Tens of billions of potentially habitable, Earth-size planets in our galaxy

Re:Tens of billions of potentially habitable, Earth-size pla... by gliese1337 on Wednesday November 06, 2013 @01:41PM (#6684485)

That's not how Alcubierre-derived warp fields work. The time inside a warp bubble is predicted to remain synchronized with the time in the originating frame. Thus, if your warp bubble goes at .95c, it'll take you 105.26 years one way, 210.52 going there and back.

And I'm sceptical of your calculation, anyway. From Earth's unchanging perspective, if your are going at .95c in a conventional manner relative to Earth, Earthlings will see your trip as taking the same 210.52 years. Time dilation will only affect the time that passes for the people on board, which will make it seem shorter, not longer. So, really, if your warp drive can't break c, it's better from the passengers' perspective not to use one. This is explained in the StackExchange article you linked to- you put the factor of gamma in the wrong spot (http://physics.stackexchange.com/questions/31105/how-to-calc...).

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Re:Tens of billions of potentially habitable, Earth-size pla... by thangalin on Wednesday November 06, 2013 @01:54PM (#6684598)

I was assuming conventional propulsion at 95% c. An Alcubierre warp field would be ideal, assuming the problems can be overcome:

http://en.wikipedia.org/wiki/Alcubierre_drive#Difficulties

http://arxiv.org/abs/1001.4960

http://arxiv.org/abs/1202.5708

I'd enjoy seeing your calculation of the number of years that would have passed on Earth for a round-trip of 100 light-years out.

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Re:Tens of billions of potentially habitable, Earth-size pla... by gliese1337 on Wednesday November 06, 2013 @02:05PM (#6684683)

You've seen it. 210.52 years. The passengers on the ship should only experience 65.7 years- (210.52)sqrt(1-.95^2). Hence the famous twin paradox- the twin who goes on a relativistic trip comes back younger than the one who stayed behind. What you calculated was how much time would pass on Earth for a trip that took 100 years and 100 light-years from the perspective of the people on the ship, which is not generally what people mean when they say that a star is 100ly away.

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Re:Tens of billions of potentially habitable, Earth-size pla... by thangalin on Wednesday November 06, 2013 @03:50PM (#6685417)

I found the source of my confusion.

The post I replied to stated, "I don't know how much time would have passed on Earth though." You stated I calculated "how much time would pass on Earth."

The OP was wondering, "if a person on a ship visited a star 100ly away, how much time would have passed on Earth when they returned?"

However, the OP was wondering about time frames in terms of a warp drive, rather than a conventional almost-light-speed drive. Take my upvotes. :-)

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