The Aurora

 

A different Aurora.

[*This is an article I wrote for a class in response to an incorrect article in a local newspaper*]

The winter season brings with it more viewings of the Aurora Borealis or more commonly the Northern Lights. Sheets of red, blues and greens dance in the skies of far northern (and southern) latitudes. While it is commonly thought that the aurora is more prevalent during the winter it is in fact constantly active throughout the year. Winter months just provide longer nights in which to view the aurora.

The Aurora is caused by the interaction of energetic particles with the Earth’s ionosphere. These particles come from interactions within the magnetosphere of the Earth. The magnetosphere is the space created by the interaction of the Earth’s innate magnetic field (which we use for compasses) and the solar wind. The solar wind is a consistent flow of particles in the form of plasma that have blown off the surface of the sun.

When the solar wind reaches the magnetosphere of the earth a bow shock, similar to a boat, forms on the sun side of the planet. This deforms the magnetosphere into the shape of an elongated tear drop. In the stretched out tail of the magnetosphere the magnetic fields get stretched out and oppositely direction fields get closer together. These opposite fields can collapse together and send particles streaming back towards the earth.

These streaming particles then approach the upper reaches of the atmosphere where they are accelerated to high energies. As they zoom into the atmosphere they interact with the ambient particles and molecules, giving away their energy as they slow down. The now excited oxygen and nitrogen give off the characteristic red, green and blue lights that we see as the Aurora.

The current location of the auroral oval can be seen at spaceweather.com along with more information about the current space weather conditions. For more in-depth information on the physics of the aurora visit: http://deved.meted.ucar.edu/hao/aurora/

 

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Starfish Prime

 

Safe and away.

Twice in one day I have heard references to Starfish Prime. First in my plasma physics course and second in a paper on electromagnetic resonances in the earth-ionosphere cavity.

So I looked it up.

Starfish Prime was one in a series of high altitude nuclear tests. This particular one was detonated over 400km, well into the ionosphere. The EM pulse wiped out many low earth satellites, it destroyed electronics in nearby Hawaii and lunched a bunch of radioactive particles into space along the earth’s magnetic field lines.

The one good thing it did was introduce a lot of radioactive tracers into the inner radiate belt, thus allowing for the lifetime of particles in the belt to be measured.

Otherwise the thought of high altitude nuclear tests is a bit worrisome.

 

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Jackson Problems

One of the Greenlake docks.

Graduate Physics Electromagnetism is know as being difficult. In particular it has been noted among many who have taken the series that the homework can be slightly challenging at times. Most of this arrises from the pervasive usage of the Jackson text Classical Electrodynamics.

Unfortunately for me I now look forward to Jackson problems as they are easier then the ones my professor writes. If not easier they have easier to access help online in the way of physics forums and even posted solutions to some of the problem (though this rarely help).

Overall I have decided I dislike problems that involves words like ‘proof’, ‘prove’ and ‘corollary’. Especially if they are all in the same sentence.

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1.9 Kelvin

My guess as to what it would look like to look down the LHC while it is running. Assuming one lived.

Looks like everyone’s favorite soon to be turned on particle accelerator is about to start to be turned on!

At least it is down to a balmy 1.9 Kelvin at the moment with the hopes of running at full or near full power by December. Next week they may turn on the beam at low power to mark the start of the slow ramp up to full on Higg’s Boson finding power.

It will be really neat once the LHC is running at full capacity and sending out more data in a second then I can possible imagine. Also once that data is sifted through, analyzed and thought about will it start to get exciting. Maybe they will find a Higg’s boson (exciting) or perhaps nothing new at all (even more exciting). It will be exciting times in particle physics and I am glad to say that I will just be reading the final results and not searching through that data.

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Bullet Hole

A basket in the San Francisco Asian Art Museum.

At my grandmother’s house today an interesting thing happened: a bullet hole appeared in a glass door.

If we were in a city or in an area with a particularly active night life this might not be surprising. However she lives in the mountains with roughly an acre of land behind here and the hold appeared in the back of her house. Looking at the hole the first thing I tried to determine is whether the projectile went through or ricocheted off and based on the small hole (about a millimeter) I figured it simple bounced off, though the bounce did leave a conical explosion of glass on the inside of the pane.

Knowing it bounced off I looked at the shape of the hole to figure out the rough direction it came from, then assuming a bounce that is perfectly elastic and something akin to Snell’s Law (though it is not a wave, at least not appreciably) I figured out the direction the projectile should have flown. Unfortunately I could not find it, though it is likely from a BB gun or other non-lethal weapon.

Or at least we hope.

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End of Homework

The sun actually came out today.

Today I turned in my last homework assignment of my undergraduate degree. While I still have a lab report and presentation there are no more problem sets or hours spent involved in math. Only four more classes left until the end, then finals. The end is soon but it still feels far away, mostly because there is this lab report in the way.

On an unrelated note (sort of) we discussed the Cosmological Constant, Λ, today in general relativity. Most notably the difference in the predicted value based on dimensional analysis (usually a few orders of magnitude correct) and the measure value. The measured value was 10^50 the predicted value. This is the biggest failure of dimensional analysis in all of physics.

Overall I have liked upper-division physics a lot more then lower-division especially for the times when we discuss what we do not know. Learning what we know is nice and all but the uncharted territory is a much more interesting subject (like quantum gravity, I mean an infinite set of coupled equations can’t be that hard…).

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Lab Data

A classic science trap, wait for them to look at the spectrometer and pull the stick away.

After seven weeks of work we have finally taken real data for our senior lab project.

Normally the class is broken into three week labs (2 for the lab, 1 for the report) but two friends and I are creating a new lab. Yesterday everything finally came together and we could actually hook everything up and get some really nice results.

The hard part of our lab is that it encompasses digital electronics, analog electronics, computer interfacing, frequency space, optics and beam vibrations. If we took a few of these parts out it would be a lot easier but not as satisfying.

What we are doing is using a novel interferometer to measure how far a metal beam is displaced at different resonant modes. The trick bit is that when not at a resonant mode the beam is moving fast and far enough to produce a 500 kHz signal. Getting this 10mV sine wave into a series of binary pulses that can be graphed on a computer is a little bit harder then we initially expected.

But now it works. Seven weeks in we can start doing some physics.

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