I was born in the past, I will die in the future and I'm living in the present...So my being born is not longer happening and I haven't died yet...right?
Firstly I want to apologize for this post being late. My laptop decided to die on me and I am having the write this mainly on my iPod.
If you read the first "The Irregularity of Time" post (which I recommend doing, otherwise some of this will not make sense to you), I said I would be talking about general relativity this week but I realized I had a lot more to talk about in the realms of Special Relativity.
We found out last time that time is not constant for two people moving at different speeds viewing the same event. But all this can get confusing, lets say I'm on the phone to a friend of mine in New York who has just walked one step up a flight of stairs, from the perspective of an astronaut in space my friend has walked up two steps and from the perspective of a different astronaut my friend hasn't even started walking up the stairs yet. These differing perceptions of time and space can be confusing. We have all heard someone, trying to get one up on someone else, most often, saying "Everything is relative", they would be very wrong. You can not summarize relativity that simply. Despite this, all measurements of space, time and speed are related through the equations we have worked out and others we can derive in other situations illustrated in special relativity.
We all have different perceptions of the space we are in or the object we are looking at. For example, if two people are looking at a pencil being held up in the middle of the room:
Someone looking from position P would see the pencil like it is shown at position PV where as someone looking from Q would see the pencil in position QV. PV and QV are projected views but we are used to seeing 3D objects in a 2D way, in fact, it is this affect that 3D movies, shows and games are aspiring to get. The new range of auto-stereoscopic TVs in development track head movements to apply this.
Ok less about games, more about relativity. This example with the pencil shows our different perceptions of space and time. Three years after Einstein published his theory of special relativity, one of his teachers, Hermann Minkowski, decided to approach the idea differently, proposing that what relativity was saying was that we did not just have the three dimensions of space, and then the one dimension of time, instead, we had four dimensions of space-time. The dimensions of time that we can see and the dimension of time that we can measure with a clock are only appearances.
Instead of in the original three dimension, things are defined as events, having a place in all three dimensions and a certain time. Now let me give you something quite incredible to think about: If we can move, with enough energy, to any point within the three dimensions of space, then, if space and time dimensions are intertwined, should we not be able to move to any point in time? Yes...according to the space-time theory, time travel is totally possible...
I'm sorry that this is late and not very long but I did not have very much time this week. Check out our next post on the kerfuffle about neutrinos going faster than the speed of light. The problems with the idea, the theory behind the unusual results and how it relates back to what we have been talking about in my Irregularity of time posts. The irregularity of time [2/2] is here, check it out! I hope you enjoyed this post, bye.
Main source for this and the other articles based around relativity is the book about relativity here. It goes into more detail on all these subjects and the other books they do are brilliant too, I recommend them a lot.