How far could you travel in a spaceship?

[n2doc]

23 September 2009 by Rachel Courtland


HOW far could an astronaut travel in a lifetime? Billions of light years, it turns out. But they ought to be careful when to apply the brakes on the return trip.

Ever since cosmologists discovered that the universe's expansion is accelerating, many have wondered just how much this will constrain what we could see with telescopes in the future. Distant regions of the universe will eventually be expanding so fast that light from any objects there can never reach us.

Likewise, dark energy - the mysterious force behind the acceleration - places a limit on human exploration of the universe, says Juliana Kwan at the University of Sydney in New South Wales, Australia, who has now refined this limit on our travels. Even with rockets that could take us to within a whisker of light speed, expansion would still eventually leave us behind.

The furthest that light emitted from our sun today could reach, as it races in vain to outdo the accelerating expansion, currently lies around 15 billion light years away. According to previous calculations by Jeremy Heyl of the University of British Columbia in Vancouver, a super-advanced rocket could get most of this way in a human lifetime. Accelerating at around 9 metres per second per second - which would feel roughly like a comfortable 1 g - a craft could get 99 per cent of the way to the expansion "horizon". Despite the vast distance, this would take only about 50 years in the astronaut's reference frame, because time would pass slower than on Earth due to relativity (Physical Review D, DOI: 10.1103/PhysRevD.72.107302).

more:

http://www.newscientist.com/article/mg20327274.200-how-far-could-you-travel-in-a-spaceship.html

[stuball111]

1. Yeah.. but where would you go?

And will there be a Wal Mart there? :rofl: Seriously, thanks for the post, and it makes one feel.... insignificant....

[baldguy]

3. I know this little cantina in Mos Eisley on Tatooine...

It's a little seedy - but there's always something happening.

[stuball111]

4. Hmmm.. sounds delicious...

How are the Tatooine babes? Or are those the aliens that are both male and female, and reproduce internally? (eeww)

[baldguy]

5. Some girls are scaley, some are gooey

But stay away from the ones that eat their mates.

[stuball111]

6. I like the Gooey ones..

Thanks for the heads up... when does the next Lightship leave? And is there Universal health care there?:headbang:

[caraher]

11. Is it still open?

Wasn't that joint hopping a long time ago, as well as in a galaxy far, far away? I'd worry that I'd get there to find they'd closed!

[Uben]

2. That's good to know.........

...I have some friends living on the edge. I may go for a visit!

[get the red out]

7. Can we put Glenn Beck on the ship and tell him to let us know?

With Rush Limbaugh for company? Tell them it is for the good of the country and don't hesitate to write.

[Aragorn]

8. interesting

but all we know is it goes farther than 15 billion light years. Maybe 150,000 light years - we can't tell.

Waiting for FTL and a good map. kthnx

[qazplm]

9. of course

if you could, and you probably cant, but if you could go FTL, then seems a bit that all bets are off?

[comtec]

10. Light speed is so brute force!

Now WARP speed...

So far the concept of a warp drive has not been disproved as possible.

The idea that you cause a dent in space, just in front of your ship and coast along the wake is very possible.

The technology for "dropping" into subspace so that FTL - by normal observation - is the really tricky part.

But the idea of building a "rocket ship" that can go .9c has pretty much been given up as impractical - because of the massive amount of time passing in "real-time"

[qazplm]

12. you'd have an interesting situation

Assume:

1. Humanity lives (effectively) forever. Advancing at some constant rate technologically speaking. Spreading through the universe, also at some constant rate.

2. We can build and do send out ships at .9c

You'd have a situation where the main branch of humanity would be slowly advancing out in all directions while pockets of significantly less advanced humanity (probably billions of years less advanced) would be out even further sort of as advanced scouts.

If your scouts were sent out with enough people and stuff to build colonies. You'd have the farthest colonies being hopelessly backwards and possibly not even able to communicate with the main branch of humanity. It would effectively be two different species. You could have the two groups encounter each other at some point, and wouldn't that be interesting. Sounds like the makings of a good sci-fi story. I'm sure it's already been written several times.

[Phoonzang]

13. There's also the interesting possiblity that

when the .9c ships get to their destination, the crew finds that a ship with some sort of FTL drive has already gotten there hundreds or thousands of years before them.

[sspeilbergfan90]

14. 5 billion trillion gazillion miles

[gk88850]

15. several billion miles