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I am trying to build a hard science-fiction world where the interstellar travel might work like this:

  • Travellers bodies are scanned and all relevant information regarding body structure, neural connections, chemical concentrations, etc. is stored. The body of traveller is then destroyed.

  • The information from previous step is modulated on a EM wave and beamed towards another star.

  • After some time, the beam is received on the destination. The organic body is rebuilt from the demodulated information and the traveller steps out.

To make sure that this is the right fit for the story, I tried working out the equations of special relativity (Disclaimer: I am not a physicist). However, since the value of 1-(v²/c²) becomes zero at v=c, I can't quite figure out what relativistic effects like time dilation will happen to the people when they are being communicated this way. And since it's a static copy of the traveller being sent and not a working simulation (meaning they won't be experiencing time or anything else), will relativistic effects even matter?

Can someone please help me in working the mathematics or give me a few pointers on how to figure this out?

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    $\begingroup$ Photons don't experience time; for them, all the events in the world are simultaneous, so from the point of view of the traveller the travel is instantaneous. For external observers the travel takes exactly the time needed for light to travel between the point of departure and the destination. $\endgroup$ – AlexP Nov 19 '17 at 9:24
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    $\begingroup$ Am I the only one who worried about such teleportation methods? I mean, we're practically killing people with this. It works well for the external observers since they might not tell the difference between old and the new one, but this person being transfered should actually die! Maybe we should at least keep the originals intact? $\endgroup$ – user2851843 Nov 19 '17 at 12:39
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    $\begingroup$ @user2851843 Yes, that kind of socio-political and philosophical conflict is what this story is about. $\endgroup$ – strNOcat Nov 19 '17 at 12:41
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    $\begingroup$ The original Star Trek did some really neat episodes about this. One was about the data transmission from the transporter being hacked. They did another one in which the persons were not destroyed at the sending terminal, meaning that there were two copies of the person. They did another one where the person's data never arrived, and was not replicated, but the person was destroyed at the originating terminal. It was referenced that regulations on teleportation strictly enforced the destruction of the person at the originating end. Was this murder, or an industrial accident? $\endgroup$ – Justin Thyme Nov 19 '17 at 14:43
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    $\begingroup$ kinda unrelated to the question, but you should probably wait for confirmation that reconstruction at the target destination has been successful before destroying the original, just in case the wifi drops out half way through transmission $\endgroup$ – Aequitas Nov 20 '17 at 2:09
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The speed of object with mass is expressed relatively to the limit of speed: $c$ - speed of light.

The time dilation, length contraction and mass-increase effects, expressed through the relation: $\gamma = \frac{1}{\sqrt{1- \beta}}$, where $\beta = \frac{v^2}{c^2}$, apply on moving objects (with mass), not light (as it has no mass) and that is why immediately after the information, once stored in mass, is converted to light, it will not be affected by "the movement of light" itself.

One possible change that can occur with the information, now stored as light, is change in frequency (relativistic Doppler Effect), if the sender and receiver move with respect to each other.


Lorenz factor: $\gamma = \frac{1}{\sqrt{1- \beta}}$

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This has nothing to do with speed of light and, indeed, with any possible means of transmission.

You are effectively "backing-up to storage" whatever you need to transmit and then "recreate a perfect copy" some time later, possibly in a different location.

Actually it doesn't even matter if you destroy the "original" or not.

In this condition you can even think about making more than one "replica" in the same or in different places.

Back to your question: after you destroy the original it doesn't exist anymore.

  • It can't "feel" anything, not even the flux of time, because it simply doesn't exist.
  • What you have left is a bunch of data, which, obviously, is dead matter.
  • It doesn't matter what you do (for how long) with the data, as long as you preserve their integrity (which might be difficult for many reasons, including Heisenberg Indetermination Principle and trivial quantization errors).
  • When you recreate your "copy" (or copies) it will start behaving as-if it was right after the "scan" phase (if it is a different time from "destruction".
  • On the subject a nice reading is an article by Larry Niven.

Note: all this under the assumption (IMHO correct) of a mechanistic and non-dualistic interpretation of "mind" (i.e.: no "soul" to speak of); otherwise a whole new can of worms will open up.

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  • $\begingroup$ Thanks for the Niven's essay, I don't think I would have found it by myself. $\endgroup$ – strNOcat Nov 19 '17 at 11:00
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There are no relativistic effects. This is a pedantic answer directly addressing the OP's question. The encoded information is effectively a snap shot of the person. A snap shot image doesn't experience anything. It's simply a signal travelling across interstellar space. The person is simply reconstituted from the information in the encoded signal.

The only effects could be due to the method of transmission. Errors creeping in caused by distortions to the signal as it travels to its destination. The other sources of error can occur are during processing the information of the person prior to their disposal and transmission and during their reconstitution. These are only problems of a teleportation system of this sort.

Paradoxically this form of teleportation is often called 'matter transmission' yet no matter is transmitted only information. Matter at the transmission stays put and matter at the receiving end is assembled to recreate the traveller.

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    $\begingroup$ Ahem, Sir... what is the difference between this Answer and mine? I fail to see any. Please correct me. $\endgroup$ – ZioByte Nov 19 '17 at 11:38
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    $\begingroup$ @ZioByte I grant your answer is a good one. However, mine was a tad more specific about relativistic effects and I discussed sources of error with teleportation of this sort. I regard my answer as complementary to yours. $\endgroup$ – a4android Nov 19 '17 at 11:44
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    $\begingroup$ @a4android i have to agree with ZioByte. The only one really addressing relativistic effects was AlexP in his comment and ZioByte said that relativity does not effect the "snap shot" as you called it. I fail to see how your answer adds anything new to the table. $\endgroup$ – ArtificialSoul Nov 19 '17 at 14:05
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    $\begingroup$ @ZioByte A matter of presentation and emphasis. A perfectly valid reason for posting a separate answer. $\endgroup$ – jpmc26 Nov 19 '17 at 16:18
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    $\begingroup$ @a4android: understood. I even upvoted your answer. OP will decide ;) $\endgroup$ – ZioByte Nov 19 '17 at 18:23
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In the photon's frame of reference zero time passes between creation and destruction. It 'sees' the universe as being zero size in the direction of motion.

So your traveler doesn't experience anything in transit.

Alternately: You scanned him, the scan is spread out in time while being transmitted, he's recorded and rebuilt.

Analogy: You take a laptop, hibernate to disk. Transmit the information on the disk to Paris, where they encode it on a hard disk, stuff it into the same make laptop, and hit the key to restore from hibernation.

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Just stop and think about this for a moment, and you will have your answer.

Our modern communications system is sent over fiber optic. Essentially, at the speed of light. We talk to each other over transmissions that travel at the speed of light. Computers interface with each other at the speed of light. YouTube videos are sent at the speed of light. X-rays and other diagnostic imaging are sent over fiber optic. Robotic surgeries are being conducted over the internet, where the data is sent at the speed of light.

I do not recall that there has EVER been a relativistic effect in any conversation I have had over the internet. No uncertainty principle, either. 100% accurate data transmission.

There is nothing to figure out. You are over-thinking it. We send data all the time at the speed of light, with no relativistic effects. All you are doing is sending data.

However, there is a glitch in the system. The body is not scanned instantaneously, nor is it reconstituted instantaneously. The data, in its entirety, sent serially, is not instantaneous. It takes time to send the entire file. Unless it is sent with every data bit in parallel (a massively huge data transmission infrastructure) it will take time. Even when we send a file over the internet at the speed of light, we are still limited by 'download speed' - the speed at which sequential bits can be sent. The entire process, from beginning of scan to final replicant, is not done 'at cee'.

Just stop and think of exactly how huge this data file would be, and how fast the download speed would have to be in order for it to be dome in a reasonable time.

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – JDługosz Nov 21 '17 at 21:21
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I advise you to read the story called Rogue Moon. It has VERY similar theme.

Dr. Edward Hawks runs a top-secret project for the U.S. Navy, using the facilities of Continental Electronics to investigate a large, deadly alien artifact found on the Moon. Volunteers enter and explore it, but are inevitably killed for violating the unknown alien rules in force within the structure. Hawks "must continue to send duplicates into the artifact, however, because each one moves a little closer to finding a way through the alien labyrinth"[3] and, thus, closer to understanding what it is.

Vincent "Connie" Connington, Continental's head of personnel, tells Hawks that he has found the perfect candidate for the next mission. Connington is amoral and manipulative, openly testing Hawks and anyone else he meets for weaknesses. He takes Hawks to see Al Barker, an adventurer and thrill-seeker. Hawks also meets Claire Pack, a sociopath of a different kind. Where Connington covets power, and Barker seems to love death, Claire enjoys using sex, or the prospect of sex, to manipulate men. Connington wants her, but she stays with Barker because he has no weaknesses in her eyes. Hawks has to appeal to Barker's dark side to persuade him to join the project. Claire tries to get under Hawks' skin while simultaneously playing Connington off against Barker.

Hawks has created a matter transmitter, one which scans a person or object to make a copy at the receivers on the Moon. The earthbound copy is placed in a state of sensory deprivation which allows him to share the experiences of the doppelgänger. However, none of the participants have been able to stay sane after experiencing death second hand.

Barker is the first to retain his sanity, but even he is deeply affected the first time, exclaiming, "...it didn't care! I was nothing to it!" He returns again and again to the challenge, advancing a little further each time. Meanwhile, his relationship to Claire deteriorates, even as Connington continues his disastrous attempts to win her, at one point receiving a severe beating from Barker. Eventually, Connington announces he is quitting, and Claire leaves with him.

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  • $\begingroup$ Could you explain how Rogue Moon's premise is similar, and how it provides an answer to the question? $\endgroup$ – F1Krazy Nov 20 '17 at 9:35
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    $\begingroup$ Could you expand this please? As it is this looks more like a comment. Answers shouldn't necessitate that a reader goes somewhere else to find the answer. If it's only an interesting resource for the OP, please post this as a comment. If it fully answers the question raised please write why it answers the questions, possibly using the spoiler markdown (">! " at the beginning of a line) to show the answer. $\endgroup$ – Secespitus Nov 20 '17 at 9:36
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    $\begingroup$ Editing the answer. $\endgroup$ – jo1storm Nov 20 '17 at 9:48
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    $\begingroup$ For future reference: Are answers solely referencing novels/movies/etc. okay? $\endgroup$ – user Nov 20 '17 at 10:48
  • $\begingroup$ Good to see you edited your answer! $\endgroup$ – Secespitus Nov 20 '17 at 12:42

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