Saturday, April 27, 2013

Why We'll Never Meet Aliens

And we don't need ANY arguments about what such beings would be like in order to understand that there is nothing unique here to want. The Solar System is composed of approximately 99.95% hydrogen and helium. This is basically the same as the composition of the rest of the Universe. While some elements may be slightly more common or concentrated in slightly more convenient forms in one place than another there simply isn't anything particularly unique in one star system that isn't present in another.

Furthermore look at the energetics of interstellar space travel. "Accelerating one ton to one-tenth of the speed of light requires at least 450 PJ or 4.5 ?10^17 J or 125 billion kWh, without factoring in efficiency of the propulsion mechanism. This energy has to be either generated on-board from stored fuel, harvested from the interstellar medium, or projected over immense distances." -- Wikipedia. In 2008 the world used roughly 474?10^18 J, which means the entire power output of the human race for a year would suffice to accelerate one starship of 40 tons to 0.1C, roughly. This is about the weight of the 'J' class Apollo Lunar mission payload (LEM, CM, SM, etc). Clearly even the most limited interstellar travel would have an energy cost that is frankly hard to imagine.

So, considering the enormous cost and the high degree of technology required to traverse interstellar space, why bother? Certainly it can never be economical. The energy costs quoted above indicate that even the most expensive conceivable processes for making things would be cheaper (IE using solar power to perform nuclear reactions to transmute one element into whatever other ones you need and then make whatever you want out of it) than traveling to where you can find something.

Clearly a civilization could in principle literally consume all matter in its vicinity. It is hard to imagine how this would lead to expansion for economic reasons though, there'd never be any hope of getting a return on your investment.

Obviously someone can always invent some new hypothesis as to why, for reasons of alien psychology, aliens would want to travel, but nobody knows squat about alien psychology, so there's really no point in debating it. The very fact that such an undertaking would be VAST in scope, significant even for a Kardeshev level 2 civilization indicates it wouldn't be carried out on some whim, and it seems unlikely that a civilization which spent its energy so profligately on whims would survive long.

I know it isn't a real popular opinion to hold, but everything I see indicates that interstellar distances are pretty close to uncrossable for physical beings like humans. Frankly I think that is the plain answer to the whole Fermi Paradox that people just don't really want to come to grips with. The gulfs between the stars are so wide that nobody crosses them, EVER.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/5GlVZLBNdfk/story01.htm

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