LightHeavyW8

If you would like to look at the work of someone who appears to have studied this subject (and the table I linked) extensively, Google TON 202. It seems that some unseen censor has decided to prevent the site from being linked directly. Judge what you see there on its merit, not on the preemptive dismissal by another poster as being the work of a "crackpot". This site goes into detail about how the proper motion info is extracted.

Gee, it appears that ANYONE can confirm the proper motion of TON 202. Or do you also label the astronomers Hewitt and Burbridge "crackpots" ? http://heasarc.gsfc.nasa.gov/db-perl/W3Browse/w3table.pl?tablehead=name%3Dqso&Action=More+Options

Science, unlike religion, should be able to handle all the scrutiny and hard questions anyone can put to it, imho. We do agree, however, that EO observes "A & B exchanging info at 1.7 c", do we not? I agree that no observer will observe light travelling at > c. To me, this is NOT the same as saying "nothing can go faster than light". The EO has the same perspective as the operator of a particle collider - "closing speed" tells him WHEN a collision will occur. If "nothing can go faster than light" is truly a dictum of the Universe, then c must be the maximum expansion rate of the Universe. All those remote galaxies, bound together by the force of Lorentz covariance - it boggles the mind...

Umm, didn't EO see it that way, though? Playing Devil's Advocate here, If A & B set their watches when they cross the reference beams that are sent from Earth, and they look at their watches when they collide, they may disagree with EO about how many seconds elapsed, but that's all, isnt it?

Yes, that is the post, and my interpretation of it is the same as you. Please note that TON 202's proper motion as angular velocity may be verified by any good amateur astronomer. Its redshift has hopefully been re-verified. The meaning of its redshift may be open to debate, as I understand it.

My apologies for my poor choice of wording. I am enjoying all the responses, and am trying to respond to them all thoughtfully. Please clarify what you mean by "So expressing it like "A & B exchanging info at 1.7 c" could be interpreted as slightly misleading". It seems to me that the collision is an event that all parties can set their watches by - I understand that EO's knowledge of the event will be delayed by the time it takes the light to reach him.

Back in my original post, one of the questions I posed was - would A & B somehow merrily continue to exist in their own spacetime continuum, or reference frame, even AFTER EO sees them collide? I was hoping for a simple "yes" or "no", not "it depends".

And if amateur astronomers can measure TON 202's proper motion in the sky, which, if its redshift truly indicates its remoteness, means it is moving at 1100 c or more, shall we label them all "crackpot" as well? Or shall we question, as Janus does, the possible implications of TON 202's measured redshift?

Now this is where you start to sound dogmatic. As we see in Janus' animation, B is clearly approaching the light from A at 1.7c from our perspective, and A & B will collide at 1.4c from our perspective, and ALL parties may stop their watches at the same instant. This is consistent with the known behavior of particles (from our perspective) in accelerator/colliders. If you claim otherwise, will we not have a paradox?

And how many superluminal QSOs does it take to throw a monkey wrench into the BB Theory? Google TON 202 and see... ! Moderator Note Thread has been split from here

As far as I can tell, the bottom line is that just as there is no problem with EO observing A & B close at 1.4 c, there is no problem with EO observing A & B exchanging info at 1.7 c by using light, although A & B will not see it that way. Anyone who wants to explore the implications of particle collisions at nearly 2 c may want to look at http://en.wikipedia.org/wiki/Proper_velocity. And if I want to discuss Superluminalityas it pertains to QSOs, I'd better open a new thread in the Cosmology Area. Peace, y'all!

I like Janus' response MUCH better. Please note that the topic description of MY thread is Superluminality, so I hereby declare TON 202 intimately related! Umm, please go to http://www.scienceforums.net/topic/54179-if-two-spaceships-close-at-14c/page__view__findpost__p__585420

In http://www.scienceforums.net/topic/54179-if-two-spaceships-close-at-14c/page__view__findpost__p__585351 you said "The first link doesn't apply, since we are in inertial reference frames." Please clarify who is and who is not in an inertial reference frame - You? Me? A and B? TON 202?

Sisyphus - Please see http://www.scienceforums.net/topic/54179-if-two-spaceships-close-at-14c/page__view__findpost__p__585400

Regardless of the title, the wiki article contains the statement "In an inertial frame an observer cannot detect their motion via light signals as the speed of light in a vacuum is constant." This led me to think there may be something here which is inconsistent with Janus' animation, AND indeed DOES apply to the scenario I posed - if you can clarify the wiki statement, please do. And if you can explain why there are numerous QSOs (Quasi-Stellar Objects) where superluminality is observed from Earth (assuming their red shifts are indicative of their velocities) - including one known as TON 202, with a proper velocity of 1100 c, I will give you extra credit!

Swansont - The formatting is certainly not something I am intentionally adding - is there any problem with using Firefox for a browser? I see the formatting appear in everyone's posts when I try to reply, so I laboriously remove it all and preview before I post. To your point, I am having trouble correlating the wiki statement: "In an inertial frame an observer cannot detect their motion via light signals as the speed of light in a vacuum is constant." with your statement: "The first link doesn't apply, since we are in inertial reference frames."

Janus et al - Wiki entries such as this led me to my question about your animation: http://en.wikipedia.org/wiki/Propagation_of_light_in_non-inertial_reference_frames' "In an inertial frame an observer cannot detect their motion via light signals as the speed of light in a vacuum is constant." But that entry also pointed to Proper Velocity which has clarified things greatly: http://en.wikipedia.org/wiki/Proper_velocity Thanks again to all responders!

I assume this is due to length contraction. Won't his measuring stick contract as well? Weirder, I will agree with! The problem with almost every scenario I have read is that it involves clocks and rods and lanterns and mirrors, and everyone in a different reference frame tells a different story. Believe it or not, I tried very hard to stay away from ambiguities. This is why I ended my experiment with a collision - there is no difference for anyone. Perhaps we could work backwards from there... But closing speeds are not merely deduction from the EO's viewpoint - they are what he observes. And for the operators of particle accelerators/colliders, closing speeds tell them WHEN the collision will occur. And not to rain on the Relativity Parade, but there are numerous QSOs (Quasi-Stellar Objects) where superluminality is observed from Earth (assuming their red shifts are indicative of their velocities) - including one known as TON 202, with a proper velocity of 1100 c. As ever, I do thank you and appreciate all your responses! On one thing Professor Dingle's critics are all agreed, that he is wrong. They do not all agree, however, on the nature of his error. - E. G. Cullwick It's a great animation - but doesn't it violate Einstein's postulate? Shouldn't B's motion change the frequency of the light B receives instead of arriving at B at a speed of 1.7c? I can see why some dogged stalwarts are still looking for the aether...

Let's say that A and B are each 210,000 Km from the collision target, so their separation is 420,000 Km at that instant. Traveling at .7c, they will collide in 1 sec. If A fires a laser pulse to B at that instant, it will travel only 300,000 Km in 1 sec regardless of B's velocity, so both A and B will collide before light can inform B. I claim that this is by itself information at >c (for everyone's information, they collided). My second claim is that a proton stream fired from B should add to B's velocity just as A's velocity is added to B, even though it exceeds c in both cases. Keeping all observations in Earth's reference frame, we would see the proton stream from B reach A (and signal us with a laser pulse aimed at Earth). Next, we would see the collision and finally we would actually never see any laser pulse aimed at Earth from B, because the light pulse from A did not reach B before the collision. And when all the participants meet in the Hereafter, we will find out if A got to know about his imminent collision, just as the Earthlings saw that he did...

WE see them close AND COLLIDE at almost 2c. A Hypothetical observer riding alongside one of the particles may only be able to see the other particle approach at c, but will he be able to anticipate his collision? Some responses insist that light must precede the particle, but Einstein's Postulate states that c is a constant for all observers. Particle accelerators make particles close, and "open" if they miss, at almost 2c, according to our reference frame, yet responders here claim that a proton stream fired at .99c ahead of B will not simply add to the .7c he already has, it must instead be transformed ala Lorenz so it does not exceed c in our reference frame - this seems inconsistent with what we see happen in accelerators, imho.

I assume you are referring to remote galaxies receding due to the rapid expansion of Space, i.e., Nothing. Would you care to define just where locally ends? Except, and speaking strictly from the viewpoint of the reference frame we both share, remote galaxies and colliding particles, apparently. Umm, albeit with the greatest respect to all of you, no. Sorry, the bolded part was my own contention - I did not mean to make it look like it was in wiki.

Except light emanating from A, apparently...

At the risk of repeating myself, 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... Perhaps another way to put it is, can nothing truly travel faster than c, or are we just unable to tell?

You now have light moving at 1.7 c - would Einstein approve? Demonstrably? Please, do! From Wikipedia: The speed of light, usually denoted by c, is a physical constant important in many areas of physics. Light and all other forms of electromagnetic radiation always travel at this speed in empty space (vacuum), regardless of the motion of the source or the inertial frame of reference of the observer. Therefore light CANNOT get from A to B faster than c, but A and B themselves CAN. Here is where your numbers depart from what is demonstrably so, i.e., particles that can be made to close and collide at up ro 1.99c. And if they miss each other, they are opening at 1.99c. If particles can do this, why would a proton shot ahead of B at .99c relative to B not be added to his .7c, i.e., 1.69c? And again, to separate "what the observer sees" from what ultimately and synchronously happens, rely upon A's proton detector, which is demonstrably NOT limited to c.

I do not dispute this - I only claim they will be totally surprised by their collision at 1.4 c as observed from Earth, if they rely upon light for their information. Imho, this statement is inconsistent with the behavior observed by particles which can be made to close at > c in accelerator/colliders. An answer that requires a separate space-time continuum for every particle is somehow less than satisfying for me, stuck as I am in the same one as you. I still appreciate and thank you for your response! This is why I tried to distinguish between OBSERVING an event and the EVENT ITSELF. Like my poor "blind" observer who would duck too late if he waits until he hears the rifle fire, how do you know that the same problem cannot occur for Space Traveller B, if he relies upon light which is limited in speed to c? Particle closing speeds > c are not so limited.