RECENT ARTICLES

Why do we remember the past and not the future? Untangling the connections between cause and effect, choice, and entropy.

Philosophers, physicists and neuroscientists discuss how our sense of time’s flow might arise through our interactions with external stimuli—despite suggestions from Einstein's relativity that our perception of the passage of time is an illusion.

A devilish new framework of thermodynamics that focuses on how we observe information could help illuminate our understanding of probability and rewrite quantum theory.

An unusual approach to unifying the laws of physics could solve Hawking's black-hole information paradox—and its predicted gravitational "memory effect" could be picked up by LIGO.

Objective reality, and the laws of physics themselves, emerge from our observations, according to a new framework that turns what we think of as fundamental on its head.

FQXI ARTICLE

January 21, 2020

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

May 22, 2009

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, 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.

Click here to discuss this article is FQXi’s forum.

Comment on this Article

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

function ValidatePostText_main () {
form = document.addPostForm_main;
var recaptcha = $("#g-recaptcha-response").val();
if (recaptcha === "") {
event.preventDefault();
alert("The reCaptcha Box below must be checked before you submit the form");
}
else if (form.postText_main.value == '') {
alert ("The post contains no text");
return false;
}
else {
return true;
}
}

**Your name:**
(optional)

Recent Comments

read all article comments

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

Please enter the text of your post, then click the "Submit New Post" button below. You may also optionally add file attachments below before submitting your edits.

HTML tags are not permitted in posts, and will automatically be stripped out. Links to other web sites are permitted. For instructions on how to add links, please read the link help page.

You may use superscript (10

^{100}) and subscript (A_{2}) using [sup]...[/sup] and [sub]...[/sub] tags.You may use bold (

**important**) and italics (*emphasize*) using [b]...[/b] and [i]...[/i] tags.You may also include LateX equations into your post.

Insert LaTeX Equation
[hide]

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

Attachments
[hide]

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

KATIE MOLINA wrote on March 12, 2019

It's called the Holographic Principle. It's when what appears to be n+1 dimensions is represented in n dimensions much as a holographic film can represent a 3d volume. The concept was brought up with string theory in resolving the information loss paradox of a black hole. It brings certain limitations as to information density and so far, everything including black holes has observed these limits. custom coupon codes saver Many people imagine the issue as being the universe is really represented...

It's called the Holographic Principle. It's when what appears to be n+1 dimensions is represented in n dimensions much as a holographic film can represent a 3d volume. The concept was brought up with string theory in resolving the information loss paradox of a black hole. It brings certain limitations as to information density and so far, everything including black holes has observed these limits. custom coupon codes saver Many people imagine the issue as being the universe is really represented...

QUANTUM ANTIGRAVITY wrote on April 17, 2017

EXPERIMENTAL quantum Anti-gravity — https://quantumantigravity.wordpress.com

I have made a theoretical as well as an empirical scientific discovery

of quantum gravity and quantum antigravity.

Present day quantum gravity theories suffer from

too many mathematical space dimensions, and from

too few conclusive experimental results.

My hypothesis is simple, clear,

and subject to easy empirical verification :...

EXPERIMENTAL quantum Anti-gravity — https://quantumantigravity.wordpress.com

I have made a theoretical as well as an empirical scientific discovery

of quantum gravity and quantum antigravity.

Present day quantum gravity theories suffer from

too many mathematical space dimensions, and from

too few conclusive experimental results.

My hypothesis is simple, clear,

and subject to easy empirical verification :...

DARIUS M wrote on June 22, 2014

The structure of spacetime is God's Mind. Individual minds are a part of this Universal Mind. This way each point in the Universe represents the whole - i.e. the Universe is holographic.

Time is what Kant called the act of spontaneity which generates the representation 'I think'. This act performs synthesis. I.e. time is mind processing information. Space is the medium where information is processed. Each qubit has its own processing rate (its own time) and is a parallel...

The structure of spacetime is God's Mind. Individual minds are a part of this Universal Mind. This way each point in the Universe represents the whole - i.e. the Universe is holographic.

Time is what Kant called the act of spontaneity which generates the representation 'I think'. This act performs synthesis. I.e. time is mind processing information. Space is the medium where information is processed. Each qubit has its own processing rate (its own time) and is a parallel...

read all article comments