Tuesday, September 19, 2006

Deep Background on the Background

But in science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs. ~Francis Darwin

Hardly a week goes by when some bright scientist announces some new observations or analysis that promises to unhinge some long-established theory. Today's conjecture comes from Richard Lieu at the University of Alabama whereby he has announced that observations of nearby galaxies do not reveal distortions in the cosmic microwave background (CMB) radiation that theory predicts should be there. Therefore, he says, the Big Bang theory is in doubt. Note that the CMB is not in doubt, just a predicted effect caused by the radiation interacting with clusters of galaxies.

Predictably, there is skepticism about the data. The data was taken using WMAP, a satellite that has been taking extensive data for some time on the CMB. The trouble is that the resolution of WMAP may not be sufficient to detect the distortions; scientists using ground-based radio telescopes and WMAP have, in fact, already confirmed the distortions in distant galaxy clusters. Mr. Lieu says, naturally enough, that WMAP's resolution is fine for nearby clusters, so he isn't buying that argument.

But, a Harvard astrophysicist points out that even if Mr. Lieu's team's observations are correct that says less about the Big Bang theory than it does about our limited knowledge of how clusters of galaxies work. Mr. Lieu snappy rejoinder to this? "That I do buy. I myself am not at this point prepared to accept that the CMB is noncosmological and that there was no Big Bang. That would be doomsday."

Well, he may not accept it, but he's saying it somewhere because David Spergel of Princeton is quoted as referring to the team's conclusions, which implies that at least one of those conclusions is questioning the Big Bang. I've written before about this business of making pronouncements on slight or controversial data, but the story of CMB adds another dimension to why scientists might be a little quick to publish a theory.

Most people have heard the story of how Robert Wilson and Arno Penzias discovered the CMB using an old horn-shaped radio telescope at Bell Labs. Wilson and Penzias used the device to bounce signals off the old Echo satellite (actually a huge balloon); as a reward for a job well done, they were given access to the scope to do further work on radio astronomy. To do the job, they decided to make sure that the old horn was in tip-top shape. After cleaning and tuning it, they found that there was a hiss that occurred wherever they pointed the antenna. Figuring that this was a malfunction, they went through all sorts of gyrations trying to get rid of it,including removing pigeons (and their droppings) over and over again. According to Penzias, one day they got a man with a shotgun to do something about the pigeons. Penzias claims that he never knew what the man did, but the pigeons went away.

But the hiss didn't.

What some folks don't know is that a group of people over at nearby Princeton University had come to the conclusion that the Big Bang should have left an "echo", the initial outpouring of radiation at the moment of creation. The radiation would now be very cold (less than 5 degrees K) and very redshifted. It would be so redshifted that it would be observed in the microwave portion of the spectrum. Jim Peebles had prepared a paper in 1964, only to have it rejected with the suggestion that he actually research the literature on the subject. It turned out that he had overlooked the fact that, about 20 years earlier, George Gamow had proposed almost precisely the same thing.

Peebles did the research and found that no one had ever followed up on whether the CMB could actually be detected, so he and Dicke decided it would be a hoot (and a possible Nobel Prize) if they could find it. So Dicke put a couple of associates to work on a detector.

Meanwhile, Penzias and Wilson had decided that the hiss wasn't going away. If it didn't go away, it had to be important, but they didn't know what it was. So they decided to do paper on the calibration methods for the antenna and mention the hiss in an "oh, by the way" manner. While preparing the paper, a colleague tipped off Penzias to Peebles' paper. Penzias got a copy, read it, and called Dicke at Princeton to tell them that they might want to come over to Bell Labs and look at some interesting data.

So, now everyone was excited. Peebles and Dicke were happy because someone found evidence of the CMB; Penzias and Wilson were thrilled because they could stop having the pigeons killed now that they knew what the hiss was. Oh, and they were kinda thrilled to have made a significant observational discovery (that probably outranked the pigeons, but my way is funnier). So the Bell boys (ouch) wrote a paper on their observations, while the Princeton guys wrote a brief paper on the CMB and its cosmological implications. And everyone looked forward to the Nobel Prize presentation.

It might have happened that way except for one thing: The New York Times found out about the story and gave it a page one treatment. And George Gamow read the newspapers.

Gamow, by now (1965) retired, was incensed. He wrote an angry letter to Dicke, essentially accusing the Princeton scientists of stealing his work. Gamow's associates, Ralph Alpher and Robert Herman, who had published specific predictions about the nature of the CMB in 1949, actually quit physics in disgust over the perceived slight.

Penzias and Wilson, meanwhile, escaped unscathed because they had just done the observational work. They didn't claim to have determined its significance or its origin. As a result, when the Nobel Committee finally got around to giving a Prize in 1978, they gave it to Penzias and Wilson for discovering the CMB. They gave no one anything for its prediction.

Now Peebles and Dicke surely did not set out to steal Gamow's work (and that of Alpher and Herman),. Besides, they actually went beyond the earlier work. But there was precedence, and the Princeton team had not acknowledged it, even after Peebles had discovered the existence of the earlier work. Had they referenced the earlier work, it's possible that Peebles, Dicke, and Gamow all would have received a prize for the predicition of the CMB (assuming Gamow was still alive when it was awarded; Nobels are not given postumously).

Scientists know about such things. Serious students working in the areas where Nobel Prizes are awarded can recite the history of winners and near-winners from their fields of study. No one wants to be one of those who missed the opportunity to grab the gold ring. Perhaps that's one more reason why scientists rush to make bold claims. Better to be proved wrong and suffer a little embarrassment than to hesitate and wonder what might have been.

So maybe the rush to publish is understandable, but history has taught us to take claims with a grain of salt until more data is in. That's why the Nobel people wait so long to give out awards.

They don't like being embarrassed in Stockholm.

Reference: Lonely Hearts of the Cosmos, Dennis Overbye, HarperPerennial, 1991

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