Bohr is known chiefly as a theoretical physicist, but he was
also a great teacher and organizer who contributed to the rapid
development of physics during this exciting time by attracting
bright, creative, and often iconoclastic, students from all over
Europe to study at his Institute for Theoretical Physics (now named
the Niels Bohr Institute) in Copenhagen.
Bohr's legacy includes the Copenhagen Interpretation (a way of
thinking about quantum theory) and complementarity (you probably
don’t want to know). If you took chemistry or physics in high
school, you probably learned that his was the first model of the
atom that used the quantum hypothesis and explained why elements
give off light whose spectra show narrow, bright bands of
individual colors separated by complete darkness. If you were
really lucky, you got to look at flame tests and gas discharge
tubes through a spectroscope so you could see these spectra for
yourself. (My students are required to build their own
spectroscopes. Maybe I’ll make that lab into that a cache
some day!)
He managed to convince nearly everyone in physics that quantum
theory was more than a curiosity, more than a mathematical trick.
Oddly, one of the scientists he could not convince was Max Planck,
who had invented the quantum hypothesis to begin with. The other
was Albert Einstein, who had been the only other physicist to use
Planck’s hypothesis before Bohr. Einstein used it to explain
the photoelectric effect, for which he won the Nobel Prize, but
couldn’t reconcile himself to the weirder and more random
consequences of the theory, famously saying, “God does not
play dice with the universe.”
Bohr was “a man who knew too much” to leave in
Denmark after the Germans invaded. He was also half Jewish, so what
he knew or didn’t know mattered little to the Nazis. Just
before he was to be arrested by the Gestapo, he was smuggled out to
Sweden. He lay prone in the tail section of a tiny plane that was
not designed to carry passengers as it bounced over a rough pasture
to become airborne. Apparently it was a pretty close thing. He made
his way to London and then to Los Alamos where he joined the
Manhattan Project and worked on the atomic bomb. His friend and
collaborator on the Copenhagen Interpretation, Werner Heisenberg,
headed the German effort to build a nuclear weapon.
Although he worked on the atomic bomb project, he was concerned
about the prospect of a nuclear arms race and advocated open
sharing of nuclear secrets as a way of avoiding dangerous
competition. This belief led Winston Churchill to consider him a
danger to society—one of the loony left, as they say in
Britain.
He returned to Copenhagen after the war and advocated for
peaceful applications of nuclear energy. He died there in 1962
after winning many honors, including the Noble Prize for Physics in
1922.
Bohr Trivia
• Bohr’s son Aage also won the Nobel Prize. Niels won
for advancing our knowledge atomic structure, specifically of how
electrons orbit the nucleus. Aage Bohr won 53 years later for
contributions to the theory of the structure of the nucleus itself.
There are several parent-offspring pairs of Nobel Prize winners.
You’d be surprised by how many. (Are you curious enough to
check it out?)
• The Michael Frayn play Copenhagen revolves around a
meeting between Bohr and Heisenberg in 1941. You may have seen the
opening in London. Perhaps you saw it on Broadway. I was very
lucky. I got to see the wonderful production mounted by our very
own Vermont Stage Company.
• A chemical element, number 107, is named after him: Bohrium
or Bh.
• A chemical element is named after one of his students, Lise
Meitner, as well. Her element is number 109, Meitnerium or
Mt.
• Bohr’s name is a member of the largest group of
homophones that I know. There are four other words with different
spellings that have essentially the same sound as his name
(Sacajawaner says that's because I’m not very careful about
my pronunciation). Can you name the other four?
First to find: mwein