∆ Light clocks and Odometers.

Figure: Einstein's light 'clocks' may be more useful if they also display any change in location they are making.

Back to >> ∆ Timeless v.Time distinctions (Rhetoric and Semantics).

Odometer tidies things up.

One of the problems that arises when looking at ‘time dilation’ and relative motion is that it always seems questionable as to who is stationary and who is moving. The classic example of this is what happens when we are sitting on a smooth comfortable train and become distracted inside the train while glancing at a magazine etc. sometimes when this happens, particularly near a station, we may see some motion out of the corner of our eye and identify it as another train on another set of tracks. For a moment we can be completely confused as to whether our train, the other train or both are stationary or moving.

If we imagine two spacecraft ‘A’ and ‘B’ each travelling without acceleration and passing each other in outer space who is or is not moving becomes unanswerable. For an observer on one ship it will be their own craft that ‘feels’ as if it is not moving, and the other ship will seem to whizz past it.

The problem is that this will seem to be exactly the same for an observer on that other ship. Even if there is some nearby planet to use as a third reference this wouldn’t help. If you on your ship seemed not to move at all relative to the reference planet then you might insist that you were stationary and the other ship whizzed past you. But as far as the other ship is concerned it still feels as if it is not moving, while you and the planet whiz past it together.

This doesn’t seem that important, it’s not surprising that its hard, or even impossible, to tell who’s moving and who’s stationary in space but what is significant is that on spaceship ‘A’ plants, people and machines (clocks if you wish) will all seem to function normally, while looking through the window of ship B as it whizzes by (at a significant fraction of ‘C’) things within the ship will actually be seen to be happening much more slowly than normal.

Theory and experiment prove that if you could do this any ‘clocks’ you might observe on the other ship will seem to display time passing more slowly (say 1/10^th normal speed for example) than your own ‘local’ (stationary) clock.

What is really significant about this is that because the exact same thing would seem to be true for observers on space ship B looking at you on A as the ships pass each other, then for you on A, everything on B seems to be happening at 1/10^th normal speed and simultaneously for those on B, you seem to be moving at 1/10^th normal speed! This seems to be physically and logically impossible, but it can be explained... timelessly.

(XXX add notes on the distinction between what might actually be observed say through windows on a passing spaceships, and what is calculated to be happening on distant fast moving objects)

In some of the previous discussions on ‘Time travel’ it was suggested that a lot of mysteries could be dispelled by imagining a ‘glass box time machine’. If we had a machine that sat in the corner of a room such that anything put in it would change more slowly there, then some confusion or even apparent paradoxes can be clarified.

So a subject might be in the box for ‘2 weeks’ of ‘outside time’ – which would seem to be only 1 week of ‘inside time’. In this case on leaving the box the subject might explain this as them having ‘travelled one week into the future’, while to the people in the room the subject will seem to have ‘come from one week in the past’. But throughout the whole experiment everyone could constantly sit and directly observe and agree that the person in the box just constantly existed, and just moved and changed more slowly than the people outside of it. Conversely the person in the box would say those outside just moved faster so accounts would still logically tally – the point being that no signs of the ‘past’ or ‘future’ existing, and no examples of anyone whizzing ‘from the past into the future’ are actually seen, though someone insisting that time exists, and that it must be forced into an explanation of the experiment may use these intangible notions.

For the ‘relative motion’ experiment though this would be like placing two glass box machines in one room and trying to make it so that for the people in machine ‘A’, those in Machine ‘B’ could be directly seen to be moving and changing unusually slowly - while simultaneously those in machine ‘B’ also directly observed those in machine ‘A’ to be moving SLOWLY!

This seems logically impossible, for one to see the other as moving more slowly or quickly is fine, but for both parties to see the same effect ? How would things appear to both parties if they stepped out of the boxes together, who would be in whose past or future, or more simply who would have been able to get more done than the other while both were in identical machines.

This situation is easily resolved however of we consider again the idea that only change exists, and consider again the idea of light-clocks (XXX poss rename all light clocks to light boxes to clarify) with built in odometers, or ‘trip meters’. With trip meters measuring the ‘distance covered’ by any light clock, (i.e. the distance between the space ships) and adding t

his to the light clock ‘tick counter’ (which really just adds up the distance the trapped photon has covered within the box) in the correct way we have seen that given two such clocks at rest relative to each other their counters stay in sync. And even if one clock is moved away, although its photon seems to slow down the trip meter adds on the fact that other motion has occurred, and so both device’s counters still always show identical values.