Letters

Forgotten Works and the Fragmentation of Physics

That Alpher and Herman's work predicting the cosmic microwave background is often forgotten (APS News, Letters, October 2002) is not surprising. This happens all the time. What is more surprising is the rediscovery of their prediction by Bob Dicke in seeing a signal in the noise discovered by Penzias and Wilson and making the connection with the cosmic microwave background. In this year which mourns the departure of Viki Weisskopf and celebrates the 100th anniversary of the birth of Eugene Wigner we see that physicists like Dicke who can see beyond the limits of their own specialties are disappearing.

I saw symptoms of this disease back in 1958 with the publication of Rudolf Mossbauer's first paper which was later awarded the Nobel Prize for what has since become an active field of research. His experimental result was clearly understandable from already- published theoretical papers, particularly a paper by Willis Lamb on neutron absorption in crystals. But my generation had already fragmented into nuclear and solid state physicists who did not talk to one another. Several groups of nuclear physicists were so sure that the experiment must be wrong that they repeated an already-published experiment which was clearly consistent with already-published theory, obtained exactly the same result, and published it as original research.

I was a nuclear physicist at that time, but was fortunately at the University of Illinois in Urbana, where we could ask Fred Seitz about the Mossbauer paper. Fred's first response was: "Who is this fellow Mossbauer?

Does anybody know him? Is he reliable? Give me a few days to think about it." A few day later he told me: "This work is perfectly all right. But when I first saw it I was sure it was completely crazy."

Trying to understand why Fred thought it was crazy enabled me to learn a great deal as I penetrated the barrier between nuclear and solid state physics. I found that one can make a fruitful career by discovering nothing new and only acting as an interpreter between different groups of physicists who do not talk to one another.

Harry J. Lipkin
Rehovot, Israel

Article Overstates Earth's Field

I was very interested in reading your article of "Physics News in 2002." Thank you for putting forward this excellent section.

On page 6 under the subtitle of "Microtesla nuclear magnetic resonance" the statement that the Earth's field is roughly 50mT is incorrect. It is well known that the Earth's field is about 0.5 Gs or 50 microT, not 50 milliT.

It might be possible that the line above this "...a much weaker orthogonal measuring field of 5mT" is incorrect too. My guess is 5 microT.

Dexin Wang
Eden Prairie, MN

Ed Note: The writer is correct on both counts. The Greek letter mu was erroneously transcribed as an English m. For interested readers, the article on which this item was based is: Science 295, 102 (2002).

Bohrs' Reaction Logical

With regard to the letter from, Klaus Gottstein in the February 2003 APS News: At the risk of belaboring the obvious, may I suggest that Bohr's reaction to Heisenberg's "involved language" regarding their now- famous meeting in Copenhagen-granting that Heisenberg's 25-years-after-the-fact explanation was sincere-is the only logical reaction possible.

The head of the Nazi atomic bomb project, at a time when many people still believed that the Nazi's would win the war, tries to suggest that both sides abstain from pursuing this ultimate weapon. Who has the most to gain from such an absurd (at the time) proposition?

Perhaps Heisenberg sincerely (if terribly naively) actually believed that this argument would appeal to Bohr. If he actually believed that, it is simply another example of why a great physicist's views about topics outside his or her field of expertise can readily be discounted.

A less charitable interpretation would be that Heisenberg may have consciously ignored his own interest in the matter at the time and, long after the fact, could still not accept the unequal position he was in vis-a- vis Bohr at the time.

Robert A. Myers
New York, New York