Can anyone explain Einstein's theory of general relativity to me?

Question

I'm doing a report that has it as a background concept, and erm, I haven't really learned about it so I'm finding the report a little difficult. :p Can anyone explain it to me in English? Without any equations, please, my brain can't handle those right now. :)

Thanks jack d that helps a lot! I guess I should add something to the question though... what does general relativity have to do with black holes? Thanks guys.

Brad -- Haha, I like that one.

gp4rts -- Thanks a lot, that really helps!!

braxton_paul -- That's a cool way to explain it, awesome. Cool avatar btw :)

Answer 1

General relativity has to do with gravity and acceleration. It is based on the equivalence principle that states that you cannot distinguish between being in a gravitational field and being accelerated. The usual example used is that of an enclosed elevator on the surface of the earth. If the elevator is stationary, the occupants will feel a force pulling them down; if they drop an object, it accelerates at g. Take that elevator into outer space, attach it to a rocket and accelerate it at one g. The equivalence principle says that there is no way for the occupants to tell the difference.

From that simple concept Einstein developed the concept of gravity being a manifestation of the curvature of space-time produced by masses.

The idea of black holes comes from the mathematical solution of Einstein's equations for a concentrated mass. The equations showed that there is a radius from the mass such that within that radius nothing can escape, even light. This is called the Schwarzchild radius (after the mathematician that solved it). At the time it was believed that no mass could be so concentrated that the S. radius existed outside the mass. However, the discovery of collapsed stars has indicated that this can happen.

There are many excellent books on this subject; do a search if you want to learn more.

Answer 2

General relativity deals almost exclusively with gravity and acceleration --

Acceleration and what we call gravity are exactly equivalent. If you were drifting in space inside an enclosed room and suddenly felt yourself being pressed to the floor you could not tell whether that force was due to gravity or to the room accelerating upward.

What we call gravity is actually a distortion in the "fabric" of space-time caused by the presence of anything with mass. Imagine a thin rubber sheet with a bowling ball resting on it. Where the ball touches the sheet there will be a dimple. In this analogy, the sheet is space-time and the ball is mass. If you wanted to climb up the slope of the dimple it would take energy to do so. If the bowling ball was massive enough, the dimple (..gravity..) would have a slope so steep that no applied energy would be enough to enable one to climb out of the hole. Not even light could escape back onto the flat areas of the sheet. Such a condition occurs in nature where mass is so great that nothing can escape from the gravity it produces. We call these things black holes.

It logically followed from the above that the path followed by light itself must curve when it passes by some mass. Many very precise experiments showed this to be true.

What still hasn't been explained, though, is just how mass effects space-time the way it does.

Answer 3

In simplest terms Einstein's general theory of relativity states that any physical occurrence is relative to the point of reference from which it is observed.

For example. I am standing still watching a plane in the sky. To me it appears to be going very fast. My friend is on a train going very fast in the same direction as the plane. From my friends point of reference, the plane appears to be going slower than it appears from my point of reference. Even though, the plane is speed does not change.

Hope that helps.

Answer 4

on your classification room, you experience sleepy mutually as your instructor teaches... you close up your eyes and sleep for what feels like an hour...yet then you fairly locate that purely 5 minutes have surpassed... yet interior the morning, after switching off the alarm, you prefer to sleep for yet another 5 minutes...yet once you awaken, you detect which you have slept for an hour! theory of relativity is extremely the belief of "actual"itivity !

Answer 5

a great example that i like is (if your a guy or a lesbian i guess) and your holding hands with a girl you like 30 minutes will seem like 30 seconds if your just sitting by yourself 30 minutes will seem like an hour