h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The other idea that relativity is based on is that the laws of physics are the same everywhere, under all circumstances. For example, a ball dropped in an aeroplane falls in the same way, relative to the plane, as it would on the earth's surface, relative to the earth.

Annoyingly, the equations of general relativity are undefined in black holes, so there *is* a circumstance where they might be different.

Speaking of general relativity, there's no mention of it at all in this article. As it stands, though, the article is a fairly good explanation of special relativity.

I would appreciate it if you kindly define in the same way. A ball dropped from a airplane would fall at the same speed, in theory, as everything else. And, as I recall, relativity states that as ones gravity is increased time seems to slow down, hence the gravity in a black hole. But that gets rather confusing.

Standing on a plane is much the same as standing on the ground. The plane and everything in it just happen to be moving relative to the earth.

If you drop a ball at sea level on earth, the ball will accelerate towards the earth at 1 g. The same is true of a ball in a plane. The difference between the two balls is that the one in the plane is moving relative to the earth. This motion is at right angles to gravity and is therefore unrelated. Since you are moving horizontally at the same speed as the ball, this motion makes no difference to the ball's behaviour from your perspective.

On the other hand, if someone were able to look through the window and see you dropping that ball, he would see you moving in a straight horizontal line, and the ball in a curve, the ball's trajectory getting steeper as it gets closer to the cabin floor. This is best described by a pair of stop-motion photographs... unfortunately I don't know of any on the web so ASCII art will have to do: http://www.bbc.co.uk/dna/h2g2/classic/A523766

In general relativity, if you got really close to a black hole, going head-first or foot-first towards it, you would be torn apart by the difference in gravitational pull between the two ends of your body. However, the effects on your perception of time might be such that you would die of old age before that happened.

Thanks, I think.

That ASCII thingy looks best in Classic Goo for some reason. I've added a bit of explanation to it.

One more try,

1. The black hole only chagens the perspective of time, not actually slowing time?

2. The ball from the airplane falls much like a graph of exponential decay. Assuming so how did things, such as bombs, droped from planes over the intended target hit that target?

#2 Bombs were not dropped over the target, using a specially designed sight which made allowance for height, speed,wind etc the bomb was dropped Before the plane got to the target.

Despite their claims to the contrary the USA was no better at hitting the target than anyone else.

One of the few raids that were designed to be reasonably certain of hitting their target was the RAF raids on the Dams made famous by the film 'Dambusters'. The reason for their accuracy was that they were dropped from a very low heght, but in general bombing in the second World War was something of a hit and miss affair