Sidewalk Chalk

I wasn't sure who I was going to vote for in the primary, coming up this Tuesday. I guess it's basically between Obama and Clinton at this point, but they both make such good points in their debates, I really can't decide between them. Luckily, someone at USC decided to make it easy for me. They wrote, in big sidewalk-chalked letters, multiple times, on the corner of Jefferson and McClintock, "Vote for Barack Obama," "Vote Obama Feb. 4th," etc. I guess now I don't have to worry about their voting records in the Senate, their policies on gay rights, immigration, the war in Iraq, etc. Someone has made the decision for me, and informed me of this service, via sidewalk chalk. Thanks guys.


Spring Semester 2008

There's no better way to celebrate surviving the first week of class than going directly into the first three-day-weekend of the semester. And no better way to spend a Sunday afternoon on such a weekend than to blog about that week. These are my classes for the semester:

MATH 445: This class is going to be all about partial differential equations and such, but so far all we've done is Fourier analysis, which allegedly is an important step towards solving PDEs. My favorite parts of this class are the professor telling us that the required textbook kinda sucks, but we have to buy it anyway, and the fact that we spent almost no time on boring administrative stuff, instead diving right into Fourier series, deriving the formula for it, and then proving it converges, all in three lectures. For the first time in a USC math class, the homework is actually required, but there's none assigned yet.

EE 101: Very low-level digital logic stuff. Binary representations of numbers, and gates, or gates, etc. The "textbook" for this class is a course reader that only cost about $18, and since everything so far is fairly trivial, I've been reading ahead about how to build multiplexers and adders and such. Seems like this is going to be an easy A.

MUEN 308: Men's choir. I did this last spring, but I've never done it in the fall. I guess this is a pattern that could continue to work: Band in the fall, choir in the spring. Anyway, the director is redoing some pieces from last semester, which puts the new people (there are about five of us) a little behind. This was fun last year and it's looking like it will be fun again this year.

PHIL 262: This is my category I GE. The title is something about "Mind and Self." Since this is a philosophy class, I was worried it would be a little like this. And it might be, but I'm very optimistic about it, at this point. The professor told us we can call him Jake. "You do NOT need to call me Professor Ross. My father was Professor Ross. Well, my father wasn't a professor, but if he had been, then he would have been Professor Ross." What's more amazing, he actually listens when students ask questions, instead of assuming he knows what they're going to ask, then going on and on about something unrelated. Again, it's only the first week, and we've already examined five alleged "proofs" for the existence of God. Not an easy A, but it should be interesting.

CSCI 101: I had already heard from my friend Greg, who took this class last semester from the same professor, that the professor wouldn't be all that great, and it's looking like it's going to be a few weeks before we get into anything remotely challenging. Eventually, I might learn something, and it looks like another easy A.

Basketball Band: Another semester of Tony Fox. Joy. This week, we recorded this Foo Fighters song for some youtube contest. Every other week is going to be pretty lame in contrast.

Concert Band: This year's show is all Broadway songs, so I couldn't really pass this up. Still, I feel like the music is way over my head, so I'm going to have to practice a lot. Apparently, I'm allowed to reserve PIC rooms since I'm officially in this class, even though I'm not a music major. This could end up being a really rewarding experience.

Overall, I'm pretty excited about this semester, and I'm fairly confident that my GPA will go up when it's all over.


Cloud Appreciation Society

Through my youtube subscription to AtGoogleTalks, I found this talk by Gavin Pretor-Pinney, a man who started the Cloud Appreciation Society. From their website:

You love lying in the park on a summer’s day and looking for shapes in the cumulus clouds. You think a mackerel sky of puffy altocumulus stretching off towards the setting sun is one of the most beautiful sights in the world. In short, you love clouds. And yet everyone else just seems to complain about them. Are you the only one who thinks life would be poorer without these glorious ‘patron goddesses of idle fellows’?

No, you’re not. There are others like you. And together we’ll fight the sun fascists and their obsessions with ‘blue-sky thinking’. As a member of The Cloud Appreciation Society, you’ll receive a free membership certificate and a badge (as shown to the right).

The badge is a little pin, and the certificate says:
The Cloud Appreciation Society

We do hereby certify that [name] was elected as a member of this society on [date] and will henceforth seek to persuade all who'll listen on the wonder and beauty of clouds.
I don't want to get in the habit of just posting links without adding my own insight or comments, but the main reason I want to post this is that I think it's extremely amusing that this exists. It's not a joke either. Mr. Pretor-Pinney seems completely aware that this is a rather whimsical idea, but he also seems completely serious about the goals of the society, and fighting the sun facsists. As I'm typing this, I'm almost halfway through his hour-long talk at Google, at which he apparently just talked about clouds, showed pictures of clouds, waxed poetic about clouds, on and on, in his British accent.

But if you think about it, why shouldn't there be such a society? Clouds are amazing if you don't know how they form, and arguably even moreso if you do. Why should we think of it as childish to appreciate them? It's no weirder than birdwatching, or mountain climbing, is it? Why aren't there millions of societies out there for the appreciation of each different natural phenomenon or flower or animal? (I realize there probably are such societies, actually.) I probably won't actually join, even though that pin is kind of awesome. I have a tendency to lose pins, anyway. But it's great that this website exists and everything.

Okay, what's my point in posting this? Besides just saying, "Hey look at this. Look at how silly this is." I suppose my point is this: Clouds are easy to see, it only takes a little bit of imagination to enjoy them, and if you take the time to enjoy them, you can see all kinds of different shapes. Maybe this guy is really onto something important, or at least something fun and obvious that everyone has forgotten.


Portal Physics

I really want to post with some consistency, even if I'm just rambling. So tonight, I will be rambling about the physics of the popular video game Portal. In case you're unfamiliar, you can read about it online, but basically, you're in an enclosed room, armed with nothing but a special portal gun. Shoot it at a wall to create a bluish portal, and at another wall to create an orangish portal. As if by magic, the two portals will be connected, so that you can send any object, including light, or yourself, through one portal, and it will come out the other. You use this to transport yourself or other objects to places that would otherwise be unreachable. It looks kind of like an FPS, but it's actually more of a puzzle game, which is why I like it. Of course, teleportation in video games isn't new, but what's unique about Portal is that the momentum of objects is also transferred through the portal, which leads to some very interesting solving techniques. For example, if you're on a high "cliff" next to a wide, deep chasm, and you need to get across the chasm, but can't create a portal on the other side (some walls resist the portal gun), you can shoot one portal in the wall next to you, so that it faces across the chasm, then shoot another on the ground of the chasm, way below you. Then jump into the lower portal, and you will soon find yourself shooting out of the wall portal, across the chasm. Of course, almost as much fun as actually completing the game is running through some interesting hypothetical scenarios. I really am just rambling here.

Put one portal on the ceiling, and another on the floor, directly below it. Jump into the floor one, and you'll fall out of the ceiling and into the floor, infinitely many times, moving faster and faster each time. (You can actually do this in the game, and there is apparently some kind of randomization built in that causes you to slightly miss the floor portal after a few iterations. Suppose that didn't happen though.) Suppose you keep your body oriented the normal way. If you look up or down, you see an infinite tunnel of portals, similar to the infinite "hall of mirrors" effect if you stand between two parallel mirrors. Clearly, each time you go through the portal, your kinetic energy is unchanged, but your potential energy increases by your weight times the height of the ceiling. So yes, conservation of energy is being violated, but don't worry about that for now.

As the person goes faster and faster, they measure the distance between the floor and the ceiling to be shrinking, according to special relativity. Eventually, this effect should be so pronounced that, according to the person, two or more parts of the body are at the same place relative to "the" floor. For example, suppose the room has contracted enough that its height is half that of the person. Just as the person's feet are entering the floor portal, his waist is also entering the "previous" floor portal. The person might cite this as evidence that there truly are an infinite number of portals. Meanwhile, an observer sitting quietly in the room would see the portal traveller shrunk to about half his normal height.

I can see that having a basic understanding of special relativity, and almost no understanding of general relativity, is going to be a problem. Still, let's go on. What if the falling portal traveller starts feeling sick, and shoots a portal onto the floor nearby, with the same color as the current floor portal, so they will instantly stop? Putting aside the broken bones and bruises that will likely result, we now have a paradox. If the portal traveller and the stationary observer were both wearing watches, each would have said the other's was running slow. Now that both are in the same frame of reference, which watch has the earlier time, assuming the traveller's watch miraculously didn't break upon impact? Admittedly, no real physical theory should be required to answer this question, as we've already violated conservation of energy, but it's still an interesting thought.

One thing that is completely absent in the game (and probably for good reason) is any significant quantity of liquid. Suppose you have two large tanks. Tank A is full of water, and sits on the ground. Tank B is elevated somewhat, and initially empty. A portal is created that connects the bottom of both tanks. What happens? My first thought is that it works like a siphon, with water "seeking its own level" -- that is, water will flow through the portal, filling tank B, until both tanks have exactly the same water level, relative to the ground. By this logic, if tank A is lifted up after equilibrium is reached, water will again flow from A to B. I can't see why this would happen, so I think a new hypothesis is needed.

One of the first things we learned in PHYS 162 last semester is that electric field lines always diverge from positive charges and converge to negative charges. They never form closed loops, and can only start and end on charges or go out to infinity. Suppose a room contains a single positive charge. If you can trace a field line through a portal, it should come out the corresponding portal, potentially at a different angle. Assume the portals are as in the first situation: one on the ceiling, one on the floor. It seems to me the only way to draw the field lines accurately would have to be by modeling the setup as an infinite set of rooms, stacked one on top of the other, each containing a single positive charge. Further evidence that the portals really do create "copies" of the room, rather than simply connecting two parts of the room which are normally separate.

What if you dropped the positive charge into the portal, the same way we dropped a person through it originally? You would have a moving positive charge, i.e. a current. I suppose this would set up a magnetic field in the room, which would be constantly increasing. If you used two floor portals, instead of a floor and ceiling portal, you would effectively have two nearby AC currents, thus instead of infinite kinetic energy, you could create infinite electromagnetic energy.

I think that's enough for now.