Friday 26 June 2009

Time Time has been the study of many physicists over the past two centuries. Einstein was the first to really understand it by saying that it was a 4 dimensional object. In this post I will write about Time Dilation and what this has to do with a theory of time travel. As in the Google Video in the last post, up until Einstein people thought that time was the same everywhere in the universe and that everything else varied according to a velocity. Then Einstein came along and said the speed of light was always constant and that time was variable. This formed Einstein’s special theory of relativity and also explains time dilation. Let’s assume that there is a man who travelled at the speed of light for eternity. Let’s also assume that you have a twin brother who goes about living his ordinary life. Your brother lives for 80 years but you live on for eternity. The obvious question to ask is why? This is where time dilation comes in. Time dilation is based around Special and General Relativity. General Relativity explains gravity. A body of some sort, in Einstein’s view, curves the Space-Time Continuum. This curvature creates the affect that we know as Gravity. Time Dilation occurs in two ways. The first is to do with General Relativity. The less affect that gravity has on you, the slower time goes by. It varies in minute amounts but it still slows down. The second explains the brother example that I gave earlier on. It states that the faster you go, the slower time goes by. However, if an object were to travel faster than the speed of light, it would travel back in time. In the brother principle, the speed of light is in the middle where time stops. Hence, the first man never ages. This is one of the many time travel theories. If man could create a machine that could travel faster than light, we could time travel. However, this is currently an impossibility as the laws of physics don't allow us to do this. According to Einstein Special relativity theory, when an object gains a certain amount of energy, this energy converts into mass as explained by E=mc2. Another way to possibly time travel would be to use wormholes. Wormholes are like a shortcut through space-time. As in the diagram on the left, space-time sort of folds in half allowing two point that would usually be very far apart to come together. It may also help you travel in time. Look on Wikipedia for more advanced reading. `