10:30 a.m. Research Techniques Seminar - Curia II
Speaker: Daniel Holck, Durham University
Title: CHOUGH, the Canary-Hosted Upgrade for High-Order Adaptive Optics
2:30 Theoretical Physics Seminar - Curia II
Speaker: Hojin Yoo, University of Wisconsin, Madison
Title: Nanoshots from the Crab Pulsar and Schwinger Sparks
8 p.m. Fermilab Lecture Series - Auditorium
Speaker: Diandra Leslie-Pelecky
Title: The Science of Speed: Why Driving Fast is Harder Than You Think
Tickets: $7
Click here for NALCAL,
a weekly calendar with links to additional information.
Brian Greene welcomes the Internet to physics class with World Science U. Photo courtesy of World Science U
Professor, author and string-theorist-about-town Brian Greene wants to expand the ways we learn about science. Greene, the author of popular physics books such as The Elegant Universe and the host of several science specials on PBS, recently led the creation of a free online learning hub called World Science U.
The site offers video courses on topics such as special relativity and quantum mechanics. It is a spinoff of the World Science Festival, an annual event run by a nonprofit organization Greene founded in New York.
Greene says he's been thinking about digital education since the 1990s, when he moved from Cornell University to Columbia University but wanted to continue teaching his former students.
"I was doing videoconferenced courses way back then, when the technology really couldn't support all that we needed," Greene says. "And now there's a huge opportunity to leverage the technical prowess we have to create a new type of educational experience."
The challenge has been finding the resources to make the most use of the available tools, he says.
"It's expensive to make animations," Greene says. "It's hugely time-consuming to make computer-based interactive demonstrations. But if you're not just reaching 30 kids in your own classroom, when you're creating things that can reach hundreds of thousands of people, then the investment becomes worth it."
The World Science U site is currently populated with WSU's pilot offerings, including a short course and a longer, university-level course, plus more than 500 "Science Unplugged" clips, basic explainers with Greene candidly answering frequently asked scientific questions in about a minute or less each.
Some of the classes require no math knowledge at all; others require high-school-level calculus and physics.
The WSU website went live earlier this year. Since March, about 130,000 people have signed up to access the videos and courses, according to WSU's tally. And the total number of views for the "Science Unplugged" clips is just shy of 1 million.
WSU has worked with 10 institutions, both domestic and international, to offer college credit when an onsite instructor teaches a class using WSU material. These include Greene's own Columbia, as well as Duke University, the University of California, Santa Barbara, the University of Cape Town and others, says Kadi Hughes, special projects manager at World Science Festival.
Classes are taught in a "flipped" format, with the students watching videos of lectures as homework and then working through problem sets with the professor during class time.
Scientist John Stupak talks about the discovery of the Higgs boson. Did scientists find the Higgs boson predicted back in 1964 or did they find just one of a group of particles, with the others still to be found? View the video. Video: U.S. CMS
Photo of the Day
Luna moth
A luna moth settles on a wall outside the linac gallery. Photo: Kerbie Reader, AD
In the News
U.S. Energy Department to make researchers' papers free
From Science, Aug. 4, 2014
The U.S. Department of Energy (DOE) today unveiled its answer to a White House mandate to make the research papers it funds free for anyone to read: a Web portal that will link to full-text papers a year after they're published. Once researchers are up to speed and submitting their manuscripts, that will mean 20,000 to 30,000 new free papers a year on energy research, physics, and other scientific topics.
Although the plan will expand public access to papers, some onlookers aren't happy. That's because the papers will not reside in a central DOE database, but mostly on journal publishers' websites. Open-access advocates say that will limit what people can do with the papers.
It is the holiday season, when many scientists head off around the world to exotic locations, to give talks at conferences, to install and maintain their experiments, and, occasionally, to relax. So here are some of [Jon Butterworth's] favourite recent and not-so-recent physics-related snaps.
A: When the 3 and the 4 are in different directions.
Walk 3 miles due east, say, then 4 miles due north. You are not 7 miles from your starting point; you are 5 miles from your starting point.
To be fair, telling someone to go "3 miles due east" isn't the same as saying to go "3 miles." It also includes the direction "due east." The reason your final distance from the starting point is less than 7 miles is because you have a 90-degree angle between the two legs of your journey. On the other hand, were the two directions the same, then indeed you would be 7 miles from your starting point.
A similar thing can happen in the decay of subatomic particles. In the process of calculating the rate of the decay, we compute a thing called the amplitude, which has both a distance and a direction to it. The distance and direction are in an abstract mathematical space rather than on the surface of the Earth, but otherwise it is similar. If there are two ways or paths in which the decay can happen, we add the two amplitudes and take into account the angle between them.
For example, the Upsilon, Υ, can turn into a photon, which turns into a muon pair; that is one path. The Υ can also turn into a Z boson, which turns into a muon pair; that is another path. To add the two paths correctly, one has to allow for the angle between them in this abstract space. This effect is called interference.
Some of the differences between matter and antimatter are due to this effect; the angle between two amplitudes for two paths in the decay of a particle and the corresponding angle for the antiparticle can be different. As a result the sum of the two paths for the particle and the antiparticle are different.
The particle containing a charm quark and a down antiquark is called a D+ meson. It can decay to a kaon, K-, and a pair of pions, π+, through several different paths; two are shown in the figure. In the Standard Model though, all the amplitudes have the same direction, and they add up directly — there is no interference. Accordingly, the expectation is that the D+ meson and its antiparticle, the D-, should decay at the same rate. On the other hand, if there is new physics involved, the amplitudes might be in different directions. Then there could be interference and there could be a difference between decays of the particle and the antiparticle.
The
DZero collaboration has measured the difference (called the asymmetry) between the rate of this decay for the D+ and the D-. The result is that the asymmetry is -0.17 ± 0.17 percent. In other words, the asymmetry is indeed zero, allowing for the uncertainty in the measurement. The previous measurement, by the CLEO experiment, had an uncertainty of ± 0.98 percent, and so the DZero result is almost six times more precise. Even with this improved measurement, the Standard Model prediction that 3 + 4 = 7 holds up.
—Leo Bellantoni
Mark Williams of Indiana University is the primary analyst for this result.
The DZero collaboration welcomes these members, who will in the coming year ensure the highest quality of scientific output from DZero by serving as physics group conveners: Top, from left: Iain Bertram (Lancaster University, England), Regina Demina (Rochester University), Hengni Li (University of Virginia). Bottom, from left: Raphael Lopes de Sa (Fermilab), Jan Stark (LPSC, Université Joseph Fourier, Grenoble, France), Daria Zieminska (Indiana University, Bloomington).
Sunny
