Elementlr

This blog has three jobs: a) document my travels, b) show cool things from museums around the world, and c) talk about stuff

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A new paper argues that the asteroid that killed the dinosaurs resulted in global forest fires. That would be consistent with the conclusions of Beerling and co. (2002) who found that CO2 concentrations rose by 2,300 ppm (in context, Global Warming is an increase of ~100ppm over the past century). 

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Yes that is a Pollock, and yes we're seeing what it is made of

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Photons

The speed of light is 299,792,458 meters per second. If you're American, that's 670,615,200 miles per hour or so. This calculation means that when you see light, it has traveled a certain distance. For example, it takes a photon of light from the sun 8 minutes to reach you. Weird, right? Next time you look at the sun, realize that you only see the sun as it was 8 minutes ago. If it had been blown apart by a bunch of hyper-intelligent velociraptors with advanced space lasers riding on sharks, it would take 8 minutes for you to realize that something was amiss. 

...also known as the twin paradox. If one twin gets on a spaceship and travels for a year at a very high velocity from Earth and returns to meet her sister, she will find that while she has aged only one year, her sister has aged many more. This is because time is not constant - it is dependent upon your reference frame. At very high velocities that approach that of light, time slows down from the vantage point of the traveling twin, but continues trucking along as usual from Earth. This bizarreness is due to the fact that we each have an inertial frame of reference. 

What always bothered me about this was the role of light. If light is the fastest thing in the universe, what is its experience while traveling across the galaxy? In science fiction, when a ship moves at the speed of light, how much time actually passes on that ship as it goes to its destination?

Well, the short answer is nothing. Remember the bit about inertial reference frames? That only occurs when you have mass, and space time unfolds into its dimensions and stuff. A photon, or quanta of light, has no mass, and thus has no inertial reference frame. Usually the conversation stops there, with people being politely quiet because no one wants to expose another person's (or their own) ignorance so blatantly. But there is an interesting consequence of this. 

For a photon with no mass, traveling at the speed of light, the lack of an inertial reference frame means that there is no actual distinction between a point of origin and a destination. While our twin had to get on a spaceship to experience the time dilation effect, the photon does not have that problem because it has no mass and thus no particular location in space-time. It is less like a little bullet whizzing around the universe and more like a piece of string that ties its point of emergence and final destination all at once. 

So remember when I said that the light of the sun takes 8 minutes to reach you? Well, that is from your inertial frame of reference due to the fact that you are made up of stuff. For the light, it does not make the distinction of distance. It emerges from a boiling hot pool of radioactivity and enters your eye at the exact same time. It is a string that ties you to the sun. And there are about 10 to the 22nd power doing that all at once in daylight. This is why you should wear sunscreen. It also has some interesting implications for the way we describe light.

For example, it is common for people (well, common among physicists anyway) to harp on and on about the wave-particle duality of light. There are some complex equations that make sense if it is a wave, and others if it is a particle. There's also this thing called the standard model of physics that says that a photon is a gage boson and moves on to talk about other things. But all these concepts, where light is a wave, a particle, and a boson, are incompatible. A particle can't be a wave. A wave would explain interference patterns, but gage boson's aren't suppose to interfere with one another. 

So we end up with this really hard to figure out set of rules. For me, the most troubling problem is that the equations that treat light as a wave work  - different wavelengths produce the electromagnetic spectrum, which explains pretty much everything I use in a typical day. 

But have you noticed the problem with describing light as having a wavelength? Not only does it not explain the boson/modern physics stuff in particle accelerators, it betrays (at least I think) the basic thing about light in Einstein's relativity. A wavelength implies, you  know, a length. But light doesn't have a length, not really. At the speed of light, you are in all places at once. You are emergent from the sun and causing a sunburn on a beech in SoCal at the exact same time.

My physicist boss likes to use diameters as a metaphor for understanding photons (e.g. wavelength = diameter perpendicular to direction of momentum). That way it is easier to understand and doesn't upset the length thing. X-rays have lots of energy, thus are really small and go through you. Cell phone signal has less energy and thus interacts with the iPhone/Android/Blackberry (just kidding, iPhone/Blackberry) in your pocket. It all comes down to metaphors to describe light (equations and all), because it is hard to fit something that doesn't have a frame of reference in our frame of reference. Let me know if I got any (or all) of this wrong, but it seems like there is still a lot of darkness surrounding light. 

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My roommate in Okinawa

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Suddenly, some of the spectra I've been seeing makes sense. 

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...and here, in case you wondered what it sounded like.

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Everyone should learn about the fossilized cookie monster. Like, right now. 

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Energy, Current, Filter, Time, Atmosphere

Today I worked at the Baekje Museum in Seoul, South Korea. While working on glass, we tried to look at the sodium in glass. "Sodium in glass?" You might ask. "Like, salt in glass?"

NaKa1 - means K-alpha shell in Sodium. A peak is a good sign. 

For visible light to pass through silica (the element that comprises most of glass) it needs an additional element to set it straight. Usually this is sodium (cheap) glass, potassium (iPhone) glass, and lead (dangerous) glass. Both lead and potassium are easy to see because they are 'heavier' atoms in the sense that they have more protons and neutrons. Sodium is at the lower level of detection because it is a lighter element. 

Because sodium is so light, it is easily blocked by photons bouncing around the nitrogen and oxygen in our air. We can use a vacuum (atmosphere) to remove those troublesome elements, but we need to tailor our analysis a bit further. I reduced the keV (energy) from 40 to 4.5 by working in x-ray ops and tinkering around with settings. This concentrates the elements we engage to just those between Titanium and Sodium (or, more like the copper L lines). I then ran it with these settings at a high current with no filter and for a long time to engage as many photons as the sodium as possible. Thus, sodium in the glass. 

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While I was in Tokyo, there was never a chance to see Mt. Fuji. On the plane, departing at sunset, the horizon was totally pink. As it banked away from Tokyo, Mt. Fuji wore the sunset like a cloak. I wish this photo did it justice.

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On a plane to Seoul. Goodbye Tokyo!

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Inaugural post: on the way to Narita Airport via Tokyo