Tuesday, July 26, 2011

Speed of Light Confirmed

We got it working! Our contraption that we had hoped would measure the speed of light actually worked this morning. Well, I shouldn’t say that WE got it working. Apparently the same problems that were occurring with our apparatus were also present in several other groups. Because of this, Bill and the TAs stayed after class several hours yesterday to diagnose and fix the problems with our machines. Apparently the problem was with the scanning range of our oscilloscopes. This was a relief because it meant that we did not cause the problem. Once we did the final checks on our circuits and oscilloscope, we moved our cart with our apparatus on top into the hall. We had to place the laser and light-receiving diode at one end of the hall and put a mirror far enough away so that we could get a decent measurement. We placed our mirror about fifteen meters away from the laser. Once we had everything aligned correctly, which actually took a while because the laser was so small and the mirror was so far away, we began taking our measurements. We measured the wavelength of the laser at two points: one about two centimeters away from the tip of the laser and the other at the diode when the light was bounced back by the mirror. The oscilloscope showed us both wavelengths on different channels so we could find two peaks in the wavelengths and measure the time between the peaks. Our first time was about two-hundred nanoseconds, which means that is how long it took for the light to go from the laser to the diode. We divided the distance traveled by the light by the time it took for the light to travel that distance, because velocity is distance divided by time, and our answer was not what we were looking for. Our results actually told us that the laser was travelling at twice the speed of light. After much trial and error, we asked Ryan what we could have possibly done wrong and he told us that there was too much noise in our data. He helped us get a stronger focus on the wavelengths of the oscilloscope and once he did that, the rest was easy. We found two peaks, measured the time, and came to the correct result, 3*10^8 . Well, we actually got 3.06*10^8, but the difference is negligible. Ryan actually did not believe us when we told him that our measurements were not that close to the actual result. Apparently other groups were getting results around 3.20*10^8 or 2.8*10^8, which is understandable because there are several errors that could occur. We did it though. We measured the speed of light.

Believe it or not, that's a tape measure...a deadly tape measure...

Bill helps us with our oscilloscope

After our lab, we were given a lecture by Penn professor Dr. Ken Lande. Dr. Lande focuses his research in experimental astrophysics and the investigation of fusion energy. His lecture was one of the most interesting yet. He discussed the energy crisis and the different options we have in fighting it. According to Dr. Lande, our options for alternative energies include photo-voltaic solar light converters, solar thermal concentrators, wind turbines, bio-fuels, and nuclear power. The most viable solution of these choices at the moment is the implementation of wind turbines. This is because they are cheap to produce and construct (relative to the other choices) and they are the most efficient form of capturing natural energy. I was very interested to hear about what Dr. Lande said about the best form of alternative energy was because I had to debate that very topic three years ago in Forensics. He also discussed the use of nuclear power, primarily fission reactors. The US has only one-hundred and two fission reactors that we use for twenty percent of our energy needs. France has many more reactors and supplies 70% of its energy needs using fission. It is astonishing how politics can get in the way of what could possibly end one of the most significant issues of the century, certainly of my lifetime. I asked Dr. Lande about the use of IFRs (Integral Fast Reactors) and whether they were more or less safe and about their efficiency after the lecture. He told me that this style of fission reactor was incredibly efficient and was proven to be safe, but because of the political climate and decisions made around the ‘70s the project was put on hold indefinitely (thank you SO much former President Carter). I enjoyed Dr. Lande’s lecture very much and it was clear that Bill had been saving one of the best for last.

Dr. Lande presents a possible solution to the crisis

After our guest lecture and lunch, Brian, Julia, Mike, and I met back at DRL to begin our PowerPoint presentation on the Sooperdooperlooper, the roller coaster we had to analyze during our time at Hershey Park. We did not finish the PowerPoint at the labs because Mike had to commute back home and we preferred to finish at the dorms. We decided to include some history on the ride and a detailed description of what riders experienced while on the coaster. In addition to these, we had to type up descriptions of the physics behind the ride, which is the real meat of the presentation. We conclude our presentation with our graph data on the different accelerations of the carts as well as the altitude throughout the ride. Following our graphs, we will show the video we took of the ride, even though the protective bar on the cart obscures most of the view. Due to the low quality of our video, we also included a link to the YouTube video that shows the ride from a first-person point of view. The video is much better than ours and I think it will be a great way to conclude the presentation. I have a lot of confidence in our presentation as well as the data we will be presenting.

After putting the finishing touches on our PowerPoint, I headed down to a large field near the DRL to play in what was supposed to be the staff vs student ultimate Frisbee game. This wasn’t exactly how it played out because there were only three RCs. It was still a great game, regardless, and I definitely had a lot of fun. I even got to know a couple of the RCs better that I had not had the opportunity to meet previously. I also surprised myself in this game because I was a lot more useful to the team than I usually am. Usually I just hang around the other team’s goal, unnoticed by the other team for the first few goals of the game, and wait for my teammates to get the Frisbee. I can usually get a few goals this way because I am relatively open and already near the goal while everybody on the other team has to run back to play defense. Instead, I was much more mobile in this game. Although throwing was still my Achilles heel, I was playing more offensively by intercepting and blocking throws, in addition to my usual strategy. It was a great game concluding game of ultimate Frisbee and I will miss playing such a fun game with my Penn peers.

The rest of the night was basically just spent lounging around the dorm. Fred, Onur, Alison, Brian, and I were all quite tired from our intense game of Frisbee so we did not feel like doing much of anything. We all sat around in my dorm listening to music, sharing our favorite videos on YouTube, and playing a game called QWOP. In this game, you control an Olympic runner and you have to control his thighs and calves using the Q, W, O, and P buttons in order to make him run. It is nearly impossible to control the runner, but it is incredibly entertaining to watch. We also ordered Insomnia Cookies and had them delivered to the dorm. It was quite the evening, even though we didn’t do much of anything. We just enjoyed each other’s company.

Three days remain.

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