Our universe could be a parcel of space and time in an infinite archipelago

Is our part of the universe a tiny, atypical fragment of a vast archipelago of universes? “By the end of this century we should be able to ask ourselves whether or not we live in a multiverse, and how varied its constituent ‘universes’ are.

The answer to this question will determine how we should interpret the “biological” universe we live in (sharing it with aliens we may one day come into contact with),” according to Lord Martin Rees, Britain’s leading cosmologist and astrophysicist.

What we have traditionally called the ‘universe’ – the aftermath of ‘our’ big bang – may be just an island, just a patch of space and time, in a perhaps infinite archipelago,” continues Rees, Britain’s leading astrophysicist, in Nautil.us. There may have been many big bangs, not just one.

However, if the universe spreads out enough, anything could happen: somewhere beyond our horizon there could even be a replica of the Earth.

This requires the space to be VERY large, described by a number with not just a million digits, but 10 to the power of 100 digits: a one followed by 100 zeroes. Ten to the power of 100 is called a googol, and a number with a googol of zeros is a googolplex.

If space really is infinite,” observes cosmologist Dan Hooper, head of the Fermi National Accelerator Laboratory’s Theoretical Astrophysics Group, in At the Edge of Time, “the implications are staggering.”

Within an infinite expanse of space, it would be hard to see any reason why there shouldn’t be an infinite number of galaxies, stars, and planets, and even an infinite number of sentient or intelligent beings, scattered throughout this limitless volume.

That’s the thing about infinity: it takes things that would otherwise be highly unlikely and makes them inevitable.”

The disturbing implications of the multiverse
The universe we see around us is a small portion of a much larger multiverse. The multiverse theory says that what we have always called the “universe” is actually nothing like that.

Rather, it is but an infinitesimal fragment of a much larger and more elaborate system: a set of “universes,” or distinct cosmic regions, according to Paul Davies, in The Riddle of Goldilocks: Why the Universe Is perfect for life?

When asked about the possibility of ever obtaining proof of the existence of another universe, Yasunori Nomura, director of the Center for Theoretical Physics at Berkeley, replied in an email to The Daily Galaxy: “This picture of many universes – the multiverse – is not a random idea, but a specific scenario suggested by theories of fundamental physics, such as string theory.

As such, we could test the predictions of the scenario, even without going to another universe. For example, our universe could collide with another universe, the traces of which can, in principle, be seen in the sky, in particular as a characteristic pattern in the so-called cosmic microwave background radiation.

“Furthermore,” Nomura explains in the email from him, “according to this many universes scenario, our own universe must be ‘negatively curved,’ meaning it must have a certain geometric property.” Although the theory does not predict the degree of curvature, this prediction could be confirmed in future observations.

Perhaps most importantly, if a future observation were to find that the curvature of our universe is positive, rather than negative, then the version of the multiverse that many physicists are currently talking about would be ruled out by the observation.”

When asked if an adjacent universe is likely to operate under different physical laws, Nomura replied, “Based on what we currently know, we expect other universes to have very different properties from our own.

“For example, the nature of elementary particles and the law that governs their behavior have different forms. For some universes, even the number of dimensions of spacetime may be different. Certainly, we expect universes “adjacent” to ours to look very different from our own.

“This, however, does not mean that there are no physical laws that govern the multiverse. For example, all universes are expected to obey the principles of quantum mechanics. Quite simply, some of the properties of our universe that we have conventionally considered to be fundamental are not as fundamental as we once thought. The nature of the elementary particles – even the existence of the electron, the photon, etc. – is between them».

“In some pockets of space, well beyond the limits of our observations,” Dan Hooper wrote in an email to The Daily Galaxy, referring to the theory of eternal inflation and the inflationary multiverse: “the laws of physics could be very different from those we find in our local universe.

There could be different forms of matter, which experience different kinds of forces. In this sense, what we call «the laws of physics», instead of being a universal fact of nature, could be an environmental fact, which varies from one place to another, or from one time to another.»