|Frontiers | Pages 160-161 ||
out of the planet. Until recently, biologists didn't know that life could flourish in such extreme settings, often far beyond the reach of sunlight. These organisms--so-called extremophiles--have raised hopes that Earth's biological garden is just one of many oases in an otherwise barren cosmos.
Whether life has sprouted in other parts of the universe is one of the great cosmic questions we face today. We also seek to understand the behavior of matter on the tiniest scales and the origin and fate of the universe itself. Addressing these mysteries requires us to push our scientific skills to their limits. But if we continue to make steady progress in our explorations of motion, matter, and energy in the universe, even these answers may lie within reach.
Does Matter + Energy = LIFE?
At first glance the topic of life seems far removed from our discussion of the basic physics of the cosmos. However, all living things behave according to the laws of physics, no matter what or where they are. In 1917 the Scottish biologist D'Arcy Thompson noted in the introduction to his classic book, On Growth and Form: "Cell and tissue, shell and bone, leaf and flower, are so many portions of matter, and it is in obedience to the laws of physics that their particles have been moved, moulded and conformed." Thompson also recognized that those laws extend beyond the bounds of Earth: "Everywhere Nature works true to scale, and everything has its proper size accordingly. Men and trees, birds and fishes, stars and star-systems, have their appropriate dimensions . . . ." Thompson wasn't suggesting that life might exist elsewhere. Nevertheless, his thoughts provide a framework for our scientific inquiries into extraterrestrial life.
Thompson's observations cast a biological light upon two principles that guide our understanding of the physical nature of the universe. The Copernican principle, named for Nicolaus Copernicus, asserts that Earth is not the center of the cosmos. Rather, it is an ordinary place. Planets like Earth probably circle stars like our Sun throughout our galaxy and in similar galaxies elsewhere. We don't yet have the means to detect Earth-like planets, but we may within the next decade or two. On a more sweeping scale, the cosmological principle holds that the universe is the same (continued)