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.
No comments:
Post a Comment