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FQXI ARTICLE

September 22, 2014

The Holographic Universe

Take one universe. Turn it into a hologram. Find its quantum wavefunction. Understand the birth of the cosmos.

FQXi Awardees: Alex Maloney

August 17, 2010

ALEX MALONEY

McGill University

"Even when I didn’t have a name for it, I sort of had a good idea of what I wanted to do," says Maloney, now at McGill University, Montreal. He credits his grandfather Dewitt Stetten, a prominent biochemist who would rather have been a mathematician or a physicist, for this insight. In his later years, Stetten went blind and it fell upon young Maloney to read to him. But this was no ordinary reading list. Maloney had to read aloud books like

Even when I didn’t

have a name for it,

I sort of had a good idea

of what I wanted to do.

have a name for it,

I sort of had a good idea

of what I wanted to do.

- Alex Maloney on physics

"I remember very clearly how excited everybody was by this set of discoveries," says Maloney. "Even though it didn’t have a direct influence on the thinking in string theory, it had an indirect influence."

String theory has been formulated as a candidate theory of

Hawking and Holograms

So now Maloney is turning to techniques that were forged to understand another arena where immense gravitational forces meet microscopic volumes and quantum gravity cannot be ignored: black holes. And that’s where holograms come in.

In the 1970s, Hawking and Jacob Bekenstein showed that the information stored in a black hole is proportional to its surface area rather than its volume. This encoding of three-dimensional information on a two-dimensional surface came to be called the holographic principle. In 1997, Juan Maldacena of the IAS formalized the principle, showing that the string theory description of a black hole is mathematically equivalent to a quantum field theory without gravity that describes the surface of the black hole.

"PROBABLY THE MOST INTERESTING QUANTUM GRAVITATIONAL

SYSTEM."

Alex Maloney assesses the universe.

Credit: Ephraim Brown

The holographic principle came to the rescue; physicists used it to show that the information of the constituents of the black hole is actually encoded in the radiation that emanates from its surface. So no information is ever lost.

The next step, says Maloney, is to try and apply these sorts of ideas to "what’s probably the most interesting quantum gravitational system"—the universe as a whole.

Holography right now

is the most powerful

tool to understand

precise formulations of

quantum gravity.

is the most powerful

tool to understand

precise formulations of

quantum gravity.

- Alex Maloney

"Holography right now is probably the most powerful tool to understand precise formulations of quantum gravity," says Maloney.

But it won’t be easy. The correspondence that Maldacena found works in very particular circumstances. It deals with a simple form of spacetime, called

"You might think that because they only differ by one word, the description is rather similar," says Maloney. "But it turns out that describing de Sitter space using holography is much more subtle, and much trickier."

Black-Hole Universe

One of the key differences is that the volume of de Sitter space changes with time. That makes sense when you want to describe the early universe, which is thought to have increased nearly 10

LAUNCHING THE QUEST FOR A THEORY OF QUANTUM GRAVITY

The Ariane 5 launcher lifts-off from the European spaceport in Kourou

on 14 May 2009, carrying the Planck satellite.

Credit: European Space Agency

Treating the universe as a hologram might sound like just a nifty mathematical trick, with little relevance to reality. But if holographic techniques can be applied to de Sitter space, they can also be used to make predictions about patterns etched in the cosmic microwave background (CMB), the relic radiation left over by the big bang.

Maloney’s main strength

is his ability to

discover new angles.

is his ability to

discover new angles.

- Andrew Strominger

The European Space Agency’s Planck satellite, launched on 14 May 2009, will be trying to home in on those tantalizing hints offered by WMAP, and Maloney is eagerly awaiting the outcome. "Understanding how it deviates is a question that might be relevant for a theory of quantum gravity," says Maloney.

Maloney’s combining all that he’s learnt: mathematics and physics, general relativity and quantum mechanics. "Applying quantum gravity to quantum cosmology is a very exciting thing to be doing nowadays," he says. Those childhood days spent reading Hawking’s obscure musings to his grandfather are certainly paying off.

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ANONYMOUS wrote on November 9, 2013

Baggott[Farewell to Reality: How Fairy-Tale Physics Has Betrayed The Search For Scientific Truth] and even more spot-on Unzicker-Jones[Bankrupting Physics: How Top Scientists Are Gambling Away Their Credibility] critiques shame physics’ shameless rock-star media-hype P.R. spin-doctoring veracity-abandoning touting sci-fi “show-biz” trending viral exacerbated by online social networks veritable diarrhea via proliferation of uncritical “pop-sci” science-writers where all is spectacle...

Baggott[Farewell to Reality: How Fairy-Tale Physics Has Betrayed The Search For Scientific Truth] and even more spot-on Unzicker-Jones[Bankrupting Physics: How Top Scientists Are Gambling Away Their Credibility] critiques shame physics’ shameless rock-star media-hype P.R. spin-doctoring veracity-abandoning touting sci-fi “show-biz” trending viral exacerbated by online social networks veritable diarrhea via proliferation of uncritical “pop-sci” science-writers where all is spectacle...

GRAINNE wrote on October 17, 2011

when things expand the surface becomes thiner as it spreads and the cause of it's expansion increases i.e. a balloon - what is causing the expansion of the universe as we know it?

when things expand the surface becomes thiner as it spreads and the cause of it's expansion increases i.e. a balloon - what is causing the expansion of the universe as we know it?

NARSEP wrote on September 17, 2010

The previous note refers to string theories, Hawking's calculations on black holes, M-theory, black hole information "paradox", and many other paradoxes ... of modern physics that I am happy having no any idea of.

The previous note refers to string theories, Hawking's calculations on black holes, M-theory, black hole information "paradox", and many other paradoxes ... of modern physics that I am happy having no any idea of.

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