Because the Universe is Confusing
Archive for April, 2008
Physics is Cool #2
Apr 26th
In an effort to shun all practical thinking about how a career path is really about the people who pursue it, I continue to persist in my efforts to believe physics is cool. After all, just because Hitler was a shit painter doesn’t mean painting is a bad idea, right? Okay, the analogy does not entirely work, but it makes me happy for the moment. Speaking of Hitler, happy Passover kiddies! You may or may not have noticed that this year’s Pesach celebration began on the 65th anniversary of the beginning of the Warsaw Ghetto Uprising. As Mel Gibson (my favourite Jew-hater ever) once said in a decent movie, “You may take our lives, but you will never take our freedom!”
Can you tell that I am in the middle of Ben-Hur? I feel bad saying this since he just died, but that movie starred another fascist piece of work. But, the messaging is good, and somehow Judah Ben-Hur (Judah Son of Hur) is a slave hero even though he’s a slave owner himself …
But I digress. I was babbling about how physics might still be cool despite the coworkers who like to make Nazi jokes. Ha … h ….
In physics there is physics and then there is technique. The difference between technique and mathematics may simply be personality and personal taste — one man’s technique is another man’s physical wonderland (just ask the string theorists if you don’t believe me). Quantum field theory is an example of something I think of as technique, but it would never be taught in a maths department. In the maths department it would be called group theory for physics, or group theoretical applications to physics for mathematicians. Bla bla bla.
What is quantum field theory? It is a way of making the possibly unholy marriage of special relativity with quantum mechanics possible. In some sense this is a very basic idea — we want quantum mechanics to be accountable for the fact (so far) that the speed of light is finite. In other words, information takes time to arrive somewhere and cannot instaneously jump from point A to point B.
In order to make quantum mechanics amenable to our purpose, however, we must do some fancy tap dancing. Dance puppets dance, the universe yells! The modifications are somewhat complex, but I think it can be put simply to this sort of strange idea: we have to build a quantum mechanics at each point in spacetime, and this collection of quantum mechanics’ is known as a quantum field.
Tada!
To the hoosier who is saying, “but who gives a fuck?” I offer the following. Isn’t it kind of radical that such a simple idea requires a complete rethinking of how we apply what we already know? Even as we build on what we already know, in the process we reshape what we thought we knew. The development of quantum field theory is a case in point. Additionally, it turns out to be an incredibly rich way of looking at the quantum world: every tiny particle that we have observed so far has been predicted in the rich accounting of quantum field theories, which we call the Standard Model.
Cool Science #1
Apr 20th
I’ve been kind of depressed/busy/depressed/who knows lately, which has meant no posting either here or on the phunsics blog. Basically, I haven’t been having a good time with physics recently, for the usual reasons that grad students are totally miserable. Things have been so yuck that I actually got even more serious about my persistent to threat to apply to law school than I usually do. I actually picked out schools I might want to go to!
This has made me thoroughly depressed about life. As I approach my 26th birthday, I am approaching the anniversary year of my first foray into academia. What have I done with myself? Who I have I become? Where am I going? Nowhere good if the demoralization keeps up. So, in an effort to curb the Great Sadness, I have decided to try to write entries on a regular basis about something in physics or science that is cool.
Tonight’s entry is about why the moon looks orange near the horizon. So, what’s the deal with that?
First of all, where does moon light come from? The sun! The only objects in the universe that are energetic enough to produce light are highly energetic ones like stars, gases near the centres of black holes, [whatever makes cosmic rays], etc. The sun shines light onto the moon just like it shines on earth, and in turn some of the light bounces off of the moon and lands on the earth.
However, before the light gets to our beautiful eyes, it must travel through earth’s atmosphere. The atmosphere is made of a lot of (increasingly man-made) gases. Generally speaking, when light passes through a gas, the gas acts like a filter. What kind of filter depends on the properties of the gas. Thus, the atmosphere acts like a filter, which happens to discriminate against bluer wavelengths. Everything is a little bit redder when it gets to us!
But if the atmosphere is essentially the same in all directions, why do we see the moon in different shades depending on where it hangs in the sky? This is actually a geometry problem. When the moon is at the horizon, the light from the moon has to travel through the atmosphere longer than when the moon is overhead. The longer the light travels, the more it scatters inside the atmospheric gases, and the more the poor blue gets filtered out! When the light finally does get to your eyes, it’s red.
So, why is this cool to know? Well, light is always a cool thing to think about. It is ubiquitous in the human universe — essential for survival from the physical plane to the psychological. And it’s fun to think about this thing we observe regularly, the moon rising, and how we can understand its red appearance with the same math and physics that we use to understand all sorts of stuff, for example the electrical properties of a material. (Look up mean free path on google if you want to know more.)
Black On Both Sides: Misconceiving the Black Canadian Experience
Apr 9th
So a lot of stuff has been going on recently: my back has been behaving sucktastically, the sun started coming out again (unfortunately), I read a bunch of books, I spent too much time at PI which meant I got little work done, and I went to Montreal and spent a lot the visit in Lucy’s hotel room writing an essay, published today on Is Greater Than.
Black On Both Sides is my ode to the Black experience in Canada. I hope you read it and comment on it (thoughtfully and respectfully of course!). I had also hoped that in writing it I would excise some demons, which didn’t happen in the end. But at least in writing it I understood some things. I hope others will too.
