By Dr. Mark R. Showalter
Planetary astronomer at the Carl Sagan Center for the Study of Life in the Universe, SETI Institute
It was just a few months ago that Stephen Hawking was making headlines with his bold assertion that extraterrestrial beings, if they exist, are best avoided. His argument was based in part upon the fact that the arrival of Christopher Columbus to the "New World" didn't work out so well for the Native Americans who were already here. However, upon closer inspection, Hawking's ideas fell apart. Even if nomadic tribes of ETs are really out there looking for a handy source of protein, the probability that they would crave Earth's particular blend of amino acids is essentially nil. If they are just looking for energy, then our own meager Sun is an unlikely pit-stop. And besides, we cannot exactly hide from them; I Love Lucy re-runs have already been propagating outward through the Universe for 59 years.
I work at the SETI Institute, which is surely Ground Zero in the flight plan of those hungry extraterrestrials. Nevertheless, I take great comfort in Stephen Hawking's words. Not because I believe them---far from it, in this case---but because they provide a welcome reminder that even profoundly brilliant people can have really silly ideas. Especially when they veer out of their own fields of expertise.
Stephen Hawking has been in the news again recently. His latest book, The Grand Design, is a brief and (relatively) readable treatise about the M-theory. What the "M" stands for is under debate, but this is a description of recent ideas about how the Universe came to exist. For Dr. Hawking to present the latest ideas from the most advanced fields of modern physics in such a readable form is remarkable. He and his co-author, Dr. Leonard Mlodinow, rightfully deserve our praise for making such difficult material so accessible.
However, the M-theory itself is not what is making the news. As an astronomer, I can only dream of a day when scientific ideas would reach the headlines based upon their own merit. Instead, the news reports center around Hawking's most provocative assertions, which are that Philosophy is obsolete and that God is unnecessary.
I'm just a rings guy. I study the dynamics of planetary systems. The laws of physics that arise in my day-to-day research harken back to Newton, not even Einstein. If you want to know the latest news from Jupiter or Uranus, I'm your guy, but black holes and the Origin of the Known Universe? Not so much. Astrophysicists sometimes deride us planetary astronomers as the ones who merely study "rocks." So perhaps I should heed my own advice and not veer out of my own field of expertise.
(Perhaps this is also a good time for me to note that I am speaking for myself, not the SETI Institute or any of its diverse research scientists.)
Think back for a moment to recent history. It is February 2002, the war in Iraq is raging, and Donald Rumsfeld is Secretary of State. In a speech, he describes the situation there as one involving "known unknowns" and "unknown unknowns." For this painful contortion of the English Language, Rumsfeld is excoriated by the press. With so many lives at stake, no wonder. However, as a scientist, I understood exactly what Rumsfeld meant. Many times during my career as an astronomer have I seen the most elegant scientific explanation collapse, not because the math was wrong, but because a theorist overlooked one obscure physical process that rendered the whole exercise irrelevant. I could cite many examples of these unknown unknowns. I have been on the losing end of several such scientific debates myself; it is a humbling place to be.
This brings me back to Dr. Hawking. It would be silly for me to challenge him on the subtleties of the latest version of M-theory. If our Universe is but one of an infinitude within the broader "Multiverse," so be it. If the Universe exists merely because "nothing" and/or the laws of gravity require it, fine. Nevertheless, one of the things I have learned from my studies of rocks is that even painfully simple Newtonian physics continues to hold surprises. We should never be too bold in our claims when we live in a Universe (let alone a Multiverse) where the unknown unknowns abound. How lucky we are that they do.