Is the universe a hologram?

Credit: TU Wien
 
What we perceive as three dimensional may just be the image
of two dimensional processes on a huge cosmic horizon.
 
 
"Our own universe could in fact be two dimensional and only
appear three dimensional -- just like a hologram."

I have long been a science geek, even though my degree and work experience has little to do with science.  Yet, I've followed science over the years, often in total bewilderment.
 
The story out of the University of Vienna is full of promising lines like this:
"It is like finding out that equations from an astronomy  textbook can also be used to repair a CD-player." 
People still have CD players? Never mind.
 
This story intrigues, but I must admit I haven't a clue about the science.  The universe may be two dimensional?  And only appears three dimensional?  This reminds me of a sophomore philosophy course.  Something about a cave with images cast on a wall.

This is one of those stories about which J.B.S. Haldane wrote in 1927, "I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose."
 
Feynman once said that no one really understands quantum mechanics.  S.J. Perelman once wrote that a report like this would "put a glaze on your eye like a Sung vase." Noted social commentator, Hairy Monster of Sesame Street, has been quoted, "Brain hurt." 
 
All apply.
 
Here's the story:

Is the universe a hologram?

The 'holographic principle,' the idea that a universe with gravity can be described by a quantum field theory in fewer dimensions, has been used for years as a mathematical tool in strange curved spaces. New results suggest that the holographic principle also holds in flat spaces. Our own universe could in fact be two dimensional and only appear three dimensional -- just like a hologram.

At first glance, there is not the slightest doubt: to us, the universe looks three dimensional. But one of the most fruitful theories of theoretical physics in the last two decades is challenging this assumption. The "holographic principle" asserts that a mathematical description of the universe actually requires one fewer dimension than it seems. What we perceive as three dimensional may just be the image of two dimensional processes on a huge cosmic horizon.

Up until now, this principle has only been studied in exotic spaces with negative curvature. This is interesting from a theoretical point of view, but such spaces are quite different from the space in our own universe. Results obtained by scientists at TU Wien (Vienna) now suggest that the holographic principle even holds in a flat spacetime.

Zen in the Art of Writing

by Ray Bradbury

Click on image to order
Powell's Books
The Holographic Principle
Everybody knows holograms from credit cards or banknotes. They are two dimensional, but to us they appear three dimensional. Our universe could behave quite similarly: "In 1997, the physicist Juan Maldacena proposed the idea that there is a correspondence between gravitational theories in curved anti-de-sitter spaces ("anti-de Sitter space (AdSn) is a maximally symmetric Lorentzian manifold with constant negative scalar curvature".  I don't know what it means either.) on the one hand and quantum field theories in spaces with one fewer dimension on the other," says Daniel Grumiller (TU Wien).

"It is like finding out that equations from an astronomy
textbook can also be used to repair a CD-player."

Gravitational phenomena are described in a theory with three spatial dimensions, the behaviour of quantum particles is calculated in a theory with just two spatial dimensions -- and the results of both calculations can be mapped onto each other. Such a correspondence is quite surprising. It is like finding out that equations from an astronomy textbook can also be used to repair a CD-player. But this method has proven to be very successful. More than ten thousand scientific papers about Maldacena's "AdS-CFT-correspondence" have been published to date.

Correspondence Even in Flat Spaces
For theoretical physics, this is extremely important, but it does not seem to have much to do with our own universe. Apparently, we do not live in such an anti-de-sitter-space. These spaces have quite peculiar properties. They are negatively curved, any object thrown away on a straight line will eventually return. "Our universe, in contrast, is quite flat -- and on astronomic distances, it has positive curvature," says Daniel Grumiller.

However, Grumiller has suspected for quite some time that a correspondence principle could also hold true for our real universe. To test this hypothesis, gravitational theories have to be constructed, which do not require exotic anti-de-sitter spaces, but live in a flat space. For three years, he and his team at TU Wien (Vienna) have been working on that, in cooperation with the University of Edinburgh, Harvard, IISER Pune, the MIT and the University of Kyoto. Now Grumiller and colleagues from India and Japan have published an article in the journal Physical Review Letters, confirming the validity of the correspondence principle in a flat universe.

Calculated Twice, Same Result
"If quantum gravity in a flat space allows for a holographic description by a standard quantum theory, then there must by physical quantities, which can be calculated in both theories -- and the results must agree," says Grumiller. Especially one key feature of quantum mechanics -quantum entanglement -- has to appear in the gravitational theory.

When quantum particles are entangled, they cannot be described individually. They form a single quantum object, even if they are located far apart. There is a measure for the amount of entanglement in a quantum system, called "entropy of entanglement." Together with Arjun Bagchi, Rudranil Basu and Max Riegler, Daniel Grumiller managed to show that this entropy of entanglement takes the same value in flat quantum gravity and in a low dimension quantum field theory.

"This calculation affirms our assumption that the holographic principle can also be realized in flat spaces. It is evidence for the validity of this correspondence in our universe," says Max Riegler (TU Wien). "The fact that we can even talk about quantum information and entropy of entanglement in a theory of gravity is astounding in itself, and would hardly have been imaginable only a few years back. That we are now able to use this as a tool to test the validity of the holographic principle, and that this test works out, is quite remarkable," says Daniel Grumiller.

This however, does not yet prove that we are indeed living in a hologram -- but apparently there is growing evidence for the validity of the correspondence principle in our own universe.

Related stories:
Story Source: Materials provided by Vienna University of Technology. Arjun Bagchi, Rudranil Basu, Daniel Grumiller, Max Riegler. Entanglement Entropy in Galilean Conformal Field Theories and Flat Holography. Physical Review Letters, 2015

Comments

Post a Comment

Popular posts from this blog

Greek Bronze Age ended 100 years earlier than thought

Image
Source: www.shef.ac.uk The charred remains of Assiros Toumba in Greece. Writing historical fiction set in the Greek Bronze Age?  Or simply enjoy reading this genre'?  Here's a study you may find interesting. C onventional estimates for the collapse of the Aegean civilization may be incorrect by up to a century, according to new radiocarbon analyses. While historical chronologies traditionally place the end of the Greek Bronze Age at around 1025 BCE, this latest research suggests a date 70 to 100 years earlier. www.weather-forecast.com Archaeologists from the University of Birmingham selected 60 samples of animal bones, plant remains and building timbers, excavated at Assiros in northern Greece, to be radiocarbon dated and correlated with 95.4% accuracy using Bayesian statistical methodology at the University of Oxford and the Akademie der Wissenschaften Heidelberg, Germany. Researcher Dr Ken Wardle says, 'These new results tell a story that is totall
Read more

How the lives of Georgian gaolbirds and highwaymen shaped modern Britain

Image
Writing historical fiction requires solid research of available materials and databases.  The key word here is available.   So news of a new publicly accessible database that allows an author to research a very interesting past era is priceless almost beyond words.   I expect some exciting fiction to come out of this announcement. Here's the story, with a link to the source in the attribution. *  *  *  *  * London Lives, a landmark project led by Professor Bob Shoemaker from the University of Sheffield and Professor Tim Hitchcock from the University of Sussex, has uncovered a mass of extraordinary new evidence which reveals how the lives of thousands of 18th-century poor and criminal Londoners helped shape modern Britain. Based on evidence made available in a publicly available database, the study sheds new light on the everyday lives of thieves, prostitutes, vagrants, highwaymen, con-men, paupers and jailbirds, revealing how their daily fight for survival led to t
Read more

Mood Instability and Your Characters

Image
You're putting together a character who's mood simply bounces all over the place, happy one moment, in a fit of rage the next.  Researchers at King's College London note that this sort of mood instability is part of a number of mental health disorders.  So how do you structure the personality and behavior of a character like this?  Below is the King's College report, along with a brief description from mentalhealth.com, of typical behavior, sometimes in the extreme, of a person who is very emotionally unstable.  This is offered strictly as a guide for crafting character in fiction - and NOT for the amateur diagnosis of the state of someone's mental health.  That is always best left to trained professionals. Another note about emotionally unstable behavior:  as any parent will tell you, this is how adolescents and teen-agers often behave.  It's a normal part of growing up - but it is a matter of degree .  In the extreme, however, this behavior can be diag
Read more

Remember faces but not names? You got it wrong.

Image
Source:   Daily Excelsior So, you think you're good at remembering faces, but terrible with names? New research has revealed we are actually better at remembering names than faces The cringe-worthy experience of not being able to remember an acquaintance's name leads many of us to believe we are terrible with names. However, new research has revealed this intuition is misleading; we are actually better at remembering names than faces. With the Christmas party season fast approaching, there will be plenty of opportunity to re-live the familiar, and excruciatingly-awkward, social situation of not being able to remember an acquaintance's name. This cringe-worthy experience leads many of us to believe we are terrible at remembering names. However, new research has revealed this intuition is misleading; we are actually better at remembering names than faces. The authors of the study, from the University of York, suggest that when we castigate ourselves f
Read more

Poor Mental Health, Casual Sex Reinforce Each Other

Image
Self-loathing and disgust are all too often the result of a one night stand - for both men and women. Now study suggests that poor mental health and casual sex actually feed off each other in teens and young adults, with each one contributing to the other over time. Researchers found that teens who showed depressive symptoms were more likely than others to engage in casual sex as young adults. In addition, those who engaged in casual sex were more likely to later seriously consider suicide. “Several studies have found a link between poor mental health and casual sex, but the nature of that association has been unclear,” said Sara Sandberg-Thoma, lead author of the study at The Ohio State University. “There’s always been a question about which one is the cause and which is the effect. This study provides evidence that poor mental health can lead to casual sex, but also that casual sex leads to additional declines in mental health.” Poor mental health and casual sex  linked
Read more