|"Time" by LetsgomusicStyle - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons|
So I started with the question - what is time?
From a human perspective we experience time in a linear fashion in a single dimension. In spatial terms it is a line, with one direction - forwards. That doesn't quite answer the question, so let's try again. We measure time in terms of movement and by different methods liek the rotation of the Earth and its orbit around the Sun. Again that doesn't quite provide a useful definition, although it does point in the direction of one. Movement is change in spatial terms so we can look at time being an agent of change.
That makes some sense, after all without time you couldn't have change at any level. Movement is the translation of position of time. Fron the quantum scale up to the entire universe time is needed for change to occur. There's a question whether time exists to allow change or if it's an emergent property of change.
From Einstein we know two things about time. One is that it is not absolute. He set out that time passes differently depending of the speed you are moving. From that I wondered if the rate of change (in this case the movement) has some sort of feedback loop on time. Almost like an acceleration or an application of force. A nice idea on teh face of it, but it didn't really take me anywhere.
Now spacetime led to some fun thoughts. For there is the basic concept of it with three spatial dimension entwined with time. If it were possible to view spacetime (which is essentially the universe) as an observer you would see the whole of it. That's easy enough to visualise as its the world we're all familiar with, but how does that work for time. From an outside perspective you would essentially see all of the change that would happen throughout the life of the universe. So for the Earth's motion you would see the Earth in its changing states throughout time in each of the positions it occupies.
I can picture it as some crazy spirograph.
Spacetime itself isn't constant either. For its life so far it has been in a state of expansion, so space itself is getting bigger and that's not just for the overall size of it, but also the space inbetween things as well. If the spatial dimensions are expanding then it makes sense that time is as well. That fits our human experience so that as time expands it advances and so change occurs. Eventually entropy will cause the heat death of the universe so the change will stop and so would time. Or would change stop becaue entropy stops time?
At some stage when thinking about time the subject of time travel has to rear its head. If time expands as part of the universe then that indicates that travel into the future isn't possible because it doesn't exist yet. Travel into the past though - why couldn't that be possible as that exists? I'm still equating time in a similar fashion to spatial dimensions here so the movement metaphor applies.
Of course if you travel back in time then is it possible to change what happens?
That's hardly an original thought, but it did lead me to thinking about if time wasn't a single dimension, but two. Now that brings something interesting with it. What would it mean to be able to move sideways in time? Visualising it my head brought me the conclusion that adding another dimension for time leads to the quantum concept of parralel worlds. By stepping sideways you would traverse each possible state the universe could have been at that given moment.
Which was pretty cool, but not the problem I set out to solve. That's the way it goes, but it did give me an idea for a future story. In the meantime if you've made it this far then you deserve a little treat.