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Can We Travel To That Exciting New Exoplanet?
An anonymous reader writes "The news last week that exoplanet Gliese 581g may be in the 'Goldilocks zone' and could therefore hold liquid water and alien life got everyone all excited, with good reason. A potentially habitable planet — and only 20 light years away! But to put things in perspective, here are a couple of estimates on what it would take to travel to Gliese 581g. One scientist puts the travel time at 180,000 years based on current space flight technology, while another explains that it could be quite quick if we build a matter-antimatter drive, and can figure out how to bring along 530 times as much mass in fuel as is contained in the ship and cargo itself."
kudos to A.C. Clarke for the reference.
How dare you call Clarke an anonymous coward!
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I think you mean Star Wars.
No, I didn't forget that in principal, though it is true that I didn't recall the exact ratio.
You will note that I did not present any numbers about what the radius or volume would be, I only said that they would likely be proportionally bigger. I didn't specify what that proportion would be, because I couldn't remember and didn't want to take the time to look it up and show exact math, nor did I want to complicate my point by introducing an assumption of constant density.
I then estimated that .8G to 1.2G would be a more likely range than 4G, which it is. I probably should have said .8G to 2G. You are completely correct to say that 1.6 would be the exact value if the density remained constant, but I was only out to illustrate the fallacy that 4x mass -> 4x gravity.
Thank you for backing it up with more concrete values.
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