Wednesday, July 16, 2014

Special Relativity and Nanotechnology

Proving the speed of light is constant in all directions
Today in physics we began with our postponed presentation on Special Relativity, given by Craig. Special Relativity is really just a special case of General Relativity that assumes constant velocity. The idea actually began with Galileo, who realized that on a ship moving at a constant speed, if you didn't look out the window you would not be able to tell if you were moving or not. Einstein challenged the Newtonian model of the universe, stating that the laws of physics are the same for all observers moving at constant speeds, that motion is relative.

A diagram explaining time dilation
Craig also talked about Faraday, Maxwell, Michelson, Lorentz, and other physicists whose work Einstein built upon. The main consequence of Special Relativity is that space and time are linked (space-time) and therefore simultaneity does not exist and motion (through both time and space) is relative. Also, time travels at the speed of light and it is impossible for anything with mass to travel at the speed of light, though at speeds near the speed of light both distance and time shorten, and the moving object becomes more massive.
"Fundamental" particles as they were discovered

Then Mary talked to us about elementary particles--or at least, all the particles that people have thought were elementary over the years. Atoms were named so because people thought they were "indivisible," then they found out they were made of protons, electrons, and neutrons, which people called elementary particles. Then people discovered that protons and neutrons are made of quarks--up quarks and down quarks. Leptons are fundamental particles that (we believe) have no internal structure. They are electrons, muons, taus, and their matching neutrinos, the electron neutrinos, muon neutrinos, and tau neutrinos. Quarks, which never appear alone but only in groups, have charges of +2/3 or -1/3. There are six types of quark--up, down, charm, strange, top, and bottom, but only the up and down quarks are found in the matter we interact with. A group of two quarks is a hadron, and a group of three quarks is a baryon. Fermions are leptons or quarks. Despite all of these particles that exist in our universe, only electrons, up quarks, and down quarks make up our matter. The other particles just float around, part of cosmic rays or similar phenomena.

Fields of science united in nanoscience
Mary also presented on anti-matter, something that is basically the exact same as ordinary matter, but with opposite spin and charge, and if an anti-matter particle meets its corresponding particle of matter, they completely annihilate, turning into pure energy. Finally, she closed with how scientists are trying to combine gravity with the other three fundamental forces to create a Grand Unified Theory, a single force that governs the entire universe.

Different forms of carbon that can be used in nanotechnology
Then we had two guest speakers. The first, Charlie Johnson, spoke before lunch about nanotechnology with graphene and carbon nanotubes. He talked about how nanotechnology crosses physics with biology to create something that is a hybrid and more useful than either. This technology could be used to analyze DNA and detect different chemicals, among other things. The second speaker, Bob Johnson (no relation) spoke after lunch. He talked about computational nanotechnology. He uses computer simulations for better visualizations and calculations for the development of nanosensors. He talked about how what they developed could be applied for use in environmental safety, disease diagnosis, DNA sequencing, homeland security, and scientific and medical research. Though both speakers spoke about almost the same topic, had the same last name, and had worked together in the past, neither knew the other was speaking today.

Our group did the RC Circuit lab
Afterwards, in the lab, we collected the data for the experiments we chose in groups this morning. This was the only day we'll be doing our group projects in the lab, so afterwards we have to meet with our groups and put together our presentation sometime.

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