Eggs, Baskets, Mortality

Humans are mortal.  It's one of the sad facts we all live with until our own mortality overtakes us.  There are two main ways people handle that depressing news.  Religion offers the comfort of an afterlife:  your body may die, but your soul, some immaterial essence of identity, lives on forever.
    The other comfort is continuity.  You may die, but your family and your people will go on, and maybe you will be remembered.  This was the ideal of the ancient Greeks, and has always coexisted uneasily with the concept of the afterlife in Western civilization.
    The big problem with continuity is that families and communities are just as mortal as individuals.  Whole languages are dying out right now, even old and famous ones.  In a century how many people will speak Italian or Dutch?
    An optimist would point out that while certain groups or languages may dissolve, the greater mass of humanity will continue.  But even humanity as a whole is vulnerable now.  There are a lot of ways to destroy the Earth, and even more ways for humanity to make itself extinct.  And the open, international nature of science puts those methods at the disposal of everyone.  Even crazy people. 
    More distressingly, there are plenty of accidents just waiting to happen.  Even if all humans someday are sane, moral, and kind, we can still be smashed by a giant rock from space.  Giant rocks don't care what they hit.  Gamma-ray bursters don't care what they irradiate.
    Stephen Hawking is a man who has probably done a lot of hard thinking about his own mortality.  When you've lived for decades completely dependent on life-support equipment and the help of others you can't ignore death.  Hawking also knows a lot more about physics than most people, and he's worried about humanity.
    A week ago Hawking told an audience in Hong Kong that permanent colonies off Earth are vital to the long-term survival of the human species.
    It's simply the old "don't put all your eggs in one basket" principle applied to a very large scale.  Don't put all your people on one planet.  The more widely humans are dispersed, the harder it would be to kill them all.  If we had colonies throughout the Solar System it would take a supernova to get us all.  A few settlements circling other stars would require a cosmic-scale disaster.
    Space colonization is hard and expensive, but the same science which makes self-destruction easier also makes it easier to get away.  Nuclear energy can level a city -- or boost a rocket to Mars.  Genetic manipulation can create super plagues or bring life to a lifeless planet.
    Some may ask, why bother?  Why work and struggle to keep our miserable species going a few millennia longer?  The Universe has a finite lifespan anyway.  "In the long run we are all dead," as Keynes put it.
    Here's why to bother.  If we are alone in the Universe, with no other intelligent life but humans, then every second of human existence is another second during which there's a point to the existence of everything.  With nobody to see it, the Universe may as well not exist. 
    And if there are other kinds of intelligence out there, shouldn't we try to hang on until we meet them?  So that humanity won't be a tree falling in the forest with nobody to hear?

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Or for some real Science Made Cool, read Stephen Hawking's blog!