TOPIC2-SPACE AND TIME

Aristotle

1.The natural state of  a body is to be at rest

2.Body will be moved only if driven by a force.

3.By pure thoughts people can work out all the laws that govern the universe.

Galileo

1.By letting go of balls of different weights on a smooth slope.

2.The effect of a force is to change the speed of a body.

Newton

1.First law :keep on moving at the same speed if not driven by any force.

2.Second law:if acted on by a force ,the body will accelerate at a rate which is proportional to the mass.

3.Law of gravity:one body attracts the other body (predicting the orbits of the earth)

4.No unique standard of rest.

5.Lack of absolute pposition,but the absolute time exists

Maxwell's equation

Radio or light waves travel at a certain fixed speed.

Albert Michelson

confirming that the speed of light is exactly the same whatever the direction

Einstein

1.Abandoning the absolute time

2.Nothing travels faster than the speed of light(because of E=MC2)

3.Time is not independent of space

4.The light spreading out from an events form a cone in the space time 

5.The special theory of relativity don not accord with Newwonian theory of gravity

6.So Einstein put forward the general theory of the gravity

I.Gravity is only a consequence of the fact that space time is not flat 

II.Light should be bent by gravitational fields

III.Time should appear to slower near a massive body like the earth