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How difficult is interstellar travel?

Meadmaker

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Meadmaker
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Apr 27, 2004
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In my musings, I've often wondered if mankind could ever possibly really make it to the stars. I've occasionally seen speculations about it, involving Bussard Ramjets, or spaceships powered by atomic bombs, or whatever.

However, there is one basic point that has eluded me, because I don't know how to do the math.

How long would it take to get there? For example, to Alpha Centauri.

Let's suppose that, somehow, you managed to find a fuel that could sustain a 1g acceleration for a spaceship, going halfway to Alpha Centauri, 4.3 light years away, then decelerate at 1 g until you stopped at the star. A quick few punches on the calculator shows that, using Newton's laws of motion, it would take right about four years, with your average speed being right about the speed of light. (Assuming I didn't mispunch the buttons. I only did the calculation once.)

Unfortunately, the problem is that the peak speed is about twice the speed of light, and Mr. Einstein says that's a no-no.

How long would it really take? For the travellers? For the Earth based observers? I did a bit of googling trying to find a site that discussed the question, but I couldn't find one. Anyone know how to work out the relativistic effects? Or know of a web site that discusses the answer?
 
And "Project Longshot" looks cool, too.

It seems to me reasonable to think that someday, our descendants just might make it....maybe.
 
You also have to consider which star you want to go to Alpha Centauri, Proxima Centauri or Sirrius, then that might be something that could be done (it would take a hell of a long time and is not feisable at the current time).

But the question is why? Is there really anything that interesting about the stars closest to our solar system? It doesn't seem like they would have any interesting planets or that much could be gained in knowledge that can't be seen by telescope or radio telescope.

So lets say you are able to somehow produce enough thrust to move faster than any probe has before. Perhaps even an antimatter engine. You go out and spend decades or centuries heading to a system that isn't that interesting?

Really if you want to travel between the stars you need some sort of "warp drive" or other type of mechanism like that, which is beyond any foreseeable technology as things stand now.

It's worth nothing though, that if you could get very near to the speed of light, if you somehow had enough energy, then you could easily travel between stars or across the galaxy even. In your time perspective, the trip would be reasonably short, but during that time the earth may have already been destroyed by the dying sun, as to outsiders it would seem much longer in time.
 
Apart from the time problem, as already mentioned, the big problem, currently, is that we have very little idea of what is at the other end. To use enormous ressources, including the lifetimes of a couple of generations of astronauts, to get to watch an uninhabitable planet system (or a star without even that) is not a very interesting deal.

Even if we could know that an Earth-type planet existed out there, we couldn't know if it was any use to us. The life forms there might be lethal, it might already be inhabited by rational beings, etc.

Hans
 
I congratulate the thread starter & all those friends who contributed to this thread.I learned so many things.The idea of Inter stellar travel always fascinates me.
 
There was an old science fiction story about this subject. In the story, when they finally arrived after about 150 years, there were people from earth waiting there to welcome them. It seems that technology had advanced so much during that 150 years that modern people were able to get there quicker than they did.
 
With speeds up to 10% of lightspeed, the time dilation will be no more than 1%. So, if you balance your math for a lower acceleration and aim for a top speed of 0,1C then the math will be relatively easy. (pun intended :D )
 
frank462 said:
There was an old science fiction story about this subject. In the story, when they finally arrived after about 150 years, there were people from earth waiting there to welcome them. It seems that technology had advanced so much during that 150 years that modern people were able to get there quicker than they did.
Click to expand...
Are you perhaps thinking of Robert A. Heinlein's "Time for the Stars" where the first interstellar starship is launched, and for "easy" communication, they use twins with telepathical abilities.
Thanks to the scientific tests done with the telepaths enroute to a star, it is discovered that telepathy is indeed immediate with infinite speed. This helps Earth scientists to develope spaceships unconstrained by lightspeed.
When the first ship finally reaches it's destination, there's a ship waiting to take them all home again in an instant.

It's one of the better Heinlein books I've read.
 
Mars:

- It's more interesting
- More tractable
- Doesn't involve distorting physics (at least as far as we currently understand)
- Still provides a difficult, but fascinating and ultimately rewarding challenge
 
No need for crew. When our technology becomes advanced enough for a non-FTL mission to be feasible, automated probes should be incredibly smart.

Send them and let the future generations see the results.
 
The problem seems to me to be that you either need a generation ship, or some way of breaking the "light barrier".

Regarding the former, exactly who is going to agree to get involved in this? Not just sacrifice the rest of their lives to the project, but the lives of their children and grandchildren too? I think we'd have to be looking at an imminently uninhabitable Earth for this to be really plausible.

And the latter is at the moment science fiction.

Which rather puts a lot of the UFO stories into perspective.

Rolfe.
 
It seems that the biggest problem with interstellar travel is that the stars are so far apart.
The obvious solution would be to move them closer together.

You can thank me latter. :D
 
MRC_Hans said:
To use enormous ressources, including the lifetimes of a couple of generations of astronauts, to get to watch an uninhabitable planet system (or a star without even that) is not a very interesting deal.
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By the time we do this most of humanity will be living amongst the asteroids. If the nearest stars have asteroids or Kuiper belt/Oort Cloud equivalents that will be fine.
 
I recall reading somewhere that any interstellar mission would be designed to be completed within a human lifetime.
This makes sense, since there would be little incentive for a scientist to devote years of his life to such a huge project knowing he won't live to see the results of his efforts.
 
Rolfe said:
Which rather puts a lot of the UFO stories into perspective.

Rolfe.
Click to expand...

Actually, distance isn't usually considered a problem. For some UFO buffs, aliens can cross space (and even "dimensions" :boggled: ) in the blink of an eye!

I'm sorry, but I'm not sure there's any perspective where this is concerned...
 
Rolfe said:
...snip...Regarding the former, exactly who is going to agree to get involved in this? Not just sacrifice the rest of their lives to the project, but the lives of their children and grandchildren too? I think we'd have to be looking at an imminently uninhabitable Earth for this to be really plausible.
...snip...
Click to expand...
I remember reading somewhere that future advances in genetic engineering could result in "tailoring" humans for specific tasks. One could design humans for space travels; individuals with longer lifespan, better adapted for zero-g during long periods, etc.

Another possibility (quite likely belonging to the science fiction field) would be to carry embryos (genetically engineered or not), triggering processes of development, "birth" and education once the ship is near its final destination.

The ethics of it all would, of course, be highly questionable (but we must not forget that our values might seem outdated by then). At this time, automated probes seem to be the solution for long-distance space travels.
 
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