LightHeavyW8

While I have read about them, I do not claim to be an expert. I have tried to pose my question and experiment around the known real-world behavior of particles which can be made to close at > c in accelerator/colliders, and that question is "can information be exchanged among observers at > c?". So far, no response has adequately supported or refuted this question, imo. In framing my experiment, I have tried to distinguish between the observation of an event and the event itself. Many discussions concerning relativity seem to regurgitate "what the observer sees" to excess and retreat into realms that are unprovable or unfalsifiable, so I included an indisputable and identical termination of the experiment that all parties must agree upon - BUT WHO WAS SURPRISED? How can light precede the 1.4 c closing speed of A and B if Einstein's Postulate says that c must be the same for all inertial observers?

In my example, A is moving at .7c relative to a stationary target, and B is moving at .7c relative to the same target, coming from the opposite direction. My original question is - "can information be exchanged among observers at > c?" I wanted to scale up an observed example where speeds > c occur, i.e., closing speeds in particle accelerators. I chose a collision so there would at least be agreement, albeit posthumously, about when the experiment ended. AND who would or would not be surprised... I tried to pose the problem STARTING with the closing speeds of particles in accelerators, which can exceed c, and scaling this up to space travellers. I claim that B, who relies on light for his information, will be surprised by his collision but A, who relies on a proton stream, will not.

But wiki's definition of "closing speed" allows the Earth observer to see A and B close at 1.4c, (or open at 1.4c if they miss each other) so why would the proton stream from B appear to be so much slower for the Earth observer than for B? Why wouldn't Earth see the proton stream precede B by adding the velocities just as we do for A + B? What if we remove the "appear to" component thusly - When the proton stream from B hits the proton detector in A, A flashes a laser pulse to Earth, and when B receives the original light signal from A, B will also send a laser pulse to Earth. I know the Earth observer will have to rely on light now, but I maintain Earth will see the laser pulse from A first, then the collision, then the laser pulse from B. This follows from the known behavior of particle accelerators, and assumes c is a constant for all inertial observers. Of course, if c is NOT constant, all bets are off - including SR and GR, no?

But if light from A cannot reach B at a speed > c (Einstein's postulate), how can light from A arrive at B before A itself does? (Unless you add c to the velocity of A, which means that c is NOT constant.) And since B is actually approaching A at 1.4c, from an Earth observer's perspective, and the proton stream B fires at A is fired at .99c relative to B itself, what is to prevent that proton stream from arriving at A before the collision, which in turn happens before B can receive the light from A? This sequence follows from the behavior observed in particle accelerators (and most likely cosmic rays, which is probably what A thinks is coming from B), or so it seems to me. My intent is to try to distinguish the OBSERVATION, or not, of an event from the EVENT ITSELF. All parties WILL agree on the instant my experiment ends, though - won't they? I appreciate and thank you for all for your responses, btw.

Although I have not as yet determined if time passes more slowly or more quickly after retirement, it has allowed me to explore subjects heretofore archived, such as Relativity. If the speed of light in a vacuum, c, is the same for every observer, does it follow that no information may be exchanged among observers at a speed greater than c? Quantum tunneling experiments appear to have succeeded in this regard. But how about space travelers? First, consider a deaf observer and a blind "observer", and two high-powered rifles fired at them in unison from a distance. If the blind "observer" wishes to survive, he would do well to put his hand on the deaf observer's shoulder and duck when the deaf observer does, since the muzzle flashes will be seen before the bullets arrive, but the muzzle blasts will be heard just a little too late. Next, consider the Wikipedia entry for particle "closing speeds" below: (From http://en.wikipedia....#Closing_speeds) - "Closing speeds An observer may conclude that two objects are moving faster than the speed of light relative to each other, by adding their velocities according to the principle of Galilean relativity. For example, two fast-moving particles approaching each other from opposite sides of a particle accelerator will appear to be moving at slightly less than twice the speed of light, relative to each other, from the point of view of an observer standing at rest relative to the accelerator. This correctly reflects the rate at which the distance between the two particles is decreasing, from the observer's point of view and is called the closing speed. However, it is not the same as the velocity of one of the particles as would be measured by a hypothetical fast-moving observer traveling alongside the other particle. To obtain this, the calculation must be done according to the principle of special relativity. If the two particles are moving at velocities v and −v, then this relative velocity (again in units of the speed of light c) ... will always turn out to be less than the speed of light, regardless of the velocities of the two particles." It seems that the particles collide and annihilate each other when an observer at rest relative to the accelerator thinks they will, and he thinks they are approaching each other at just under 2c - the poor "hypothetical fast-moving observer traveling alongside the other particle" never knew what hit him/them! Or, is he still merrily brewing tea in his own space-time continuum, somehow oblivious to the fact that we observed him/them to be annihilated? Now, let's scale this up a bit. Draw the shortest possible straight line x-y between the Earth and Moon, and place a target at the midpoint. Have two opposing spaceships approach this target on a collision course a-b which is perpendicular to x-y, each one closing on the target at a speed, relative to the target, of .7c. Shine two laser beams from Earth so they intersect a-b at the minimum distance from the target to allow the travelers in each spaceship time to eject at their closing speed of 1.4c as seen by Earth observers, provided they notice when they pass by the beams. If they don't notice, there is a backup system. When Spaceship A crosses the beam, it illuminates its own laser beam aimed at a (broad spectrum) light detector alarm in Spaceship B, and Spaceship B instead fires a proton accelerator at .99c, (relative to Spaceship B) toward the approaching Spaceship A, which just happens to have a proton detector alarm on board. It seems to me that if the travelers fail to notice when they pass by the beams, the poor ("blind") traveler in Spaceship B will never know what hit him because he cannot receive light information from A at a speed greater than c, while the traveler in Spaceship A will be alerted just in time to yell "OH, SH_T!!!". Now, the important questions - Who conveyed information to whom, and when? Did they not collide at 1.4c (according to Earth observers), imparting "information" to both parties? Did not traveler A receive "information" about the impending collision even faster, at 2.39c? Do travelers A and/or B still merrily exist in their own space-time continua even AFTER observers on Earth see them annihilated?