STRRSHIPS 155
such a cosmic time scale, the rise and fall of human civilizations are
but tiny ripples. One day we must leave the Earth or die. So how will
humanity, our descendants, cope when conditions on Earth become
intolerable?
Mathematician and philosopher Bertrand Russell once lamented
"that no fire, no heroism, no intensity of thought or feeling, can preserve a life beyond the grave; that all the labors of the ages, all the devotion, all the inspiration, all the noonday brightness of human genius,
are destined to extinction in the vast death of the solar system; and the
whole temple of Man's achievement must inevitably be buried beneath
the debris of a universe in ruins ..."
To me this is one of the most sobering passages in the English language. But Russell wrote this passage in an era when rocket ships were
considered impossible. Today the prospect of one day leaving the Earth
is not so far-fetched. Carl Sagan once said we should become a "two
planet species." Life on Earth is so precious, he said, that we should
spread to at least one other inhabitable planet in case of a catastrophe.
The Earth moves in the middle of a "cosmic shooting gallery" of asteroids, comets, and other debris drifting near the orbit of the Earth, and a
collision with any one of them could result in our demise.
CATASTROPHES TO COME
Poet Robert Frost asked the question whether the Earth will end in fire
or ice. Using the laws of physics, we can reasonably predict how the
world will end in the event of a natural catastrophe.
On a scale of millennia, one danger to human civilization is the
emergence of a new ice age. The last ice age ended 10,000 years ago.
When the next one arrives 10,000 to 20,000 years from now most of
North America may be covered in half a mile of ice. Human civilization has flourished within the recent tiny interglacial period, when the
Earth has been unusually warm, but such a cycle cannot last forever.
Over the course of millions of years, large meteors or comets colliding with Earth could have a devastating impact. The last big celes-
such a cosmic time scale, the rise and fall of human civilizations are
but tiny ripples. One day we must leave the Earth or die. So how will
humanity, our descendants, cope when conditions on Earth become
intolerable?
Mathematician and philosopher Bertrand Russell once lamented
"that no fire, no heroism, no intensity of thought or feeling, can preserve a life beyond the grave; that all the labors of the ages, all the devotion, all the inspiration, all the noonday brightness of human genius,
are destined to extinction in the vast death of the solar system; and the
whole temple of Man's achievement must inevitably be buried beneath
the debris of a universe in ruins ..."
To me this is one of the most sobering passages in the English language. But Russell wrote this passage in an era when rocket ships were
considered impossible. Today the prospect of one day leaving the Earth
is not so far-fetched. Carl Sagan once said we should become a "two
planet species." Life on Earth is so precious, he said, that we should
spread to at least one other inhabitable planet in case of a catastrophe.
The Earth moves in the middle of a "cosmic shooting gallery" of asteroids, comets, and other debris drifting near the orbit of the Earth, and a
collision with any one of them could result in our demise.
CATASTROPHES TO COME
Poet Robert Frost asked the question whether the Earth will end in fire
or ice. Using the laws of physics, we can reasonably predict how the
world will end in the event of a natural catastrophe.
On a scale of millennia, one danger to human civilization is the
emergence of a new ice age. The last ice age ended 10,000 years ago.
When the next one arrives 10,000 to 20,000 years from now most of
North America may be covered in half a mile of ice. Human civilization has flourished within the recent tiny interglacial period, when the
Earth has been unusually warm, but such a cycle cannot last forever.
Over the course of millions of years, large meteors or comets colliding with Earth could have a devastating impact. The last big celes-