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Rescuing Reality
A "retrocausal" rewrite of physics, in which influences from the future can affect the past, could solve some quantum quandaries—saving Einstein's view of reality along the way.

Untangling Quantum Causation
Figuring out if A causes B should help to write the rulebook for quantum physics.

In Search of a Quantum Spacetime
Finding the universe's wavefunction could be the key to understanding the emergence of reality.

Collapsing Physics: Q&A with Catalina Oana Curceanu
Tests of a rival to quantum theory, taking place in the belly of the Gran Sasso d'Italia mountain, could reveal how the fuzzy subatomic realm of possibilities comes into sharp macroscopic focus.

Dropping Schrödinger's Cat Into a Black Hole
Combining gravity with the process that transforms the fuzzy uncertainty of the quantum realm into the definite classical world we see around us could lead to a theory of quantum gravity.

October 23, 2016

Chaos, Consciousness, and the Cosmos
Investigating the origin of mind and matter in the multiverse.
by Miriam Frankel
FQXi Awardees: Andrei Linde
January 19, 2011
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Stanford University
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.

Eternal Chaos

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.

Spacetime Ripples

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.

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.

Cosmic Consciousness

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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Recent Comments

Does Andrei Linde anywhere define what consciousness is?

Awesome, I have the same (or very similar) idea about the time arrow being the perception of our POV (a embodied limited consciousness), travelling space structure.

Im feeling that conscioussnes & space are aspects of the same thingh.

I have written an essay on the subject but it is in spanish.

The "eliminated the impossible" quote is from Sherlock Holmes, not Linde.

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