Chaos, Consciousness, and the Cosmos
Investigating the origin of mind and matter in the multiverse.
January 19, 2011
It sounds like hocus-pocus: An infinite number of parallel universes in which hallucinating brains can pop out of empty space. So perhaps it’s appropriate that one of the leading cosmologists behind the idea, Andrei Linde
, is also an amateur magician. Now, to prove that he hasn’t just pulled his theories out of a hat, Linde is looking for concrete evidence for this "multiverse" that could be picked up by the Planck satellite or at the Large Hadron Collider. The results could change our conceptions of consciousness and time, too.
Linde, who is based at Stanford University in California, is well-known for entertaining his friends and colleagues. "He is pretty good at performing magic tricks, and draws some great cartoons and portraits," says Tufts University cosmologist, and FQXi member, Alexander Vilenkin
. More importantly, he adds, "Andrei is one of the most creative physicists I know."
That creative flair has led Linde to pioneer "the new cosmological paradigm," over the past 30 years. He had been puzzled about why distant parts of the universe look the same and have the same temperature, when conventional wisdom said that they were too far apart to ever have been in contact. To explain their similarity, Linde and others came up with the theory of inflation
, which states that the very early universe went through a period of extremely rapid expansion. This solved the problem because it meant that far-flung regions of the universe would once have been connected, before inflation hurled them apart.
But the story didn’t end there. By the mid 1980s, Vilenkin and Linde realized that inflation was not a single event. Rather, many different patches of the cosmos could suddenly start inflating and blow up to huge volumes—each a universe in its own right. The most radical version of this theory proposed by Linde, known as eternal chaotic inflation, paints a picture of the multiverse as a Mandelbrot set—a growing fractal of universes—each one with different physical laws.
Is our universe just one of many?
But critics argue that speculating about a multiverse is a waste of time—and possibly even unscientific. By definition, any neighboring universes are so far away that we could never directly observe them. The trouble is not just that we do not have any evidence for the multiverse yet, but that it seems that there is no way we could ever either prove or falsify the idea.
Linde usually responds to such criticisms by quoting Sherlock Holmes: "When you have eliminated the impossible, whatever remains, however improbable, must be the truth." In particular, he argues, the multiverse provides the only logical answer to the question of why the constants of nature seem to be finely-tuned in such a way that they allow life to exist. "If there is an infinite number of universes with different physical laws, it makes sense that we happen to live in a universe that allows life," Linde explains.
However, Linde also agrees that the multiverse needs experimental support to win over skeptics. With a grant from FQXi, he is searching for concrete scientific predictions based on the theory—and he is already making progress.
When you have eliminated
the impossible, whatever
remains, however improbable,
must be the truth.
- Andrei Linde on the multiverse
The first place to look for evidence of the multiverse is at the Large Hadron Collider (LHC), the particle accelerator at CERN, in Geneva, Switzerland. Physicists there hope to unmask the secret identity of dark matter, the mysterious unidentified substance believed to make up the majority of matter in the universe. The best candidates for dark matter are "supersymmetric WIMPS" (weakly interacting massive particles) for which LHC physicists are already on the lookout. But, if Linde is right, physicists may find out that dark matter is made out other exotic particles, called "axions," which are backed by the multiverse theory.
Linde is also looking to the skies for help. In the late 1990s, astronomers noticed that the expansion of the universe was inexplicably accelerating—something that has been attributed to existence of an unknown "dark energy." If dark energy turns out to be down to a varying energy density filling space, termed "quintessence," as some cosmologists suspect, rather than being caused by a constant energy density, then this will be a blow to the multiverse theory.
The European Space Agency’s Planck satellite could also relay evidence in the form of gravity waves—ripples in the fabric of spacetime—caused by inflation. However, if the LHC simultaneously finds evidence for the existence of certain other supersymmetric particles hypothesised to be related to gravity waves, called "light gravitons," then this will challenge some of the most popular models of the multiverse based on string theory, says Linde.
ECHOES OF THE BIG BANG-S?
ESA’s Planck satellite spies on the infant universe.
Vilenkin also has an eye on data from Planck, but for a more dramatic reason. He believes that its measurements of the cosmic microwave background radiation could reveal the bruises of collisions between our cosmos and its neighbors. (See "When Universes Collide
" and "New Year, New Universe
But even if we can never directly observe other universes, that doesn’t mean that we should necessarily dismiss them as fantasy, says Martin Rees
, an early advocate of the multiverse at the University of Cambridge. "We take Einstein’s theory very seriously because it predicts things we can test, but we also believe what it predicts inside black holes, which we cannot observe," he says. Rees argues that the multiverse will become far less controversial once physicists understand more about how and why inflation occurs.
But even those who accept the mind-boggling multiverse will have to wrap their heads around yet more "crazy" questions, says Linde. To properly understand the arrow of time, for instance, we may need to incorporate consciousness into cosmology, he claims. Quantum mechanics strangely suggests that the wave function
(that is, the mathematical description) of an entire universe doesn’t change in time, meaning that the universe doesn’t evolve, despite our observations. But if you divide the wave function into two, with one part for the observer and another for the "rest of the universe," both wave functions suddenly depend on time. The observer—and in extension consciousness—is therefore crucial for the appearance of an arrow of time, says Linde.
Understanding life and
consciousness would be even
more important than
understanding the universe.
- Andrei Linde
Once Linde started thinking about consciousness, there was no turning back. He, and others, have even calculated the probability that consciousness—in the form of thinking, disembodied brains—can be momentarily produced by quantum fluctuations in an empty universe. (See "Measuring Up the Multiverse
.") And given that there are an infinite number of universes, this probability could be quite large—a bizarre mathematical result that caused physicists to debate what consciousness actually is and what implications it has for cosmology.
"To me, understanding life and consciousness would be even more important than understanding the universe," says Linde. "But we start with the universe because it is simpler."
Whether such complicated questions can be answered remains to be seen. Hopefully our magician has an ace hidden somewhere in his sleeve.
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RIKKI wrote on July 11, 2012
The "eliminated the impossible" quote is from Sherlock Holmes, not Linde.
DOUGLAS LIPP wrote on May 4, 2012
Feedback is appreciated.
Cosmologists are encouraged to provide evidence in support or not in support.
Please prove or disprove. The theory is experimentally verifiable.
NUNO OLIVEIRA wrote on February 28, 2012
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As regards my Computer Program, I could say that the notion of time within it is one of «semi-continuity» as to inflation of several multiverses, which induce «ripples» in spacetime tissue, being the space-time comprised between TWO (of the several ripples) [in reality not caused exclusively by gravity - which only works on reduced distances - but by its interaction with dark matter, which propels galaxies and celestial bodies far away, thus resulting in Inflation of the observable (but we are...