Lessons Learned After Days Turned

Despite thinking that I had the best possible schedule last week, I think I have still improved it. I woke up today at 8:15 and made it to class with time to spare. The walk was short, but still the steadily increasing humidity meant that I was just fine with getting back inside the well air-conditioned building. 

Baker Dining Hall

The class began with a discussion of how to calculate the luminosity of a blackbody spectrum using integrals. To do so, all you need is to find the area under the curve of the graph flux of frequency. We then went on to discuss Stefan's Law, another one of the radiation laws. Stefan's Law states that the flux of an object is equal to the temperature of a blackbody to the fourth power times the Stefan-Boltzmann constant. This can be used, along with another formula relating luminosity to flux, allows us to calculate the luminosity of a star from its temperature. We then returned to the subject of spectral lines with an explanation of the opposite of absorption lines, emission lines. What they are is the re-emission of photons that are absorbed (which create absorption lines), except they don't fill in the gaps created by absorption lines completely, because the photons are re-emitted in all directions.

We were let out for lunch at about one, a bit late compared to the usual, as the explanation of emission lines took a while longer than expected. During lunch, a rising senior filled me in on the actual calculus operations used to calculate the area under the curve that our teacher had left out. I also had some questions about the emission spectrum that I discussed with a few other classmates. The question that we still have not figured out is: why do emission lines ever show up as spikes, and not troughs, on the graph? 

Once we were all back in the classroom, Gourav explained the atmosphere and properties of the sun, classes of stars based on luminosity, and the atomic fusion that powers the stars. The most common type of fusion is called a proton-proton chain, in which two hydrogen atoms fuse into a helium atom with one neutron and one electron, which then combine with another hydrogen atom to form a helium atom. In the final combination, two of the previously mentioned helium atoms combine to form a helium atom with two neutrons and two hydrogen atoms. The products of this reaction have less energy/mass (the two are equivalent, related by the equation E=mc²) than the starting components, which means that the reaction produces energy, in the form of the heat that keeps the sun stable and the light that we see.

After class finished, I went back to the dorm to grab a coupon for the bookstore, and then I headed back to the southeast side of campus, where the bookstore is located and where a meetup/check-in with the Admiral was scheduled. We got our UChicago gear, generously paid for by the ILC, and talked for a short while about communication, responsibility, and time management. We then went to the study hall on the south side of the main plaza and took a photo (definitely pulling off the bucket hat look, right?) After we were done there, I walked back to the Baker Dining Hall and ate dinner.

The rest of the evening was composed of studying and writing this blog. It was cool to learn a touch of Calculus and have an in-depth discussion about astrophysics outside of a classroom setting, and I'm excited for the project that I'm starting on the rotation of stars and its relation to the width of spectral lines. Good night!