APS News

Letters

Happer Contributions to MRI Imaging Overlooked

The article on MRI rare gas imaging [APS News, July 1999] overlooks the contributions of William Happer of Yale University. I would like to add some background. By concentrating on optical pumping processes while atomic physicists rushed into laser spectroscopy in the early 1970s, Happer paddled into what many regarded as a backwater of atomic physics. However, from his studies of relaxation and polarization transfer emerged a new understanding of atomic collision processes, and also powerful techniques for polarizing rare gases that were of value in nuclear physics. What was totally unexpected was the application of this new knowledge to MRI. It was through Happer's imagination and persistence that rare gas MRI imaging was conceived and developed into a useful medical tool. He pioneered its clinical medical applications and the company mentioned in the last paragraph was founded by him. Rare gas MRI imaging offers a paradigm of basic research, illustrating why good scientists pursue their own stars, and why the government should support them.
Daniel Kleppner
Massachusetts Institute of Technology

Getting Physical

I liked the small box "What's in a Name?" in the July issue pointing out the sometimes misunderstood significance of "Physical" in American Physical Society, Physical Review, and Physical Review Letters. It reminded me of a colleague (to remain nameless) who addressed his latest scientific contribution to "The Physical Revue" - that is until his mother, noticing the envelope waiting for the mail, asked if that was really the journal to which he was sending his communication?
Michael E. Fisher
Institute for Physical Science and Technology, University of Maryland, College Park

Readers Question "What is Science?"

The rules of scientific exchange that you list in the June issue of APS News are not applicable to those working in cosmology and on question of origins. Replication is not something that we can do with unique events. I believe that you ought to use "physical universe" rather than "world" in your definition of science. Experimental data can be gathered entirely by means of mechanical devices. However, the whole of reality may encompass more than the physical. For instance, man is a "detector" of the spiritual. Science is amoral. Its use determines whether "science extends and enriches our lives." The latter requires human moral/ethical decisions that lie outside of the purview of science.
Moorad Alexanian
University of North Carolina at Wilmington

I would like to call attention to a flaw in the definition of science as adopted by POPA, as an activity that requires "condensing the knowledge into testable laws and theories." This sounds much like the definition of physics high school teachers love to use with beginning students, and is intrinsically myopic. Were that criterion applied, most of what we sincerely believe constitutes the practice of science would be disqualified. Let us not fall into the trap of proposing a silly statement because it is brief and sounds significant.
S.H. Bauer
Cornell University

I think the publicization of an agreed definition of science will help to combat "the growing influence of pseudoscientific claims," and that this is a worthwhile objective.
David T. Read
National Institute of Standards and Technology

Although the proposed APS statement on "What is Science?" mentions the importance of testing theories in the scientific process, it does not elaborate on the nature of those tests, which needs to be understood. As scientists, many of us regard the ability to explain what has already been observed as an insufficient test of scientific understanding. We need to emphasize the role of experimentally verifiable predictions with quantified levels of ambiguity in our work. By itself, prediction is not a sufficient indicator of true understanding, although it is a necessary indicator. Personally, I would maintain that anything which otherwise has the appearance of science, but which lacks this element of testable prediction, should not be called science. It might be demagoguery, or it might be social science. It might even be one of those discussions about the wave function of the universe which occasionally appear in the Physical Review. But it is not really modern science. I urge POPA to consider rewording the proposed statement to reflect the importance of experimentally verifiable predictions when carrying out scientific inquiry.
Leo Bellantoni
Fermi National Accelerator Laboratory

A Nobel Mistake

Several alert APS News readers rightly chastised us for the typographical error in the headline an article in the July 1999 issue, referring to spin-polarized "Nobel" gases. Naturally, it should have read "noble" even though helium has certainly led to several Nobel prizes.
-Editor

Dyson's Skepticism Well-Founded

Brad Marston's reaction to Freeman Dyson's article is to label it misleading and ill-informed. However, Marston makes several misleading claims of his own. First, the deconvolution of borehole temperatures tells us only that temperature has increased worldwide during the past century-something that we know already from air temperature records. Several research groups have suggested that borehole temperatures show stable surface temperature prior to this recent increase. Yet I found a counter example that in typical circumstances borehole temperatures cannot resolve the Little Ice Age or the Late Middle Ages Optimum. If borehole temperature cannot resolve an event as significant as the Little Ice Age, then it has little to say one way or the other regarding the stability of past climate. In fact, borehole temperatures in glaciers, which, for technical reasons have better resolving power than other borehole measurements, do show wide variation of temperature over the past 10,000 years. Second, while the history of carbon dioxide concentration in our atmosphere is available through sampling in glacier boreholes, it is not easy to make estimates (simple or otherwise) of the carbon dioxide forcing function. There is dispute over whether changes in carbon dioxide concentration lead or lag the temperature variations, making even the assignment of cause and effect uncertain. Freeman Dyson's skepticism is hardly misplaced.
Kevin T. Kilty
Washington State University

Brad Marston's criticism of Freeman Dyson's article is off base. The crucial question certainly is whether greenhouse theory is quantitatively correct, i.e., whether climate models can reproduce the observations. So far at least, they have not only failed to do that, but they differ among themselves by several hundred percent in their predictions. The major failings have to do with the modeling of clouds and aerosols, whose optical properties determine the radiative forcing along with that of greenhouse gases, but whose distribution in time and space is highly variable. None of the climate models encompass properly the most important of atmospheric greenhouse gases, water vapor, whose vertical distribution determines whether water vapor exercises a positive or negative feedback on warming. Until climate models are reasonably well validated, one cannot accept their predictions, nor base far-reaching and costly policies on such predictions. Respected economists have revisited the UN's climate report and now find that CO2 increases and warming produce substantial economic benefits. Under the circumstances, one can only recommend policies like avoiding waste, cost-effective investments in energy conservation, and similar measures that make economic sense.
S. Fred Singer
President, Science & Environment Policy Project, Fairfax, Virginia

Sober Message

I am writing to you in frustration about the social message sent in the July 1999 issue of APS News. I am upset by the continuing college fraternity mentality of the physics community as represented by devoting half a page to an astronomer's drinking song ... and much of the rest of the page to articles about beer. The article Foam: Food for Thought might be appropriate, but the rest is, at best, in very poor taste. "Drinking" and "drinking songs" are clearly not about having a glass of wine with dinner. Drinking is a wide-spread problem on college campuses (the death of an MIT student at a fraternity beer party last year is an example of the worst possible consequence) and in professional communities and should not be the subject of jokes in the publication of a professional society.
Margaret Geller
Harvard-Smithsonian Center for Astrophysic


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Editor: Barrett H. Ripin
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