MIT Physicist Calls Human Life an 'Accident' of the Multiverse

Monday, 23 February 2015 - 2:33PM
Monday, 23 February 2015 - 2:33PM

Physicists and philosophers alike have been trying to explain the supposed "fine-tuning" of the universe for over a century, and modern theoretical physics may have an answer in the multiverse theory. In his book The Accidental Universe: The World You Thought You Knew, MIT physicist Alan Lightman explains in a uniquely simple (and blunt) manner that in all likelihood, the universe isn't fine-tuned for our benefit, but rather, human life is only a run-of-the-mill accident of the multiverse.


The concept of the "fine-tuned universe" explores the reasons why the physical constants of our Universe tend to be within extremely narrow ranges that allow for the presence of human life. Lightman uses the example of the amount of dark energy in the Universe, which essentially could not have been significantly different and still allowed for human life:


"On one thing most physicists agree. If the amount of dark energy in our universe were only a little bit different than what it actually is, then life could never have emerged. A little larger, and the universe would have accelerated so rapidly that matter in the young universe could never have pulled itself together to form stars and hence complex atoms made in stars. And, going into negative values of dark energy, a little smaller and the universe would have decelerated so rapidly that it would have recollapsed before there was time to form even the simplest atoms.


"Out of all the possible amounts of dark energy that our universe might have, the actual amount lies in the tiny sliver of the range that allows life. There is little argument on this point."


He then explains that these "perfect" constants have often led scientists to believe that the universe was somehow designed to allow for human life. But since, putting religious belief aside for the moment, this seems to be an unnecessarily anthropocentric theory, many theorists believe that this "fine-tuning" can be explained by the multiverse theory. If there are many coexistent universes that encompass all the possible physical constants, then it wouldn't be such an outlandish "coincidence" that we exist in a universe that allows for our presence. Rather, it's an "accident":


"One is compelled to ask the question: Why does such fine-tuning occur? And the answer many physicists now believe: the multiverse. A vast number of universes may exist, with many different values of the amount of dark energy. Our particular universe is one of the universes with a small value, permitting the emergence of life. We are here, so our universe must be such a universe. We are an accident. From the cosmic lottery hat containing zillions of universes, we happened to draw a universe that allowed life. But then again, if we had not drawn such a ticket, we would not be here to ponder the odds."


In other words, it's not that the Universe was designed for us, but that we were essentially designed for the Universe; we are only here because one of many Universes allows us to exist:


"If the multiverse idea is correct, then the historic mission of physics to explain all the properties of our universe in terms of fundamental principles - to explain why the properties of our universe must necessarily be what they are - is futile, a beautiful philosophical dream that simply isn't true. Our universe is what it is simply because we are here."


This is not a new idea; many physicists have made similar arguments, most recently Victor Stenger, a particle physicist and popular proponent of New Atheism. But Lightman's book is a particularly frank and succinct explanation, filled with apt metaphors such as this one:


"The situation can be likened to that of a group of intelligent fish who one day begin wondering why their world is completely filled with water. Many of the fish, the theorists, hope to prove that the cosmos necessarily has to be filled with water. For years, they put their minds to the task but can never quite seem to prove their assertion. Then a wizened group of fish postulates that maybe they are fooling themselves. Maybe, they suggest, there are many other worlds, some of them completely dry, some wet, and everything in between."

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