Originally posted by DeepThought
The amount of lithium in the Earth is not related to the amount of lithium in the Sun. For a terrestrial planet around that star the percentage composition will depend on the collapsing nebula's composition - not the amount of lithium in the star, since that all gets burnt in the proto-star stage.
Besides with a round trip of at least 500 years you won't get much investor interest.
Bust my party will you
As to the composition, I read an article in Scientific American a couple years ago about the stars that formed together with Sol from the same cloud, I recall there being something like 1500 to 5000 stars coming from that cloud and all resulting in more or less G2's. They then traced where they are today and they are spread out in our local arm around 1000 LY apart in more or less a straight line, kind of bunched together in a long string. Not sure whether this star under study was in that group. It sure sounds like it though.
It would be an extremely fascinating trip if we can ever achieve interstellar travel.
200 LY's puts it really close in the big picture.
A generation ship going 0.1c would take 2000 years one way with no appreciable relativistic effects. I suppose a trip like that could be planned where everyone is cryogenically frozen or you have frozen embryo's decanted say 25 years just before arrival and robots bring up the kids with lots of recordings of images and voices from Earth. Lots of ethical concerns there!
At 0.9c I think you get effective times for those onboard of about 2.3c so that would be about 86 years ship time.
At 0.99c it would effectively be about 7c or 28 years ship time. Of course round trip leaving today would still get you home in the year 2500 or so depending on how much time you sped there and how much time it takes to get to 0.99c. If you could manage 0.999c that would be about 22c ship time so that would be a trip of about 9 years, starting to get reasonable. 20 odd years round trip. You still don't get back till the year 2400 minimum though.
It gets more serious at 0.9999c, about 70c so about 6 years round trip time which helps those on board but doesn't help Earth much, you still take 400 years round trip, Earth time.
So 5 9's c gets you to about 223c so ship time of less than a year, couple years there and back. Still puts you back at the year 2400 or so, no help for that. You would need some serious propulsion though, at least 1 g constant accel. Gets you close to c in about 1 year.
Would not want to run into a meteor at that speed though
There would clearly be associated with such a ship heavy duty shields, magnetic, laser blasters (mainly to ionize stuff ahead of you so the magnetic shield would deflect it)
My guess is such a craft would be shaped like a loop, like a bracelet where the magnetic lines of force would converge inside the loop to direct ionized bad stuff and radiation looping around the lines of force.
It would be a real boon if we ever got the drives envisioned by the Nasa propulsion dudes though, the space warp drive where space would be curved positive in back and negative in front and you would be kind of like going downhill all the time achieving an effective faster than light speed but without the relativistic effects, so if you were going 10c it would take 20 years to get there and 20 years back and 40 years would go by on Earth so you would be in sync timewise, your brother would be the same age as you when you got back and so forth. That would be barely in the realm of possible, leave at the age of 20 and get back at the age of 60 or 65 or so. It would certainly be your life's work.
It would be fascinating to see an Earth like planet there 4 billion years further on than Earth, if there ever was some kind of scientific civilization there and long gone you might not EVER find evidence if there was anything like the geological activity of Earth. Of course if OUR sun was still something like what it is now, 4 billion years from now might run our core down in temperature where continental plates get fixed in place and no more major crunching taking place. Our moon would be long gone, joining the crowd in stellar space, maybe crashing into Jupiter or something but for sure not close to Earth any more, gravitational instabilities would see to that. So not much in the way of tides. Sounds like a boring planet...
On the other hand if things go like Kurzweil thinks there could be some kind of immortal life there still. Wonder what they would think of Earthlings.