第12页 | What to Think About Machines That Think | 阅读 ‧ 电子书库

INTELLIGENT MACHINES ON EARTH AND BEYOND

MARIO LIVIO

Astrophysicist, Space Telescope Science Institute; author, Brilliant Blunders; blogger, A Curious Mind

Nature has already created, here on Earth, machines that think—humans. Similarly, nature could also create machines that think on extrasolar planets in the so-called habitable zone around their parent stars—the region allowing for the existence of liquid water on a rocky planet’s surface. The most recent observations of extrasolar planets have shown that a few tenths of all the stars in our Milky Way galaxy host roughly Earth-size planets in their habitable zones.

Consequently, if life on exoplanets is not extremely uncommon, we could discover some form of extrasolar life within about thirty years. In fact, if life is ubiquitous, we could get lucky and discover life even within the next ten years, through a combination of observations by the Transiting Exoplanet Survey Satellite (TESS, to be launched in 2017) and the James Webb Space Telescope (JWST, to be launched in 2018).

One may argue that primitive life-forms are not machines that think. On Earth it took about 3.5 billion years from the emergence of unicellular life to the appearance of Homo sapiens. Are the extrasolar planets old enough to have developed intelligent life? In principle, they definitely are. In the Milky Way, about half the sun-like stars are older than our sun. Therefore, if the evolution of life on Earth is not entirely atypical, the galaxy may already be teeming with places in which there are “machines” even more advanced than we are, perhaps by as much as a few billion years!

Can we, and should we, try to find them? I believe that we have almost no freedom to make those decisions. Human curiosity has proved time and again to be an unstoppable drive, and these two endeavors—the development of AI and the search for ET—will undoubtedly continue at full speed. Which one will get to its target first? To even attempt to address this question, we have to note that there’s one important difference between the search for extraterrestrial intelligent civilizations and the development of artificial intelligence.

Progress toward the “Singularity” (AI matching or surpassing humans) will almost certainly take place, since the development of advanced AI has the promise of producing enormous profits. On the other hand, the search for life requires funding at a level that can usually be provided only by large national space agencies, with no immediate prospects for profits in sight. This may give an advantage to the construction of thinking machines over the search for advanced civilizations. At the same time, however, there’s a strong sense within the astronomical community that finding life in some form—or at least meaningfully constraining the probability of its existence—is definitely within reach.

Which of the two potential achievements will constitute a bigger “revolution”? There’s no doubt that thinking machines will have an immediate impact on our lives. Such may not be the case with the discovery of extrasolar life. However, the existence of an intelligent civilization on Earth remains humanity’s last bastion for being special. We live, after all, in a galaxy with billions of similar planets, and in an observable universe with hundreds of billions of similar galaxies. From a philosophical perspective, therefore, I believe that finding extrasolar intelligent life (or the demonstration that it’s exceedingly rare) will rival the Copernican and Darwinian revolutions combined.