Marty's voyage

Setting aside for the time being my crazy notions about time-at-a-distance, the mass of the photon, and what might happen if Einstein were wrong....

http://able2know.org/topic/263375-1

.....let's consider her voyage in terms of classical (Special) relativity. Sister Marty's trip from her home planet to visit us here, has gotten complicated, deserves its very own thread in order to address a2k respondent Bran's very pertinent objection [as well as Para's, Con's, and others'] concerning our view of her trip compared to hers. But first some background:

All clocks in our immediate Universe not in significant motion with respect to one another had previously been synchronized, presumably very tediously, supposedly by radio and our scenario takes place with Mars at a distance of ten light minutes. Marty has a very sturdy backbone, as you will see, and a ship that can withstand the most extreme acceleration.

In order to provide an avenue for such acceleration she had earlier traveled to her moon Phobos, where she has breakfast before taking off at 11:50, passing her home base in our direction at (nearly) velocity c, her hand on the tiller and her beautiful little mouth wide open in yawn. Owing to dilation, to her the entire trip is of course very short indeed, observing out the front window of her ship your watch and mine to jump ahead almost instantaneously from a reading of 11:40 to 12:00 as she arrives here at noon, hers still reading 11:50 because of course it's only a wristwatch.

[As a side note, Bran, it's important to acknowledge that in order to visit us she has to pass through two 10-minute passels of photons. Keep this firmly in mind throughout.]

[However, backtracking just a bit we can suppose she might also have on board an atomic clock of some sort, and that she's very quick-witted so that she's able to watch the advance of that "quick jump" in a more leisurely fashion. So halfway through her trip when she notes through the front window a reading of 11:50 on our watches, she glances out a side window and notes the reading of a clock we had placed on a convenient asteroid,....

http://www.answers.com/Q/What_is_a_rock_floating_in_space_called

.....also 11:50...]

But now Para brings up a very pertinent point, for which I thank him, however much more complicated that makes my description of Marty's excursion. I've described Marty's perception of our watches (that is of Earth humanoids you and me) as a "jump", [represented also by that quick advance in the reading of her on-board atomic timer]. It's here that Para, very logically and in absolute pertinence, objects to my description on the grounds that two observers passing one another in the night each notes the other's clock to run slower, where apparently I've noted Para's observation implying instead a very rapid advance.

Bran, Para, the discrepancy here, partly semantic, partly misunderstanding of terms,

http://able2know.org/topic/263375-9#post-5853178

.....two trains passing one another in the night not quite the same situation because in our account Marty's acceleration throws a monkey wrench into the works. But resolved by the observation that Marty and I can indeed observe the other's clocks as (almost) stopped, just as the two choo-choo passengers see the other train's clock apparently running abnormally slow. So let me elaborate:

Of course it's acknowledged by both sides of the discussion that we'd see Marty's watch as (virtually) stopped [that is of course after she'd arrived; but let's not complicate things further] yet if ours also stops (to her) how do we account for her apparent observation of its rapid advance?

Answer: Unlike the situation of the trains, one of our participants (Marty) had accelerated, giving her the illusion of an instantaneous jump in our time. In fact, supposing of course Marty is just as smart as we and understands special relativity, she knows at launch that (to her) our watches now read noon...

....confirmed for instance if we then assume she doesn't stop here but swishes on past us, with a really quick mutual "hi." When she looks out the rear window of her ship and sees us receding, you and I do now appear frozen in place. Indeed to her, looking back with her marvelous telescope, days or weeks later she still sees us standing there with arms up in valiant salute

....whereas some of us (not necessarily me) interpret her foregoing observation as owing merely to the fact that she's keeping up with the photons that left our bodies in salute. (Do keep this in mind for my closure.) In any case, the illusion has been conquered and now she does in fact see us as (for all present purposes) stationary. So Para there's no basic discrepancy in the principle represented by the trains and that of Marty's trip as I'd described it.

That ends the basic story, which I hope was of help (that's assuming of course I'm not dead wrong). Perhaps I'll find an expert somewhere we can ask.


[However, at this point the otherwise casual reader (you? with us standing there together telescopes in hand) may chime in with, "But Dale, it's Marty who's really rigid, there, swishing by with her mouth open and clock stopped at 11:50, whereas her observation is illusory cause we all know it's the participant who accelerates whose watch really stops."

Well I (Dale) wish, a2k helper, you hadn't breached this possibility because it gets into the validity of "stationary reference" to which all motion can supposedly be compared and the suggestion that, well, a2k fellas, it's all relative so how do we know it's not us (and our little corner, the visible part, of the Universe) that isn't in motion at (almost) c, and that in her catapult from Phobos Marty had come to a standstill. With your supposition--even though no diff in our respective observations--it's us not her who's really stopped. It's just that our brains being (nearly) stopped too, we have the impression that time's passing at its usual pace.

So guys, stay with me, we have two independent accounts here, the first concerning Marty's flight and the second (the two paras immediately above), whether or not it might be permissible for us in effect to "switch places" with Marty. I hope you might address the first account if you like, herewith; but for the second, being even more involved, let's have in a new thread.