Relativity made easy?!? WIGGITY WHAA?

If I told the average person on the street that relativity--as in Einstein's general theory of relativity--was fairly easy to understand, I'd either get a) punched for my arrogant presumptuousness or b) stared at like I was crazy. I have in fact said this to friends before, and thankfully received the latter response instead of the former.

The truth is while the mathematics of general relativity might be beyond most of us, the fundamental concepts are not. And as for special relativity, the math is something a high schooler who has mastered algebra and geometry could handle. Imagine my surprise when after calculus-ridden angular momentum, easily the most mathematically challenging aspect of my physics class, we went to special relativity--and basic algebra.

The difficulty of relativity lies in letting go of common sense. Our brains' common sense perception of the world is evolutionarily useful, but not very good when it comes to physics. For example, my common sense right now tells me that I'm sitting still at my computer, typing against solid keys. Physics tells me I am hurtling through the galaxy at bone-crushing speeds, the only force attaching me to the earth is invisible, and the keys I'm tapping on--and most of everything around me--is empty space. My mind, she is boggled. BOGGLED I SAY.

Here are a couple of the general elements of "common sense" that need to be thrown out the window before one can think clearly about relativity.

1) Absolute frame of reference. This one's pretty easy to chuck, even with Newtonian mechanics. If you're standing still on a platform and someone passes by on a train going 50 miles per hour, you perceive the person on the train moving with you standing still. They perceive themselves standing still, and you zipping by.

2) Instantaneous light. You have to think of light as something that has a finite speed--just a really fast finite speed. It's difficult since when we see a light turn on, it's instantaneous. But as a way to disabuse yourself of this notion, watch live news when the correspondent is half a world away from the anchor. There should be a slight delay in their responses to each other. That's not lag--it's because comm signals travel at the speed of light, and the time it takes the signal to get from one to another is actually perceptible to us.

3) Gravity as falling. Gravity is much more than just the force that glues us to the earth. A broader conception of gravity helps enormously with understanding relativity.

4) Absolute time. This misconception is harder to remove. A crude but effective analogy is to think of time zones. The 3:00 PM of a person living in Madagascar is not the same 3:00PM as a person living in Beijing. Now take that concept and apply it not only to hours on the clock, but also to units of time. Your one second is not the same as my one second.

Disabusing oneself of these "common sense" notions of the world is essential to understanding relativity.

DO WANT

For no particular reason, here's a list of video games that I really want now.

1) The Old Republic. I am no MMO gamer. In fact, I have a lot of trouble getting into MMOs, and I find them boring and repetitive. But a fully voiced MMO, of the Old Republic era of Star Wars, designed by BioWare? If this can't convince me to play an MMO, nothing short of a heavenly mandate will.
2) Kirby's Epic Yarn. ADORABLE. 'Nuff said.
3) Epic Mickey. Will it be as epic as Kirby running around being his adorable fluffy self? Who knows? But I'm a Disney fan and have been since about age five, so unless the game sucks--which it won't considering who's designing it--I'll enjoy it immensely.
4) Ninokuni. Studio Ghibli meets video games. There are not words to describe how awesome this could be, unless you tack "epic" onto its title too.
5) The Legend of Zelda: Skyward Sword. Ugh, that HUD from the E3 demos looks fugly. But it's a Zelda game, and it involves flying. I'm not completely sold, but it takes some effort to keep me from playing a Zelda game.
6) Dragon Age 2. I've got my reservations about this game. A lot of them, actually. How will a decade long story be implemented? Will the voice actors be good? Will the dialogue wheel make me say something I really didn't want to about a fourth of the time? But I feel like among all the game developers, BioWare have earned my trust enough where I can give them the benefit of the doubt for now.
7) Portal 2. Portal was like crack. A 2-3 hour condensed dose of gaming goodness that left a horrible crash when I realized that was it. It was all over. Now I can get my fix again :)

Of course, I would happily give up all those games if I could get an old-school BioWare style RPG set in the world of Avatar: The Last Airbender. But that only exists in my fantasies XD

The Neuroscience of Christopher Nolan's Inception: Part 2

As a movie, I very much enjoyed Inception, and I'm currently prodding my family to see it again with me. But I'm not addressing the movie's merits as a movie.

Now that I've seen the thing and no longer have to rely on conjecture, I have a few more things to say on elements of the movie, mostly based off of areas that I misinterpreted given the limited information before the movie's release. Obviously, spoilers follow.

1) The difficulty of inception: I've already covered why planting an idea in someone's head really isn't all that hard. Interestingly enough, the movie's version of inception is more complex. It involves planting an idea and making sure that person believes the idea is his/her own. Cobb's argument for the difficult of inception is that people can always trace the source of their ideas if they were from another person. Which is, unfortunately, patently untrue. Tracing the source of an idea involves remembering where it came from. Neuroscience tells us that our memory is reconstructive. We don't remember events or facts in perfect detail--instead, the brain reconstructs events in a fashion that makes sense to it. This is why eyewitness reports, despite being prized by juries, are factually less reliable than other evidence. The ability of any individual to trace the exact genesis of an idea is pretty wishy-washy.

2) Knowing what you don't know you know: The concept of subconsciously knowing things that you're consciously unaware of is older than Freud, and actually has some truth to it. Certain kinds of learning do not require conscious knowledge of learning. Muscle memory is an excellent example of this, illustrated by the famous patient H.M., who had a disastrous surgery for epilepsy that left him unable to form new memories, and presumably an inability to learn new things. However, H.M. consistently improved at motor tasks like tennis, even though every time the researchers handed him a tennis racket, he claimed he had no idea how to play. Another good example of being consciously unaware of knowledge comes from split-brain patients, who have had the connection between the right and left hemispheres of the brain severed. The two halves of the brain then act almost independently, without sharing information with one another. From split-brain studies, it appears that for an individual to be consciously aware of a stimulus, the stimulus has to be processed somewhere down the line by the left side of the brain--the side responsible for language. It might be a stretch, but it seems like conscious knowledge of something depends on our ability to put it into words.

3) The nature of reality: The ending didn't really come as a surprise to me. It would be strange if a Christopher Nolan mind-screw of a movie gave us an unambiguous ending. However, the questions it raises are more complicated than the simplistic "are we brains in a vat" version. As I said in an earlier post, the difference between REM brain activity and awake brain activity comes down to the involvement of the prefrontal cortex, and the availability of sensory input. The way the dream machine worked in the movie seemed to preserve prefrontal cortex functioning for everyone in the dream: Cobb, his team, and Fisher. Otherwise, there is no way they would be able to plan, reason, and keep track of the elaborate heist.

Now, part of the reason why we can distinguish dreams from reality is their sheer weirdness. Without the prefrontal cortex to make sense of the activity of the sensory association areas of the brain, dreams flat out don't make much sense when we wake up. However, the dreams of Inception are fundamentally different from "normal" dreams. First of all, they are constructed by not the individual's sensory association cortices, but by an architect who pulls everyone into a shared dream. Secondly, the prefrontal cortex is active during Inception's dreaming. At this point, I'm venturing into the realm of conjecture, but it seems reasonable that a dream in which the prefrontal cortex is active and making sense of things would indeed be very difficult to distinguish from reality.

Overall, though, I did really like the film. And while a lot of Inception's claims either contradict or muddle what science has discovered about sleep and dreams, I have to give the movie props for constructing its own internal logic about dreams, and sticking to it. Hopefully, I'm off to see it again :)