Fusion Experiments Generate Scientific Confusion
Fusion fever continued along one of the most tortured courses in the annals of science Friday as scientists from MIT said they had confirmed evidence of nuclear fusion in a flask, at least theoretically, and scientists from Georgia Tech conceded that they had claimed success too quickly.
Meanwhile, two graduate students said they had succeeded where others had failed, and scores of scientists struggled to come up with a plausible explanation for what is going on.
Keith Johnson, a professor of materials science and engineering at MIT, said he agrees that a controversial experiment in Utah, which supposedly produced nuclear fusion at room temperature, did involve a nuclear reaction. But the energy released by the experiment resulted from a chemical reaction, and the process holds little hope for commercial applications, he said.
‘Evidence for Nuclear Fusion’
Referring to claims from B. Stanley Pons of the University of Utah and Martin Fleischmann of the University of Southampton, England, Johnson said in a release from MIT:
“Those events they report as evidence for nuclear fusion we confirm.”
However, he said, the energy released came from “a chemical process” and it would not be possible to use the technology on a commercial scale. He said the experiment caused atoms of deuterium to vibrate, breaking the chemical bond and releasing the heat that was detected by the Utah scientists. Occasionally they vibrated so intensely that some of them fused.
But in a telephone interview, Johnson said his statement was based on “large-scale computer calculations” rather than on attempts to repeat the experiment.
Even one of Johnson’s own colleagues strongly disagrees with him, however. Peter Hagelstein, considered a brilliant physicist who came to MIT from the Strategic Defense Initiative project, also known as Star Wars, issued a fuller statement on an earlier suggestion that cold fusion may explain the Utah phenomenon. He said the process need not produce the neutrons that just about everyone else is looking for.
Trying to Patent Idea
Many laboratories have tried unsuccessfully to detect neutrons from the experiment, but Hagelstein has concluded that the cold fusion process could be producing helium-4 instead of helium-3, which would produce heat but not neutrons. That is the same theory voiced by Pons earlier, and MIT is trying to patent Hagelstein’s idea.
The effort to validate the controversial experiment entered its fourth week Friday with the Georgia Tech scientists wishing that the week had started differently. On Monday, a team of five scientists from the Atlanta institute announced that they had verified a key part of the “breakthrough” by detecting neutrons emitted by their version of the experiment, suggesting that nuclear fusion was, indeed, going on.
“It’s like being there when fire was discovered,” James Mahaffey, leader of the team, said in a statement then.
Friday, the Georgia scientists held a press conference to announce that they had--at best--spoken too quickly.
Looking exhausted and crestfallen, Mahaffey faced a battery of reporters Friday and said: “What can I say?”
The neutron detector used by the Georgia Tech team turned out to be so sensitive to heat that it was actually measuring a slight rise in temperature inside the flask rather than neutrons, the scientists said.
“We found that the thing is so sensitive we could literally use the neutron counter for a thermometer,” Mahaffey said. Georgia Tech’s problems underscore a fact that has troubled many scientists: The number of neutrons emitted by the Utah experiment is so low that it is almost immeasurable.
Mahaffey stopped just short of completely invalidating his experiment, but conceded that the results were “not nearly as dramatic or conclusive as what we thought we had.”
No Success at All
While other laboratories in the United States, the Soviet Union and Hungary are still claiming success in replicating at least part of the controversial experiment, they are outnumbered at least 10 to 1 by laboratories that have not reported any success at all.
Thus no one knows yet whether Pons and Fleischmann really did achieve fusion in a test tube, as they claimed in Salt Lake City more than three weeks ago.
The delay in successful replication of the experiment is troubling to scientists because the key to the scientific method lies in the ability to repeat an experiment over and over.
“In any scientific endeavor, the essence of science is reproducibility,” UCLA nuclear engineer Robert Conn said. “Then the trick is to understand how the beginning leads to the end.”
Although success has not come for some major labs, two graduate students at the University of Washington said they had carried out the experiment the way dozens of scientists have said it should have been done all along. Van L. Eden and Wei Liu ran the experiment repeatedly two different ways: using “heavy water,” in which hydrogen has been replaced with its heavier isotope, deuterium; and with regular water.
Different Results Sought
The idea behind the tandem experiments was to see if they yielded different results. If the process does lead to fusion, it should occur in the “heavy water” version and not the other, according to many scientists. That is known as running a “control” experiment and it provides a basis for evaluating the results.
Eden and Liu reported some evidence of a fusion reaction when the experiment was run with heavy water, and no evidence when the regular water was substituted.
The two students detected a possible indicator of tritium, a radioactive isotope of hydrogen that should be produced in nuclear fusion. The results could support the Utah team, but tritium could have been just a contaminant in the heavy water used in the experiment, so the work is far from conclusive, as the two young men readily conceded.
The graduate students were aiming at a goal set by one of the top physicists in the country earlier in the week. Harold P. Furth, director of the Princeton University Plasma Physics Laboratory, told the American Chemical Society in Dallas on Wednesday that the experiment must be repeated with adequate controls “to galvanize the great nuclear physicists of the nation” to begin working on the problem.
Excitement over the Pons-Fleischmann claim grows largely out of the fact that fusion offers a chance to end the world’s energy woes through an inexhaustible source of fuel--seawater. Fusion is the process that powers the sun, and it occurs when two atoms merge, releasing energy.
There has been a shift in attitude within much of the scientific community since Pons’ and Fleischmann’s March 23 press conference. Initially, scientists of virtually every persuasion tried to discredit the claim. Most scientists are still extremely skeptical, but of late there have been more and more efforts to explain how such a mysterious nuclear reaction might be possible.
Many scientists, including K. B. Whaley, a UC Berkeley chemist, have prepared reports for professional journals arguing that nuclear fusion could occur in the experiment because of something called “tunneling.” Physicists initially rejected the Pons-Fleischmann claim because they could see no way that deuterium nuclei could overcome the electric charge that should keep them too far apart to fuse.
But there is a process, Whaley argues, that would allow some nuclei to get closer to others of the same charge, although it has no parallel in the visible world. If enough atoms are crowded into a small enough area, some will “tunnel” through the electrostatic barrier and fuse with others.
Other scientists still insist that some kind of chemical reaction could explain the heat reported by Pons and Fleischmann. If that is the case the experiment is of little value because there are other, more efficient ways to generate energy through chemical reactions, such as throwing a lighted match on a pool of gasoline.
Chemical Reaction Disputed
Disputing suggestions that the energy he measured came from a chemical reaction, Pons said earlier that the Utah experiment generated more heat than could be produced chemically even if the flask and all its contents were consumed in the process.
Texas A&M;, which reported Monday that it had also produced excess energy from a device similar to the one used in Utah, may soon be in a position to answer the question of whether the heat that scientists detected there really resulted from fusion.
UCLA’s Conn said Friday that every known fusion process leaves one product.
“All fusion leads to helium,” he said. Furthermore, the helium should remain trapped in the palladium used in the electrode. If the heat reported by Texas A&M; resulted from nuclear fusion, then helium should remain in the palladium after the experiment is completed.
Texas A&M; plans to test its palladium soon to see exactly what comes out. If there is an excess amount of helium there, the reaction was probably nuclear fusion, Conn said. If not, it was probably chemical.
