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aldiboronti
09-15-2017, 04:22 AM
I know practically zip about science so I'm absolutely positive there's a huge hole in my thinking on this. I understand that it is impossible for people to accelerate to light speed as it would take infinite energy to achieve that. OK, that's point one.

Point two. We know that it's possible for something to travel at that speed and that is light itself, photons. The next step in my thinking may be shaky but here is point three. Photons can surely bear information. Even the absence of a photon or its presence can convey a message just as on/off in a computer does. If I send a stream of photons towards Alpha Centauri and send them in a pattern surely I have sent information at the speed of light. Someone at the other end could decode that pattern just as a computer does and reconstruct the message. That message, just as with a computer, could be anything. A two word greeting, a picture, a film, the current day's news. And perhaps at some point in the future instructions for assembling an exact replica of the human being who sent it, together with all the thoughts, memories of that human being. In other words I send such a message and in however long it takes light to get to Alpha Centauri and for my message to be reconstructed I am to all intents and purposes there in that far away system and I have traveled there at the speed of light.

As I said I know there's a flaw in my thinking but on the basis of this surely we can send information at light speed. But doesn't that mess with causality?

Mangetout
09-15-2017, 04:58 AM
Yes - we can send information at the speed of light, but not any faster.

And if it were possible to build a practically-functioning teleporter which worked by transmitting the information about a teleported object (which is more or less what you're describing), then it would be possible to teleport objects at the speed of light, but not any faster.

Mangetout
09-15-2017, 05:00 AM
I guess the flaw, if there is one, in your thinking is that transmitting information about an object is not the same as accelerating that physical object. Causality is only violated if you can exceed the speed of light, which you can't.

Teuton
09-15-2017, 05:03 AM
Information travelling at the speed of light doesn't break causality, travelling faster does.

Colophon
09-15-2017, 05:27 AM
All you need to transmit information at light speed is a torch (flashlight for the Americans). Or a flag. Or, well, anything that somebody can see.

Darren Garrison
09-15-2017, 05:44 AM
You've stumbled on a very commonly used technology (http://tvtropes.org/pmwiki/pmwiki.php/Main/MentalSpaceTravel) in science fiction. (The TV Tropes page is especially rudimentary and barely scratches the surface.)

Mangetout
09-15-2017, 07:02 AM
All you need to transmit information at light speed is a torch (flashlight for the Americans). Or a flag. Or, well, anything that somebody can see.
Nitpick: A torch would work for Americans too.

CookingWithGas
09-15-2017, 07:48 AM
[...]I am to all intents and purposes there in that far away system and I have traveled there at the speed of light.No, you haven't. Only some information has traveled there. Humans are not pure information.

naita
09-15-2017, 08:03 AM
As I said I know there's a flaw in my thinking but on the basis of this surely we can send information at light speed. But doesn't that mess with causality?

You don't need such a complicated setup to show that information can be transmitted at light speed. And it bears repeating that transmitting information at light speed doesn't mess with causality.

davidm
09-15-2017, 08:12 AM
As others have pointed out, our eyes receive information at the speed of light all the time. If you're looking for a technology that does this, it's called radio.

Riemann
09-15-2017, 08:17 AM
...Humans are not pure information.

Consider this thought experiment. Suppose, through nanotechnology, we can seamlessly replace one out of your hundred billion organic neurons with a processor that exactly replicates the input/output of that neuron. Your brain would continue functioning exactly as before, presumably you would no more argue that you are no longer "you" than if you cut your toenails. Now we replace a second neuron. Now a third, a fourth, always maintaining the same seamless functionality. Eventually all of your organic neurons are replaced by synthetic neurons. None of the original organic material remains, yet your brain continues to function just as before. Is that still you? If not, when did it stop being you?

https://sites.google.com/site/minddict/silicon-chip-replacement-thought-experiment

SamuelA
09-15-2017, 08:24 AM
This is obviously how to do this, given the known limitations about the universe. A couple of notes :

a. Faster than light travel is a literary plot device used by science fiction. Fiction, which is coming from centuries long storytelling traditions, is most interesting to human if it has human characters. You might notice that in classic stories of Greek gods, the gods, while supposedly inhuman beings blessed with incredible powers, act basically like humans....

Well, humans are well known to live only a few decades and then fail and then die. So in order to have a story where humans deal with interstellar distances, they need a short cut past well known laws of physics, or they will be elderly by the time they do a few interstellar trips, even at near lightspeed using some impossible to construct starship.

b. Realistically, it will be possible before 2100 to develop some type of artificial sentience or copy human minds to a computer. The technology is the ultimate end state, the ultimate goal, of the last several centuries of progress. Either way, this will happen long before starships of any sort are possible. Being living inside computers would have

1. Variable clock rates
2. No artificial lifespan limit

That's realistic. All the credible known information says this is basically a done deal at this point. It's just a matter of development time. The fact that artificial neural networks can now emulate any simple single function of a human, and can now stomp humans at a growing number of cognitive tasks, and that an accelerating rush of billions of dollars are flooding into developing better machine intelligence are all clear signs I am right.

Anyways, with beings with no lifespan limit and variable perception of time, interstellar travel is entirely practical.

watchwolf49
09-15-2017, 08:59 AM
Nitpick: A torch would work for Americans too.

nitpicking the nitpick ... in the West, using a torch will get us arrested for attempted arson ... unless, oh no, did we already set the forests on fire? ...

k9bfriender
09-15-2017, 09:34 AM
Consider this thought experiment. Suppose, through nanotechnology, we can seamlessly replace one out of your hundred billion organic neurons with a processor that exactly replicates the input/output of that neuron. Your brain would continue functioning exactly as before, presumably you would no more argue that you are no longer "you" than if you cut your toenails. Now we replace a second neuron. Now a third, a fourth, always maintaining the same seamless functionality. Eventually all of your organic neurons are replaced by synthetic neurons. None of the original organic material remains, yet your brain continues to function just as before. Is that still you? If not, when did it stop being you?


You replacment neurons are replicating the input and output that the original ones used to receive, but does it change that input/output over time, as a human's neuron would as you gain memories and experiences that change the membrane potentials?

It seems that if you did that, you'd still be you, but you'd always be you, and could never change. Are you the same you from ten years ago? I think not. But if your brain was all processors, you would be.

aldiboronti
09-15-2017, 09:38 AM
Humans are not pure information.

That's interesting. What part of a human being is not information?

Whack-a-Mole
09-15-2017, 09:58 AM
Well, humans are well known to live only a few decades and then fail and then die. So in order to have a story where humans deal with interstellar distances, they need a short cut past well known laws of physics, or they will be elderly by the time they do a few interstellar trips, even at near lightspeed using some impossible to construct starship.


Actually if you can get your spaceship close to the speed of light you can easily survive a trip to anywhere in the universe due to time dilation. Thousands/millions (or more) years will have passed on earth but you'd still be young.

You have to get very close to the speed of light for this effect to amount to much though but it is possible in theory even if near impossible in practice.

bob++
09-15-2017, 10:02 AM
Even at the SoL it takes 4 years to get to Alpha Centauri.

Whack-a-Mole
09-15-2017, 10:03 AM
Consider this thought experiment. Suppose, through nanotechnology, we can seamlessly replace one out of your hundred billion organic neurons with a processor that exactly replicates the input/output of that neuron. Your brain would continue functioning exactly as before, presumably you would no more argue that you are no longer "you" than if you cut your toenails. Now we replace a second neuron. Now a third, a fourth, always maintaining the same seamless functionality. Eventually all of your organic neurons are replaced by synthetic neurons. None of the original organic material remains, yet your brain continues to function just as before. Is that still you? If not, when did it stop being you?


This is a spin on the Ship of Theseus (https://en.wikipedia.org/wiki/Ship_of_Theseus) thought experiment posed by Plutarch (so it's been around a long time).

But the thing is our body renews itself all the time. Old cells die and new ones take their place. I am not sure there is a piece of you that is the same as it was seven years ago (not sure about brain cells or nerves).

Whack-a-Mole
09-15-2017, 10:06 AM
And perhaps at some point in the future instructions for assembling an exact replica of the human being who sent it, together with all the thoughts, memories of that human being. In other words I send such a message and in however long it takes light to get to Alpha Centauri and for my message to be reconstructed I am to all intents and purposes there in that far away system and I have traveled there at the speed of light.

As I said I know there's a flaw in my thinking but on the basis of this surely we can send information at light speed.

This is in principle possible.

Just know that scanning you to encode your information for transmission will kill you (it has to). A copy of you will be made at the other end.

Do you still want to get in that machine knowing that?

Whack-a-Mole
09-15-2017, 10:07 AM
Even at the SoL it takes 4 years to get to Alpha Centauri.

From the perspective of the photon it gets there instantly.

TriPolar
09-15-2017, 10:31 AM
You can't travel faster than the speed of light (we are assuming). If we consider teleportation of this kind to be travel then you can travel at the speed of light (plus some time to map yourself beforehand and reassemble a new you (or another you)). You can also travel close to the speed of light using the old fashioned method of moving really fast, so time-wise the teleportation system is only a little faster. Physical travel and teleportation each have their hazards, but with teleportation at least you get do-overs if something goes wrong.

Chronos
09-15-2017, 10:38 AM
Quoth Whack-a-mole:

Just know that scanning you to encode your information for transmission will kill you (it has to). A copy of you will be made at the other end.
It might destroy the instance of your body here, but what makes you say that kills you? It seems to me that if I walk out of the receiver just fine, then rumors of my death are greatly exaggerated.

Dewey Finn
09-15-2017, 10:40 AM
If I send a stream of photons towards Alpha Centauri and send them in a pattern surely I have sent information at the speed of light.
The trick would be to aim that "stream of photons" precisely enough that it gets to Alpha Centauri.

Whack-a-Mole
09-15-2017, 10:50 AM
It might destroy the instance of your body here, but what makes you say that kills you? It seems to me that if I walk out of the receiver just fine, then rumors of my death are greatly exaggerated.

Think of it this way.

Imagine that somehow a perfect copy of you is made without destroying the original.

Now I have Chronos and Copy-Chronos which in all ways is identical to Chronos.

I walk up and say something went wrong and I have to kill Chronos so Copy-Chronos can get on with his day.

You'd be ok with me killing you since your perfect copy will carry on?

manson1972
09-15-2017, 11:08 AM
Just know that scanning you to encode your information for transmission will kill you (it has to). A copy of you will be made at the other end

How can you make such definitive statements about a fictional technology?

I say it WON'T kill you.

eschereal
09-15-2017, 11:09 AM
There is an additional sticky-wicket, of a practical nature. If you point a powerful pin-point laser at α-Centauri, that tiny point of light will spread as it travels, until, when it reaches the receiver, it is billions of miles across (and thus, proportionally weaker).

From α-Centauri, the Earth itself is less than one arc-second (1/3600) from the Sun at its furthest. The sun itself spews something like 15Pw of various wavelengths of light on the Earth. This means that the signal of you must overcome a rather large amount of noise in order to be decoded.

Thus, you will have to buffer your signal with an absurd amount of ECC in order for it to be properly decoded. I am going to venture that the signal of you would take approximately one lifetime to transmit and receive. You corporeal form would probably be long gone before they could reconstruct your simulacrum over there.

(Granted, there are band gaps in the solar radiation that you could slide your signal into, but that is still not going to make it any stronger when it gets there.)

Riemann
09-15-2017, 11:10 AM
Think of it this way.

Imagine that somehow a perfect copy of you is made without destroying the original.

Now I have Chronos and Copy-Chronos which in all ways is identical to Chronos.

I walk up and say something went wrong and I have to kill Chronos so Copy-Chronos can get on with his day.

You'd be ok with me killing you since your perfect copy will carry on?

What if both versions are kept unconscious throughout the process. If an accidental duplicate is made, the two versions are shuffled randomly in the chamber, and one is destroyed. Nobody knows which one was destroyed. The Chronos that was destroyed has no awareness of the event. And the Chronos that is kept just remembers falling asleep and waking up again.

So far as both Chronos himself and the outside world are concerned, this is indistinguishable from any other night where he falls asleep, loses consciousness, and then wakes up again.

Is it really still meaningful to say that Chronos might have died overnight?

Darren Garrison
09-15-2017, 11:17 AM
Think of it this way.

Imagine that somehow a perfect copy of you is made without destroying the original.

Now I have Chronos and Copy-Chronos which in all ways is identical to Chronos.

I walk up and say something went wrong and I have to kill Chronos so Copy-Chronos can get on with his day.

You'd be ok with me killing you since your perfect copy will carry on?

You just need to learn to think like a dinosaur (https://books.google.com/books?id=m6Ijnw8SalYC&pg=PA239&lpg=PA239&dq=%22Kamala+Shastri+came+back+to+this+world+as+she+had+left+it%22&source=bl&ots=R4tMFJgBUJ&sig=93chqqyQcmwYXkExFcjH0dYK7mA&hl=en&sa=X&ved=0ahUKEwilgtatyqfWAhVK4CYKHfkDCXAQ6AEILjAD#v=onepage&q=%22Kamala%20Shastri%20came%20back%20to%20this%20world%20as%20she%20had%20left%20it%22&f=false).

davidm
09-15-2017, 11:22 AM
I'm not a physicist but I suspect that the uncertainty principle would stop you from scanning all of the information needed for that kind of teleportation.

k9bfriender
09-15-2017, 11:25 AM
Think of it this way.

Imagine that somehow a perfect copy of you is made without destroying the original.

Now I have Chronos and Copy-Chronos which in all ways is identical to Chronos.

I walk up and say something went wrong and I have to kill Chronos so Copy-Chronos can get on with his day.

You'd be ok with me killing you since your perfect copy will carry on?

No, in that situation, it must be settled by cage match fight to the death.

Point is, if the transport mechanism kills you in the process, then it doesn't really kill you, but instead, you walk out of the end point, a tough feat for someone that just got killed. The idea is that the scanning beam for such a thing would have to have such high energies that it would essentially vaporize you as it scanned you. I always fan waved the star trek transporters as starting with a low resolution targeting beam that makes sure everything is lined up, and ensures there is room for you at the target. Then you are hit with high intensity gamma rays that vaporize you instantly, and leave the impression of where everything goes holographically on the shield, then the shield is transported to the destination, and reverse the process, recreating a 3d object from the hologram.

If you are able to be making copies, then there are two of him. If one gets killed, then the other is not any more dead. I may not personally appreciate being the copy that gets a bullet to the head, but the copy of me that gets to live is fine. At this point, though, you are just murdering people for bureaucratic reasons, not because that is how it has to happen by the laws of the technology you are using. I would be against such laws, if a cloned copy is viable, then it should get to keep living.

Put it a slightly different way, the earth is about to blow up, and you can copy yourself into a transmitter that will send you to Mars (a colonized, safe mars to receive you). After the copy is made and transmitted, the original you dies in the cataclysm that destroys the planet we all know and love. When you step out of the transmat at the other end, are you going to feel alive?

Whack-a-Mole
09-15-2017, 11:32 AM
How can you make such definitive statements about a fictional technology?

I say it WON'T kill you.

You'd be correct if it was fictional technology but alas it is real. We are a looong way off from teleporting people (if ever) but in principle it is doable. As it happens this means of teleportation destroys the original. (bolding below mine)

In 1993 an international group of six scientists, including IBM Fellow Charles H. Bennett, confirmed the intuitions of the majority of science fiction writers by showing that perfect teleportation is indeed possible in principle, but only if the original is destroyed. In subsequent years, other scientists have demonstrated teleportation experimentally in a variety of systems, including single photons, coherent light fields, nuclear spins, and trapped ions.

SOURCE: http://researcher.watson.ibm.com/researcher/view_group.php?id=2862

Whack-a-Mole
09-15-2017, 11:34 AM
Put it a slightly different way, the earth is about to blow up, and you can copy yourself into a transmitter that will send you to Mars (a colonized, safe mars to receive you). After the copy is made and transmitted, the original you dies in the cataclysm that destroys the planet we all know and love. When you step out of the transmat at the other end, are you going to feel alive?

Mars me will feel alive. Earth me will feel the agony and terror of dying in a cataclysm. It is small consolation to earth me that there is a Mars me who is safe and happy.

Tom Tildrum
09-15-2017, 11:40 AM
That's interesting. What part of a human being is not information?

My "je ne sais quoi." Almost by definition.

Whack-a-Mole
09-15-2017, 11:41 AM
Is it really still meaningful to say that Chronos might have died overnight?

From an observer's perspective all we see is Chronos leave the room.

But imagine your setup with a little spin.

I take Chronos and Copy-Chronos into a room. I tell them I am going to give them a sleeping pill and during the night I will kill one of them and dispose of the body. The other gets to leave and live their life and as a practical matter Chronos and Copy-Chronos are the same so the world just sees an alive and well Chronos.

I am willing to bet they would both be uneasy with that setup.

All your test did was hide from them the reality of what happened. But if we see that reality then it is a scary prospect to get teleported.

aldiboronti
09-15-2017, 11:43 AM
This is in principle possible.

Just know that scanning you to encode your information for transmission will kill you (it has to). A copy of you will be made at the other end.

Do you still want to get in that machine knowing that?

I think I'll pass. :)

k9bfriender
09-15-2017, 11:44 AM
Mars me will feel alive. Earth me will feel the agony and terror of dying in a cataclysm. It is small consolation to earth me that there is a Mars me who is safe and happy.

Don't ever sleep. When you sleep, you die, and though when you get up in the morning, you are alive, that's a small consolation to the previous night's you that gave up his life so that morning you can live.

But, really, you would not feel any better about knowing that, even though your personal existence is coming to an end, your thoughts, memories, and personality; your legacy really, will continue to live on?

Would you feel this way to the point of not bothering to step into the transmitter, to give cloned you a new chance at life?

Darren Garrison
09-15-2017, 11:49 AM
You'd be correct if it was fictional technology but alas it is real. We are a looong way off from teleporting people (if ever) but in principle it is doable. As it happens this means of teleportation destroys the original. (bolding below mine)

Let's look at something simpler--an old-fashoned mechanical pocket watch. Let's say that you have a device for scanning the entire volume of the watch in high detail. Let's also say that you have a very fancy 3D printer that can print in all sorts of metal, glass, grease, semiprecious gems, and anything else found in the watch. Great, you can make a perfect copy of the watch. But can you make that copy in such a way that the new copy never stops ticking and continues to work and keep time as it is being built? I'm guessing that is a big "no."

Humans have multiple orders of magnitude more moving parts than a pocket watch. Life is a process, not a state. The idea that you can rebuild a living creature on the fly is silly fantasy that will never step outside of fiction.

Whack-a-Mole
09-15-2017, 11:50 AM
Would you feel this way to the point of not bothering to step into the transmitter, to give cloned you a new chance at life?

If I am about to die anyway I'd step into the transmitter.

But I would have reservations doing it if all I wanted to do was go check out Mars for the weekend.

manson1972
09-15-2017, 11:56 AM
You'd be correct if it was fictional technology but alas it is real. We are a looong way off from teleporting people (if ever) but in principle it is doable. As it happens this means of teleportation destroys the original. (bolding below mine)

Strange definition of "real" you have. I say another way of scanning will be invented that doesn't kill you. In principle, it's doable.

Riemann
09-15-2017, 11:56 AM
....I take Chronos and Copy-Chronos into a room. I tell them I am going to give them a sleeping pill and during the night I will kill one of them and dispose of the body. The other gets to leave and live their life and as a practical matter Chronos and Copy-Chronos are the same so the world just sees an alive and well Chronos.

I am willing to bet they would both be uneasy with that setup.

All your test did was hide from them the reality of what happened. But if we see that reality then it is a scary prospect to get teleported.

I think allowing both to become conscious changes the game somewhat, because they will immediately begin to diverge. But let's set aside that point.

It seems to me that you are begging the question. What is "the reality of what has happened"? If "Chronos" is information, then duplicating that information does not create a second Chronos; and erasing one of two identical copies does not "kill" anyone.

And if consciousness is somehow critical in the "count" of how many Chronoses exist, what happens normally every night when he falls asleep and loses consciousness? Does he die every night?

Whack-a-Mole
09-15-2017, 12:03 PM
Strange definition of "real" you have. I say another way of scanning will be invented that doesn't kill you. In principle, it's doable.

A citation of scientists proving that perfect teleportation is possible in principle, having actually teleported something, is a strange definition of real to you?

Well, it's the best I can do. If you don't believe those researchers when they say you have to destroy the original that's your lookout. I'm going with the scientists who've actually done it rather than your feelings.

Whack-a-Mole
09-15-2017, 12:09 PM
And if consciousness is somehow critical in the "count" of how many Chronoses exist, what happens normally every night when he falls asleep and loses consciousness? Does he die every night?

I don't think anyone considers sleeping as a form of "death" or "total stop of the brain" till the person wakes. The person's mind is intact and working the whole time (as evidenced that external stimuli can wake the person...the brain is still aware on some level even when asleep).

manson1972
09-15-2017, 12:11 PM
A citation of scientists proving that perfect teleportation is possible in principle, having actually teleported something, is a strange definition of real to you?

Well, it's the best I can do. If you don't believe those researchers when they say you have to destroy the original that's your lookout. I'm going with the scientists who've actually done it rather than your feelings.

I believe those scientists who say that using their method and interpretation of "teleporting" a photon destroys the photon. I don't believe actual teleportation of humans will EVER be possible. It's fiction. As fiction, it's strange to make definitive statements about it.

If you want to base your understanding of a fictional device on several experiments on single particles, then go right ahead. Just don't tell me that your idea of how a fictional device will work is definitive.

And just to humor your idea of destruction of the original, so what? I go into the teleportation machine on Earth, and wake up teleported to Mars. I'm still alive, and not destroyed.

Whack-a-Mole
09-15-2017, 12:29 PM
I believe those scientists who say that using their method and interpretation of "teleporting" a photon destroys the photon. I don't believe actual teleportation of humans will EVER be possible. It's fiction. As fiction, it's strange to make definitive statements about it.


I suggest you read the article I linked to. Teleporting humans is possible in principle.

That said it may well be a practical impossibility (i.e. the hurdles of building a machine that could do it may be insurmountable) but the rules of the universe do not forbid it.

And the "destroy the original" is the one form of teleportation that is not fictional since they have actually done it. All the non-destructive forms are science fiction as far as we know now.

dstarfire
09-15-2017, 12:38 PM
Just to poke a little hole in the mysticism of C here, but it is possible to move at a speed greater than C. In fact, you're doing it right now: the universe is expanding slightly faster than the speed of light.

Superluminal travel (and the possibilities it opens) is fun to dream about, but there's no realistic possibility that it could happen within your lifetime, unless you're secretly the Highlander (https://en.wikipedia.org/wiki/Highlander_(franchise)).

k9bfriender
09-15-2017, 12:45 PM
Just to poke a little hole in the mysticism of C here, but it is possible to move at a speed greater than C. In fact, you're doing it right now: the universe is expanding slightly faster than the speed of light.

Superluminal travel (and the possibilities it opens) is fun to dream about, but there's no realistic possibility that it could happen within your lifetime, unless you're secretly the Highlander (https://en.wikipedia.org/wiki/Highlander_(franchise)).

Depending on your reference point, the universe is either expanding slightly faster, slightly slower, or much faster or much slower, than the speed of light. That does not mean that you are moving with that velocity, just that something is receding from you at that velocity.

For anything useful, you have to be able to approach another object at greater than the speed of light, and that is, as einstein tells us, verboten.

Riemann
09-15-2017, 12:49 PM
Just to poke a little hole in the mysticism of C here, but it is possible to move at a speed greater than C. In fact, you're doing it right now: the universe is expanding slightly faster than the speed of light.

The universe is not expanding "slightly faster than the speed of light", or at any one speed. The recession velocity increases with distance. So objects far enough apart do have a mutual recession velocity that can exceed c. But this is attributable to the metric expansion of space, it is not possible to travel through space faster than c.

Chronos
09-15-2017, 01:25 PM
You don't even need to bring sleep into it. I, right now, am not the same person I was at the time that I started writing this post. That person is gone forever, and the person who goes on is a different person. Except there's no "person who goes on", either, because that person is a different person than the person I am as I complete this post, and so on.

And yet, I care about those other persons in the past, and the persons who will be in the future, and call all of them "me". Why is that? Once you have an answer to that question, you'll have answers to all of the teleporter questions, too.

k9bfriender
09-15-2017, 01:29 PM
You don't even need to bring sleep into it. I, right now, am not the same person I was at the time that I started writing this post. That person is gone forever, and the person who goes on is a different person. Except there's no "person who goes on", either, because that person is a different person than the person I am as I complete this post, and so on.

And yet, I care about those other persons in the past, and the persons who will be in the future, and call all of them "me". Why is that? Once you have an answer to that question, you'll have answers to all of the teleporter questions, too.

Well, except how to actually make one.

DPRK
09-15-2017, 01:48 PM
About this hypothetical teleporter, what is there at the other end? A receiving station? Was it also teleported there?

It seems slightly less science-fictional to suppose you have access to a nigh-inexhausible source of propulsion, so that, while you cannot travel at the speed of light, you can get close enough for all practical purposes. Even if it took 6 months to get to Alpha Centauri, I could deal with that.

davidm
09-15-2017, 02:17 PM
About this hypothetical teleporter, what is there at the other end? A receiving station? Was it also teleported there?

It seems slightly less science-fictional to suppose you have access to a nigh-inexhausible source of propulsion, so that, while you cannot travel at the speed of light, you can get close enough for all practical purposes. Even if it took 6 months to get to Alpha Centauri, I could deal with that.
Alpha Centauri is much further away than 6 light months. It's over 4 light years.

Maybe if you could reach relativistic speeds you could get there in 6 subjective months. I do wonder what level of acceleration you'd have to achieve to do that. If it's much greater than 1g you'd have a very uncomfortable ride, plus you'd have to begin to decelerate at the same level no later than halfway there if you want to be able to stop at your destination. It may not be possible to withstand the required g's.

SamuelA
09-15-2017, 02:21 PM
About this hypothetical teleporter, what is there at the other end? A receiving station? Was it also teleported there?

It seems slightly less science-fictional to suppose you have access to a nigh-inexhausible source of propulsion, so that, while you cannot travel at the speed of light, you can get close enough for all practical purposes. Even if it took 6 months to get to Alpha Centauri, I could deal with that.

Realistically, it was built there by a vehicle that is fueled with lots of antimatter, has a very tiny payload (a few thousand kilograms), and basically the capability to bootstrap an entire space based industrial civilization. Totally reasonable, actually, we can describe in detail how such a vehicle would work today. We have existence proof in that living cells have about the same density of machinery you'd need.

Anyways, such vehicle might realistically still take centuries. You need to be immortal to go to the stars. Pretty obvious. And the beings who 'rode' the vehicle will own the new star system, and anyone they accept who was beamed over is a mere guest.

These teleportation paradoxes are a complete waste of forum space, because they wouldn't exist. The actual way this technology works is, the neural network for the 'beings' (whether created artificially or made by copying the networks of a deceased preserved human brain, it doesn't matter) is just a digital file.

Whenever the being wants to go somewhere, it sends a fork (a copy) of itself via transmission networks to that location. There is such a thing as forward error correction, and there are algorithms where if you send N bits + M error correction data, only N total bits need to be successfully received, out of the whole message, to reconstruct the entire message correctly. So if the being's neural network files are 3 petabytes, it would need to send maybe 5 petabytes to make up for noise over interstellar distances.

Anyways, once the being wants to return, it just gets a fork sent back, and then the original + forked copy get merged using algorithms that weight each being's relative experiences and personality changes.

Relatively simple and straightforward and probably something that will be demonstrated in the next 40 years. (not the starship part, but the fork/merging of the network data for an artificial sentience)

Whack-a-Mole
09-15-2017, 02:38 PM
Maybe if you could reach relativistic speeds you could get there in 6 subjective months. I do wonder what level of acceleration you'd have to achieve to do that. If it's much greater than 1g you'd have a very uncomfortable ride, plus you'd have to begin to decelerate at the same level no later than halfway there if you want to be able to stop at your destination. It may not be possible to withstand the required g's.

If you accelerate at a constant 1g then it takes about a year accelerate to (nearly) light speed. Then consider a year slowing down at the other end. So two years accel/decelerating and three years or so at cruising speed (guess...not sure how to calculate that) so a five year trip.

Subjectively to the passenger the trip will go a lot faster (a bit less than two years to them...guessing again but seems it should be close).

Now you just need to figure how you can carry enough fuel to accelerate for two years (not to mention the fuel needed to push your relativisticly heavy ship).

Darren Garrison
09-15-2017, 02:40 PM
Maybe if you could reach relativistic speeds you could get there in 6 subjective months. I do wonder what level of acceleration you'd have to achieve to do that.

To reach Alpha Centari in 6 months subjective, you'd have to be under a constant 13g. At 1g, travel time would be a little more than 3.5 years.

Calculator (http://convertalot.com/relativistic_star_ship_calculator.html).

k9bfriender
09-15-2017, 03:05 PM
To reach Alpha Centari in 6 months subjective, you'd have to be under a constant 13g. At 1g, travel time would be a little more than 3.5 years.

Calculator (http://convertalot.com/relativistic_star_ship_calculator.html).

At 10,000g's you get there in less than a day.

(And fortunately, your pizzas will all be very flat.)

msmith537
09-15-2017, 03:09 PM
Anyways, such vehicle might realistically still take centuries. You need to be immortal to go to the stars. Pretty obvious. And the beings who 'rode' the vehicle will own the new star system, and anyone they accept who was beamed over is a mere guest.

The one thing that always seems to get glossed over with these "generation ships" on their hundreds or thousand year journey - building the most complex machine ever created, putting it in the harshest and most unforgiving environment imaginable and having it function without a critical failure longer than not just any machine ever built, but longer than humans have built machines at all.

k9bfriender
09-15-2017, 03:12 PM
The one thing that always seems to get glossed over with these "generation ships" on their hundreds or thousand year journey - building the most complex machine ever created, putting it in the harshest and most unforgiving environment imaginable and having it function without a critical failure longer than not just any machine ever built, but longer than humans have built machines at all.

What your saying is, don't go with the lowest bidder?

Okrahoma
09-15-2017, 03:18 PM
Alpha Centauri is much further away than 6 light months. It's over 4 light years.

Maybe if you could reach relativistic speeds you could get there in 6 subjective months. I do wonder what level of acceleration you'd have to achieve to do that. If it's much greater than 1g you'd have a very uncomfortable ride, plus you'd have to begin to decelerate at the same level no later than halfway there if you want to be able to stop at your destination. It may not be possible to withstand the required g's.
There is a very nice calculator for this:

http://nathangeffen.webfactional.com/spacetravel/spacetravel.php

at 1G acceleration/deceleration, it would take 3.5 years perceived time for the traveler to travel 4 light years out. It would take 5.6 years in observer time.

davidm
09-15-2017, 03:22 PM
To reach Alpha Centari in 6 months subjective, you'd have to be under a constant 13g. At 1g, travel time would be a little more than 3.5 years.

Calculator (http://convertalot.com/relativistic_star_ship_calculator.html).So relativistic speeds are not an answer to any useful human interstellar travel, other than to the closest stars, and then only if you're willing to give up years of your life.

Maybe some sort of suspended animation? Of course everything, including the refrigeration units, would have to work for centuries unattended by humans.

Whack-a-Mole
09-15-2017, 03:37 PM
So relativistic speeds are not an answer to any useful human interstellar travel, other than to the closest stars, and then only if you're willing to give up years of your life.

Maybe some sort of suspended animation? Of course everything, including the refrigeration units, would have to work for centuries unattended by humans.

If you can get very close to light speed then the people on the ship can get pretty far in a semi-reasonable amount of time.

Using the calculator Okrahoma provided above a 4 light year trip seems to take the people on the ship 3.5 years. A thousand light year trip would take about 13.5 years. That would probably mean you want to hibernate but you wouldn't have to if you could grow your own food and could keep the water running.

Of course if you do this roundtrip when you return everyone you know will have been dead for about 2000 years so that would be weird.

Darren Garrison
09-15-2017, 03:45 PM
So relativistic speeds are not an answer to any useful human interstellar travel, other than to the closest stars, and then only if you're willing to give up years of your life.

Also, note the amount of energy involved. At 1g accelration, each kilogram of the ship would have a maximum kinetic energy of more than 47 megatons of TNT (http://www.kylesconverter.com/energy,-work,-and-heat/megajoules-to-tons-of-tnt), which is around the amount of energy you get from mixing a kilo of matter with a kilo of antimatter. (At 13g, it would be close to 620 megatons per kilogram. Strike a 1 miligram piece of space dust? Get an explosion the equivalent of 620 tons of TNT.)

k9bfriender
09-15-2017, 03:45 PM
If you can get very close to light speed then the people on the ship can get pretty far in a semi-reasonable amount of time.

Using the calculator Okrahoma provided above a 4 light year trip seems to take the people on the ship 3.5 years. A thousand light year trip would take about 13.5 years. That would probably mean you want to hibernate but you wouldn't have to if you could grow your own food and could keep the water running.

Of course if you do this roundtrip when you return everyone you know will have been dead for about 2000 years so that would be weird.

There are a few reasons that doesn't really work that well.

There are practical speed limits in space. Just because it's vacuum doesn't mean it's empty. The little bit of stuff out there will become more and more of a problem as you speed up. Individual hydrogen atoms are going to be hitting with the force of hydrogen bombs at that sort of speed.

That's, of course, assuming you have the magic drive in the first place that allows you to expend a ridiculous amount of energy to accelerate constantly like that.

Kinthalis
09-15-2017, 03:58 PM
You can't travel faster than the speed of light (we are assuming). If we consider teleportation of this kind to be travel then you can travel at the speed of light (plus some time to map yourself beforehand and reassemble a new you (or another you)). You can also travel close to the speed of light using the old fashioned method of moving really fast, so time-wise the teleportation system is only a little faster. Physical travel and teleportation each have their hazards, but with teleportation at least you get do-overs if something goes wrong.

I think it would still be a lot faster, as traditional way of getting to close ot the speed of light would require time for acceleration and deceleration.

SamuelA
09-15-2017, 04:36 PM
The one thing that always seems to get glossed over with these "generation ships" on their hundreds or thousand year journey - building the most complex machine ever created, putting it in the harshest and most unforgiving environment imaginable and having it function without a critical failure longer than not just any machine ever built, but longer than humans have built machines at all.

Generation ships are just a napkin solution to the problem and will never be built.

As for solving it with a digital solution, that's where nanotechnology comes in. All nanotechnology is is a physical packaging of millions and millions of assembly lines into a tiny space. These assembly lines can convergently assemble any part of the starship (and the machinery needed to bootstrap up to an advanced civilization).

So it's basically taking all the complexity of all the factories on earth and cramming it into the space of a refrigerator. Living cells have this kind of machinery density, so we know it's basically feasible, eventually.

Anyways, the nanoscale assembly systems would be always working as the starship coasts through space, recycling worn pieces of the starship back to gas (probably all the way down to plasma so you can separate the elements with magnets or electric fields) and then reconstructing them.

So none of the ship is more than a few years old. It remains perpetually renewed, perpetually brand new. Even the digital computers the crew 'live' in are constantly being recycled and replaced, with the data being copied around so that redundant copies are always kept.

So, the ship is actually always brand new, and of course there are several redundant copies of every important system. If the danger of micrometeorite impact is high enough, starships might actually travel in formations of dozens of them, with the crew as digital beings who can be freely beamed between ships, so that if any one ship hits a grain of sand and detonates it's antimatter tanks, the mission can continue and none of the crew are lost. (the spacing is a light second or so)

Ornery Bob
09-15-2017, 04:50 PM
That's interesting. What part of a human being is not information?

Your body. Human beings are physical creatures. Non-physical creatures are ideas. Data is not a human.

XT
09-15-2017, 05:15 PM
The one thing that always seems to get glossed over with these "generation ships" on their hundreds or thousand year journey - building the most complex machine ever created, putting it in the harshest and most unforgiving environment imaginable and having it function without a critical failure longer than not just any machine ever built, but longer than humans have built machines at all.

Presumably, the humans on board would be up for doing some maintenance. I don't think it's that much of a stretch that the human crew could maintain a spaceship for hundreds or even thousands of years. Certainly, the reality is if we ever do decide to go to another star we are looking at hundreds of years unless some of the more radical technology envisioned becomes a reality.

I assume someone has already mentioned to the OP that fiber optics use light at light speed (in the medium of the fiber optics of course) and that radio waves also propagate at the speed of light in whatever medium they are in...and that both are perfectly able to transmit information.

As for faster than light, well, I'm sticking with entangled articles eventually being able to be used to transmit data at faster than light speeds, if anything can. Or maybe small wormholes in the quantum foam. If not, then definitely magical unicorn power!

DPRK
09-15-2017, 05:22 PM
Your body. Human beings are physical creatures. Non-physical creatures are ideas. Data is not a human.

Playing around with this idea, there is a theoretical maximum amount of information (https://en.wikipedia.org/wiki/Bekenstein_bound) contained in a given volume. On a human scale, one gets something like 1042 or 1043 bits.

Dewey Finn
09-15-2017, 05:26 PM
The one thing that always seems to get glossed over with these "generation ships" on their hundreds or thousand year journey - building the most complex machine ever created, putting it in the harshest and most unforgiving environment imaginable and having it function without a critical failure longer than not just any machine ever built, but longer than humans have built machines at all.Presumably, the humans on board would be up for doing some maintenance. I don't think it's that much of a stretch that the human crew could maintain a spaceship for hundreds or even thousands of years. Certainly, the reality is if we ever do decide to go to another star we are looking at hundreds of years unless some of the more radical technology envisioned becomes a reality.

I assume someone has already mentioned to the OP that fiber optics use light at light speed (in the medium of the fiber optics of course) and that radio waves also propagate at the speed of light in whatever medium they are in...and that both are perfectly able to transmit information.

As for faster than light, well, I'm sticking with entangled articles eventually being able to be used to transmit data at faster than light speeds, if anything can. Or maybe small wormholes in the quantum foam. If not, then definitely magical unicorn power!
In theory, humans can maintain a generation shop for hundreds of years. But how much technology and other stuff is needed to do so? For example, let's say you use LED bulbs for lighting (particularly for growing food). These bulbs might last 50,000 hours, or about five years of continuous use. So for a journey of a hundred years, you'll need twenty replacement bulbs for every one on board. Are you going to keep that many spares in inventory? Are you going to manufacture them en route? You're going need a series of complex factories to make all of the different things that will need to be replaced during the journey.

wolfpup
09-15-2017, 05:28 PM
This is a spin on the Ship of Theseus (https://en.wikipedia.org/wiki/Ship_of_Theseus) thought experiment posed by Plutarch (so it's been around a long time).

That's not really correct. The "Ship of Theseus" thing is just pure abstract philosophical rumination. The silicon chip replacement thought experiment was proposed in support of the computational theory of mind, an important if still somewhat controversial premise in cognitive science. The two things are only very superficially related.

As for the OP, I see no difficulties here. Teleportation of physical objects at a macroscopic scale and maybe even humans may be possible at some point in the future, and would pose no difficulties to relativistic physics. You just simply cannot travel or transmit information faster than light because of the way that space and time are inextricably bound together.

Mangetout
09-15-2017, 05:47 PM
nitpicking the nitpick ... in the West, using a torch will get us arrested for attempted arson ... unless, oh no, did we already set the forests on fire? ...

Nitpick back at ya. You don't need to set light to the torch - just wave it - ambient light bouncing off it will transmit information about its movement at the speed of light. :D

eschereal
09-15-2017, 09:15 PM
At 10,000g's you get there in less than a day.

(And fortunately, your pizzas will all be very flat.)

Then the calculator is missing a parameter or two. According to the calculations in SR, as you approach c, your mass increases, which means the force needed to accelerate you increases: a thing with non-zero rest mass acquires infinite mass upon reaching c, which means it requires infinite energy to accelerate to c.

Then there is the time dilation thing, that causes the 10000G acceleration to curve downward.

DPRK
09-15-2017, 11:10 PM
10000g getting you to Alpha Centauri in a day is about right (including turning around halfway and braking). Unless I missed a joke.

SamuelA
09-15-2017, 11:48 PM
10000g getting you to Alpha Centauri in a day is about right (including turning around halfway and braking). Unless I missed a joke.

Without checking the calculations, it's only a day inside the ship. Outside the vessel it would be slightly more years than the number of light-years of distance traveled.

Chronos
09-16-2017, 07:51 AM
Quoth eschereal:

Then the calculator is missing a parameter or two. According to the calculations in SR, as you approach c, your mass increases, which means the force needed to accelerate you increases: a thing with non-zero rest mass acquires infinite mass upon reaching c, which means it requires infinite energy to accelerate to c.

Then there is the time dilation thing, that causes the 10000G acceleration to curve downward.
No, your mass does not increase, only your energy. And while it's impossible to reach c, it's possible to have a constant, continual acceleration indefinitely, if you have enough energy available. The calculation is correct.

As an aside: The Queen song "In the year of '39" is about a space journey where the travelers spend a year in travel, and return to Earth a hundred years later. It's usually interpreted as being about relativistic time dilation, but to get that degree of time dilation over that time span, the ship has to be under about 800 gees the whole way (it's a surprisingly easy calculation).

k9bfriender
09-16-2017, 10:30 AM
Then the calculator is missing a parameter or two. According to the calculations in SR, as you approach c, your mass increases, which means the force needed to accelerate you increases: a thing with non-zero rest mass acquires infinite mass upon reaching c, which means it requires infinite energy to accelerate to c.

Then there is the time dilation thing, that causes the 10000G acceleration to curve downward.

To someone outside the ship (and not moving in respect to the starting inertial frame), it would seem as though your acceleration tapers off relatively quickly, by the time of flip-over, the observer would detect your acceleration as being tiny. (speaking of which, flip over would probably actually take a long time in the non-accelerated frame, it's always considered to be instantaneous in the calculations, but at these speeds, you'd probably cross most of a light year just on the maneuver, keep that in mind while planning your next interstellar trip) You are experiencing 10000gs, or 100000m/s/s (rounded), and your gamma is stupid, so the non-accelerated observe would measure your acceleration as .000~01 g's (not sure how many 0's exactly, but you get the point), and your ship would probably be a bit on the short side too. So, to the outside observer, it does seem as though it requires more and more thrust to keep accelerating, or rather, that you are accelerating with less and less thrust. But, to the passenger on the ship, the acceleration is decreased precisely with the time dilation, so it seems as though the acceleration is the same the whole time(because it is, minus flip-over).

Your outside observer could naively chalk that up to you having more mass to push, but that's because the term "relativistic mass" is misunderstood, and should probably have never been named that, as it is misleading. It's another term in the f=ma equation, the proper equation is f=p(actually a greek symbol) x m x a. In every experience you have ever had, that "p" has never been far enough from 1 to make any difference, but it's there. It doesn't get added to the mass, it is its own entry in the equation.

Crafter_Man
09-16-2017, 10:58 AM
The Queen song "In the year of '39" is about a space journey where the travelers spend a year in travel, and return to Earth a hundred years later. It's usually interpreted as being about relativistic time dilation, but to get that degree of time dilation over that time span, the ship has to be under about 800 gees the whole way (it's a surprisingly easy calculation).
And you would think Brian May (https://www.nasa.gov/feature/rock-starastrophysicist-dr-brian-may-goes-backstage-with-new-horizons/) wouldn't have made that blunder. ;)

Asympotically fat
09-16-2017, 11:50 AM
Your outside observer could naively chalk that up to you having more mass to push, but that's because the term "relativistic mass" is misunderstood, and should probably have never been named that, as it is misleading. It's another term in the f=ma equation, the proper equation is f=p(actually a greek symbol) x m x a. In every experience you have ever had, that "p" has never been far enough from 1 to make any difference, but it's there. It doesn't get added to the mass, it is its own entry in the equation.

In fact in special relativity force is not proportional to acceleration at all, so the acceleration produced by a force is not necessarily along the same axis as the force.