Relativity is Confusing...Relatively Speaking, That Is

Today was certainly out of the ordinary. Class had a different feel to it today and my time after class turned out better than I expected it to be. We started the day with a lab, which is very different from our usual schedule. We got together in our groups from the trip to Hershey to experiment. Our task was relatively simple. We had to balance a scale. However, this was no ordinary scale. This did not have a platform for weighing objects. Instead, it used metal rails for positioning very light objects (we used one-hundred milligram wires) and the scale was not used for weighing the objects we placed on it. Once the scale was balanced and hovering about a millimeter above the main body of the scale, we applied a current to the rails, which caused it to rise because there were two rails with opposing currents. Because the currents opposed each other, they were repelled. This would only happen if we applied a minimum amount of voltage so that the rails would repel so much that the top rail would overcome the forces that the wires pressed upon it. We found that the results supported our hypotheses. We observed that the amount of voltage needed would need to increase as the amount of weight on the rails increased.

Craig lectured us today and it was quite different from the lectures we have had before. Today’s topic was about General relativity. I was unaware that there were actually distinct categories of relativity, but it is actually divided into special relativity (which is what we covered previously) and general relativity. I was lost at the beginning of the lecture because the whole concept of the lecture revolved around idea that defied the theories and laws that we had learned before. Craig began by saying that general relativity was just geometry, but was a bit of a stretch. Although the ideas involved in general relativity are grounded in geometry, they quickly go against many of the fundamental ideas of the very same subject. For example, in geometry, the shortest distance between two points on a plane is a straight line. However, this is only if the case if the plane is flat. If a plane is non-Euclidian, which means that it is a curved surface, then the shortest distance between two points has to be a curved line, which defies THE most basic principle of geometry. As Craig continued the lecture, I began to grasp what he was discussing a little bit more, but I was still confused for the most part. It wasn’t until later that I was reviewing my notes with Brian that everything clicked. If you had told me at the beginning of this program that I would understand the ideas of relativity, I would have had my doubts. However, things have changed since the beginning of the Experimental Physics Academy. I have a stronger grasp on physics than I could ever gain after only a month of lessons.

Following Craig’s lecture was our guest lecture of the day. Today, Dr. Vijay Balasubramanian spoke to us about the biophysics of our brains. I find Dr. B’s background fascinating. He studied particle physics, cosmology, string theory, and several other areas of physics, but then decided to go into neuroscience. Although this was an interesting aspect of Dr. B, he was a very interesting lecturer as well. His style was energetic and he relied on volunteer participation, which is something I have not encountered in my few experiences with college professors and their lectures. The demonstrations he performed did help explain the material though. He gave specific instructions to pairs of volunteers that would be playing the parts of neurons in the brain. These instructions dictated how each pair would communicate with one another when a specific stimulus was applied. This demonstration was used to introduce us to just how the brain operates. This was part one of Dr. B’s lecture, which he called “How Brains Work.” Part two was called “Efficiency in the Brain” and covered statistics on how much energy and fuel the brain used to perform its work. The fascinating thing is, our brains consist of only two percent of our weight, but use up twenty percent of the metabolic load. It also uses only ten watts of power, which is about six percent the amount of energy per second of that used in a common light bulb. The third section of his lecture, “Can We Evolve to Be Smarter?”, covered the way we learn and how our minds came to be so advanced. Essentially, he informed us that our brains have (for the time being) hit an evolutionary roadblock. Right now, we do our learning through communication and synergy with others, not by enhancing how our brains operate. Our guest lectures continue to get more and more fascinating. I cannot wait to see what we learn about tomorrow.

After lunch we met in our special interest groups. Today, James took us to the roof of the Rittenhouse Labs to observe the sun through two different telescopes. We were actually able to see what we had been learning about for the past two days. The majority of our time on the roof was spent attempting to position the telescopes, one visual and one radio. Much to our surprise, it is not as easy to find the sun through the lens of a telescope as one may think. It actually took about twenty minutes to get a good image of the sun through the visual telescope. Once we had a good image, we were able to see a bright, orange ball emitting waves of heat. We were even able to get a view that was so magnified that we could see sunspots. Using the radio telescope was not easy in the slightest. It took a much longer time trying to get the telescope aligned. There were times when we would come close to getting the right angle, but then the graphs on the oscilloscope returned to normal after a few slight changes while the dish was moving. We spent over an hour trying to configure the telescope, when finally we got as close as we could to viewing the sun’s sound wave’s frequency output. Once we accomplished this minute feat, James informed us that we had just experienced several of the problems that come with using radio telescopes. There was a lot of interference from reflective objects in the area, which caused significant problems. The other major problem is the characteristics of the waves being used to receive the data. The waves are too spread out and are not specific enough to accurately pick up data from the sun, at least not from our location. Regardless of the problems, this experience was enlightening and I am learning through “failure.”

James staring at the sun...don't try this at home.

Our group of seven, Onur, Abheek, Alison, Julia, Fred, Brian, and I, decided to go to Center City Philly after our respective classes. We took the trolley and soon enough we were in the heart of Philadelphia again. We did not really have an agenda because we were just hoping to explore parts of Philadelphia as a group. We wound up getting some frozen yogurt, visiting the Comcast Building (which ironically looks like a phone jack), and eating dinner we picked up from a deli in the JFK Love Square. Our time in Center City was great, and it was definitely a different experience from when we rode a tour bus with Mr. Miranda three weeks ago.

Love, love, love...

The fountain/wading pool at Love Square

The Comcastic Phone Jack

My time here at Penn is dwindling. I only have ten days left in one of the greatest cities that I have ever visited. What is even more saddening is that I only have ten days left with some of the greatest friends I have ever made. Our time today at Love Square feels like it epitomizes the strong family-like bonds that we have forged over the past few weeks. We came together as strangers, but now we are the closest of friends and have made unforgettable connections. I pray that the next ten days are slow ones so I can enjoy the presence of my Philadelphia family that much longer.

I Want to be a Systems Neuroscientist When I Grow Up

Class today woke me right up (despite my late start) with a fascinating lab. We measured the distance between two balanced wires, hung tiny weights from them then ran opposite current through them until they balance again. Because we knew the length of the wires, the magnetic force needed to lift the weights, and the current we were able to calculate the constant for the permeability of free space, which is a very cool concept. Basically, what it implies is that a vacuum allows magnetic fields to emanate at a rate that is neither zero or infinity, meaning nothingness has properties of its own in a sense. As a follow up, we learned that the inverse of the square root of the sum of the permeability constant multiplied by the permittivity constant (involving electric charges rather than magnetic fields) is equal to the speed of light. This proves that light is an electromagnetic wave.

Next we sat through a lecture about general relativity, the concept that acceleration is equivalent to gravity within a single reference frame and that massive objects bent space, making euclidean geometry no longer applicable, which is what accounts for the planet's orbital motions and even, when studied further, mercury's irregular path. This lecture was fairly interesting, but honestly completely over shadowed by the presentation that followed.

Today's guest lecture was the most entertaining, excited and easily accessible speaker we have had so far. By a lot. He did not have power point slides that he simply read out loud. He drew on the chalk board, walked around, had us stand up and participate in his demonstrations in an incredibly engaging way. His name was Vijay Balasubramanian and his "lecture" (although it seemed like way too much fun to be called that) was about the physics of neuroscience. In the past he has done research in particles, cosmology, and string theory but today he talked mostly about the field he is currently doing work in, which is essentially how the brain works, and more specifically (which is what separates his field from biology) systems neuroscience: why it works the way it does.

He started the talk with a drawing of a neuron, a description of their structure and how dendrites and axons receive and transmit electrical signals. He then used volunteers to build a human neural circuit that displayed how the connections between the cells allow highly specialized cells to work together to do a broad variety of things. He lined up six students and gave them each a job (for example, if you see a white piece of paper, poke the person behind you or if you get poked raise your hand, etc.).

He also discussed with us the miraculous efficiency with which our brains operate. For example, only 10 watts is used to power it (as opposed to a standard 80 watt computer) and in one cubic millimeter of tissue, 4 kilometers of "wiring" can be found. He also mentioned that the rate at which signals are fired is only about 4 Hz, which is shockingly slow compared to a computer, but he discussed the drawbacks of having it go any faster: requiring more energy, a larger head, and not reaping proportionate benefits (as shown by the law of diminishing returns which basically states that double the information results in less than double the usefulness). It was really, really cool. So cool in fact that I cut my lunch time about half an our short to listen to him discuss how he got interested in his field and what more there is to discover in it (apparently a lot). He suggested we read the article in this months Scientific America about the limits of intelligence, in which he is quoted three times. I intend to do just that.

After lunch we went back to work collecting our single photon diffraction data and we've got a very nice looking graph to show for it now. We also started preparing for the presentation we are going to give next week. It should be cool telling our classmates the results of our lab and about how we proved particle/wave duality, but I am even more excited to hear what all the other groups have learned and maybe run across some Non Newtonian fluids.

After class, seven of us from my floor and Brian and Alex's floor signed out and looked around center city. We wandered for a while, grabbed some dinner at a sandwich shop and ate it next to a fountain that we were actually encouraged to dip our feet in. It was a great day and I'm really glad we finally got out to see the city.

Networks of Neurons

Today was full of learning and adventure from the start. I woke up and got breakfast with the usual suspects, Alex and Fred. Feeling well-fueled, we made our way to class and excitedly took our seats. I was excited for today’s lecture, because I knew that Craig was going to talk about a topic that I am quite interested in – general relativity-. Craig’s talk was very good and I enjoyed the content a lot.

Craig began to talk about the idea of general relativity which basically says that physics is just a form of geometry. While we all think oh geometry, I did that back in the freshman year of high school; Craig began to talk about Non-Euclidian geometry which is geometry on curved surfaces. In straight space, the degrees in a triangle add to 180, but in curved space, the angles can add to more or less than 180. The next thing that Craig talked about was defining what mass is. Mass can be thought of as a measure of how much matter there is, but also as a measure of inertia. While it might seem obvious, Craig stressed that an object in motion and a stationary object have the same mass. Craig then moved on to state Einstein’s Equivalence Principle which states that without an outside reference frame, it is impossible to tell the difference between gravity and acceleration.

The next topic that Craig discussed was the bending of light by gravity. Einstein predicted that light should be bent by the mass of the Sun as it passes through its gravitational field. When the experimental measurements were taken, it became clear that Newton’s Law of gravitation was not in fact a Law, and that Einstein was right. While I was confused at first why light photons, which are mass less, would be bent by gravity, Craig reminded us of Einstein’s famous equation E=mc2. Another cool thing that Craig talked about was the irregularity of Mercury’s orbit. It was interesting because he presented the idea of gravitational waves that ripple through space-time at the speed of light. While we tend to think of gravity as instantaneous, gravity also takes time to make its way through space. The new way of thinking I have about gravity now is that an object with mass bends the space around it and that other masses simply follow the paths of least resistance and approach the massive object.

Following Craig’s lecture, we were fortunate to have another guest lecturer from the UPenn faculty visit us, Dr. Vijay Balasubramanian. Vijay was one of the best speakers I have ever heard, because regardless of the fact that he has 30 more years of education than me, he presented his ideas perfectly. Vijay began his discussion by discussing how the brain works. What I found very interesting was his way of thinking about how individual neurons know nothing by themselves but that together they make up our personalities and complex emotions. Vijay continued to explain how the mind overcomes being imperfect by having redundant processes check each other and in a way ‘vote’ to decide with great accuracy what is true. An example of this is a bundle of photoreceptors that are hit by photons of light. While a ton of photons might hit them at the same time and lead to confusion, the photons cleverly figure out what happened by deciding what the majority experienced. One of the things that amazes me most is how imperfect humans are and yet we are still able to outperform machines that are superior to us statically.

All of us wonder how much smarter we can become. Vijay addressed this question from a very realistic standpoint. The most important statistic of the day that he told us is that the brain is 2% of the body’s mass yet it consumes 20% of the body’s resources. Thus doubling our brainpower would require that we eat a ton more, in which case we would spend more time food gathering and less thinking. Additionally, nature imposes limits on how smart we can get, because even if you double your mental faculties you would still not be able to think twice as fast as before. While we can’t be sure without seeing how our brains evolve over the next several millennia, Vijay seemed fairly confident that our brains are quite optimized. Hearing this from a man that was quoted three times in the latest Scientific American article on neurology was quite convincing.

What an amazing day.