by Marcelo Gleiser
Why We Matter – To the Multiverse and Back
When, in 1543, Copernicus demoted the Earth to a mere planet, he had no idea that he would, albeit somewhat slowly, turn the world upside-down. The good canon of Warmia, Poland, set off a chain of events that would, in the centuries following, lead to the progressive humiliation of our species, once the proud center of creation. So goes the bad karma of science: the more we learn about the universe, the less important we become. Is this really what modern science is telling us?
In some ways, yes. Take, for example, the laws of physics and chemistry. They are the same across the vastness of space and the duration of time, at least from fractions of a second after the Big Bang to today. If the same laws hold across our cosmic horizon—the bubble of information defined by the distance light has travelled since the dawn of time 13.8 billion years ago—we should expect that events that happened on our planet in its 4.6 billion years of existence—the development of unicellular life and its evolution to intelligent multicellular species—are not remarkable. This is the “big numbers hypothesis”: in our galaxy alone there are some 300 billion stars, most with planets and moons, making up for over a trillion worlds, each different, each with its own history. Now add the existence of some 200 billion other galaxies within our cosmic horizon, and the diversity is staggering. How can we hold any claim to uniqueness?
Modern Copernicanism thus states that we are typical observers, what Tufts University cosmologist Alexander Vilenkin and many others often cite as the Principle of Mediocrity: the properties and evolution of the solar system are not unusual in any important way. It gets worse. When it comes to the composition of the cosmos, the star stuff we are made of amounts to a mere five percent of the total. The rest is comprised of dark matter (stuff not made of the usual protons and electrons) and dark energy (stuff of unknown nature that is responsible for accelerating the cosmic expansion). Our cosmic insignificance multiplies.
But let us not stop there. Modern theories of particle physics suggest that our universe may be but a bubble in the so-called multiverse: a conglomerate of countless universes, some growing, others shrinking, some young, others old, most with physical laws different from our own. If the multiverse is real, physics must answer questions it is not prepared to answer, related to selection principles that specify not just how the laws of Nature operate but which laws of Nature should act and where. Physics would need a kind of meta-law, a law that determines other laws, including the ones operating within our cosmic bubble…