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[umiman]

I've been stuck on a problem for awhile now and was wondering if you guys could help me. No doubt you are familiar with the twin paradox.

The thing is, if the paradox were true (and it most likely is), if man were to ever colonize space, wouldn't everything turn upside down? Fathers will start outliving their grandchildren (while feeling like time hasn't passed at all), wars can be started and ended while a space traveller takes a nap, and people travelling at different speeds will basically time travel (except only to the future).

How can anything function? Imagine if we're in a world where faster-than-light travel is possible and ignoring all the Hollywood physics in shows and comics, nothing could ever get done as there would be no bloody order. A space tourist could leave the planet for a day to visit a distant galaxy and come back 200 years later feeling like he's only left for a day.

It also doesn't mean that people who travel in space live longer since time is no longer a constant. Everyone feels like they're experiencing the same amount of time, just that time is flowing differently for everyone else. So while that space tourist might have been gone from Earth for 200 years (and he's basically 200+ Earth years old), there's no difference for him at all.

What do you think? The more I look at it, the more unfeasible space travel gets... and this is very depressing. If there's a physics-type person here who can solve this paradox, please assist. The "solutions" to this paradox don't actually solve it so much as explain that it is possible and you do indeed age differently.

[Cthulhu]

Obviously you're leaving tachyon... flux... wavelength... logarithms?  Out of the equation.

[Nilocy]

Have you ever read Enders Game? That employs this method of physics and explains it quite well and how people get around it, like colonies being set up way before people arrive and. I think it would be quite good, cause colonists would get to distant place real quick and arrive young. Making everyone fairly happy and productive

On the other note of this being the only way to travel, yeah it may be. But we've not even touched the surface of space travel yet, so don't get your hopes down so soon. I'm confident enough that theres something else out there, other than this twin paradox method thing.

[LeoLeonardoIII]

I don't think it creates a paradox. It might be mighty irritating to deal with, but so are time zones and train timetables.

Imagine we set up a colony on a world 10 LY (light-years) away from Earth. When we look at them in a telescope, we see what is happening 10 years ago. We receive a message from their government one day in Year 0 that reads:

"Viva la Revolucion! Bite us"

And all other communication ceases.

We send out a fleet of lightspeed spaceships to attack them.

Ten years later, at Year 10, the lightspeed ships arrive to find that the colony had its only engineer get a hair up his ass, sent the message, and destroyed the colony's communication capability. Oh well, no war of independence after all. The lightspeed spaceships send a message to Earth asking for orders. Ten years later the message hits Earth at Year 20, and Earth replies telling them to come home. The reply reaches the colony at Year 30. The ships pack up and head home and arrive back on Earth at Year 40. The crew experiences time constriction such that it seems like little time has passed at all.

Of course this is irritating. We are, after all, just experiencing the same problems on a larger scale that the European colonists suffered in reaching the New World. Communication is slow, and often battles happen in the colony after a peace is struck back home. If I recall correctly, the American Battle of New Orleans was fought after the war ended officially in Europe.

What's the problem of faster-than-light travel? I can imagine us sending a probe to Alpha Centauri that will take 100 years to reach it, then 4.6 or whatever years for the message beamed back to reach us. But if in 20 years we develop an engine that can go twice as fast as the first probe, and we launch it, the second probe would reach the target in Year 70 and beam the data back before the first probe even reached it.
I imagine the technology of speed is a curve such that waiting 100 years expecting to be able to then launch a craft that can make the trip in 1 year is a poor plan. But waiting 10 years hoping to make a craft that can shave more than 10 years off the trip is reasonable.

Faster than light travel would simply result in the traveler leaving behind all that he knows and loves in pursuit of personal gain and adventure, or service to a cause or organization. Because while he may be able to experience 400 years of space trips during his lifetime by using cryogenics or whatever for the bulk of the trip, to the rest of the people on the different colonies thousands of years have passed.

So there isn't really a dilemma. Other than leaving your twin behind of course.

[Nilocy]

So, if we keep sending faster and faster probes to alpha centauri, they'll be flooded with them?

[Jude]

Doesn't this stuff depend on having faster than light travel, which we aren't capable of anyway?

(I don't know a damn thing about this stuff)

[rickvoid]

If you really want to see this taken to the extreme, read the Revelation Space trilogy written by astronomer Alastair Reynolds (Revelation Space, Redemption Ark, and Absolution Gap).

He didn't really "solve" your problem, he just took it to it's logical conclusion. By the time systems learn about events in other systems, it's far too late for them to do anything about it. This results in pockets of humanity the really have little to do with each other, connected by sleeper ships that act as traders between systems, crewed by men and women who, though they may only be 30 or 40 relativistically speaking, but have really been alive hundreds of years!

The universe he creates in the books is really neat, and the stories that take place in them are awesome too. If rather dark.

Make sure you read Chasm City too, put not until after you finish the trilogy.

[Fualkner]

I have no answers, but here are a few facts about light and light speed:

When something travels at the speed of light, it is infinitely long and has no width.

The speed of light seems to be the speed limit of the universe. Nothing travels faster.

At the speed of light, time stops. (Not sure about this one... or how they proved it.)

So, I think the paradox is very real. Immigrants to space colonies will most likely be sent there near birth or will be refugees/hobos. Many or all will have no homes whereever they started out, and most will bring their entire family. Traveling to new planets will be completely impractical. Cargo ships will be unmanned, or nonexistant. It will not be the grand expanse we always dreamed about, it will be a division of the species.

[rickvoid]

I have no answers, but here are a few facts about light and light speed:

When something travels at the speed of light, it is infinitely long and has no width.

The speed of light seems to be the speed limit of the universe. Nothing travels faster.

At the speed of light, time stops. (Not sure about this one... or how they proved it.)

So, I think the paradox is very real. Immigrants to space colonies will most likely be sent there near birth or will be refugees/hobos. Many or all will have no homes whereever they started out, and most will bring their entire family. Traveling to new planets will be completely impractical. Cargo ships will be unmanned, or nonexistant. It will not be the grand expanse we always dreamed about, it will be a division of the species.

Acutally, Einsteins Theory of Relativity is just that: a Theory. The truth is, we don't know for sure that light speed is the fastest we can travel.

In Einsteins Theory, he posits that if he was traveling the speed of light, he wouldn't be able to see anything. This is because light doesn't change the speed at which it is moving, and he is moving as fast as the light.

Here's how I look at it though. I'm in a car, idling. There is a fly buzzing by my ear, hovering next to me. I start traveling, and hit 65 mph. The fly is still hovering next to my ear. Is he now flying 65 mph? No, he's moving at the same rate he was before, the car is somehow also carrying him as well.

I theorize that light acts the same way. It travels at the same speed the observer travels at. Therefore, though I may experience 10 years of travel getting to my destination, reality has experienced one hundred years, because I was moving 10x faster than the rest of the light in the universe.

This all, of course, assumes that light and time are bound together, and that as light speeds up so too does time.

And now my brain hurts. 

[Nonanonymous]

I imagine that there won't be much incentive for colonizing new planets save for research or a completely new alternative to the earth, in the event that it gets FUBARed.

[rickvoid]

To be honest, I personally hope we are never inflicted upon the Galaxy at large.

We don't really have a history of playing well with others.

However, I think space is really going to be at a premium here on Terra Firma, in the very near future. I could see over-population as a reason for colonization. I've got money on Mars as the first Earth colony, shortly after which Mars will secede for the rest of the Earth and establish it's own independence. War quickly follows.

... Wow. I have a very bleak outlook on the future, huh?

[Kagus]

I think that the only way we're ever going to have real planetary "colonies", is if we develop some sort of teleportation or "wormhole" control.  Wormholes are, of course, hypothetical anomalies.  Teleportation, on the other hand, is showing some promise now that they've discovered a new particle (or something.  I don't know what the terminology is) that can exist in two places at once.  And, it can take stuff with it.

The only problem with that, is that you need to have the other end planted somewhere.  Maybe planetary colonization would require a "starter pack" of either manned or unmanned materials required to set up the other end of a teleport?


Completely out there, but it's fun stuff to think about.

[Fualkner]

I think that we will move completely underground, allowing the surface to have housing and farms, nothing more. Nature will take over again and it will all be for the better.

At least, if I ran the world, this is how it would be.

@Kagus: I'll trade you that aboratorium for three nuclear families!

[rickvoid]

Ah, teleportation.

Here's a question: If the soul exists, would it and your consciousness be transported along with the meat-machine? If teleportation does work, is it really *you* at the other end, or do *you* die in the process?

Have fun with that one! 

[qwertyuiopas]

I have seen a few equasions and put some numbers into them while I was bored in school.
I think you needed to be going very fast for a noticeable change.
If you traveled at only %90 of c, you would not find a huge change in age, solving part of the problem.