Physicist Shou-Cheng Zhang has proposed a way to physically realize the magnetic monopole. In a paper published online in the January 29 issue of Science Express, Zhang and post-doctoral collaborator Xiao-Liang Qi predict the existence of a real-world material that acts as a magic mirror, in which the never-before-observed monopole appears as the image of an ordinary electron. If his prediction is confirmed by experiments, this could mean the opening of condensed matter as a new venue for observing the exotica of high-energy physics.
Archive for January, 2009
Watch an advertisement on a video screen in a mall, health club or grocery store and there’s a slim – but growing – chance the ad is watching you too.
Small cameras can now be embedded in the screen or hidden around it, tracking who looks at the screen and for how long. The makers of the tracking systems say the software can determine the viewer’s gender, approximate age range and, in some cases, ethnicity – and can change the ads accordingly.
Jerry O’Connell (Vern) had never really acted before – he had just one commercial under his belt. When he auditioned, he recognized Rob Reiner and said, “Aren’t you the guy on channel 5?” At the time, the local channel 5 had been airing reruns of All in the Family at the time and Jerry recognized Rob as Meathead.
(BTW, John Lennon’s cover of this song is pretty good)
I’ll link to this before the day of the big game this time.
Criminals have used telephones and mobile phones since they were invented. Drug smugglers use airplanes and boats, radios and satellite phones. Bank robbers have long used cars and motorcycles as getaway vehicles, and horses before then. I haven’t seen it talked about yet, but the Mumbai terrorists used boats as well. They also wore boots. They ate lunch at restaurants, drank bottled water, and breathed the air. Society survives all of this because the good uses of infrastructure far outweigh the bad uses, even though the good uses are – by and large – small and pedestrian and the bad uses are rare and spectacular. And while terrorism turns society’s very infrastructure against itself, we only harm ourselves by dismantling that infrastructure in response – just as we would if we banned cars because bank robbers used them too.
Cole slaw on hot dogs? Ugh.
[I]t has this to say about ketchup on hot dogs: “There are many reasons why one shouldn’t eat ketchup on a hot dog any hot dog.First, the National Hot Dog and Sausage Council’s Hot Dog Etiquette rules dictate that no one over 18 should ever eat ketchup on a hot dog. Ketchup is destructive of all that is right and just about a properly assembled hot dog since its sweetness and acidic taste overpowers food and disguises its true flavor.”
Yes, there is a National Hot Dog and Sausage Council, and they do have etiquette rules. I guess I’m an outlaw or a rebel, because I like ketchup. (Cole slaw is OK, but ketchup is taboo?) But the actual admonishment is “Don’t use ketchup on your hot dog after the age of 18.” I never eat 18-year-old hot dogs, though. That would just be weird.
How do you measure the properties of something that’s really hard to detect? It turns out that because of the wonderful usefulness of conservation laws, you can infer what you can’t easily see by finding as much as you can from what you can detect, and then figuring out what’s left over. Somewhat like detecting the invisible Bilbo Baggins by spotting his shadow. The original discovery of the neutrino, in fact, was due to the beta energy spectrum being continuous, which only makes sense if there is a third particle being emitted, and conservation of charge dictated that the neutrino be neutral.
The proposed experiment is to trap a large amount of tritium at very low temperatures (meaning that the atoms are very nearly stationary), and look at the recoil of the helium that’s produced. When the tritium decays into helium, one of two things happens: either the helium captures the electron on the way out, becoming neutral helium, in which case the atom recoils in a direction opposite the direction of the neutrino; or the electron and neutrino both escape, in which case the helium ion recoils in a direction that depends on the exit direction of both the electron and the neutrino. In either case, the helium is moving, and if everything is done right, it’s moving considerably faster than the trapped tritium atoms.
To measure the neutrino mass, then, all you need to do is detect the helium and measure both the magnitude and direction of its velocity. If the electron was captured, that alone is enough to let you find the momentum (and thus mass) of the neutrino; if the electron escaped, you need to determine its velocity as well, but again, you can calculate the momentum of the neutrino.
Unfortunately the link to the Physics World article doesn’t work work for me, since it’s subscription-only. Fortunately Chad also provides a link to the ArXiv proposal
This sounds very familiar to me, since measuring the recoil from beta decay is the experiment I worked on as postdoc at TRIUMF. The idea in that experiment (for a metastable K-38 atom decaying to Ar-38, both with zero-spin nuclei) is that the parent decays and the daughter is no longer held in the trap, so the escaping beta and daughter can be detected. If the beta and Ar have traveled in opposite directions, it means the neutrino must be either counter-propagating or co-propagating with the beta, since there has been no change in the spin of the nucleus; this has implications for the type of weak interaction that has taken place (scalar or vector, i.e. does the W-boson have any spin) but each case has a different implication for the amount of recoil the Ar atom will have, and this shows up in the time-of-flight. The standard model predicts that, in this case, the beta and the neutrino will be emitted in the same direction. Here’s a PRL and ArXiv for that experiment.
In one approach of the Tritium experiment they’re banking on the electron being captured, so you remove the three-body complication, and having a metastable helium recoil to detect (rather than neutral Helium, which is a lot harder), but adding the complication of photons to detect as the He decays into that metastable state. The other approach involves the three-body momentum, in which the emitted beta is not captured. This allows them to detect a Helium ion, which is much easier to do.
The benefits of teaching the statistics of risk analysis.
“You can tick off story after story that’s probably interesting to the people it happened to, but not statistically unusual at all. There was a recent story about a family in Gloucestershire with three children all born on January 29. We were contacted by a journalist and asked what are the chances of this happening.
“The chances are about one in 135,000, or seven in a million. But there are a million families with three children in the UK. So it’s almost certain that this family is not unique and when the story went online, someone wrote in and said, ‘I was born on the same day as my two brothers’.”
The unfounded scare over the MMR vaccine, and outlandish claims of success for alternative medicines, were prime examples.“One must think all the time of what is not being reported – the dog that didn’t bark. When we see a hole-in-one video on YouTube we are sensible enough to know that this has been selected out of millions of shots that missed. We need to think the same way every time we hear of someone claiming that some new treatment has cured them.”
To test whether I was being paranoid, I ran a little experiment. On a sunny Saturday, I spotted a woman in Golden Gate Park taking a photo with a 3G iPhone. Because iPhones embed geodata into photos that users upload to Flickr or Picasa, iPhone shots can be automatically placed on a map. At home I searched the Flickr map, and score—a shot from today. I clicked through to the user’s photostream and determined it was the woman I had seen earlier. After adjusting the settings so that only her shots appeared on the map, I saw a cluster of images in one location. Clicking on them revealed photos of an apartment interior—a bedroom, a kitchen, a filthy living room. Now I know where she lives.
I am writing to request that you IMMEDIATELY contact your elected
representatives and let them know that the proposed Congressional
economic stimulus package must include a strong investment in
scientific infrastructure to ensure the future competitiveness of
our country. We also request that you contact House Speaker Nancy
Pelosi to thank her for her tremendous efforts in ensuring that
science infrastructure investments were included in the House
stimulus package, formally known as the .American Recovery and
Reinvestment Act of 2009.. You can make these contacts quickly
and easily at:
There, you will find pre-written messages to your Senators and
Speaker Pelosi. You may send these letters as they are, modify them,
or write your own. While individualizing your letter is not
essential, please at least make minor edits to the subject line
and the first line of the text of each email so that these emails
are more individualized. (See webpage pointers below for further
As you may be aware, the U.S. Congress is currently formulating a
stimulus package to help spur the recovery of our economy. In
addition to the tax cuts in the draft packages being discussed,
the packages include a number of infrastructure investments that
would create millions of jobs.
APS has actively participated in this process by providing the
incoming Obama Administration, and the leadership in the House and
the Senate, with recommendations for investments in scientific
infrastructure that would create more than 100,000 direct and
indirect jobs. The investments we proposed are principally in
infrastructure in our national laboratories and universities, high
performance computing, in procurements of scientific instruments
and material for projects such as ITER, and in creation of jobs for
young investigators at our universities to ensure that they have a
place to go during these trying economic times. As a result of our
efforts, many of our recommendations were used by the House and
Senate in formulating their proposed stimulus packages.
On January 15th, the leadership of the House of Representatives
proposed a bill that would give a significant boost to science
infrastructure, including allocating $2 billion for the Department
of Energy Office of Science (OS), $2.5 billion for the National
Science Foundation (NSF), $500 million for the National Institute
of Standards and Technology (NIST) and $100 million for advanced
computing. On January 23rd, the Chairman of the Senate
Appropriations Committee released a summary of a proposed Senate
stimulus package. Unfortunately, the announcement did not offer
many details about how much funding science would receive in that
package. However, we are receiving troubling signs that science
may not receive the same levels of funding as in the House package
and would even, in some scenarios, be cut or even eliminated. We
are therefore urging the Senate to follow the House lead in helping
to ensure American competitiveness in the 21st century by making
critically needed infrastructure investments.
The attached letters would 1) thank House Speaker Pelosi for her
support of science and 2) request that the Senate follows the House
by including a robust amount of funding for scientific
(1) While individualizing your letter is not essential, we ask that
you make minor edits to the subject line and the first line of
the text of each email.
(2) If you are a government employee, please do not use government
resources to send a communication.
(3) Your browser will take you to a page where you will enter your
name and address.
(4) After entering your address, click the .Edit/Send Email button..
A window with an individual email message to the four offices will
appear. Click .Send Emails. to transmit the communication.
(5) Electronic submission is preferred.