Astronomy Packet:  8
Assignment # 3

The Theory of Relativity:

A Clerk in a Swiss patent office realized that Newton's law of gravity while right most of the time, was incorrect when talking about very large and very distant objects.  This man's name was Albert Einstein.  Einstein revised Newton's laws of gravity to make them more accurate.  We call what he developed the theory of relativity.

It is actually two theories.  The first is called Special Relativity.  This theory states that it is impossible to determine whether or not you are moving unless you can look at another object.

Think about that.  If you were in the middle of outer space far from any other objects, how would you know whether or not you were moving?  All movement is relative to other objects.  For example, right now relative to your computer you are not moving at all, but relative to the distant quasars you are moving at nearly the speed of light.  Relative to the Earth, most meteorites move at about 25,000 miles an hour (40,233 km), but if you were standing on a meteorite looking at another meteorite going in the same direction as you and at the same speed, it would not appear to move at all.

Special Relativity also says that the speed of light is always constant.  This means that no matter what you do to light it will always go the same speed.  (Scientists are learning how to make light go faster, but it is very difficult).

The Theory of General Relativity is the one which redefined the laws of gravity.  It says that it is impossible to tell the difference between gravity and the force of inertia from a moving object.

In other words, if you climb inside of a spinning spacecraft, the inertia will cause you to move towards the outside walls in a way that would feel just like gravity.  This is why future spacecraft designs often have large spinning cylinders attached to them.

The Theory of General Relativity also says that large objects cause outer space to bend in the same way a marble laid onto a large thin sheet of rubber would cause the rubber to bend.  The larger the object, the further space bends.  Just like a bowling ball would make the rubber sheet bend much more than the marble would.

Assignment # 3:

Describe Einstein's Theory of Special Relativity.

Describe Einstein's Theory of General Relativity.