Celebrating Einstein

The opportunities for groundbreaking new discoveries as profound as those of Albert Einstein, whose achievements were documented in your September issue, have diminished. The review and approval processes for obtaining research funding from the federal government are not friendly to new ideas and approaches. Those who have demonstrated high levels of skill and creativity should be given more freedom to explore innovative approaches approved by a review system that does not eat up half their careers in chasing funding.

Laguna Woods, Calif.

I was surprised to find no mention of the only practical application of Einstein's general theory of relativity, the Global Positioning System (GPS).

Around 1966 I worked at Aerospace Corporation in El Segundo, Calif. Part of my job was applying general relativity to correct the rates of the clocks that were to be launched into orbit.

The work was classified at the time, but I did publish a sanitized version in a physics journal. Civilian handheld GPS receivers became available many years later, and I was finally able to tell my wife what I had been up to!

Professor emeritus, University of Arizona

Free will vs. determinism

Toward the end of “Is the Cosmos Random?” George Musser makes a case for the existence of free will that ignores the following evidence against it: Some people would pay to do what others wouldn't do, no matter how much you paid them. People don't suddenly drastically change their personalities. And their preferences control everything they do.

via e-mail

MUSSER REPLIES: One might argue that our preferences constitute our will, and therefore if we act on the basis of those preferences, we act freely. In a sense, free will requires determinism, in that your acts are determined by you. When our actions don't align with our desires because of some kind of compulsion, we have lost our free will.

Time travel

A Brief History of Time Travel,” by Tim Folger, gives a scenario in which an astronaut traveling 1,040 light-years at near the speed of light ages just 10 years while Earth ages 1,000 years.

Given that the human heart will beat only so many times in a person's lifetime, how can the astronaut age only 10 years?

via e-mail

FOLGER REPLIES: The time dilation of special relativity affects all clocks, even biological ones. So an astronaut traveling at the speed of light does age more slowly—as seen by some stationary observer. The astronaut herself will not notice anything unusual—she will age at the normal rate.

Shoulders of giants

In “Cleaning Up after Einstein,” by Corey S. Powell, there is a photograph of string theorists, including Leonard Susskind, at Stanford University. On the table are the three volumes of The Feynman Lectures on Physics, by Richard P. Feynman, Robert B. Leighton and Matthew Sands.

This is an elementary introduction to college physics. I cannot imagine that the researchers need to consult it at this stage of their careers and like to think that it was included as a homage to a great scientist.

I also spied a copy of Gravitation, by Charles W. Misner, Kip S. Thorne and John Archibald Wheeler (aka MTW). It's much more advanced, but again, I suspect the motive for its inclusion was homage.

Berkeley, Calif.

SUSSKIND REPLIES: If I recall, the photographer suggested that we place a few of the books that I use most often where they could be seen. Feynman's books may have been intended for a freshman class, but the insights are very subtle. If you are confused about a subject in physics, the first place to go is Feynman. If the subject is gravitation, then the second is MTW.

Improving forensics

In “Forensic Pseudoscience” [Skeptic], Michael Shermer claims that the AAAS Forensic Science Research Evaluation Workshop held last May demonstrated that “many fields in the forensic sciences ... employ unreliable or untested techniques.”

Flawed science is not unique to the field, but it is important to discuss it when it happens. The workshop highlighted some areas that have been recognized as problematic, but this is far from an indictment of all forensic science. We forensic scientists are grappling now with the implications of cognitive bias, and significant progress has been made in the field. It seems indisputable that forensic science is doing more to help convict the guilty and exonerate the innocent than the reverse.

Department of Forensic Sciences, George Washington University

SHERMER REPLIES: That forensic scientists are turning a skeptical eye toward their own practices is good to hear, but I find Weedn's final proclamation to be quite disputable. At the workshop I attended, I was told by a number of forensic scientists that no one knows how many innocent people are rotting in jail because of forensic pseudoscience. What to do about the wrongly convicted? Those who were convicted on, say, bogus arson pseudoscience should be set free. Will the leading forensic science organizations stand up for them?

Hole history

In “Don't Blind NASA to Earth's Climate” [Science Agenda], the editors refer to NASA as having “spotted a dangerous, growing hole” in the ozone layer in the 1980s.

I thought that the discoverers of the ozone hole were scientists from the British Antarctic Survey, who reported it in Nature in 1985.

Hayes, England

THE EDITORS REPLY: The 1985 paper did document the existence of the ozone hole. But the disturbing fact that it was growing was chronicled by NASA during the next several years.


The issue's introduction, “Einstein,” by the editors, states that Sir Arthur Eddington confirmed a prediction by Albert Einstein that starlight would bend as it passed the sun. Rather Einstein's prediction, confirmed by Eddington, was that it would bend twice as much as predicted by Newtonian physics.

In “What Einstein Got Wrong,” Lawrence M. Krauss describes Einstein's erroneous initial calculation of light's deflection by gravity (which put the deflection at half its true value). The text says the error was made in 1912 and never published. Einstein did publish the error, in 1911. Also in Krauss's article, the box “Einstein's Blunders” has an incorrect illustration of Einstein's earlier and later conceptions of gravitational waves and a flawed description of the later conception. The corrected description and illustration can be seen at www.ScientificAmerican.com/sep2015/erratum.