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Logically, any object that has zero length in the direction that it is traveling in can only move in discrete steps because any movement away from it's original location must be greater than zero. Regardless of how small the distance is, it must, even if infinitely small, be > 0 for it to have moved at all. Conversely, an object with non-zero length can move while occupying, for a period of time, the same point in space. It really comes down to how precisely you can locate something; the entirety of a zero length object can be located by a single precise coordinate but the entirety an object with length cannot because it occupies a region. Now you could choose to pick a particular datum point along the length of the object, and work with that, but that would not describe the entire object.
Yor_on:Yes, we can treat time differently, but not too differently. It's not too difficult to see the similarity between objects that move at 'c' through our three spatial dimensions and our movement through the temporal dimension. Things that move at 'c' through space do so in a straight line (through space-time that may be curved) without speeding up, slowing down or changing direction (within their own space-time frame and unless they interact with something). This doesn't seem too different to the way that we seem to move through time i.e. at a constant rate (within our own space-time frame) and without changing direction. One does wonder though, about collisions/interactions within the time dimension - if it can happen with light-speed objects in the spatial dimensions it would seem to be possible in the temporal dimension too.
What would time move relative to?
"One does wonder though, about collisions/interactions within the time dimension - if it can happen with light-speed objects in the spatial dimensions it would seem to be possible in the temporal dimension too."do you have another description of how you think here?It sounds intriguing.
But the question of a flow or 'events' seems very important to physicists.If you look at a Feynman diagram time can go backwards, right?
QuoteWhat would time move relative to?I don't think you can say that time moves. It's a direction, in which objects can move, but is not an object itself, which can move. The only frame of reference that makes consistent sense is the object's own frame of reference; it moves relative to itself. That is, within it's own frame of reference, and having moved, it now occupies different coordinates to what it did before it moved. Heh - invoking 'did' and 'before' brings us back to the difference with time. There seems to be a clear two-level hierarchy in the way that dimensions are organised, with time occupying the root level and the spatial dimensions occupying the level below it. Regardless of how many spatial dimensions you work with, you need a temporal dimension for any change to occur. Hypothetically, you can even get away with no spatial dimensions at all and still have change, for an object might just consist of a value, and that value could change without moving spatially. However, if you try to get change without time, what you actually end up with is several different values existing simultaneously; it's like the difference between a single object moving from location A to location B, and an object that exists both at A and B. In the first case there is a single object, but in the second there are two.Quote"One does wonder though, about collisions/interactions within the time dimension - if it can happen with light-speed objects in the spatial dimensions it would seem to be possible in the temporal dimension too."do you have another description of how you think here?It sounds intriguing.Nope - I'm afraid not - it seems weird to me too.QuoteBut the question of a flow or 'events' seems very important to physicists.If you look at a Feynman diagram time can go backwards, right?Well, if time is a direction, it doesn't mean that that direction no longer exists behind you, just as the road you drive along doesn't vanish behind you as you pass. The start of the road is still there, but you're not. The obvious difference is that you can turn around and drive back to the start of the road to prove it still exists. Or at least that's how it seems. In fact, when you turn around and drive back to the start of the road, it is no longer exactly the same road because it will have changed as a consequence of your journey along it. With roads, the difference is virtually imperceptible - there'll be a tiny bit of rubber from your tyres deposited on it, there'll be a little more wear of the road surface, and some of the dust and dirt will have moved, or even been washed away if it has rained. Now this is because although you have reversed your direction in space, you haven't reversed your direction in time, so both you and the road are now in different time locations. Were it possible for you to reverse your direction in time though, then you would be able to get back to the same location in time, where the road would be unchanged.There might be a problem with this however; movement through space affects the rate of time and because you were moving and the road was not, the rate of time for you will be different to the rate of time for the road. Also, if movement through space affects the rate of movement through time, and movement through space can be considered equivalent to movement in time, does movement through time also cause time dilation, bearing in mind the hierarchical relationship between time and space?
Quote from: LeeE on 05/01/2009 20:58:21Logically, any object that has zero length in the direction that it is traveling in can only move in discrete steps because any movement away from it's original location must be greater than zero.That's the sort of thing I hate about physics - zeros (and infinities). My little brain can't wrap itself around something having zero length.
Logically, any object that has zero length in the direction that it is traveling in can only move in discrete steps because any movement away from it's original location must be greater than zero.