Tuesday, July 26, 2011


Yesterday I talked about how building our light-speed measuring device tied together many of the concepts we’ve been learning, but today was even better because we actually operated our device and got values for the speed of light. The first thing we did was to take our laser in the hallway, remove as much light from the hall as possible, and to set our mirror a ways down the hall from our laser. The next step took a lot of fine tuning, because the laser was far away from the mirror which was small, any tiny adjustment to the angle of the laser would throw it feet away from our target, the mirror. After plenty of trial and error we got our laser beam aimed perfectly so that it the beam split in half where one beam immediately entered the oscilloscope and the other beam went down the hall bounced back and then entered the oscilloscope. In order to keep our data as clear as possible, we did several things such as re-concentrating the laser beam onto our sensor after it had hit the mirror and bounced back. Once we got the whole system set up, taking our measurements and understanding what they represented was actually relatively easy.

By reading the time difference between the wave leaving the laser and immediately hitting the oscilloscope and the one that travelled, we had a time measurement for how long the trip down and back the hallway took our light beam. We recorded this data and then measured the distance down the hall and the distance back to our sensor. As I said earlier, the technology we used was complicated, but the idea was simple because all we had to do to calculate our value for the speed of light then was to divide the distance we measured by the time it took to get our speed value which ended up at 3.4*10^8 meters per second. We measured the distance after we got our time values so that we would essentially be doing a ‘blind’ experiment so that we couldn’t change the numbers to better fit the already known value of approximately 3.0*10^8 meters/second. For two days of high school students working, I was quite impressed by how close we got to the actual value. Once again, many thanks to Bill, Ryan, Craig, and Mary for guiding but not pushing us through the experiment.

Once again I was excited to listen to another guest speaker, Dr. Ken Lande. I was particularly excited to listen to him speak because he was speaking about one of the topics I am most interested in – solving our energy problems-. I have had a passion for energy conservation since I was much younger and I changed all the bulbs in our house to compact fluorescents. Ken began his talk by painting the picture of the sad state that American energy supply is in today. Nearly as pressing as the budget deficit deadline, the world is approximately at the date of ‘peak oil’ where the most oil is being extracted per day and the extraction can only decline from here on out. Obviously this is a huge problem, because while our oil supplies are dwindling, our appetite for oil is not. Additionally, climate change has presented a huge need to immediately begin weaning ourselves off of fossil fuels.

While the first part of Ken’s talk was quite frankly depressing because of the seemingly unsolvable crisis of fossil fuels, Ken soon shifted his talk to possible solutions to our energy need. The main possibilities for our energy supply as Ken sees it are photovoltaic panels, solar thermal concentrators, wind turbines, bio-fuels, wind, and nuclear power. I suppose I am biased towards solar energy because I live in California where we have tons of intense sunlight, but Ken presented his best idea as a blend of wind power and nuclear power. He presented a very well-developed argument because we already have the technology to make millions of wind turbines, and wind is also a close second to fossil fuels such as coal economically. While it’s a painful reality to face, it’s important to realize that all change in the world is driven by economics, so the fact that wind is comparable in price to fossil fuels makes it very appealing compared to solar which costs nearly 3 times as much as coal. Additionally, Ken argued for nuclear power because although it isn’t renewable, we have a massive amount of energy that we can harvest from uranium and plutonium. Although nuclear power is currently frowned on because of the meltdowns in Japan, there are much safer reactor designs that are possible, and either way nuclear energy is a must because the problems of climate change and literally running out of fossil fuels will force alternatives. Additionally, Ken pointed out that for the number of deaths associated with mining for fossil fuels compared to those from nuclear meltdowns, nuclear is safer. In a sense, the stigma associated with nuclear power vs. coal is like that of airplanes vs. car crashes. Although the deaths due to car travel per mile are literally orders of magnitude higher than those for plane travel per mile, people make a bigger deal out of plane crashes because they are so conditioned to accept car crashes but plane crashes happen rarely and are therefore a big deal. I don’t mean in any way to say that nuclear meltdowns are a small matter, but based on the safety statistics and energy demand, it is a good alternative.

I was very impressed by Ken’s lecture and the thoughtful questions that my fellow students asked. I have been interested in this field for a long time, and today only wet my appetite more.

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