In the last decade, there has been dramatic progress in exploring the cosmos. Highlights include close-up studies of the planets and moons of our solar system, the realization that most stars are orbited by planets, and that there may be millions of Earth-like planets in our galaxy. On a still larger scale, we have achieved a better understanding of how galaxies have developed, over 13.8 billion years of cosmic history, from primordial fluctuations. These fluctuations might have been generated via quantum effects when our entire cosmos was of microscopic size. Also, Einstein’s theories received further confirmation with the detection of gravitational waves—a tremendous technological achievement.
The pace of advance has crescendoed rather than slackened; instrumentation and computer power have improved hugely and rapidly and future advances will depend on increasingly powerful instruments, which could reveal evidence of life on exoplanets and yield a better understanding of the big bang and the ultimate fact of our cosmos. While human spaceflight has somewhat languished in the decades since the Apollo program and the moon landings, space technology has burgeoned—for communication, environmental monitoring, satnav, and so forth.
Even though humans have not ventured further than the moon, unmanned probes to other planets have beamed back pictures of varied and distinctive worlds. During this century, the entire solar system—planets, moons, and asteroids—will be explored and mapped by flotillas of tiny robotic craft. Giant robotic fabricators will be able to construct, in space, huge solar-energy collectors and other artifacts. The next step would be space mining and fabrication, and it is robots, and not humans, that will build giant structures in space.
The question that astronomers are most often asked is: “Is there life out there already? While prospects look bleak in our solar system, they improve if we widen our horizons to other stars—far beyond the scale of any probe we can now envisage. The hottest current topic in astronomy is the realization that many other stars like the sun are orbited by retinues of planets.
While prospects look bleak in our solar system, they improve if we widen our horizons to other stars.
We are especially interested in possible “twins” of our Earth—planets the same size as ours. We may learn this century whether biological evolution is unique to our Earth, or whether the entire cosmos teems with life—even with intelligence.
We have made astonishing progress. Fifty years ago, cosmologists did not know if there was a big bang. Now, we can draw quite precise inferences back to a nanosecond. So, in fifty years, debates that now seem flaky speculation may have been firmed up. But it is important to emphasize that progress will continue to depend, as it has up till now, ninety-five percent on advancing instruments and technology—less than five percent on armchair theory, but that theory will be augmented by artificial intelligence and the ability to make simulations.
Finally, I want to focus back closer to the here and now. I am often asked: is there a special perspective that astronomers can offer to science and philosophy? We view our home planet in a vast cosmic context. And in coming decades we will know whether there is life out there. But, more significantly, astronomers can offer an awareness of an immense future. Darwinism tells us how our present biosphere is the outcome of more than four billion years of evolution. But most people still somehow think we humans are necessarily the culmination of the evolutionary tree. That hardly seems credible to an astronomer—indeed, we are probably still nearer the beginning than the end.
But my final thought is this. Even in this “concertinaed” timeline—extending billions of years into the future, as well as into the past—this century may be a defining moment. This century is special. It is the first where one species—ours—has Earth’s future in its hands, and could jeopardize life’s immense potential. We have entered a geological era called the anthropocene. Our Earth, this “pale blue dot” in the cosmos, is a special place. It may be a unique place. And we are its stewards at an especially crucial era. That is an important message for us all.
Martin Rees is a cosmologist and space scientist.