the passing of time

interesting. althoug i am sure there is a viable explanation(or two) from the conglomerate of this site but this question does baffle me.

The narrative at the end spanned a lot of elapsed time on the moon, from taking a hike to the other pyramids, prepping the new ship and taking off. It's just an editorial device. It could easily have taken a few days. Like when they first drop into the atmosphere – we see events compressed into a few minutes, yet Ridley suggests they were surveying for several hours before they landed. Of course, the actual sentiment of the message does not really mean anything in absolute terms because there is no such thing as absolute time. It's hard to say what Shaw's Christmas is because her time is not the same as Earth time. Even speaking subjectively, ignoring the effects of time dilation, her body clock has also been messed with by the hypersleep chamber.

At first I thought that it was ship time which would be based on a 24 hour clock. Who knows what then Moon's day is or even what the work /explore times are for the crew. I think that after consulting with David(he would keep the correct time) she gave her final date based on his reference. I think the timing of the Holidays was just an added part of the religious overtones of the movie. Significant in human terms but in the Grand Scale just a Earth's week in the life of of our remaining crew.

irt. [b]zzplural[/b]: You'll have to explain that again. Why does you seeing yourself 35 years ago make any difference? As in, why is it any different than seeing yourself in an older picture? Where does the extra meaning come from? And, Magic A is Magic A. In all settings with FTL (looking at you Star Trek and Aliens) it's fairly clear that traveling between A and B does not result in the travelers encountering a world which has aged faster than they have. If you abolish relativity (and for FTL, you do) you essentially insert an absolute, 'valid' frame, aka universal time.

irt. [b]zzplural[/b]: It is funny, coming from another thread discussing carbon dating, to jump here into a discussion on time dilation. Where we switch sides. :P No time dilation happened. They have FTL engines. Therefore, Magic. Relativity need not apply.

Let's suppose for a moment that FTL travel is possible (even if it is magical). You have a look at your stopwatch and set off for LV_223. Let's suppose further that the engines are so good that you make the journey in no time whatsoever. You have a look at your stopwatch again when you get there. The same time. Then you hang around for 35 years and use your super-duper telescope to have a look at yourself taking off from Earth. You see yourself looking at your stopwatch. The same time again. Except now you think you are 35 years older, and your stopwatch has moved on by this amount. It's a rat's nets of conundrums and twists. There is no consistent notion of "now" whichever way you look at it. Relativity will get you in the end, even with a bit of magic thrown in.

if youre saying that person looks at stopwatch then enters lightspeed immediately goes from a to b then immediately looks back with telescope well wouldnt the image have dissapeared as soon as person hit lightspeed wouldnt there be nothing to see?

spinning round room like an idiot "if i move fast enough maybe i might see the back of my own head" p.s laughing at my own grasp of quantum physics [b]not[/b] anyone elses!

Not quite, [b]zzplural[/b]'s thought experiment involved going from a to b instantaneously. Or at [url=http://www.youtube.com/watch?v=mk7VWcuVOf0]ludicrous speed[/url], in any case. Then, assuming one goes into plaid then stops at b, and waits for a while, and looks back, something is supposed to happen.

hmmm o-O nope i'm out ttly lost

According to time dilation... A crew of spaceship travelling at the speed of light on a 10 light year round trip back to Earth, would return to earth 1000 years after they left Earth. Yet from Earths perspective, with said ship taking 1000 years to travel said distance of 10 light years, the ship would be perceived to actually be travelling 1/100th the speed of light. Thus this begs the question what speed is the ship actually travelling - the speed of light or 1/100th the speed of light.

Well, if you want to try something fun like breaking the speed of light in a vacuum, try this for size. Spinning in a room, at dawn, look at the Sun, say. You know you're spinning, but you might as well say that you're standing still and everything else spins. In particular, the Sun will turn around you once every second, or whatever. The radius of the Sun's orbit around you is 8 light minutes, the circumference of the orbit is about 24 light minutes, which means you are seeing the Sun revolve at about 1440 times the speed of light. Woo! Too forced an example? Ok. Take a laser pointer. It should be pretty powerful. Aim it at the moon. Shake it a bit in your hand. Assuming the pointer is powerful enough to get to the moon, and you are shaking fast enough, [url=http://www.physlink.com/education/askexperts/ae497.cfm]the spot will travel across the surface of the moon at above light speed[/url].

irt. [b]Snorkelbottom[/b]: something seems weird there, yes. Specifically, this- "[i]A crew of spaceship travelling at the speed of light on a 10 light year round trip back to Earth, would return to earth 1000 years after they left Earth.[/i]" Replace the ship with a light beam, put a mirror at the far away point, 10 light years away. Send a pulse towards the mirror, time the (Earth) time it takes to get back- 20 years.

My point exactly, light can travel from A to B then back to A, at the time frame it should yet, nothing else can because it will be affected by time dilation. this has always sounded fishy as further emphasized by another example... if a vessel was travelling at or near the speed of light and one of the passengers at the back stood up and ran to the front of the vessel, would that individual not be, relatively speaking, moving faster than the speed of light - allegedly impossible. Answer - no they wouldn't because time dilation would make time appear to pass slower for the occupants of the vessel... a very cushy answer that cannot be proven as is filled with holes as shown in my last post.

@ BlandCorp... The spaceship example I used initially is the same one used by astrophysicists to explain the effects of time dilation in laymans terms.

There is a problem with time dilation, as understood because of pop-sci 'documentaries'. Basically, it appears to be commonly assumed that 'moving close to the speed of light makes time slow down on the ship'. This is [url=http://en.wikipedia.org/wiki/Twin_paradox]false[/url]. Velocity has nothing to do with it, precisely because things are relative. If I travel, at constant but large velocity, and look at Earth, it's the same thing as if I were standing still and the Earth was moving with that high velocity. That's what (special) relativity is about. So I see time on Earth slowing down, Earth sees my time slowing down. If we are to -meet-, one of us must decelerate. Whoever does the deceleration gets the slower time. But acceleration profile matters. irt. [b]Snorkelbottom[/b]: well actually, you're on the way to recreating Einstein's thought experiments there. That particular thought experiment (shining light along a fast moving ship) is what requires [url=http://en.wikipedia.org/wiki/Space_contraction]length contraction[/url]. In other words, someone on Earth, looking at a fast moving ship, will see that time passes slower on that ship AND that the ship has shrunk on the direction of movement. EDIT: Also, once SpecRel effects become important, one needs to use [url=http://en.wikipedia.org/wiki/Velocity-addition_formula]a different formula[/url] for composing velocities. Just adding them won't do.

It's complicated. Have a look at [url=http://www.mrelativity.net/CauseEffectPrinciplesLightSpeedConstancy/Cause%20and%20Effect%20Principles%20of%20Light%20Speed%20Constancy.htm]this[/url] to see the kinds of things that are involved if you really want to dig into it. One problem is what is meant by the word 'now'. We'd like to think that if we could 'instantaneously' hop from one galaxy to another, 'now' in that place is the same 'now' as in the place that we left. But it's not. In fact, light itself does exactly this: when light moves from one galaxy to another, no time at all passes for the photon (that's relativity taken to the extreme). As far as it is concerned, it makes the journey, no matter how far, in zero time. But we think the photon took maybe millions of years. Clearly there's a paradox there, until you accept the notion that there is no absolute time whatsoever. If there is no absolute time (or indeed any absolute inertial frame of reference), words like 'instantaneously' and 'simultaneous' dissolve into meaningless abstractions when taken to the extreme. An FTL drive would mean travelling somewhere faster than a photon does, in other words in less time than zero time. You're going to have to resort to maths to make any sense of what you mean by all that, and that's beyond me, I'm afraid. FAL (fast as light), I can just about cope with. Looking back in time and space at a much younger version of yourself in the now (as opposed to an old photo in your hand) needs to be qualified by what you mean by now and then. Maths gets involved. Better people than I spend entire working lives thinking about such things. @BlandC... I suspect you've already read and know about the widely known and false premise of communicating information FTL by sweeping a beam of light across a wide arc. It's just an illusion that a message is going FTL. When you delve into it, you're not passing any information from the end points of the arc.

irt. [b]zzplural[/b]: I put the spot on the moon thing as a bit of whimsy. Of course in real life, you can't use that spot to convey information. As to your link, which is fine - we are discussing different worlds here. Alas, a lot of SF is simply choosing to disregard all that relativity thing and say, no, there is a universal now. You don't need maths to see why the universal now exists in Aliens, for example. Or in any episode of Star Trek. That's the only way the story makes sense. You may need maths to work out the further, unobvious implications of that universal now, but thankfully none of us is willing to do that, so we can sweep them under a rug and forget about those when enjoying a story. So if you accept that some kind of magic can remove the speed limit, anything goes. Would it help if, say, travel was taking some kind of shortcut? What if in my room there's a magical portal where a patch of land/spacetime from LV-223 is "glued" to my local space time, and I can just walk there in a second? Even though light, when not passing through the portal, needs 34 years to get there as measured by an Earth observer?

@ Blandcorp - the alleged effect of Spacial Contraction would not be observable from Earth, therefore its mention is needless and mute. @ ZZ - if photons travel in Zero time, then one could argue they also travel in Zero Space, yet if that was the case the photon would be stationary. Yet as Einstein clearly stated space and time are relative, if light travels through space it also travels through time or more precisely, because they are relative to one another - spacetime, at the rate of 186,000 miles per second.

irt. [b]Snorkelbottom[/b]: we have experimental confirmation of length contraction (there's a whole host of papers and reports linked on the wikipedia article about it). So whatever else may be true, length contraction is also. Indeed, the whole of SpecRel is fairly well experimentally established. Time dilation, length contraction and all. It works.

@blandcorp - so I have seen and heard from various sources yet that does not seem to answer the original question does it (highlighted in bold)... A crew of spaceship travelling at the speed of light on a 10 light year round trip back to Earth, would return to earth 1000 years after they left Earth. Yet from Earths perspective, with said ship taking 1000 years to travel said distance of 10 light years, the ship would be perceived to actually be travelling 1/100th the speed of light. [b]Thus this begs the question what speed is the ship actually travelling - the speed of light or 1/100th the speed of light.[/b]

I answered that on the previous page. This- [i]A crew of spaceship travelling at the speed of light on a 10 light year round trip back to Earth, would return to earth 1000 years after they left Earth.[/i] is wrong. Wherever it's from, someone made a math error. Round trip time, as measured by Earth, is 20 years.

@ Blandcorp - so if the question posed is wrong, explain its presence here - [url=http://www.youtube.com/watch?v=xh4kzreQxwY]Through the Wormhole[/url] time frame 10 minutes 28 seconds.

That would be further proof- if any were needed- that shows like Through the Wormhole are ... uninformative. But alas, I am denied a cheap shot at TtWh (for now), because what they claim is different from your question. I'll quote them verbatim. "[i]Decades from now, spaceships traveling near the speed of light could fly into the stars for a ten year mission. For the people on board it would be ten years. On Earth, a thousand years will pass.[/i]" There's no mention of a ten light-year round trip. The ship might jolt around from star to star in whatever configuration, on a journey much longer than 20 light years.

@ Blandcorp the questions are the same, just worded differently... [i]A spaceship travelling near the speed of light on a ten year mission[/i] - is as good as - [i]A spaceship travelling a ten light year round trip at or near the speed of light[/i]. Either way a spaceship after travelling for 10 years at or near the speed of light returns to Earth after 1000 years has passed - not 10, nor 20. Furthermore calling that particular episode into question would question the acceptability of the scientists in the episode, namely Leonard Susskind, whom doubtefully would appear in a show that was [i]uninformative[/i].

Pop sci is uninformative at best, but that's another discussion. If you want to be informed about physics, and you want Susskind to do it, I recommend his lectures at Stanford. They can be found [url=http://www.youtube.com/watch?v=pyX8kQ-JzHI]on youtube[/url] (link is to one of several courses), and they are the real deal. Not any watered down pop sci like TtWh. But back to our issue here- You claim that [i]"A spaceship travelling near the speed of light on a ten year mission" - is as good as - "A spaceship travelling a ten light year round trip at or near the speed of light".[/i] This is not correct. Who measures ten years, the ship or Earth? The show, pretty clearly, measures the ten years on the ship. Since the ship accelerates and decelerates, time dilation (because of acceleration) happens. More time will then pass on Earth than the ship, and the two statements are not equivalent. This is covered in the [url=http://en.wikipedia.org/wiki/Twin_paradox]twin paradox[/url] article I've linked to btw.

@ Blandcorp... If the ship returns to Earth 1000 years later, then the measure of a ten year trip is obviously taken by those on the ship, as per the original and more specific rephrasing of the question in my first post. Furthermore despite the mentions of time dilation in your last post, your claimed answer was 20 years, in which you referred to your example below in reference to my first post, in which you also misunderstood the meaning of a 10 year mission at lightspeed/10 light year round-trip as 10 light years there and back (as evidenced)... [i]Replace the ship with a light beam, put a mirror at the far away point, 10 light years away. Send a pulse towards the mirror, time the (Earth) time it takes to get back- 20 years.[/i] then again in response to the 1000 years time dilation effect [i]...is wrong. Wherever it's from, someone made a math error. Round trip time, as measured by Earth, is 20 years.[/i] A vessel travelling 10 light years there and then the same distance back at or near the speed of light, arriving back at Earth in 20 years, as per your explanation shows no effects of time dilation, and thus breaks both the laws of general relativity and the laws of physics.

I said, 20 years, measured by Earth, if the ship takes a 10 light year round trip. 10 ly one way, 10ly the other, at about light speed. Incidentally, why you no read the wiki article? [url=http://en.wikipedia.org/wiki/Twin_paradox#Specific_example]An example of this exact situation[/url] is described there. The numbers are a bit different but the conclusion is the same. So in one scenario, you have point B, 10 ly away from Earth. Send a ship there, and somehow it instantly reverses direction once it gets there, it returns in 20 years as measured by Earth. To the people on the ship however, less than 20 years pass. There's no contradiction with Spec Rel. But it does show that it matters where you measure the ten years for the ten year mission. If on Earth, then ten years to get to B, ten years to get back (and much less in ship time). If on the ship - well, on Earth more time will pass. And also the ship will cover more distance than just 10 (or 20) ly (certainly, Earth will see it cover more distance).

@ Blandcorp, You have just rephrased my last post, confirming your misunderstanding yet, posting your answer in the positive. In monkey English, you claim... Spaceship (travelling at speed of light)... Earth >>>>>>>>>>>>>> 10 Light years away >>>>>>>>>>>>>> Earth = 20 years Earth time your answer does not include an effects of time dilation and is misunderstood from both phrasings of the question, which was in fact by phrased, quite clearly by myself and the link in Through the Wormhole as... Spaceship (travelling at speed of light for 10 years)... Earth >>>>>>>>>>>>>> Earth = 1000 years Earth time. This last I called into question because of the alleged speed (see my first post in this thread) being observable from earth as 1/100th the speed of light.

irt. [b]Snorkelbottom[/b]: my answer is about time measured on Earth, in a specific mission scenario which was, apparently, clear enough. I have repeatedly, in [b]clear[/b] English, stated that the ship will experience less than 20 years. In other words, there would be time dilation. So then, if you want to discuss another scenario, here is a question first. How far does the ship travel, as seen by Earth, in your scenario?