Our Students Visit and Observe at the Green Bank Observatory

Being able to breathe a few steps away from the largest steerable thing on the surface of Earth is something an astronomy minor would not say no to, especially if that thing is a telescope which has the power to answer mankind's biggest questions.

We are talking here about the Robert C. Bird Green Bank Telescope, the site of which (The Green Bank Observatory, or GBO) our astronomy minors had the chance to visit and explore.     Eighteen of our students were accompanied by four faculty members for an overnight trip there, where they got the chance to observe with GBO's 40-foot teaching telescope and participate in quite a number of other educational programs.

Overall, the experience seemed to be overwhelmingly positive: one might not get the chance to see so many smiles and hear "wow"s from physics, computer science, or engineering majors, all while learning about the our host galaxy, Milky Way, through their own observations of Hydrogen emission.

Far away from hot O and B-type stars, the hydrogen in space is in the ground (i.e., lowest energy) state.   However, when the spin of the electron flips from being parallel to anti-parallel with the spin of the proton, there is a tiny energy difference that is emitted at the wavelength of 21 cm (or a frequency of 1420.4 MHz).   While a hydrogen atom can wait on average a few million years before it undergoes this transition (YES, it is this rare!), the large amount of hydrogen gas makes this particular emission one of the most prominent and easiest to detect with radio telescopes.

The 40-foot spectrometer allows us to detect radio waves from this particular transition by
blocking (filtering) out all of the waves but the ones coming at this exact frequency.  This 21-cm line radiation provides the best way to map the structure of the Galaxy (note: for astronomers, Milky Way is the only galaxy with capital "G").

Here is an example of detection of (the center of the) Milky Way's emission at 21 cm with the 40-foot telescope's spectrometer (sorry folks! no pic from there). The red line is a calibration measure, while the black line records the data, i.e., the intensity (in Jansky units) as a function of frequency.  The two  strong peaks at the left side of the spectrum show detection of HI at two different frequencies: the strongest peak is located at 1419.5 MHz, and the other at 1485 MHz, depicting two different clouds of Hydrogen emitting the 21-cm transition that is redshfited (smaller frequency, or longer wavelength), implying that the detected Hydrogen is moving away from us (while rotating in the disk of the Galaxy).   The peak at the far right depicts an artificially created signal of 500 Jy, for calibration purposes.

Multiple data sets from eight groups of students, acquired during the night, were collectively analyzed the next morning.   After not much debate, there was a pretty good agreement that the data shows strong evidence that Milky Way has the shape of a flat disk, that is rotating counterclockwise.

Here are some of the students' thoughts about this trip, with some cool, funny, or downright amazing things they have learnt:

* Mary Ogborn & Ebony Williams (physics majors):  This trip really illustrated aspects of radio astronomy that I wasn’t aware of before. Although I was aware of radio interference, I was not aware of how sensitive these telescopes could be to various sources [...] The control room was also impressive, as it was copper-insulated, in order to keep in the radio waves coming from all the computers and machines. [...] it was interesting to step into the past and see how the original radio astronomers operated these huge telescopes. I can’t imagine having to manually dial in the declinations, change the frequency every second by pushing the mark button, and having the chart reader draw out the peaks without any other form of labelling. [...] I now understand how observatories in the past would hire people to be ‘computers’ before the advent of computers.

*Ryan Ferrell (physics major):  I did not expect to be able to extract this much information from the data which made me appreciate how much information can be brought out of even just a little data.[...] I learned was how many common things cause radio interference. I knew previously that most electronics caused radio interference, however I did not know that signals from modern electronics are a billion times stronger than the radio waves that the GBT was measuring from the Milky Way. [...] I never knew the GBT was the largest radio telescope in the world or that the Drake Equation had been thought of there. [...] I was very surprised to find the control center so close and surrounded in a giant Faraday Box. 


* Tanna Walters (engineering major) & Brandon O'Neal (physics major):  This trip to Greenbank Observatory has taught us a good bit about the actual ways in which the data is collected and how the hardware works.  GBT actually has a clam-shaped dish and an arm that is off-center that collects the radio waves. The purpose for this is to allow for the collection of more radio waves as opposed to parabolic telescopes that have the receiver in the middle of the dish, blocking a significant portion of the incoming radio waves.   [...] we learned just how sensitive the telescopes are to interference (RFI). Even taking a picture with our phones could interfere and ruin astronomers’ data all over the world. 

In the control room of the GBT

* Tom Gagne (computer science major) & Kris Pickens (physics major):  We learned the remarkable fact that if a cell phone were placed as far away as Mars, it would still outshine the brightest distant radio sources by several orders of magnitude.  So we had to turn them off when out among the telescopes. We also learned that a shipbuilding company built one of the telescopes and put an enormous ball-bearing in it. The ball-bearing was so large that the bridges had to be fortified along the path of the train that took it there. 

* Cameron Kelahan (computer science major):  For the first time, I was able to operate a radio telescope and perform radio astronomy. I learned how to operate a 40 foot radio telescope, the equipment that goes along with it, the meaning and importance behind the 21 cm line, and how the shape of the Milky Way was originally discovered. I also got an idea of what it may be like to work at an observatory from talking with [GBT operator].  His job seems very interesting and also challenging! 12 hour shifts are something one can get used to, but there is also a lot of responsibility that goes into operating a MASSIVE TELESCOPE!  The overall experience [...] allowed me to strengthen friendships with classmates and possibly future colleagues while learning with them about something we all have a passion for.  

Demystifying the Expert: Dr. Kendra Letchworth-Weaver

To introduce the public to science in a combination of comedy and education, Dr. Anca Constantin and Dr. Klebert Feitosa host the event Demystifying the Expert. The program brings together a guest speaker, who is an expert in their field of science, and comedians from JMU’s very own New & Improv’d, who attempt to “demystify the expert.” Questions, games, trivia and improvised skits all contribute to the fun as the audience learns about the expert’s work. Podcasts for previous Demystifying the Expert events can be found here on SoundCloud!

            Kicking off the spring Demystifying series on February 28, 2018, Drs. Constantin and Feitosa and JMU’s New & Improv’d hosted Dr. Kendra Letchworth-Weaver (who typically goes by Dr. Weaver) from the Department of Physics and Astronomy.  She completed her Bachelor of Science in physics at the College of William and Mary in 2007, and went on to pursue her Doctorate in physics at Cornell University in 2015.  After this, she worked at Argonne National Laboratory in Illinois, and is now a first year assistant professor at JMU. 

The members of JMU’s New and Imrpov’d who participated in the event were: Caroline Buddendorf, a sophomore theatre major whose favorite thing about theater is how active she gets to be, Ethan Shultze, a junior SMAD major who really hates The Incredibles II, and Noah Etka, a junior ISAT major who’s really into NASA. 

            The night kicked off with the twenty questions game, where each comedian took turns asking Dr. Weaver yes or no type questions to help them deduce what area of science she studies.  Our comedians went on a rocky start, but their questions were moving them towards the area of chemistry.  However, when asked if she studied chemistry, Dr. Weaver was only able to say that she did so half-way.  They did narrow down the field to something with materials chemistry, and in the end, our comedians deduced that Dr. Weaver worked in materials physics.

            After carefully dancing around this field, Dr. Weaver explained to everyone just what made materials physics different from materials chemistry and its applications with her elevator pitch.  She told us how, while some areas of both disciplines focus on characteristics of materials themselves, her work focused more on the interfaces between solids and liquids.  In particular, what makes these interfaces interesting to her is how they play with the properties of both solids and liquids with wildly different interactions in statistical mechanics, electricity and magnetism, and quantum mechanics, all of which give a potential for many different possibilities of material property expression.  And how Dr. Weaver studies these interfaces is through the use of computer simulations, where she’ll put in some descriptions of a material that she could manufacture and then have the computer then produce information that she can extrapolate to determine what qualities this new molecule will exhibit.  Her work applies to renewable energy applications, in particular like batteries, and she also explained that cell phone fires due to poor interface design.

            The second game was the headliner game, during which the comedians guess words that complete titles of articles that relate to Dr. Weaver’s research.  From the get-go, our comedians were thrown a curveball, as the first word was actually cats!  From the headline provided by the Washington Post, “Cats are both solid and liquid, according to science,” for their propensity to have a defined shape when they want, but also occupy the space of containers that they were put into.  Dr. Weaver had a quip that showed us how these related to work, noting that since cats did this, they were very much like the nanoparticles that she works with.  The second word had a more obvious link to Dr. Weaver’s work, and was water.  As it happens, companies are working on developing materials that can act like sponges to extract water from the air and release it on demand, helping to solve a water scarcity we face.  The final word, supercomputer, gave us harrowing visions of a potential Terminator or Blade Runner scenario, with the headline stating that IBM’s new supercomputer is not only capable of taking orders, but also arguing against them!  As Dr. Weaver explained, supercomputers are being used in order to grow new knowledge out of current data and make their own decisions with neural networks, and this could be applied to materials data as well.  It remains to see if we will reach the technological singularity, but as of current, we aren’t quite there yet.

            

Next was the jargon game during which the comedians guess what certain acronyms or terms mean in the expert’s field. Here, the comedians learned about DFT, density functional theory, which is a way to approximate how packed electrons are in a certain material, and the reason for this is because if we know how packed they are, we can start to discover some more properties of how they will interact with each other and with external materials.  The second group of words showed us all how scientists have some fun in their labs, with the words being opium and pot!  Our comedians were able to deduce after some giggles that pot meant potential, like electrical potentials, but opium was harder – Dr. Weaver explained that Opium was a name for what is called an optimized pseudopotential generating code, which creates a stand-in electrical potential based off of the electrons surrounding an atom. 

            Finally, the audience got to learn more about Dr. Weaver outside of her work as a computational materials physicist with the two truths and a lie game.  First, we learned that not only is Dr. Weaver a talented physicist, but she also used to be very involved with the performing arts as well!  She participated in theatre in high school, and also did a lot of tap dance before her college years.  Not believing that Dr. Weaver could tap dance, our comedians dared her to prove it, and much to everyone’s delight, she did!  In the second round, we learned that Dr. Weaver’s path to being a computational physicist was lined by a broken spectrometer (a very useful and expensive tool in many science laboratories) that she had dropped, and that her old babysitter ended up becoming someone she would publish papers with!

            The final planned event of the night was the improvised skit with physics-themed quotes from pop culture like Alice and Wonderland and the Warriors novel series by Erin Hunter, with a new title “The Game of the Fortune Cookie!”  In a first for Demystifying history, Dr. Weaver joined our comedians in the troupe, and what a skit it was!  Our group were engaged in the office hours of Professor Ethan’s Computer Violence 101 class, and entered a theological discussion of the toxic nature of water, the Old Testament divinity of computers, and a strange venture into a live student burial to ascend to a higher plane of existence.  You can view some of this wonderful impromptu using this link to access our Facebook page!

            We’d like to thank everyone for a great start to Demystifying the Expert’s spring run, and a very warm welcome to Dr. Weaver at James Madison University!  To hear more about future Demystifying shows and when podcasts of our previous shows are released, be sure to follow our Facebook page.  We'll see you in the fall!