Thursday, July 28, 2011

Our PENNultimate Day

Today was exciting from the start because we began our class with a talk with Rick Vanberg. For the first few minutes I munched on my bagel and listened, but soon his talk became quite captivating. The first thing that Rick talked about was the standard nuclear model for the sun. Based on the observations of nuclear activity on small scales, scientists came up with a model that accounted for the gravity, high pressure, and high nuclear activity in the center of the sun. One problem was that the accepted model at the time predicted a large number of neutrinos would be released for every fusion reaction in the sun.

Because there are so many reactions every second, scientists predicted a certain number of neutrinos per second would hit each meter of the Earth’s surface. To test this model, a scientist filled a large vat full of liquid and then waited for a while. Although the experiment was underground, neutrinos are tiny and have no charge so they very rarely interact with the matter in the way. When the neutrinos strike the liquid, they are absorbed and they change the atom that they strike into a different element. When he took the measurements of the number of neutrinos that he detected, he found that there were only about 28% of the neutrinos that there should be.

To solve this conundrum which either implied that our model of the sun was totally wrong or that we didn’t understand neutrinos, a Russian scientist stepped up to the plate. Communicating through the veil of the Iron Curtain, this scientist published several papers where he claimed that we misunderstood the neutrino. To test this claim, a project called SNOW was developed. Snow basically consisted of a huge neutrino detector built to detect all kinds of neutrinos unlike the past models. To filter out background radiation, SNOW was built 2 kilometers beneath the surface of the Earth in a nickel mine in Ontario. SNOW ended up successfully measuring all of the neutrinos that came from the sun and we learned that the neutrinos were being morphed into other flavors and that the nuclear model of the Sun is actually correct.

Next on our schedule were the student focus group presentations. Each of us spent 4 days last week with our groups researching a subject that we picked. My group studied a non-Newtonian fluid called oobleck which basically means that it is a material that behaves both as a solid and a liquid. The peak of our presentation was on Monday when we used the oobleck in a demonstration. Because oobleck acts a solid when it’s under pressure, each of us could run over it. Today, we showed some graphs of how objects decelerate when they hit oobleck compared to when they hit water. The graphs were neat because you could really see how the oobleck gave away for a moment and then hardened and stopped the incoming solid whereas the water allowed the object to easily pass through. It would be way too much to talk about every other group’s presentation, but they covered many amazing topics such as quantum mechanics and radio astronomy. Each group had a unique perspective to offer and we all learned a lot from each other.

When we returned for lunch, we got to do something pretty interesting. We split into groups and then visited different parts of our building and the one across the street. We got to go into research labs and listen to brief talks by the researchers themselves about what they were working on. The first lab we stepped into was a lab where a grad student and a professor from UC Santa Barbara (WHOO California) were developing technology for better mammograms. Because current mammography methods require the breast to be squished tightly between pressure plates so that the waves could get better images, these researchers were searching for a way to do mammograms with near infrared light. The advantage of this is that the discomfort of the plates could be avoided and therefore more women might show up for their mammograms. I was impressed by how applicable this research seemed and that it truly was for a good cause. We heard many other talks about great stuff like carbon nano tubes and grapheme. These researchers were researching grapheme so that they could manufacture tiny detectors for things such as bomb detection. Overall, I was very impressed by how passionate these researchers were about their areas of study.

I am in shock that tomorrow will be my last day here at UPenn, but who knows; maybe I’ll be able to spend another 4 years here.

Thanks to Alex for capturing Julia's momentary lack of enthusiasm.

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