Is time linear?

I therefore suggest you throw away any satnav equipment you have, because it requires relativity theory to operate. Even better, to save yourself further embarrassment, throw away your computer, because the quantum electrodynamics behind that is even more problematic than relativity as far your lay concept of 'science' is concerned.

We are thus led also to a definition of “time” in physics.(*)

For this purpose we suppose that clocks of identical construction are placed at the points A, B and C of the railway line (co-ordinate system), and that they are set in such a manner that the positions of their pointers are simultaneously (in the above sense) the same. Under these conditions we understand by the “time” of an event the reading (position of the hands) of that one of these clocks which is in the immediate vicinity (in space) of the event. In this manner a time-value is associated with every event which is essentially capable of observation.

This stipulation contains a further physical hypothesis, the validity of which will hardly be doubted without empirical evidence to the contrary. It has been assumed that all these clocks go at the same rate if they are of identical construction. Stated more exactly: When two clocks arranged at rest in different places of a reference-body are set in such a manner that a particular position of the pointers of the one clock is simultaneous (in the above sense) with the same position of the pointers of the other clock, then identical “settings” are always simultaneous (in the sense of the above definition).

I PLACE a metre-rod in the x'-axis of k' in such a manner that one end (the beginning) coincides with the point x' = 0, whilst the other end (the end of the rod) coincides with the point x' = 1. What is the length of the metre-rod relatively to the system K? In order to learn this, we need only ask where the beginning of the rod and the end of the rod lie with respect to K at a particular time t of the system K. By means of the first equation of the Lorentz transformation the values of these two points at the time t = 0 can be shown to be



the distance between the points being



But the metre-rod is moving with the velocity v relative to K. It therefore follows that the length of a rigid metre-rod moving in the direction of its length with a velocity v is



of a metre. The rigid rod is thus shorter when in motion than when at rest, and the more quickly it is moving, the shorter is the rod. For the velocity v = 0 we should have




and for still greater velocities the square-root becomes imaginary. From this we conclude that in the theory of relativity the velocity c plays the part of a limiting velocity, which can neither be reached nor exceeded by any real body. 1
Of course this feature of the velocity c as a limiting velocity also clearly follows from the equations of the Lorentz transformation, for these become meaningless if we choose values of v greater than c. 2
If, on the contrary, we had considered a metre-rod at rest in the x-axis with respect to K, then we should have found that the length of the rod as judged from K' would have been



this is quite in accordance with the principle of relativity which forms the basis of our considerations. 3
A priori it is quite clear that we must be able to learn something about the physical behaviour of measuring-rods and clocks from the equations of transformation, for the magnitudes x, y, z, t, are nothing more nor less than the results of measurements obtainable by means of measuring-rods and clocks. If we had based our considerations on the Galilei transformation we should not have obtained a contraction of the rod as a consequence of its motion. 4
Let us now consider a seconds-clock which is permanently situated at the origin (x' = 0) of K'. t' = 0 and t' = 1 are two successive ticks of this clock. The first and fourth equations of the Lorentz transformation give for these two ticks:
t = 0
and



As judged from K, the clock is moving with the velocity v; as judged from this reference-body, the time which elapses between two strokes of the clock is not one second, but



seconds, i.e. a somewhat larger time. As a consequence of its motion the clock goes more slowly than when at rest. Here also the velocity c plays the part of an unattainable limiting velocity.

The whole thing of relativity is based in "moving clocks" going slow.

Relativity is based on the axiom that the speed of light is measurably the same for all observers.

From that point it follows that there is no such thing as 'absolute simultanaity' and therefore, that 'time' as measured by the pointing of a hand on a clock is relative to reference frame of the observer looking at the clock.

Thus two observers moving at constant velocity relative to each other will each report that the other one's clock was 'slow' relative to their own. This is a separate phenomenon to the concept of 'differential aging' (of twins for example ) as this involves acceleration not just velocity.

The inclusion of accelerated frames moved 'special relativity' to 'general relativity' in which time and space constitute a unified concept.

You are merely one of the many who fail to understand relativity. Not surprising since your warped attitude to even simpler science has already been noted.

You really don't have clue do you !

Alas, he is somewahat typical of those dogmatic misfits who tend to populate forums, because nobody would give them time of day in real life. I suppose its cheaper than going to a therapist!

Whether an individual sees a train (or anything that is mobile) going fast or slow is of no consequence; it's traveling at the speed it is traveling. Guessing the speed is only that; guessing. Even the speedometer on cars are not accurate.

Wasn't it lucky for you, professor, that your Grandfather wasn't one of the millions who were murdered in the gas chambers that you have 'scientifically shown' not to have existed !

BTW I am one of the few atheists round here who requires no 'empirical demonstration of the existence of God'. Since 'God' is a concept like any other, it stands or falls on the basis of its utlility, and that is as far as we can get as fas as 'existence' of anything is concerned. So 'time' is useful to us both, whereas 'God' is only useful to theists.

'Physicality' may or may not add to judgement of utility, but we must bear in mind that 'physicality' is itself only another concept based on our particular species physiology.

I realise that the above is likely to fall on religiously deformed ears, but I re-iterate it anyway for the consideration of fellow atheists.

Nah...! Nobody is going to fall for your futile attempt to divert attention from your moronic views. You must be a five star idiot mentioning 'gas' on the other thread !