We look at results of the Great Physics Bake-Off, sneak preview the next Department Speaker Series event, and remind you of the upcoming Society of Physics Students graduate school panel event!
Contents
CHAIR’S WEEKLY MESSAGE
“Anticipation”
The discovery of the Higgs particle in 2012 was exciting. Why? It was a long-anticipated event with cosmic implications regarding the origin of mass and the nature of the fundamental description of the universe. The discovery of this particle set in motion a multi-decadal program of measurement.
The direct observation of gravitational waves in 2016 was exciting for the same reason. After 100 years, we as a species had finally achieved the technological prowess to literally watch space and time themselves wobble. The discovery quickly turned into a tool for measuring insane things like the properties of colliding black holes and limits on the particle nature of gravity itself.
Science is done by people, and being people we like the anticipation of new discoveries or ideas. We like to be part of something big, whether we are directly involved in the observation or just part of the audience getting to hear about it for the very first time.
Here’s another one, though at first glance it might not tickle your fancy: the magnetic dipole moment of the muon.
The what now?
Let’s unpack that. “Muons” are heavy cousins of the more familiar electron. Where do you find them? Not in atoms, but as the by-product (for example) of particle collisions. Cosmic rays slamming into the upper atmosphere of the Earth create huge sprays – cosmic ray showers – of new particles. Some of them are unstable and decay, and some of those decay products are muons. 200 times heavier than the electron, muons are unstable. Thanks to special relativity, they live long enough to travel from the upper atmosphere to the surface of the Earth. In fact, you can visit the basement of Fondren Science Building and view an instrument that detects their presence. It’s across from the biology teaching labs in the basement level, a vertical black cylinder hooked up to a computer behind a glass case. You can even see the current “muon weather conditions” on the web which are derived from the data taken by this muon detector.
Muons, just like their cousin electrons, have a small amount of electric charge. Because they also possess of a property called “spin,” they should act like little loops of electric current … which means they act like teeny tiny electromagnets. Just like a refrigerator magnet, they have something called a “dipole moment” – a property that defines how magnetic they are given their charge and spin and how they respond to the application of an external magnetic field. In fact, the modern theory of nature at its fundamental scale – the Standard Model of Particle Physics – makes some very definite and precise predictions about just how big this bar magnet property should be.
But what is amazing about this little property of this tiny particle is that if there are previously undiscovered particles out their in the universe they can act to upset the muon’s dipole moment … they could change its observed value. So we can calculate this feature of nature, and we can observe it … and we can see if those two numbers agree.
This may not sound like a big deal, but it’s a big deal. The reason is two-fold: we have the ability to both make precise calculations and measure a subtle property of nature at a comparable or better level than the calculation; and previous observations of the muon dipole moment have turned up a small surprise. When you compare the two numbers, even using calculations from as recently at 2020, there is a slight disagreement between them. It’s not enough to be definitive – definitely consistent or inconsistent – but it’s a tempting tension between experiment and theory. What this cries out for, of course, is more measurement and more calculation to understand if the tension is real or just a statistical (or, worse, measurement) fluke.
If you’ve ever taken an introductory physics lab class, where you know you’re supposed to get one number but your experiment finds a disagreement with expectation, you’ve experienced the thrill of the following thought: am I wrong or is the accepted description of nature wrong? For introductory physics labs, usually the problem is you; sometimes, it’s the equipment that is wrong, even when you did everything right. Almost never is it that you have discovered a mistake in our understanding of nature. That is because intro physics labs exercise practice in well inside the boundaries of human understanding. The observation and calculation of the muon dipole magnetic moment operates very close to the margins of human understanding, and there real discoveries may lie.
That’s where April 7 comes in. The famed Muon g-2 Experiment, relocated to the Fermi National Accelerator Laboratory a few years ago, will announce first results from its latest improved observing run on April 7. A lot of excitement is building in the community. What will they announce? Will it be a big reveal, or just a status report showing they have been able to conduct the experiment after relocating it? Probably it’s the former, but it might just be the latter. If it’s a reveal, what will the reveal be? Will it be more tension … maybe even definitive disagreement? Or will it be consensus between calculation and measurement? Or maybe they will just show some nice calibration results … but probably not. But maybe?
We just have to stay tuned and see what April 7 brings!
This week, we look at some fun things going on in the department. We look at the outcome of “The Great Physics Bake-Off” as published in the CERN Courier, and we remind everyone – mostly students – of the upcoming Society of Physics Students graduate school panel event. RSVP today! Finally, we take a peek at the upcoming Department Speaker Series event on Monday, March 22.
And we wait anxiously for April 7!
Sincerely,
Stephen Jacob Sekula Chair, Department of Physics |
DEPARTMENT VIEWS
The CERN Courier Profiles the Great Physics Bake-Off!
(reprinted from the March/April edition of “The CERN Courier” magazine, edited for clarity and American English)
Cakes were baked, votes were counted, and United Kingdom student Maddie Watkins beat off stiff competition from a baker’s dozen of high-energy physicists to be crowned star baker of the inaugural #GreatPhysicsBakeOff for her depiction of Archimedes’ eureka moment. “We had gravitational-lensing gateaux, stellar-nucleosynthesis sponge and recreations of the International Space Station, the NASA Space Shuttle and Fermilab’s iconic Wilson Hall,” says organizer Katharine Leney (Southern Methodist University, @PhysicsCakes) of the January competition, which took place on social media. “We’re still wondering if you lose weight eating antiparticle cupcakes,” adds co-organizer Steph Hills (Science and Technology Facilities Council).
Prof. Bob Kehoe (SMU) speaks on Cosmic Distances and the Geometry of the Universe
The next event of the Spring 2021 Department Speaker Series is on Monday, March 22, at 4pm. We welcome our own Prof. Bob Kehoe (SMU) to speak about cosmic distance measurements. These measurements hold the key to unraveling a wide array of astrophysical and cosmological questions. Transient stellar phenomena have provided critical means from which to obtain cosmic distances and probe the structure and history of the universe. Prof. Kehoe will review results from experiments, including measurements from the DESI experiment and SMU’s ROTSE-IIIb telescope, and discuss current efforts to test and identify alternative approaches.
Miss a Colloquium or Seminar? Don’t Panic … They’re Recorded!
You can catch up on the Spring 2021 (and Fall 2020!) Physics Speaker Series by checking out your favorite subjects from archives! Explore supermassive black holes, the new Electron-Ion Collider planned for construction in the U.S., new ideas about dark matter or other novel particles or forces, or the basic research needs for future scientific instrumentation in HEP … all from your personal devices! Enjoy our archive of the Physics Speaker Series Talks below.
FACULTY NEWS
If you have something to share please feel free to send it along. Stories of your activities in research, the classroom, and beyond are very welcome!
STAFF NEWS
Staff In-Office Schedule for Week of March 22
The in-office staff schedule for the week of March 22 is nominally as follows:
- Monday: Lacey
- Tuesday: Michele
- Wednesday: Lacey
- Thursday: Michele
- Friday: Lacey
Of course, both are always available on Microsoft Teams, by Email, or by phone.
Full staff in-office calendar for March:
STUDENT NEWS
If you have something to share please feel free to send it along. Stories of students in research, the classroom, internships or fellowships, awards, etc. are very welcome!
Reminder: Next Society of Physics Students Event: Graduate School Workshop and Graduate Student Q&A on March 24
SMU’s Society of Physics Students is hosting a workshop presentation on the process of applying to graduate school in physics and the basic information around graduate school in physics. The event will take place on Wednesday March 24th at 6:30 PM.
The SPS encourages any undergraduate students who are interested in continuing into physics graduate school to join and learn more about physics graduate program opportunities. The event will feature several current SMU physics graduate students who will share their experiences in graduate school and answer questions from students.
Please RSVP for the event using the link in the flyer (also shared below). The organizers will send out Zoom connection information only to registrants. If you are an SMU student, please register using your SMU email address.
RSVP link: https://forms.gle/u9ueSJoRJ4gCWjGd7
ALUMNI NEWS
If you are an alum of the doctoral, masters, majors or minor programs in Physics at SMU, or have worked in our program as a post-doctoral researcher, and wish to share news with the community, please send your story to the Physics Department and we’ll work with you to get it included in a future edition.
THE BACK PAGE
How to Watch the Muon g-2 Announcement on April 7
You can find the press release announcing the Muon g-2 April 7 public event on the collaboration’s website. The collaboration promises to make the streaming video connection information available on that same website, closer to the event itself.
