ETI_2 - Interstellar Travel Search for Extraterrestrial...

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Interstellar Travel Search for Extraterrestrial Intelligence Stephen Eikenberry 23 November 2010 AST 2037 1
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Interstellar Travel: Why Bother? 2 Real answer: If you can’t actually GO there, it is pretty hard to kill them and take their stuff!
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Current Rocket Travel Time 3
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Our Friend: Time Dilation So … at v = 0.5c, we on Earth see a trip to α Cen take 6 years each way But, the astronaut on the ship sees it take about 5 years each way (!) Now, try v=0.99c We see it takes 3 years each way Astronaut sees it take about 6 weeks each way (!) Twin paradox: one twin on Earth ages 6 years during the round-trip, the other twin ages only 3 months (!!) 4
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Light Speed: Rocket Trouble Energy of flying mass is γ mc 2 To deliver payload mass m 1 , need enough fuel to slow-down and stop it For nuclear fusion (VERY efficient), this is 0.007 m fuel c 2 So, mass of fuel needed to stop m1 is m fuel = γ m 1 /0.007 This means you need about 3500x as much fuel as payload, just to stop (not to mention the fuel to get started in the first place!!!) 5
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This note was uploaded on 07/26/2011 for the course AST 2037 taught by Professor Eikenberry during the Fall '08 term at University of Florida.

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ETI_2 - Interstellar Travel Search for Extraterrestrial...

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