PROBLEM OF NUCLEAR WASTE

In “Stop Dithering on Nuclear Waste” [Science Agenda], the editors argue that the U.S. needs to create a deep repository for nuclear waste and should revisit its decision to close the proposed Yucca Mountain repository in Nevada. I agree that Yucca Mountain should be revisited. I think a series of town hall–type meetings could be set up to inform the public about the issue.

I also think that all presidential candidates should be asked what they would do about nuclear waste handling. This could be achieved by including the issues in debates and forums that are already scheduled or by sending letters or e-mails to the respective campaign offices.

STEPHEN A. HODGSON
Galveston, Tex.

So the editors think it is a great idea to place nuclear waste in the “barren” Yucca Mountain site, do they? Out of the 99 nuclear power plants operating today, only a handful are located west of eastern Texas. Clearly unlike the West, the eastern portion of our nation has embraced nuclear power in a big way and now wants to dump their garbage in someone else's backyard.

How to dispose of the nuclear waste has always been an afterthought to proponents of atomic energy, but that waste makes it a stillborn idea. No one wants to store it on-site because of the inherent dangers of doing so. Transporting the waste via rail or truck presents dangers all its own, but after the waste passes to the West, most Easterners would stop caring what happens to it.

KIRK WAYLAND
Irvine, Calif.

MEASUREMENT MYSTERY

In “The Neutron Enigma,” Geoffrey L. Greene and Peter Geltenbort describe an approximately nine-second difference in the two most precise measurements of the neutron's lifetime and explain how one of the measurements uses what is called the “beam method” and the other the “bottle method.”

Is it possible that the beam method shows a longer neutron lifetime than the bottle method because of time dilation of the neutrons' speed?

DAVID LAPADULA
Raleigh, N.C.

It would seem that, as the authors did mention, a strong argument could be made that the differences observed were related to the different methods used. What if the electromagnetic field has some effect on the neutron decay process?

LORETTA BROWN
Grand Blanc, Mich.

THE AUTHORS REPLY: Like Lapadula, several readers thoughtfully suggested that relativistic time dilation might explain the discrepancy because of the difference in neutrons' velocity in the two approaches. This is a real effect, and it is known that the lifetime of an unstable particle moving at a speed approaching the speed of light is longer when it is measured in the laboratory rest frame than when it is measured in the frame of the moving particle. In the beam experiment, the typical neutron speed is about 1,000 meters per second; in the bottle experiment, it is only a few meters per second. But these speeds are far less than the speed of light, and so the effect is very small. The lifetime difference caused by the relativistic effect is only a few nanoseconds, or only about a billionth of the observed effect.

Regarding Brown's question: Quite a few readers were also concerned about the fact that in the beam experiment, the decaying neutrons were in a magnetic field, whereas in the bottle, there is no field. In fact, if the magnetic field were extremely intense (far, far stronger than in the real experiment), its effect on the outgoing charged particles (electrons and protons) would change the lifetime to a detectable degree. This effect can be reliably estimated because the dynamics of neutron decay are well understood. For any practical laboratory magnetic field, the effect is far too small to cause a detectable change. More recent experiments with magnetic traps, in which there is a strong magnetic field, are consistent with this analysis.

GALÁPAGOS TOURISM

In “Galápagos Stampede,” Paul Tullis describes the conflict facing Ecuador's government between the need to cap the number of visitors to the Galápagos Islands at a level that doesn't threaten their unique ecosystem on the one hand and the need for greater revenue from tourism on the other. This appears to be a classic case of an economics problem for which the solution is well known: charge a (higher) fee.

There should be a permit required for foreign tourists wishing to visit any part of the islands, with the cost set high enough that visitors will self-cap at the desired level.

DAVID HOFFMAN
via e-mail

BRAIN EVOLUTION

In “Tales of a Stone Age Neuroscientist,” Dietrich Stout describes research supporting the idea that the evolution of the human brain was encouraged by the development of stone tools. But he does not mention another, possibly parallel technical development that did not leave many archaeological traces: string.

The act of twisting plant fibers and tying knots requires careful use of an opposable thumb and may have helped develop human dexterity and the fine control of a precision grip.

COLIN LEDSOME
London

Stout ignores the most obvious source of linguistic evolution in the human brain: communication between mothers and children. Toolmaking is essentially silent and solitary, whereas child-rearing is noisy and communal. The slow development of human children is thus as likely a source for the emergence of language as the knapping of flint.

BARBARA WILSON
Newport, Ore.

TERMS OF ACHIEVEMENT

In his Skeptic column, Michael Shermer describes Deepak Chopra's statement that “attention and intention are the mechanics of manifestation” as nonsense in “Hooey. Drivel. Baloney …” But it has real meaning to people who participate in that self-reflective mode of being called mindfulness. Contrary to Shermer's skepticism, the effort that leads to manifesting mindfulness most definitely requires the mechanics of attention and intention.

BILL HAXTON
Three Rivers, Calif.

CLARIFICATION

“The Paradox of Precision Medicine,” by Jeneen Interlandi [The Science of Health], stated that because a lot of tumors eventually developed mutations that rendered the malignancies resistant to the cancer drug Gleevec, that drug was able to buy patients with a particular form of leukemia a little time but did not change their final outcome. The article should have qualified that whereas many patients experienced those disappointing results, the drug has helped a number of people live eight years or more.

ERRATUM

“Quick Hits” [Advances] incorrectly said the next Square Root Day would occur in 11 years. The next one is in nine years.