got them into
planetary science and mass spectrometry, a lot of it devoted to understanding how the solar
system and Earth started and evolved.
So, getting back to Kellogg, there was Charlie Barnes, who had come after the war. Also
Ralph Kavanagh, who had been in the navy during the war, had come back to be a grad student
here and then stayed on as a junior faculty member. He was an assistant professor when I first
got here. Barnes and Whaling were associate professors.
ASPATURIAN: That would be Ward Whaling [professor of physics, emeritus]?
TOMBRELLO: Yes. Ward had been in the Signal Corps during the war. He had been an
undergrad at Rice, so I sort of knew about him but had never met him. He had come here after
the war. Hoyle appeared, apparently, sometime in the 1950s, with his idea that there seemed to
be a gap in the nucleosynthesis sequence. There would seem to be no way to make carbon,
because beryllium 8 was unstable in its ground state and broke up immediately into two helium
nuclei. Therefore, you could get as far as beryllium, and then things came apart again. Hoyle
had this idea that if the star were big enough, hot enough, and dense enough in its core, three
alpha particles would have a chance to make carbon directly if there were a nuclear excited state
at just the right energy to sort of hold them together just long enough so that they could decay to
the ground state, the first excited state.
ASPATURIAN: Alpha particles being helium nuclei?
TOMBRELLO: Helium 4. Hoyle appeared with this notion. He said that since carbon exists, there
must be a state of this particular property, and you should look and find it. Whaling was the one,
I think with a collaborator—I can’t remember the collaborator’s name—who found this state
exactly where Hoyle said it was. That was the first big Kellogg thing.
http://resolver.caltech.edu/CaltechOH:OH_Tombrello_T