Indian scientist claims holy grail of physics

THE TIMES OF INDIA ^ | TUESDAY, MARCH 05, 2002 9:04:47 PM | CHIDANAND RAJGHATTA

[CWRWinger]

Just a hunch, but Taleyarkhan probably got his masters from the University of North Carolina.

[rdww]

Typical Indian -- they're nuts for cricket.

[JasonC]

I have since read the "Science" article in which the data is presented. My basic attitude is the same - interesting, but probably not what they hope it is. I'll go over what they saw and what the alternate explanations are.

They were using high speed neutrons to start the bubbles - 15 MeV. They did not try to detect fusion by energy budgeting, but by tritium build up and slow neutrons, 2.5 MeV, which is about what you would see released by fusion reactions. They reported a 4% increase in the slow neutron emissions, and a large build up in tritium over a time scale of several hours.

The implied fusion reactions, if that is the source of both, are an order of magnitude higher by the tritium measure, which is reasonable when you allow for the difficulty of detecting the fleeting slow neutrons, compared to the lasting tritium which can be measured afterward.

The most intriguing aspect of it, though, was the use of controls and the sensitivity. They found neither marker effect when using acetone with hydrogens as opposed to heavy hydrogen (regardless of temperature), and they also saw neither marker effect when using a room temperature target instead of a 0 C cooled target. They also did not see it without sonic stimulation.

Why does the last bit matter? Two reasons. One, the failure of others to rapidly duplicate it may be due to the sensitivity of the conditions needed to bring about the effect, whatever its cause. Two, on the surface the obvious competing explanation for the origin of the tritium build up should occur in at least one of the control cases.

The alternate explanation (which is not in the article, but clear enough to me) is that their bubble originating neutrons are causing the nuclear reactions indeed taking place in their sample, not fusions of deuterium with deuterium in the target itself. The order of magnitude of the neutrons fired at the target and of the amount of tritium seen afterward is consistent with this explanation.

They don't think that can be the cause for two reasons. One, the controls. If their stimulus neutrons are the cause, why didn't they see the same in e.g. the warmer deuterium trial? Second, some delicate timing analysis, trying to match the order of neutrons detected with the timing of bubble collapse, which they interprete to mean the slow neutrons originate very close to the center-line of the target cylinder near the final stages of bubble collapse.

I don't find the timing analysis very compelling. It is easy to get such things wrong, experimentally - it is a matter of matching events recorded by different detectors, spaced by milliseconds. Also, they have many events going on, on after another, and many bubbles forming and collapsing at once. It is just as likely they have picked out one of the myriad ways of associating neutrons detected with bubble collapses, which they happen to find encouraging.

The controls are more compelling, but an alternative explanation of them is possible. They think the temperature sensitivity reflects dynamics of bubble formation and collapse - longer build times and more violent collapses are associated with the cooler initial temperature. Fine. But the cooler temperature combined with sonic stimulation should also make for more concentrated targets for the fast neutrons.

See, the sound waves should set up pressure density variations throughout the sample. And the colder target has the atoms more closely packed to begin with. The fast neutrons may be more likely to hit something, when moving through a sample with some denser areas, a more regular lattice, or both.

The obvious way to try to eliminate this possibility is to try a test in which the bubble forming stimulus is not fast neutrons, to avoid the ambiguity they create. Instead of trying to disentangle possible causes of tritium formation, design a test in which the same conditions of bubble collapse they postulate as the cause, is the only possible way for tritium to build up in the sample. Until they do that, they will not convince me.

It remains interesting that they saw tritium build up in some cases (temperature and sound stimulation) and not in others still using deuterium in the acetone target. But it doesn't have to be caused by what they hope they've found.