Raptor Interplanetary Transport Engine

Why has SpaceX chosen methane to fuel its Raptor rocket engine? Robert Goddard’s first rockets used liquid oxygen Oor LOX and gasoline. The Saturn V moon rocket first stage used LOX and refined kerosene. The Saturn V second stage used LOX and hydrogen that burn to water in my favorite chemical reaction, 2H2 + O2 → 2H2O. Methane CH4, gasoline (a C7H16 to C11H24 blend), and kerosene (a C12H26 to C15H32 blend) are all linear hydrocarbons CnH2n+2 that burn to carbon dioxide and water (and residual carbon if the burning is incomplete).

Hydrolox is most efficient but requires huge tanks (due to hydrogen’s low density), which must be cooled to just a few degrees above absolute zero. Kerolox is less efficient but needs smaller tanks (due to kerosene’s high density), which can be at normal temperature and pressure. Methalox is a compromise. But unlike kerolox, methalox does not coke the engines with residual carbon that makes reuse more difficult. Also, to improve efficiency, SpaceX will densify the oxygen and methane by cooling them to just above their freezing points (rather than just below their boiling points).

However, the real advantage of methalox is that it can be manufactured from carbon dioxide and water by CO2 + 2H2O → CH4 + 2O2 on Mars.

Raptor rocket engine powered by supercooled liquid methane and oxygen or methalox

Raptor rocket engine powered by supercooled liquid methane and oxygen or methalox

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Maggie Lankford `16: National Finalist for Top Award in Undergraduate Physics Research!

I’m excited to report that Maggie Lankford, who graduated summa cum laude this year as a Wooster physics major, has been selected as a finalist for the American Physical Society’s LeRoy Apker Award– known as the preeminent honor for undergraduate physics research in the United States!  Maggie received this recognition for work reported in her Senior Independent Study thesis, entitled “The Production and Manipulation of Nonseparable Spin-Orbit Modes of Light Under Hong-Ou-Mandel Interference Conditions.”


Maggie with the apparatus she helped to design and build.

In short, Maggie built a device which produced novel structures of light (photons), in which two of the light’s degrees of freedom–polarization and spatial intensity distribution–could not be characterized or described without direct reference to one another.  Her thesis also demonstrated that this setup is capable of imparting such structures onto pairs of photons that are simultaneously exhibiting quantum interference, which is a key component in a number of quantum computing protocols.  If you’d like to know more, just click this link to our open-access publication, which recently appeared in the research journal Optics Express. 


Maggie presented her work last June at a poster session at the Quantum Electronics and Laser Science conference in San Jose, CA (see photo above).  Then in August, she gave an oral presentation on her research before the Apker Award selection committee in Washington, D.C., along with the six other finalists from other institutions including MIT, Kenyon and Dartmouth.  Two winners – one from a Ph.D. granting institution and one from a non-Ph.D. granting institution – will be announced in October.  She is the third Wooster physics graduate to be named as an Apker finalist.

Maggie’s Apker recognition has been reported by the American Physical Society Newsletter and Wooster News.  A quote from Maggie from one of these articles sums up her research nicely: “We developed this new apparatus … made a mathematical model of it, then built it, then used it to generate this new type of pattern of light that can be used for information processing or for communicating between two parties.”

This is what I love about being a tabletop experimental physicist– a field in which it is still possible for a small group of scientists to hatch an original idea, work out the relevant predictions from first principles, design and build the associated experiment, and carry it on to completion!


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Summer Research Program 2016

We had a fun and productive summer research program again this summer!  We were fortunate last fall to be awarded an REU site grant from the National Science Foundation, so that enabled us to enlarge the program from the size that it has been for the last few years.  We have a very long history of summer research, but this was one of our biggest programs ever, with five faculty and 14 students!


Figuring out the size of the solar system at BWISER

Figuring out the size of the solar system at BWISER

The outreach program for BWISER is always a hit with both the BWISER campers and the summer research students.  The group doing the “Lightyears in the Movies” demo had the students put on caps with various solar system objects (the sun, the moon, Pluto, etc) and try to stand at scale distances apart.  We have a complicated program where the BWISER campers rotate through seven different demonstrations, learning about light and sound waves, and are completely wowed by the end of two hours.


Ice cream social for all summer research students

Ice cream social for all summer research students


In addition to our weekly picnics, and infamous pie festival, we also had a delicious ice cream social for not just the REU students but all the summer research students on campus.  I’m pretty sure the professors had as much fun dishing up the ice cream as possible.



The finale for the program was the poster session where all the REU students presented their work to family, friends, and colleagues.  Due to the size of the program, we held the poster session upstairs in the Taylor atrium for the first time, and it was a lovely sunlit space for the event.


We had a great turn-out with lots of interested people asking questions about the research each of the students did.  It never fails to amaze me how much the students learn and accomplish during the 10 week program!

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First Deep Space Walk

In 1971 during Apollo 15’s return from Earth’s moon, astronaut Al Worden performed the first deep space walk nearly 200 000 miles from Earth to recover external service module film canisters that had mapped the lunar surface. Worden was able to pause and orient himself to simultaneously see both Earth and moon as disks against the blackness of space, the first human to do so. Looking back toward the command module, he saw astronaut Jim Irwin waiting in the open hatch against the colossal moon — but did not have a camera to record the breathtaking view, the iconic photograph that never was. Fortunately, back on Earth Worden was able to collaborate with artist Pierre Mion for National Geographic magazine to reconstruct the vista. Deep space walks may occur again next decade from NASA’s Orion spacecraft.

The first deep space walk, by Al Worden reflected in Jim Irwin's visor, during Apollo 15 in 1971, as painted by Pierre Mion

The first deep space walk, by Al Worden reflected in Jim Irwin’s visor, during 1971’s Apollo 15 mission to the moon, as painted by Pierre Mion for National Geographic magazine

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Found in a Box

I recently ascended to Czar of Physics. (Oops — I mistyped Chair and it autocompleted to Czar!) It’s not my first year as Czar, but this time, during the handover from the previous Czar, I inherited a small cardboard box. Inside I found a stack of old Wooster ΣΠΣ membership cards. (ΣΠΣ is Greek for SPS and signifies the SPS honor society; SPS is an initialism for the Society of Physics Students.) The two cards in the accompanying photograph are especially interesting. Karl modestly lists his position as president of the Massachusetts Institute of Technology. His brother Arthur reports being a professor at the University of Chicago but doesn’t mention the Nobel Prize he won four years earlier for scattering light from electrons. The Compton effect helped convince physicists of the wave-particle duality of matter and subsume classical mechanics in quantum mechanics.

Wooster Compton brothers sigma pi sigma membership cards

Some Wooster Sigma Pi Sigma membership cards; click for a larger view

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If Apple Designed Buildings…

When Steve Jobs phoned Pritzker Prize architect Norman Foster in 2009 for help designing Apple’s new Cupertino California campus, he said “Don’t think of me as your client; think of me as one of your team”. The design that evolved from that collaboration features an unprecedented annular building over a mile in circumference enclosing an orchard and park. The roof is covered with solar panels and the basement is underground parking for thousands of cars. The inner and outer walls are giant uninterrupted curved panes of glass. From inside, one can always see outside to the park-like surroundings.  A thousand bikes help people get around the campus.

The combined ceiling-and-floor “void slabs” are factory-made hollow polished concrete forms. The awnings block the direct rays of the high summer sun for cooling but transmit the direct rays of the low winter sun for heating. Mirrored undersides (added after the cross sectional illustration below was created) provide indirect illumination. The new campus is powered by 100% renewable energy, and the HVAC system is only for backup. Apple Campus 2 opens in early 2017.

Apple Campus 2 partial cross section

Apple Campus 2 main building partial cross section illustrates over a mile of uninterrupted curved glass with awnings and empty spaces to passively control natural light and temperature.

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Commencement Weekend

It was a beautiful weekend for Commencement this year.  With the record number of majors (20 physics majors!!) graduating, we tried hard to get some group photos, but of course we knew it was hopeless to get absolutely everyone looking into a camera all at the same time.


Sunday of commencement weekend, we were able to gather almost half the class for a nice photo in front of Kauke Arch.  It was a little chilly at that point!

Faculty marshals begin leading the graduates through the lines of faculty and through Kauke Arch

Faculty marshals begin leading the graduates through the lines of faculty and through Kauke Arch

Monday was also slightly chilly at the start of commencement, but (speaking from experience), slightly chilly is definitely better than too warm!

One of my favorite parts of commencement is when the students precess through the lines of faculty as they walk through Kauke Arch on their way to the ceremony.  We faculty applaud the students as they walk through, and it’s a nice opportunity to congratulate individual students, if you spot them as they walk past.

The commencement ceremony was quite nice this year, with very good student speeches and a nice address from President Nugent.  And, it really kept moving, which is always good!

Many graduates and faculty!

Many graduates and faculty!

Yash, Ziyi, Maggie, Catherine, and Carlos

Yash, Ziyi, Maggie, Catherine, and Carlos

Woo Women in Physics!

Woo Women in Physics!





Congratulations, Wooster Physics Graduates of 2016!

(And if you have better pics you want me to add here — please just send them!)



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Singing in the Wind

Wires suspended above our streets are a late 19th century technology stubbornly persisting into the 21st century. They can hum in a breeze. A wire disturbs the air flow by shedding eddies alternately up and down, sometimes fast enough to be heard as a musical note. The wire’s vibration can enhance the sound’s volume and persistence.

The animation below shows a section of a wire shedding vortices and oscillating transversely to the wind. Saturation indicates wind speed (with white least), and hues indicate wind direction (with cyan rightward), like the polar plot legend. The simulation is an example of desktop computational fluid dynamics, a trans-generational collaboration between the senior thesis of Danielle Shepherd’14 and the junior thesis of Dylan Hamilton’17. Until recently, such simulations have required supercomputers.

Cross section of a wire shedding vortices and oscillating in the wind. Desktop computational fluid dynamics by Danielle Shepherd'14 and Dylan Hamilton'17 Saturation indicates wind speed (with white least); hues indicate wind direction

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April Whirlwind – Part 2!

In addition to the outreach events in April, we also had a lot going on to finish up Senior IS — the senior research project or thesis that all Wooster students complete. You might think that IS Monday is the end of IS, but after handing the thesis in, students also defend their thesis in an oral exam.
In the physics department, we ask the student to prepare a 20 minute presentation summarizing the key points of their IS project, and then after that the advisor, 2nd reader, and any other physics faculty able to attend ask questions.  Since we advised a record 17 IS theses this year, it was pretty challenging just to get all of these oral defenses scheduled before the IS symposium!

I know the IS defense is stressful for the students, but as a faculty member, it is one of my favorite parts of the IS process.  It isn’t that we are only asking questions that we know the answer to — rather the student is now the expert and we are really asking their opinion or perspective on a problem.  Because of the way that the defense requires that we pull together information from a lot of sources, and because we have multiple perspectives on the problem, it is often a time when we figure out something new, which is tremendously satisfying.

Popi smiles with relief at being done with the defense!

Popi smiles with relief at being done with the defense!


After the question period, the student steps out for a few moments, the faculty confer, and then we invite the student back in to tell them whether they have officially passed their Senior IS.  Then, we have a nice ceremony of the advisor and second reader officially signing the thesis.


Personally, I am a fan of ceremonies — it is important to take a moment and recognize an accomplishment, to take stock of where we were before and how far we have come!


Dr. Ramsey signs the thesis.

Dr. Ramsey of the Math Department signs Popi’s thesis.




Every department has slightly different traditions and requirements for their students IS defense.  In physics, we have intentionally modeled it after a Ph.D. defense, and I know that it is a bit intense.  For double majors, we do compromise between the traditions of the two different departments.  Luckily, since we have a good number of physics – math double majors, the traditions of the Math Department are pretty close to the Physics Department, so it is not too challenging to merge our requirements.


Finally, the culminating event of Senior IS is the Senior Research Symposium, held  on the next-to-the-last Friday of the spring semester.  Classes are canceled for the full day, and the whole campus takes part in an awesome celebration of the research that the students have done all year.

Physics students have always been required to do a poster presentation to complete their I.S., but we used to have our own poster session all on our own.  Since the IS Symposium started about 8 years ago, we’ve been able to be part of an all-campus event, which is more fun.

In addition to the posters, students can also elect to do a “Digital IS” presentation and develop alternative ways of presenting their IS research.  This year, senior Nathan Johnson built a Lego Mindstorms version of a scanning tunneling microscope (STM) to show attendees the concept of how an STM uses feedback as it scans in order to map out an image of the surface of the sample.  It was a bit challenging to get the built-in Mindstorms sensors to work well enough and the Lego pieces were not quite as rigid as we really wanted, but it worked to map out the surface, which was cool!

Nathan shows off his Mindstorms STM to President-elect Sarah Bolton

Nathan shows off his Mindstorms STM to President-elect Sarah Bolton

He had a good crowd interested in it during the digital IS session in CoRE, including President-elect Sarah Bolton.  Since she is a physicist and actually knows how an STM works, her questions were rather more perceptive than the average ones!


Overall, the IS Symposium is one of my favorite days of the year!

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April Whirlwind – Part 1!

Whew!  So much happened here in April, I’m just barely catching my breath now!

Prepping an egg for its trip to the ground.

Prepping an egg for its trip to the ground.

We had two great outreach events early in April.  The second weekend of April was the Expanding Your Horizons event, with a variety of science workshops for 5th & 6th grade girls.  This is a massive event, coordinating presenters from all over the Wooster community — not just the College. This year we were quite surprised to be having the event with 3 inches of snow!   In physics, we’ve been doing a workshop on The Humpty Dumpty Experience, which is an egg drop challenge.  Egg drops have gotten really popular, so a lot of girls have a little experience with the project.  Apparently peanut butter is the new concept in egg drop.  This year, all the girls wanted to know if they could have a jar of peanut butter.  Nope — you can have 8 popsicle sticks, 6 cotton balls, some paperboard, some string, some newspaper, 8″ of duct tape, and a plastic bag.  Even with these limits, most teams were successful in keeping their egg safe, and their eggs were retired to the Egg Hall of Fame.

DSCN7631                      DSCN7627

Girls waiting on the sidewalk for me to drop their eggs from the second floor of Taylor

Girls waiting on the sidewalk for me to drop their eggs from the second floor of Taylor

We dropped the eggs from one of the upper windows of Taylor, which worked really well.  The most amazing thing was that the wind caught  the very first egg holder that I dropped, and it went up instead of down!  We actually lost it on the roof — it never came down!










The very next weekend we held the 8th annual Science Day!  This is a student-run outreach event for the whole local community.

Physics Club coordinates with all the other Wooster science clubs and fills Taylor Hall with demonstrations — liquid nitrogen, comets, tie-dye milk, glowing pickles, DNA made from red licorice twists, erupting volcanos and sheep brains!



The Twizzler DNA station is always very popular, and just a little sticky

The Twizzler DNA station is always very popular, and just a little sticky

Tie dye milk

Tie dye milk

Michelle and Nate, stirring away in the process of making a 'comet'

Michelle and Nate, stirring away in the process of making a ‘comet’

Three young attendees particularly interested in physics and total internal reflection

Three young attendees particularly interested in physics and total internal reflection

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