2010/09/26

Taking things for granted

When I was in high school I first tried to understand the concepts of special relativity, because it seemed such a strange idea that nothing can move faster than light. Even after learning that Einstein basically derived the theory from the principle that everyone, no matter their speed, experiences the same laws of nature, and therefore the same speed of light, I couldn't just accept what was now an almost trivial conclusion.

A few weeks ago I read somewhere (it's a shame that I forgot where exactly) about Einstein realizing that special relativity was built on a circular definition of inertia. There's a relativistic formula for calculating the mass of an object given its speed in some frame of reference, but it also defines the rest mass of an object as the inertia it has at speed 0. So even Einstein himself had doubts about his own theory.

Now consider the following thought-experiment: a meteorite of 1 kg speeds right at you at 99% of the speed of light. A quick calculation learns that the relativistic mass would be around 50 kg. Regardless of whether or not this calculation was right, suppose that it misses you by inches, and right at that particular moment you give it a sideways push. I'm pretty sure that you would experience the meteorite to have a mass/inertia of 1 kg, still. So did the mass of the meteorite have a direction or something?!?

So assuming conservation laws of momentum and energy, and the principle of invariant laws of nature in moving frames of reference, I'm lead to the conclusion that my concept of mass is flawed. And now I'm wondering why I took it for granted for more than 33 years, and whether I should redefine the concept, or just ignore it and go with momentum all the way instead.

And, I'm beginning to wonder what else I'll have to give up, and what I'll be left with eventually.

2010/09/15

Why another blog?

It's a strange paradox that the more you read about a complex topic, the more you realize that you won't ever be able to grasp it all. This paradox certainly applies to physics, and I therefore feel that it's a miracle that humanity has been able to adequately describe the universe at all, and that it was possible using only two theories: general relativity and quantum mechanics. Unfortunately they don't mix well, and yet our universe is predictable and consistent.

I would like to recommend the book that made me first realize just how incompatible those two theories are: 'The Emperor's Mind' by Roger Penrose. It tantalizingly gives a few of those ideas that demonstrate rather painfully how incomplete physics actually is.

Optimists are convinced that a grand unifying theory of everything ('GUT') is just within our reach, but I doubt that their knowledge is sufficiently broad to discover such a theory. And the more involved they get into the subject, the more insufficient it'll get too. With plenty of potential ideas that could attribute to GUT, it becomes exponentially harder to choose the right ones. We seem to be in need of a new "Homo Universalis", someone like Leonardo da Vinci, someone who's proficient in every branch of physics, with a sound philosophical background, to see the entire picture, and know what is to be done. But my hopes are slim. Who knows, maybe the efforts of a curious layman just to organize the current mess of hypotheses will help a bit. It'll surely be useful to myself, and that's frankly the main reason for me to start this blog.

So what are our candidate ideas exactly? What mysteries are still left unsolved? What clues did history leave behind for us? It's time for a journey.