via hopesandfears.com
Is this real life? How do we know that we are not hallucinating it all? What if we're plugged into a Matrix-style virtual reality simulator? Isn't the universe a giant hologram anyway? Is reality really real? What is reality?
We asked renowned neuroscientists, physicists, psychologists, technology theorists and hallucinogen researchers if we can ever tell whether the "reality" we are experiencing is "real" or not. Don't worry. You're going to be ok.
Jessica L. Nielson, Ph.D.
Department of Neurosurgery, Postdoctoral Scholar, University of California, San Francisco (UCSF), Brain and Spinal Injury Center (BASIC)
"What is our metric for determining what is real? That is probably different for each person. One could try and find a consensus state that most people would agree is "real" or a "hallucination" but from the recent literature using imaging techniques in people who are having a hallucinatory experience on psychedelics, it seems the brain is hyper-connected and perhaps just letting in more of the perceivable spectrum of reality.
When it comes to psychosis, things like auditory hallucinations can seem very real. Ultimately, our experiences are an interpretation of a set of electrical signals in our brains. We do the best to condense all those signals into what we perceive to be the world around us (and within us), but who is to say that the auditory hallucinations that schizophrenics experience, or the amazing visual landscapes seen on psychedelics are not some kind of bleed through between different forms of reality? I don't think there is enough data to either confirm or deny whether what those people are experiencing is "real" or not."
Sean Carroll
Cosmologist and Physics professor specializing in dark energy and general relativity, research professor in the Department of Physics at the California Institute of Technology
"How do we know this is real life? The short answer is: we don't. We can never prove that we're not all hallucinating, or simply living in a computer simulation. But that doesn't mean that we believe that we are.
There are two aspects to the question. The first is, "How do we know that the stuff we see around us is the real stuff of which the universe is made?" That's the worry about the holographic principle, for example -- maybe the three-dimensional space we seem to live in is actually a projection of some underlying two-dimensional reality.
The answer to that is that the world we see with our senses is certainly not the "fundamental" world, whatever that is. In quantum mechanics, for example, we describe the world using wave functions, not objects and forces and spacetime. The world we see emerges out of some underlying description that might look completely different.
The good news is: that's okay. It doesn't mean that the world we see is an "illusion," any more than the air around us becomes an illusion when we first realize that it's made of atoms and molecules. Just because there is an underlying reality doesn't disqualify the immediate reality from being "real." In that sense, it just doesn't matter whether the world is, for example, a hologram; our evident world is still just as real.
The other aspect is, "How do we know we're not being completely fooled?" In other words, forgetting about whether there is a deeper level of reality, how do we know whether the world we see represents reality at all? How do we know, for example, that our memories of the past are accurate? Maybe we are just brains living in vats, or maybe the whole universe was created last Thursday.
We can never rule out such scenarios on the basis of experimental science. They are conceivably true! But so what? Believing in them doesn't help us understand any features of our universe, and puts us in a position where we have no right to rely on anything that we did think is true. There is, in short, no actual evidence for any of these hyper-skeptical scenarios. In that case, there's not too much reason to worry about them.
The smart thing to do is to take reality as basically real, and work hard to develop the best scientific theories we can muster in order to describe it."
Fredrick Barrett
Instructor in Psychiatry and Behavioral Sciences, Behavioral Pharmacology Research Unit, Johns Hopkins School of Medicine
"With psychedelics or "classical (serotonergic) hallucinogens", individuals can often distinguish between perceptual disturbances, visualized experiences (it feels as if I was in another place, or I had traveled to another time, but I realized my physical body was still "here"), and whatever is happening "outside" in the "real" world. However, in psychosis (for instance, in the midst of a psychotic break in a person who has schizophrenia), hallucinations are quite clearly defined as something that an individual believes is real, persistent, and seemingly independent and autonomous in the world.
The "hallucinations" of schizophrenia and psychosis are accepted as real, and individuals with schizophrenia often do not have insight into the nature of their hallucinations as being "not real" to the rest of us. This highlights a bit of a misnomer in the name of the drug class "hallucinogens", in that the experiences with these compounds are not taken as consensual reality in the same way that psychotic hallucinations are taken as "real".
How or Why can we tell the difference between reality and what is perceived during the acute effects of psychedelics? I'm not sure science has definitively answered that question ... but I think it may have to do with access to the insight that you've consumed a substance that can have these effects. It also may have to do with the transient effect of many perceptual disturbances and visualizations that can occur with hallucinogens. Maybe if the subjective effects of hallucinogens acted more like every-day perceptions (i.e. they weren't so extraordinary) or if they were more fixed or persistent (i.e. they didn't shift, warp, or morph so often) they would seem more real to the individual experiencing them."
George Musser Jr
Contributing editor for Scientific American magazine, Knight Science Journalism Fellow at MIT 2014–2015, author of The Complete Idiot’s Guide to String Theory and Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time--and What It Means for Black Holes, the Big Bang, and Theories of Everything
"The holographic principle doesn’t mean the universe isn't real. It just means that the universe around us, existing within spacetime, is constructed out of more fundamental building blocks. "Real" is sometimes taken to mean "fundamental", but that's a very limited sense of the term. Life isn't fundamental, since living things are made from particles, but that doesn’t make it any less real. It’s a higher-level phenomenon. So is spacetime, if the holographic principle is right. I talk about the holographic principle at length in my book, and I discuss the distinction between fundamental and higher-level phenomena in a recent blog post.
The closest we come in science to "real" or "objective" is intersubjective agreement. If a large number of people agree that something is real, we can assume that it is. In physics, we say that something is an objective feature of nature if all observers will agree on it - in other words, if that thing doesn’t depend on our arbitrary labels or the vagaries of a given vantage point ("frame-independent" or "gauge-invariant", in the jargon). For instance, I'm not entitled to say that my kitchen has a left side and a right side, since the labels "left" and "right" depend on my vantage point; they are words that describe me more than the kitchen. This kind of reasoning is the heart of Einstein's theory of relativity and the theories it inspired.
Could we all be fooled? Yes, of course. But there's a practical argument for taking intersubjective agreement as the basis of reality. Even if everyone is being fooled, we still need to explain our impressions. An illusion, after all, is entirely real - it is the interpretation of the illusion that can lead us astray. If I see a smooth blue patch in the desert, I might misinterpret the blue patch as an oasis, but that doesn’t mean my impression isn't real. I'm seeing something real - not an oasis, but a refracted image of the sky. So, even if we're all just projections of a computer simulation, like The Matrix, the simulation itself has a structure that gives it a kind of reality, and it is our reality, the one we need to be able to navigate. (The philosopher Robert Nozick had a famous argument along these lines.)"
Karl Friston
Institute of Neurology, University College London, Wellcome Principal Research Fellow and Scientific Director, Fellow of the Royal Society
"First, you pose an extremely interesting question about how do we know we are hallucinating. Strictly speaking, one never has insight into a true hallucination, if one does, these are generally referred to as pseudo-hallucinations, which are not unrelated to illusions. The very distinction between illusions and hallucinations is itself fascinating. This is because it suggests we have the capacity to represent our own representations – or representational validity. This speaks to all sorts of deep philosophical issues; for example, auto epistemic closure (in the sense of Thomas Metzinger), metacognition, self-awareness, lucid dreaming and so on.
The very fact that we can infer are perceptual influences are false speaks to a hierarchical composition of mind and perception; in which not only do we have perceptual influences but also inferences about those inferences (CF metacognition). The implications for self awareness are clear. This is why people like Allan Hobson are so fascinated by lucid dreaming. This provides a wonderful test bed to compare situations in which dream reality is perceived as real and when one becomes aware of the fact that it is a dream. Neurobiologically, this seems to rest on frontal lobe activity, suggesting, again, a hierarchical aspect to our fantastic organ (i.e. the brain – that generates fantasies that are checked against reality).
The usual notion that perception is just hallucination grounded by sensations is somewhat subverted by the fact that we can, on occasions, know that our perceptual inference is false."
Rich Oglesby
Creator and editor of Prosthetic Knowledge
"There is a well known phrase: "We shape our tools and thereafter our tools shape us” (often associated with media theorist Marshall McLuhan, although it was actually a quote from Father John Culkin, a Professor of Communication at Fordham University in New York). This makes sense from an anthropological perspective - to put it crudely, whilst early humans evolved the ability to speak, the controlled sounds and utterances gained meaning to each other through localized consensus. Fast forward to the twentieth century and industrial nations, one can discover technologies that we can recognize their purpose yet have differences to our own, depending on our cultures and others - for example, the differences with electricial sockets or which side of the road you drive from one country to another. This was noted in William Gibson's book Pattern Recognition which he labelled 'mirror-world'. Technology alsocan become taken for granted and familiar over time unless we find ourselves taken out of our habituated situation - nothing so easily reminds ourselves of change as a power cut, taking us back a couple of centuries.
In the past twenty years or so in the industrial world, the biggest impact on our experiences has been from the field of computing. While many focus on the internet as the biggest game changer, it neglects developments and permutations which other computing tech has reached - how the computer monitor tech has crossed over into television displays, graphics cards have altered how we work with colours transforming Pantone, photography and printing, sound cards and music sequencers, mp3 and Flac. Personal computing technologies have radically changed the way we make, define and experience the world we exist in. To describe the last twenty years, the best term I can think of is the Recon-Naissance, combining the terms reconaissance (the practise of gathering, formulating or expressing information) and renaissance (both 'rebirth' and revival of interest), it is the widespread outcome of ideas and production of post-WW2 investment in computational and telecommunication technologies. The Renaissance Man polymath has been replaced with the Renaissance Machine - the personal computer. The same PC could be used by scientist or businessperson, coder or student, in the office or in the warehouse, in the studio or in the bedroom. This has been most advantageous to the modern creative.
With the development of the smartphone ten years ago, modern computing became pocketable. With it, computing components became smaller. Due to commercial popularity, upgrade cycles changed from a year and a half to just one. Information creation and reception became domesticated. It became mainstream and more conveniently portable. Music, photography and video could be captured and seen on the same device, replacing the personal media player and the portable camera. Life could be documented and experienced 'en plein Hertz'.
But the developments of the smartphone benefitted a once neglected but now up-and-coming field: Virtual Reality. With small displays and accelerometers now refined and cheaper, and gave the opportunity to start ups to produce a new experiences with a new computing medium. Initially produced to complement video games, other startups are producing other narratives, such as 360 documentaries, animations and first person tools for creativity and design. Whilst the consumer implementation of these ideas are not truly available yet, the technology is being used by scientists, architects, artists and gamers with current developer builds. It would appear how we engage and relate with information will change again - the Recon-Naissance is still going strong."
Brad Burge
Director of Communications and Marketing: MAPS, Multidisciplinary Association for Psychedelic Studies
"These aren't really scientific questions per se though they are fascinating and valuable to think about. I think it comes down to our definitions of both "hallucination" and "reality"—to what extent is any experience we have really "real"? That may be one the main things that hallucinations teach us, regardless of whether they're caused by drugs, neurological conditions, or intense meditation: to trust in our own experience, while always remembering that our experience is always our own."
Showing posts with label hologram. Show all posts
Showing posts with label hologram. Show all posts
Friday, October 16, 2015
Tuesday, June 23, 2015
Black holes are not ruthless killers, but instead benign hologram generators
via ScienceDaily
Are black holes the ruthless killers we've made them out to be? Samir Mathur says no. According to the professor of physics at The Ohio State University, the recently proposed idea that black holes have "firewalls" that destroy all they touch has a loophole.
In a paper posted online to the arXiv preprint server, Mathur takes issue with the firewall theory, and proves mathematically that black holes are not necessarily arbiters of doom.
In fact, he says the world could be captured by a black hole, and we wouldn't even notice.
More than a decade ago, Mathur used the principles of string theory to show that black holes are actually tangled-up balls of cosmic strings. His "fuzzball theory" helped resolve certain contradictions in how physicists think of black holes.
But when a group of researchers recently tried to build on Mathur's theory, they concluded that the surface of the fuzzball was actually a firewall.
According to the firewall theory, the surface of the fuzzball is deadly. In fact, the idea is called the firewall theory because it suggests that a very literal fiery death awaits anything that touches it.
Mathur and his team have been expanding on their fuzzball theory, too, and they've come to a completely different conclusion. They see black holes not as killers, but rather as benign copy machines of a sort.
They believe that when material touches the surface of a black hole, it becomes a hologram, a near-perfect copy of itself that continues to exist just as before.
"Near-perfect" is the point of contention. There is a hypothesis in physics called complementarity, which was first proposed by Stanford University physicist Leonard Susskind in 1993. Complementarity requires that any such hologram created by a black hole be a perfect copy of the original.
Mathematically, physicists on both sides of this new fuzzball-firewall debate have concluded that strict complementarity is not possible; That is to say, a perfect hologram can't form on the surface of a black hole.
Mathur and his colleagues are comfortable with the idea, because they have since developed a modified model of complementarity, in which they assume that an imperfect hologram forms. That work was done with former Ohio State postdoctoral researcher David Turton, who is now at the Institute of Theoretical Physics at the CEA-Saclay research center in France.
Proponents of the firewall theory take an all-or-nothing approach to complementarity. Without perfection, they say, there can only be fiery death.
With his latest paper, Mathur counters that he and his colleagues have now proven mathematically that modified complementarity is possible.
It's not that the firewall proponents made some kind of math error, he added. The two sides based their calculations on different assumptions, so they got different answers. One group rejects the idea of imperfection in this particular case, and the other does not.
Imperfection is common topic in cosmology. Physicist Stephen Hawking has famously said that the universe was imperfect from the very first moments of its existence. Without an imperfect scattering of the material created in the Big Bang, gravity would not have been able to draw together the atoms that make up galaxies, stars, the planets -- and us.
This new dispute about firewalls and fuzzballs hinges on whether physicists can accept that black holes are imperfect, just like the rest of the universe.
"There's no such thing as a perfect black hole, because every black hole is different," Mathur explained.
His comment refers to the resolution of the "information paradox," a long-running physics debate in which Hawking eventually conceded that the material that falls into a black hole isn't destroyed, but rather becomes part of the black hole.
The black hole is permanently changed by the new addition. It's as if, metaphorically speaking, a new gene sequence has been spliced into its DNA. That means every black hole is a unique product of the material that happens to come across it.
The information paradox was resolved in part due to Mathur's development of the fuzzball theory in 2003. The idea, which he published in the journal Nuclear Physics B in 2004, was solidified through the work of other scientists including Oleg Lunin of SUNY Albany, Stefano Giusto of the University of Padova, Iosif Bena of CEA-Saclay, and Nick Warner of the University of Southern California. Mathur's co-authors included then-students Borun Chowdhury (now a postdoctoral researcher at Arizona State University), and Steven Avery (now a postdoctoral researcher at Brown University).
Their model was radical at the time, since it suggested that black holes had a defined -- albeit "fuzzy" -- surface. That means material doesn't actually fall into black holes so much as it falls onto them.
The implications of the fuzzball-firewall issue are profound. One of the tenets of string theory is that our three-dimensional existence -- four-dimensional if you count time -- might actually be a hologram on a surface that exists in many more dimensions.
"If the surface of a black hole is a firewall, then the idea of the universe as a hologram has to be wrong," Mathur said.
The very nature of the universe is at stake, but don't expect rival physicists to come to blows about it.
"It's not that kind of disagreement," Mathur laughed. "It's a simple question, really. Do you accept the idea of imperfection, or do you not?"
Are black holes the ruthless killers we've made them out to be? Samir Mathur says no. According to the professor of physics at The Ohio State University, the recently proposed idea that black holes have "firewalls" that destroy all they touch has a loophole.
In a paper posted online to the arXiv preprint server, Mathur takes issue with the firewall theory, and proves mathematically that black holes are not necessarily arbiters of doom.
In fact, he says the world could be captured by a black hole, and we wouldn't even notice.
More than a decade ago, Mathur used the principles of string theory to show that black holes are actually tangled-up balls of cosmic strings. His "fuzzball theory" helped resolve certain contradictions in how physicists think of black holes.
But when a group of researchers recently tried to build on Mathur's theory, they concluded that the surface of the fuzzball was actually a firewall.
According to the firewall theory, the surface of the fuzzball is deadly. In fact, the idea is called the firewall theory because it suggests that a very literal fiery death awaits anything that touches it.
Mathur and his team have been expanding on their fuzzball theory, too, and they've come to a completely different conclusion. They see black holes not as killers, but rather as benign copy machines of a sort.
They believe that when material touches the surface of a black hole, it becomes a hologram, a near-perfect copy of itself that continues to exist just as before.
"Near-perfect" is the point of contention. There is a hypothesis in physics called complementarity, which was first proposed by Stanford University physicist Leonard Susskind in 1993. Complementarity requires that any such hologram created by a black hole be a perfect copy of the original.
Mathematically, physicists on both sides of this new fuzzball-firewall debate have concluded that strict complementarity is not possible; That is to say, a perfect hologram can't form on the surface of a black hole.
Mathur and his colleagues are comfortable with the idea, because they have since developed a modified model of complementarity, in which they assume that an imperfect hologram forms. That work was done with former Ohio State postdoctoral researcher David Turton, who is now at the Institute of Theoretical Physics at the CEA-Saclay research center in France.
Proponents of the firewall theory take an all-or-nothing approach to complementarity. Without perfection, they say, there can only be fiery death.
With his latest paper, Mathur counters that he and his colleagues have now proven mathematically that modified complementarity is possible.
It's not that the firewall proponents made some kind of math error, he added. The two sides based their calculations on different assumptions, so they got different answers. One group rejects the idea of imperfection in this particular case, and the other does not.
Imperfection is common topic in cosmology. Physicist Stephen Hawking has famously said that the universe was imperfect from the very first moments of its existence. Without an imperfect scattering of the material created in the Big Bang, gravity would not have been able to draw together the atoms that make up galaxies, stars, the planets -- and us.
This new dispute about firewalls and fuzzballs hinges on whether physicists can accept that black holes are imperfect, just like the rest of the universe.
"There's no such thing as a perfect black hole, because every black hole is different," Mathur explained.
His comment refers to the resolution of the "information paradox," a long-running physics debate in which Hawking eventually conceded that the material that falls into a black hole isn't destroyed, but rather becomes part of the black hole.
The black hole is permanently changed by the new addition. It's as if, metaphorically speaking, a new gene sequence has been spliced into its DNA. That means every black hole is a unique product of the material that happens to come across it.
The information paradox was resolved in part due to Mathur's development of the fuzzball theory in 2003. The idea, which he published in the journal Nuclear Physics B in 2004, was solidified through the work of other scientists including Oleg Lunin of SUNY Albany, Stefano Giusto of the University of Padova, Iosif Bena of CEA-Saclay, and Nick Warner of the University of Southern California. Mathur's co-authors included then-students Borun Chowdhury (now a postdoctoral researcher at Arizona State University), and Steven Avery (now a postdoctoral researcher at Brown University).
Their model was radical at the time, since it suggested that black holes had a defined -- albeit "fuzzy" -- surface. That means material doesn't actually fall into black holes so much as it falls onto them.
The implications of the fuzzball-firewall issue are profound. One of the tenets of string theory is that our three-dimensional existence -- four-dimensional if you count time -- might actually be a hologram on a surface that exists in many more dimensions.
"If the surface of a black hole is a firewall, then the idea of the universe as a hologram has to be wrong," Mathur said.
The very nature of the universe is at stake, but don't expect rival physicists to come to blows about it.
"It's not that kind of disagreement," Mathur laughed. "It's a simple question, really. Do you accept the idea of imperfection, or do you not?"
Friday, March 13, 2015
Simulations back up theory that the universe is a hologram
From Nature:
A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection.
In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.
Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa (see 'Collaborative physics: String theory finds a bench mate'). But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.
In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.
In one paper, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence (see 'Astrophysics: Fire in the Hole!'). In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match.
“It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, New Jersey and who did not contribute to the team's work.
Regime change
The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”
“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture — namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.
Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.
Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.
Leonard Susskind explains his ideas here:
A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection.
In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.
Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa (see 'Collaborative physics: String theory finds a bench mate'). But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.
In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.
In one paper, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence (see 'Astrophysics: Fire in the Hole!'). In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match.
“It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, New Jersey and who did not contribute to the team's work.
Regime change
The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”
“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture — namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.
Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.
Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.
Leonard Susskind explains his ideas here:
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