Wednesday, January 31, 2007

John Edwards is consuming good bloggers at an alarming rate

by that I mean he's hiring them. And it's a good thing. He seems to be courting the feminist vote, what with hiring Amanda Marcotte and Shake's Sis. I've always liked Edwards, and I think this speaks well for him. I have grave reservations about Hillary Clinton, mostly because I think she's just too much of a politician, too much about compromise, and making a deal, and not enough about standing up for the issues. I also like Obama, but I think it's a bit early to put him on the ticket, maybe when he's got some more experience under his belt (though I would probably forgive him that if he weren't so pushy about religion).

Of course none of the candidates are perfect, but Edwards it at least worth consideration in a race most consider to be between Hillary and Obama.

(neurotic note: I call Hillary Clinton by her first name to avoid confusion with Bill Clinton, but call the other candidates by their last names because other than Barack Obama, all of their names are nondescript)

I've just realised

google owns the internet.

That is all.

hmm... this could be bad

so my computer is making strange noises, and the power supply fan is not running. The power supply isn't hot, but as that is where the noises are coming from I am going to replace it (with a really beefy 550w one).

In other news, I need a job, if anyone in the Philadelphia region is looking to hire an undergraduate physics student for six months drop me an email

Sunday, January 28, 2007

a qualitative comparison of music websites

I have found 4 relatively new music sites. All offer free music listening, 3 offer music downloads, 1 for free and 2 for money. The sites are:
  1. Magnatune, a music store that offers free streaming as well as cheap ($5) album downloads, with no DRM (you can get a plain mp3).

  2. Mindawn, a music store that offers free demos that self-destruct after 3 plays, and not quite as cheap downloads ($6.99 for a lossy format, 8.99 for a lossless format, or pay by minute) without any DRM either.

  3. Jamendo, a free music site that offers streaming music and bittorrent downloads. It also has the prettiest website I've ever seen.

  4. iRateRadio, a java app that runs on all the major platforms and streams music from a variety of free sources, and tries to determine what you like from how you rate the music.

I liked Magnatune the most, the music is all very good, the interface is good, and the downloads are cheap. It seemed to be the most developed, having the largest number of download options. Oh, and it has Amarok integration. Jamendo is also good, the music is a little bit more iffy, and lots of the "albums" are very short, more properly EPs, but the interface is very nice and offering free bittorrent downloads (which are always well seeded) is very nice. Jamendo is a Luxembourger website, so the music is very Europe biased, whereas the others seemed more American biased, so it was a nice change. Mindawn seems to have a very large selection, but requires its own client to listen to music, and is more expensive than magnatune. One thing that is nice about it (for someone like me who is an amateur musician) is that all the artists get at least 55% of any profits, and 75% for Mindawn exclusive content. Magnatune splits all profits 50-50 with the artists. iRateRadio is a promising idea, but I found the client clumsy and slow (it is java, so these things are to be expected), and I listened to 3 songs that I didn't like before I gave up. It might be nice if you give it a chance, and maybe I will, but be prepared to listen to some stuff you don't like first.

Nonlinear Dynamics: what is it?

So I'm taking a course in nonlinear dynamics this term, and its really cool. Nonlinear dynamics is the study of chaotic systems in physics. So what does that mean?

Chaos is a technical term in physics meaning that something is deterministic (follows knowable laws), but unpredictable. Weather is chaotic, we understand a lot about how temperature and air pressure affect the weather in the short term, but long term prediction is almost impossible, very small errors in the measurements of the weather now leads to very large errors later on, and since there is always some error in any measurement we are stuck.

That doesn't mean that things are hopeless, however. There is quite a bit we can learn about chaotic systems, especially by studying simple mathematical chaotic systems. One of the simplest is the logistic map. Basically given some value x, you can get a new value x' by x' = λ * x (1-x). Given suitable values of λ x will stay between 0 and 1, no matter how many times you iterate it. It is used to model populations in biology. I you iterate this a whole bunch of times (like 10000) one of three things will happen depending on your value of λ: 1) x could diverge off somewhere, these are what we would consider unphysical solutions, these values of λ are not interesting, and we do not study them. 2) x could settle on one (or more) stable values, we call these orbits. 3) x could be chaotic, essentially be randomly distributed within a certain range.

One very cool thing about this, is that if you start with a stable orbit and increase λ by a certain amount, you will have 2 orbits, increase it by a smaller amount and you will get 4 and so on, we call this a period doubling cascade and it goes on until the number of orbits is essentially infinite and the system becomes chaotic (the picture from wikipedia is a graphical representation of this). The interesting part about this is that if you take the ratio of the amounts you have to increase λ by to go from the start of the orbit to the end of the orbit, and the same for the next one you get a number that is constant for lots of similar types of systems. This is called quantitative universality.

OK, that's enough for now, maybe I'll post some more on this in the future.