When I began working at Princeton as post-doctoral fellow in 1975, there was a long way to go to reach that point. The energy produced in the lab was about a trillionth of the energy required to heat the gas. By 1995, the energy gain had been improved by a factor of 100 billion. And in the mid-1990s, the TFTR at PPPL and the JET Tokamak, a sister experiment in the U.K., performed a series of experiments with the easiest hydrogen isotopes to fuse (a deuterium and tritium mixture) and came within 30% to 65% of the breakeven point! This was a remarkable scientific achievement because it involved a continuous evolution of the design and implementation of solutions needed to better heat, contain, and fuel the hot gas.
I can point to only one other technical endeavor that has shown such a
large improvement in key performance parameters. Most people know it as
Moore's Law. The continuous improvement of microprocessors is largely due
to miniaturization of transistors. Advancements in microelectronics manufacturing
technology have enabled the size of a transistor to decrease by about a
factor of two every two years. Intel made the first microprocessor chip
commercially available in 1971—the 4004 contained 2,300 transistors.
Today's chips contain more than 2.6 billion transistors.
When I was involved with fusion research, I was often asked what motivated me to work on this difficult problem, even though I would probably never see a satisfactory solution in my lifetime. I didn't have to ponder this question very long. The yearly progress from the '70s into the '90s was exciting enough. I was fortunate to cut my scientific teeth on the challenging problem of fusion research. Such scientific endeavors need to be nurtured worldwide given the scale of investments required for frontier research, and the United States needs to reinvigorate its leadership role.
|Scientists studying the dynamics of molecular collisions would like to capture quantum mechanical effects without having to solve the sometimes impossibly complex Schrödinger equation. This challenge is the topic of The Journal of Chemical Physics' most recent Perspective article in the Spotlight Collections section. In a podcast on the JCP website, William H. Miller, professor emeritus of chemistry at the University of California at Berkeley, describes how semiclassical theory provides a systematic way of adding quantum coherence to classical molecular dynamics. Miller notes that while much of semiclassical theory was developed in the ‘60s and ‘70s, the last decade has seen its growing application to more complex molecular interactions. JCP's Spotlight Collections section features invited papers on current topics of interest to the physical chemistry research community, as well as audio interviews with researchers. The papers highlighted in the series are among the most downloaded papers from the JCP site.|
|Restricted Data" blog rare footage from a Cold War nuclear test that addresses this question directly. The footage of the March 17, 1953, "ANNIE" test has murky visuals, but crisp, unedited audio, unlike most nuclear test films (which are usually dubbed in post-production). With a good pair of headphones on, one can hear murmurs of soldiers and newsmen before the blast countdown starts. The camera "sees" the explosion about 30 seconds before the audible blast wave arrives, because the camera is 11 kilometers away from the explosion. As the fireball is rising, a sharp "bang" can be heard, followed by a long, thundering roar as the blast wave echoes off of the nearby mountains. The crowd can then be heard to shout out spontaneous expressions of awe. The footage is a rare example where the sound of the blast has not been edited to be simultaneous with the actual explosion, giving a more realistic impression of the on-the-ground experience.|
|Spring issue, 2012: "Why should honor societies ask their members to do anything beyond achieving good grades?" Outgoing Sigma Pi Sigma President Diane Jacobs of Eastern Michigan University poses this question in a special issue of Radiations magazine devoted to "Science and Service." The entire issue delves into the service mission of Sigma Pi Sigma, complementing the theme of the upcoming 2012 Quadrennial Physics Congress.|
|43rd International Physics Olympiad. So, how did these high-school students fare in their quest for gold? To find out, see AAPT's 2012 U.S. Physics Team webpage.|
July 28–August 1
Tuesday, July 31
July 29–August 2