Monday, May 17, 2010

Thinking about time

We all know what time means in our every day lives. Time is money and time is what we always have too little of doing stuff. We also know that we only have a finite amount of time to live. In that context time is precious, especially when for some reason our mortality is made more evident. Yet, mostly time is taken for granted. Young people complain everything takes too long while old people complain that everything goes too fast. We all know the past has been and can not be revisited and that the future has not happened yet. So, where are we? How long is the moment of now? When does it become the past and how big is the chunk of future that becomes now instead?

What actually is time? Is it an illusion or the only real thing in the universe? On wikipedia the following text opens the “Time” entry:

“Time is a component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects. Time has been a major subject of religion, philosophy and science but defining it in a non-controversial manner applicable to all fields of study has consistently eluded the greatest scholars.“

OK, so that does not help us a lot. It does however, describe some of the elements we will need to understand time. It is mentioned that we use time to describe certain properties of events. An event can be defined as a phenomenon or object in time. An event occurs but to tell when it occurred you need to use a reference system. This reference system introduces other events in such a way that we can say that an event happened simultaneously with a certain event in the reference system. We assume that the events in the reference system are sequential. Right, that still is not helpful as the reference events are separated by the very thing we try to understand. As it were, time got created by the situation.

Let us continue on that line of thought. Time seems to be the property that separates events. Imagine an empty universe. If suddenly an event occurs there is no way to identify the moment it occurred. In essence there is no time. If a second event occurs one would think that at least it could be said that the second event happened after the first. But I say that there still is no time because there must be something that observed the first and the second event occurring. So what do we have so far? Time is a property that separates events observed by an observer. (ignoring for now how the observer observes the events)

There is another property that separates events and that property determines where an event occurs. It too needs a reference system for comparison that also is constructed of the very property we want to describe and again, without an observer that property has no meaning. We call it space.

It is fair to assume that without space there are no events. No events means no time. If there are no events, space and time have no meaning. Let that sink in for a while. Try to imagine yourself in a space with objects distributed in it. Now try to imagine there being no events. This means there are no interactions of any kind and you can not observe the objects in the space. You will not experience time. In fact you will not even notice the volume of the space. If time stops, spatial volume collapses. It does seem that time and space are closely related and together form four dimensional spacetime.

Conclusion: time is a special direction in four dimensional space and the property that separates events is four dimensional space. Travel in three dimensional space and time is movement through four dimensional space. What separates one event from a later event is that the latter event existed in a different place in space time.

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