Defining time

[horvack]

So I recently read that it is very difficult to formulate an abstract definition of time, and that one of the primary difficulties is avoiding circularity (using the time concept in the definition).

Keeping relativity in mind, why can't we just say that time is the perceived order of events? Admittedly, the perceived order may not be consistent for different observers, but we seem to be able to generate enough precision when desired.

One implication is that when nothing happens, there is no time, a concept that I find pleasing. Keep in mind that watching an empty room does not constitute a lack of events, as the the particles involved are constantly moving (if they weren't, you wouldn't experience anything).

Is there some way that this definition is not meaningful or usable that I'm missing? I have no training in physics, so please enlighten me.

[randomthoughtsracing]

If the brain were likened to a computer, and memories were likened to files theirin then time would be (or at least part of) the default "filename". I would suggest that the brain catalogs memories in linear order, by category, and any other number of other cross refferences. The linear listing seems relevant in recounting the order of events to other parties. Thus, to me, time is a concept used to "sync up" with the other brains as it were, using the common cataloging method "linear order"

[aphemix]

events, themselves, are temporal objects. Your definition is already circular. The order of these objects is simply an arrangement. Time is not an arrangement: it includes a procession from one item in the arrangement to the next. But that, too, requires a circular description.

::thinks hard::

time is the medium through which differentiations between states are created by causal stimuli. But even that is kinda cheating. What is cause?

this is interestingly tricky. Should've posted it in the games forum.

[elfsprin]

time is change

start with that and pick it apart.

[horvack]

events, themselves, are temporal objects. Your definition is already circular.

I thought an event was merely "something that happens." I can see that you can't "happen" without existing in space/time, but I don't see how this makes my definition circular. Surely the requirement for not being circular is not that time exists independent of space/time?

The order of these objects is simply an arrangement. Time is not an arrangement: it includes a procession from one item in the arrangement to the next.

That's my entire point, why isn't time merely the arrangement? Why isn't is valid to say that no time exists in-between events? There is such a proliferation of events that we seem to be able to achieve all the granularity we need.

[horvack]

If the brain were likened to a computer, and memories were likened to files theirin then time would be (or at least part of) the default "filename". I would suggest that the brain catalogs memories in linear order, by category, and any other number of other cross refferences. The linear listing seems relevant in recounting the order of events to other parties. Thus, to me, time is a concept used to "sync up" with the other brains as it were, using the common cataloging method "linear order"

Linear order of what, along what axis?

[mthomps]

Time is just another dimension you perceive. That's the way I've always thought of it and always will. I picture a still image smearing as things happen to it. It's why humans can't think in 4 dimensions.

[Utisz]

events, themselves, are temporal objects. Your definition is already circular. The order of these objects is simply an arrangement. Time is not an arrangement: it includes a procession from one item in the arrangement to the next. But that, too, requires a circular description.

QFT.

I thought an event was merely "something that happens." I can see that you can't "happen" without existing in space/time, but I don't see how this makes my definition circular.

Whatever about an event being independent of time (perhaps arguable), how do you define the ordering of events?

For example, an order where my post is less than yours would not be "consistent" with time. You need to make the criteria for ordering explicit in the definition.

...so making your definition sufficient, "time is the ordering of events... along a time dimension".

Your definition is either insufficient (criteria for ordering of events are not defined) or circular (ordering of events is defined using time).

[Utisz]

Time is just another dimension you perceive. ... It's why humans can't think in 4 dimensions.

Speak for yourself, not for humanity.

*picks his nose in defiance*

[mthomps]

You are implying you can? Or are you saying the majority of us think 4 dimensionally?

So you design a machine and you can visualize it's operation in a fluid 4d picture, or what?