THE THEORY OF RELATIVITY

SPECIAL RELATIVITY

• 1. Albert Einstein was a man truly ahead of his time. His theory of General Relativity was a revolution in physics. But now, as I sit here, 83 years later they seem only logical. If you have read any books about Relativity and couldn’t understand some of what you read, I will try to simplify the theory for you.
• 2. In 1905 Einstein wrote published his Theory of Special Relativity (The General Theory was published in 1915). Special Relativity deals only with non-rotating, rectilinear motion. That is to say a body that is moving in a straight line and in not spinning. Imagine you are in a car on the freeway. Our free way has two lanes. Now let suppose that you had no reference points to tell you that you were moving at. No trees on the side of the road, no wind rushing by the car, not even the g forces you normal feel when the car speeds up or slows down. You don’t even have a speedometer. No scenery or external forces at all for you to judge motion with. Suppose now you see another car coming towards you in the opposite lane. You just happen to have a radar gun with you so you measure the cars speed and 50 mph. You believe that you are sitting still and the other car is moving at 50 mph. But there is a problem with this. How do you know you really are stationary. Maybe you are the one who is moving the other car is stationary. Or maybe you both are moving toward each other and your combined speeds are 50 mph. You might say to your self, I could drop a ball out of the window and if it fall straight to the I am not moving, and if fall behind the car I must be moving. You would be wrong in the assumption. Remember there is no wind resistance to push the ball back if you are moving. Try not to this or wind resistance in your experiment. The ball that you dropped out of the window will always drop in a straight line to the ground in these conations. Your ball in traveling at the same speed as you are, and with no air to slow down it forward motion once you release it, it will keep it forward speed. Take away the ground under you and the ball would keep up with you until you couldn’t see it anymore. And if you slowed down, it would pass you. So you could only wonder as to which of the two cars was actually moving.
• 3. These are the conditions relative to you. Lets imagine now there was an outside observer watching all this. We will call his car A your car B and the car coming towards you C. What he sees is your car(B) moving at 10 mph and the other car(C) moving at 60 mph. But how can the be, your radar gun told you your speed, in relationship to the other car(C) was 50 mph. He sees it as 70. Something is rotten in Denmark. Well what is happening is relative to you he(A) is moving away at 40 mph. Your Speed(B) is 30 mph and the car coming towards you(C) in moving at 20 mph. So he sees is speed (A)minus speed (B) and speed (A) plus speed (C). What we have just covered is Special Relativity. This, however, is not the case in General Relativity. In General Relativity 1+1 does not equal 2.

  GERERAL RELATIVITY

• 1. Special Relativity deals only with objects moving in a straight line and not rotating. General Relativity deals with all objects no matter what is motion may be. Usually, when we think of General Relativity, we are dealing with object that are traveling at a large percentage of the speed of line. Light travels at 186,282 mps(miles per seconds), and no physical force or information can exceed its speed. Lets refer back to ours cars in the pervious paragraph. Now we have to assume you, car(B), is completely at rest. Along comes car(C) again, but this time we don’t see him until he has passed us! You think to yourself, how did he just appear past me, and why didn’t I see him in front of me? The way information works is it leaves one source and is received by another source. When you look at something you can see it because light waves from it are reflected back to your eyes and your brain as information processes those light waves. But if the source of the information is moving towards you at the speed of light, it get to your position at the same time as it's light waves do. Before, when car (C) was moving towards you at a relative speed of 50 mph, you could see it before it got to you because it light waves were being reelected back to your eyes at 186,282 mpc. So the light ways, traveling much faster than the car get to you first and you see car(C) coming. But if car(C) is traveling at the speed of light it's light waves cant out run it. It light waves are actually trailing behind it a little because once it reflects them is "runs of and leaves them trailing behind. So car(C) gets to you a little faster than it light waves do. So you will only see it once it passes you.
• 2. If now we assume you, car(B), are traveling at 80 percent the speed light, and car(C) is coming towards you at 90 percent the speed of light. You know what your speed is (car B)and you know what his speed is (car C), so your relative speed should be 170 percent the speed of light. Your speeds should be combined as before in our pervious experiment, but again this is not the case. If you pulled out you radar gun again and measured the speed of the on coming car, you would find you are only traveling a 100 percent the speed of light, not the 170 percent you though you were. But where is the extra speed at, you ask? I will explain where it has gone.
• 3.When an object approaches the speed of light, time on the object slows down in relationship to any slower moving object. The rate at which this slowing of time accurse, in relationship to a slower moving object, can be calculated using what is known as the "gamma factor"(see link 186,282 mpc on the main page for gamma factor chart). This means all time for you and the object you are fixed to, car B, has slowed down. Also, when an object is approaching the speed of light, the object becomes shorter. This affect can also be calculated using the gamma factor. Now the clock the your radar gun is using to measure the time it takes for the radar wave to return is ticking off time slower than normal. In addition to that, the radar gun itself is shorter than it normally is. This Shortening affect as well as the slowing of time is directly related to your speed. Now car(C) is coming at you at 170 percent the speed of light and the radar wave should get back to you much faster than if it. car C, were traveling at only 100 percent the speed of light. The radar way does get back to you much faster but time for the radar gun is running slower, as well as for you. So in your reality, the time it takes for the radar wave to return to you is the same as if your combined speeds were only 100 percent the speed of light.
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