This post will be a prologue to our fifth point, which I will reveal in the next post, okay? With that done, today’s lesson has something to do with gravity. Oh, yeah! We’re finally entering the General Theory of Relativity sphere! Hooray! Now, let’s go forth!
In case you have forgotten, the first ones we tackled were for the Special Theory of Relativity which deals with smooth, straight motion. But since smooth, straight motion isn’t the only type of motion in the world, Albert had to think of the Theory of Relativity that dealt with all types of motion — spinning, curving, slowing down, etc. Thus, the General Theory of Relativity was born.
It took some time for Albert to find a foothold idea for this. Until one day, in his office, he had ‘Eureka!’ moment, or, as he called it, his ‘happiest thought’. That would be: gravity disappears when you fall of a house. Funny, ain’t it? This would be best explained with an illustration, so prepare for another one of my crappy photos.
This means that when you’re falling, you don’t fell the pull of gravity. D’you know that scene in Spy Kids II: Island of Lost Dreams where they fall into this hole and it seemed like it never ends? That’s how the sensation’s like, I think. Basically, it means that if you don’t feel gravity while you fall, it means that the pull is exactly right to cancel your inertia.
At this point, Albert states that whatever gravity could do, acceleration can do too — and vice versa. In essence, gravity is a form of acceleration. If this is really the case, then a beam of light on Earth should behave the same way as a beam that accelerates upwards. Through a though-experiment, we can see how light behaves in an accelerated room.
Take two super-ultra-athletic…athletes into the scene. Athlete A stands behind a laser gun while Athlete B hold a plate of dome-shaped jelly. Yum.
1.) First. As Athlete A fires, Athlete B simply holds the plate of jelly still. This would, of course, simply drill a hole through the jelly, producing a straight line through.
2.) Second. While Athlete A fires the laser while Athlete B holds the plate up. So, the edge of the melted area is a sloping line, forming a right triangle.
3.) Finally, As Athlete A fires, Athlete B moves the jelly slowly and gradually accelerates it. This results to the melted part of the jelly being a curve. So, if acceleration curves light, then gravity does too. Just like how gravity curves the water coming out of the hoses our two athletes are using now to kill the fire from from the burning jellies.