Quite awhile ago i spent some time thinking about Einstien Minkowski spacetime. I was given a link to a website that describes this fundemental of relativity and given a descriptive label of "Light Cones" From my understanding this suggests that accordingly the universe changes at the rate of 'c'. The following is a diagram of those famous light cones and an extract from their description. <img src=http://www.paygency.com/light%20cones.jpg> The Einstein-Minkowski Spacetime Introducing The Light Cone The characteristic feature of this spacetime is the Light Cone, a double-cone centered at each event in Spacetime. (By the conventional choice of units used in relativity, the sides of the cone are sloped at 45 degrees. This corresponds to choosing units where time is measured in seconds and distances in light-seconds. A light-second is the distance light travels in one second.) The upper-cone (called the future light-cone) represents the future history of a light-flash emitted at that event. The lower-cone (called the past light-cone) represents all directions from which light-flashes can be received at that event. The Light Cone represents the idea that "the direction of the light-flash does not depend on the motion of the source---but just on the event at which the light-flash is emitted." In addition, by the Einstein Principle of Relativity, all observers, regardless of their motions, must (because of Maxwell's Laws) measure the speed of light to be the same constant, in all directions. That is to say, "all observers will universally agree on the Light Cones at each event." This means that each observer drawing a spacetime diagram in which he is at rest must have the worldlines of light-flashes at the same angle of 45 degrees from his worldline (his time axis), and 45 degrees from his plane of simultaneity (his space axes)." Care of http://www.phy.syr.edu/courses/modules/LIGHTCONE/minkowski.html Now if we know that the universe is changing at the rate of 'c' and the photon travels at the rate of 'c' this would I think imply that the photon is stationary relative to this rate of change. So my question is: "When we are measuring the speed of light what are we actually measuring?" Of course I am suggesting that we are just measuring the rate of change in continuum with the photon. An extension to this approach would indicate that time dillations occur not because of the objects velocity but because of the objects Lack of velocity The rate of change for the object is slower because of it's Lack of velocity. Because if it was travelling at 'c' it would be changing at the same rate as the rest of the universe. There are of course other ramifications and I am sure this is not a new idea and explored by many others........ Care to discuss?
It doesn't make any sense to say "the universe is changing at the rate of c" until you have explained exactly what you mean by "change". c has, of course, units of "distance divided by time" so that couldn't apply to every possible change.
the rate at which the future becomes the past is 'c'. If light is the fastest velocity then it means that it's change in postion or should I say it's change is at the rate of 'c' .......so therefore if the fastest change in position is 'c' then the rate the future becomes the past is also 'c'
ansd because 'c' is invariant to all observers then this is a universal constant for the rate of change.....i hope that makes sense?
the interesting thing is this light cone business is what lead to the development of Einstiens postulates that light is invariant and also the maximum speed permitted with out time reversal...(as I understand it) This was the key to his theories.
c is the rate of change of position of a light ray, a photon or anything massless. The units at which you measure the speed of light is Length/time. The rate at which the future becomes past is not c, it is 1 second/second
so, then, what is the rate of change for a photon? 1sec/1second =zero. Are you saying the change is instantaneous?
I think it is more a question of perspective here. To us, as part of this change the change from future to past is at a rate of zero or instantaneous but if we take a perpsective from outside the universe the rate is 'c'. because the rate of 'c' of a universal constant, that can't be exceeded with out making the past change into the now.........time reversal.
I am sorrry . my mistake.......but how can the rate of future to past be considered as 1 second. 1 second over what? or 1 second of what?
1 second of change in the location of a photon is normally approx 300,000 ks. 1 second of change in a relatively rest mass is also. (oscillating movemnent over time = 300000 ks per sec)
ahhh as 'enry Higgens siad to Lisa in My Fair Lady, I think I got it!!! see if you follow my logic..... If change happens at the rate of 'c' then the reflector or mirror changes at this rate. If light travelled at the spped of 'c' and the reflector took 'c' to change then the overall spedd would be measured as 'c'*2 time of travel plus time for the mirror to change ( reflect the effect of light) BUT, if the reflector takes 'c' to change then light must be instantaneous. JamesR I hope your reading this....... summary to the thread question What are we measuring when we measure light? Answer: The time it takes for the reflector to change, which according to the light cones is 'c'. Light is instantaneous due to length contractions as per velocity of 'c'
