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Introduction to Einstein and Relativity.

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Introduction to Einstein and Relativity.
milkyrain
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Joined: Dec 04, 2007
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Posted 12/05/07 - 09:55 AM:
Subject: Introduction to Einstein and Relativity. 		quote post
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St. Augustine thought that time did not exist before the beginning of the world and Einstein confirmed this one hundred years ago. Time was shown to be just another dimension like the three spatial ones we experience. Time and space are entwined so time too curves under gravity when the universe does.
Einstein thought about Galileo's relativity, that we did not feel the movement of the Earth because we were moving at the same speed as it. It is only a change in acceleration that can be felt and so Einstein realised that no scientific experiment could distinguish whether you were moving at a constant speed or if you were still without looking outside to see if anything else was moving. You are only moving in relation to what is around you. It is not just constant speed that can't be felt but a constant acceleration which is why it works for something which is not just travelling in a straight line. Because of this Einstein realised that the constant acceleration of gravity would be indistinguishable from any other type of acceleration.
Einstein saw that gravity wasn't something in the mass which pulled directly on the object. It pulled on space itself, space was soft like a 4 dimensional blanket and anything heavy placed on it bent the blanket. Anything too close rolled into the well it made. Light would roll into it too even though it was thought by most that light had no mass.
Einstein worked out that energy, invisible forces and the bright waves of light were interchangeable with mass, the particles that make up people. This meant that even light was effected by gravity and would grow colder the steeper the curve it had to fight against. Energy and mass were connected by a number that reoccurs in countless laws of the universe, the speed of light times by itself. It would take an infinite amount of energy to go over the edge and travel faster than light and so nothing ever could, and if they did they would find there was no universe to travel through. Because there is a limit to the speed that information can travel we can only ever know of the things which will have time to travel to us. We can not see past any light that will not have had time to reach us.
Light can be used to break down a wall and that matter can turn into pure white energy. Energy is like a ripple in universe as one thing changes into another.
Einstein realised that this meant that the shape of the universe depended on what it contained. There was perhaps no such thing as flatness and the shortest distance between two objects could often become a curve. Everything had to role around the bumpy currents of spacetime and nothing could accelerate faster than gravity allowed, no matter what their mass. Feathers fell on the moon at the same rate as kilos of lead. There were black holes as heavy as 250 million Suns and some as small as an atom. The shape of space could make time stand still in some places and go slower and faster in others. According to relativity the universe exists in this way with time laid out like the dimensions of space all inside a 4 dimensional sphere. The concept we have of presence is merely an illusion.
Einstein discovered that if the universe had too much mass close together then it wouldn't balance out like in Newton's universe and space could curve so much that it would bend back in on itself until it got so small that it disappeared. As space curves so does time and some heavy universes could curve in on themselves completely. When people looked at all the different possible universe's a man called Gödel found a possibility where time looped at every point, wherever you went time take you back to when you begun.
Knowing that the universe was pulled into shape by what lay inside it people could measure just how curved our universe was. A giant triangle was measured in the sky and the angles added up to a number greater than 180 degrees, the universe had curved in on itself.
As space curves and we accelerate around it space and time distort themselves so that the speed of light remains the same and so we measure lengths as being shorter as we accelerate past them as it takes us less time to get from one end to the other. Time is measured differently if you are in a space ship compared to someone on the Earth. Seconds take longer to tick by the stronger the gravitational force you are in, or the faster you go.


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