Posts Tagged ‘Physics’

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

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.

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 is running. Assuming on lived.

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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A basket in the San Francisco Asian Art Museum.

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.

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.

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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The LHC beam line leading to the ATLAS detector.

The LHC beam line leading to the ATLAS detector.

I watched Angels and Demons last night and could not get over the bad science. It came it two distinct varieties, the first is straight up bad or media-hyped style science the other is in the character of Vittoria, a CERN physicist. (There may be spoilers)

In the film there is concern  the LHC, when switched on, will create antimatter for the first time in the start up event (but not afterwards). This part hurt. Anti-matter, first proposed by Dirac in 1928 is created quite often in particle accelerators and hospitals.

The LHC had some typical science-movie computer interfaces though I was concerned with the part where people were walking in the tunnels as the collider was running. Personally I would not want to be in those tunnels during operation, the massive x-ray radiation generated would not be conducive to ones health, in any situation.

There are also some issues with the device used to hold the ant-matter but I will let that go as it is movie and necessary to the plot.

Then there is Vittoria the bio-entanglement physicist. I wish I knew what bio-entanglement research is or in particular how it links to energy companies, it must be a nascent field. Two comments she made in the film diverged to how a physicists (at least those I know) would really think.

First she said that she never thought that collecting a significant amount of antimatter could ever be used as a weapon. This is just wrong. Physicists realize that their work often leads to improvements in military technology, likely due to the military being a source of funding.

Finally there was the reference to the Higgs Boson. But she never said the word Higgs or boson, instead kept using God Particle. Something that is only done by the media or scientists talking to the media in an attempt to stop that particular nomenclature. I suppose that since this movie had a lot of religious themes in it the god particle seemed like a better choice. Still it hurts to hear it.

Eventually a big budget summer blockbuster film will consult with a few scientists while writing the script to get the science right.

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Refocusing a camera lens onto radioactive material.

Refocusing a camera lens onto radioactive material.

Going farther into physics results in some interesting numbers.

The mass of the sun is 1.48 kilometers.

The mass of an electron is 0.510 mega-electronvolts.

And of course the greatest equation relating the speed of light and Newton’s gravitational constant:

c = G = 1

The great thing about the above equation is that everything can be measured in terms length and units no longer pose a problem, just add them in until the equation balances.

And compared to the sun the earth has a mass of 0.443 centimeters.

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Cold Feet

Just cold.

Just cold.

Either physics students either have a propensity to not wear shoes or people who don’t wear shoes are drawn to physics.

In either case there is a disproportionate number of physics students who do not wear any footwear at all, no matter the situation. I thought it was just a Santa Barbara thing, seeing as we have fairly nice weather, then when visiting other school I notice that it is a national phenomena. Snow, rain, sun – no shoes.

I understand it a little bit, in particular the not wearing shoes around campus. But not having protective footwear when venturing into Isla Vista, labs or into, say, dining commons just seems a bit risky.

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