## Why Our Universe is Not a Hologram

Article Updated: 23 Dec , 2015
by

Editor’s note: This article was originally published by Brian Koberlein on G+, and it is republished here with the author’s permission.

There’s a web post from the Nature website going around entitled “Simulations back up theory that Universe is a hologram.” It’s an interesting concept, but suffice it to say, the universe is not a hologram, certainly not in the way people think of holograms. So what is this “holographic universe” thing?

It all has to do with string theory. Although there currently isn’t any experimental evidence to support string theory, and some evidence pointing against it, it still garners a great deal of attention because of its perceived theoretical potential. One of the theoretical challenges of string theory is that it requires all these higher dimensions, which makes it difficult to work with.

In 1993, Gerard t’Hooft proposed what is now known as the holographic principle, which argued that the information contained within a region of space can be determined by the information at the surface that contains it. Mathematically, the space can be represented as a hologram of the surface that contains it.

That idea is not as wild as it sounds. For example, suppose there is a road 10 miles long, and its is “contained” by a start line and a finish line. Suppose the speed limit on this road is 60 mph, and I want to determine if a car has been speeding. One way I could do this is to watch a car the whole length of the road, measuring its speed the whole time. But another way is to simply measure when a car crosses the start line and finish line. At a speed of 60 mph, a car travels a mile a minute, so if the time between start and finish is less than 10 minutes, I know the car was speeding.

A visualization of strings. Image credit: R. Dijkgraaf.

The holographic principle applies that idea to string theory. Just as its much easier to measure the start and finish times than constantly measure the speed of the car, it is much easier to do physics on the surface hologram than it is to do physics in the whole volume. The idea really took off when Juan Martín Maldacena derived what is known as the AdS/CFT correspondence (an arxiv version of his paper is here ), which uses the holographic principle to connect the strings of particle physics string theory with the geometry of general relativity.

While Maldacena made a compelling argument, it was a conjecture, not a formal proof. So there has been a lot of theoretical work trying to find such a proof. Now, two papers have come out (here and here) demonstrating that the conjecture works for a particular theoretical case. Of course the situation they examined was for a hypothetical universe, not a universe like ours. So this new work is really a mathematical test that proves the AdS/CFT correspondence for a particular situation.

From this you get a headline implying that we live in a hologram. On twitter, Ethan Siegel proposed a more sensible headline: “Important idea of string theory shown not to be mathematically inconsistent in one particular way”.

Of course that would probably get less attention.

### 53 Responses

1. Anonymous says:

I must have missed the part where you explained why the Universe isn’t a hologram…?

• ?œarar Ó Murchadh says:

its right here.

” It’s an interesting concept, but suffice it to say, the universe is not a hologram, certainly not in the way people think of holograms. “

• Criminoboy says:

That’s a statement – not an explanation.

• ?œarar Ó Murchadh says:

No, that’s a quote of a statement of which is not my own, unlike this statement of me explaining something, like this very statement explaining statements.

• Unsooper says:

How about this? I see you because photons fire off cells in my retina. You could just be a hologram to me (or not) because someone could measure my nerve response and not tell the difference by measuring cause and effect in me….but since that doesn’t measure the actual “you” at all it turns out the theory is weak.

• Nimrod0 says:

Because most people read “hologram” and think “fake,” when here it is a technical word meaning something else, namely information flux crossing a boundary into a volume.

• psychman33 says:

It’s actually never explicitly stated in an idiot proof kind of way. But the gist is that it’s a theoretical concept applied to another theoretical concept that is not necessarily an accurate representation of our universe, just a model of a possible hypothetical universe. So you have a theoretical concept on top of another theoretical concept that shows the possible existence of a hypothetical. That’s pretty shaky external validity, no?

• hjhjh says:

But his assertion is “our universe is NOT a hologram” not “it’s not known yet whether or not our own particular universe is a hologram.” Yet he fails to prove his case. I guess a more modest headline would “probably get less attention.”

• Criminoboy says:

Well – if that is the point he forgot to make, it would make sense if this study stood on it’s own, but it doesn’t. It is one more very compelling piece of evidence, which can be stacked onto the growing pile of evidence which has grown awfully weighty over the past decades. This evidence isn’t just theoretical, but physical as well.

We’ve very likely already measured the quantum flux of the plank length in Germany via the GEO , and we’re probably very close to definitively measuring it at Fermilab:

http://www.gizmag.com/fermilab-holometer-examines-spacetime/16829/

The author of this article states that the universe is not a hologram in a way which purports to indicate that this experiment doesn’t actually attempt to show that – and then fails to demonstrate the validity of that position in any meaningful way whatsoever. You attempt to show the universe isn’t a hologram by attempting to critique the validity of the study. Two very different positions – each of which fail to allocate the appropriate level of validity which should be afforded to this yet unproven theory considering the weight of the evidence behind it.

• psychman33 says:

“It all has to do with string theory. Although there currently isn’t any experimental evidence to support string theory, and some evidence pointing against it, it still garners a great deal of attention because of its perceived theoretical potential.”

“While Maldacena made a compelling argument, it was a conjecture, not a formal proof. So there has been a lot of theoretical work trying to find such a proof. Now, two papers have come out (here and here) demonstrating that the conjecture works for a particular theoretical case. Of course the situation they examined was for a hypothetical universe, not a universe like ours. So this new work is really a mathematical test that proves the AdS/CFT correspondence for a particular situation.”

These are the excerpts wherein the author made the same basic statement that I just made. It’s his critique. I simply boiled it down.

• Criminoboy says:

You’re right – I missed your point.

I’m reactive to the author’s definitive statement that “the universe is not a hologram” when the weight of the evidence seems to be leaning so heavily in that direction. The Nature article clearly states the study represents, “if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.” The study doesn’t exist in a vacuum – and the implications of the combined evidence don’t appear to warrant the blanket dismissal this article represents.

Thanks for the clarification.

• Andrei Patrascu says:

The article just verifies something known in a model where we know that something exists and works. So, indeed, it is not a proof and no evidence for anything related to reality. There are in fact lots of evidence that the universe is NOT a hologram in the sense understood by string theorists. Area law violations are everywhere in nature and in fact the entropic area laws appear in any systems where we choose not to make some kind of measurements and not to ask some questions. There is no justification whatsoever for these choices of ours. Also, the statement about string theory is correct. It is more than obvious that string theory and the holographic principle are in good agreement with each other but that is not a fact of nature or reality. String theory is constructed such that in its critical dimension it recovers Weyl invariance (actually even conformal invariance) on the worldsheet. So, by construction it is a theory that has the holographic ideas already included in it. That doesn’t mean they are also a part of reality… String theory is a perturbative construction. It is designed such that it gives a natural UV cutoff in the form of the length of the string but that also doesn’t have to be a part of reality either. It just is a method that makes some calculations easier (but makes all the others, many times more harder… ) String theory is at best a representation for some aspects of reality but it is not even remotely a theory about reality. The mere assumption that string need to be quantified in some form is in fact not known to be necessary and in M theory branes cannot be quantified at all…

• psychman33 says:

Mathematics is formal logic following from foundational axioms. Logical consistency is not a valid inference for actuality of the findings. Just as purely rational arguments cannot establish validity to the world of experience, so these papers cannot be necessarily applied to the actual universe we inhabit. He’s saying that what they have established is true enough in a useful model establishing the plausibility of the scenario. But it’s overstating the findings to say that it applies to this universe. He’s not challenging the findings so much as the external validity of these findings. The media pickup of these papers have, as media so often does, overstated the valid inferences that follow from the character of these studies.

In a separate point he is saying that hologram as used in these studies is not the way that the layperson uses the word in colloquial conversation.

• Andrei Patrascu says:

also, the main reason DMRG fails for D>1 is a good reason too…

• A guy says:

Your query is valid; I don’t think he explains why the Universe is not a hologram. Instead, he’s just asserting that the math behind a hypothetical universe being a hologram is accurate, which doesn’t necessarily prove that our universe is or isn’t. It’s like proving that testicles can be made of metal, but doesn’t really prove that yours are. For that we’ll have to kick you in the nuts and find out.

… I think you get my analogy, f’d up as it is.

2. David McElroy says:

“And God said, Let there be light: and there was light,” Genesis 1:3 states. Light was the first and most basic element created, and science seems to document that the whole universe is a tapestry woven of photons. Hence, an intelligently designed holographic universe.

3. JOSHUA VEGA HAWKINS says:

Reel them in with the headline.

4. Skeettz says:

First off I want to point out that all though Gerard t’Hooft was the first to publish a paper on this idea,
it didn’t get much attention. It wasn’t until Leonard Susskind published his
paper “The World As a Hologram” that the idea really started taking
hold among theoretical physicist. In 1993 the mathematics of the idea were not
worked out and it was Leonard Susskind who was giving lectures upon lectures to
try and get more people working on the idea. t’Hooft saw the idea in a little
different light and didn’t like the fact that sting theory was involved.
Susskind’s said once “black holes really do have hair” meaning parts
of a tangled up mess of string acted on by gravity could stick out of the
horizon and form the black holes entropy was kind of the first real glimpse
that black holes might act “like” a hologram. It wasn’t until much
later that the idea was thought of on the scale of the entire universe, which
again Susskind has proposed a way this might work, using string theory. I
really think anyone that wants to learn more about how this holographic
principle works should read his book “The Black Hole Wars” which is
great at getting his points across. I would imagine that Brian Koberlein would
have read that book or at least gave the idea a little more thought before
writing an article like this, but considering nothing in this article really
explains anything on the idea and the analogies used to try and explain it are horrible
and don’t really work. Your car speeding analogy has nothing to do with a
hologram or even how possibly a holographic universe would work. Think of an
ever evolving hologram to start with. Something that can change its
“computer code” of 1s and 0s or dots and dashes like in Morris Code
if you will. Those 1s and 0s are plastered on a 2 dimensional boundary somewhere
far out in space. Most likely much further out than the 13.7 billion light
years we see, and everything on the inside of that boundary can be described by
the 1s and 0s plastered on that 2 dimensional boundary. All the 3 dimensional
world that we see and everything around us including everything in the universe
would be described by those 1s and 0s, also known as information, each 1 and 0
would consume 1 Planck area. I won’t get into how this works with the black
holes, you can pick up Leonard’s book if you want to learn more, or try to read
and maybe ignore a little of the math and hard equations in his paper. Hope
this makes a little more sense, because this article did a horrible job of
first explaining the idea for the layman and then showing “Why Our
Universe is Not a Hologram”.

Thanks!

• Criminoboy says:

Thank you for the great post. I’m not a physicist by any stretch, but have been fascinated by the developments of the Holographic theory over the past few years, and this article almost seems to be referring to a different topic altogether.

I get the impression that Brian isn’t a big fan of String Theory? Your description of the “2 dimensional boundary” is very much what I have managed to grasp from what I’ve read. I’m aware that this likely only represents the best incomplete description to provide a layman – but this article doesn’t cover any of the main concepts under discussion, as you have.

It also seems to fail to recognize that the Fermilab Holometer is currently being constructed for the purpose of detecting the quantum flux of the Holographic Universe – or the pixels that are made up of the individual plank areas you mention. That should be the next big breakthrough for this theory if it turns out to actually measure the flux.

Very exciting stuff – maybe we’ll see some clarification from Brian.

5. Brian Joe Wells says:

the only thing real is Squirrel Girl…..

6. Gary Denton says:

This article appears to so wrong it is not be in the same classroom of why physicists are excited.

7. Skeettz says:

lmao all I can say… because the bible has so many facts imbeded in it along with all its contradictions. Intelligent design is an illusion.

8. daniel_rey_m says:

Alfonso Caycedo, M.D., the developer of sophrology, came back from a trip to the Far East having confirmed that the mind can achieve the dematerialization of the body. In the Tibetan monasteries some monks go into their cells and never come
out again. All that remains is the robe, the shoes, the hair and the fingernails, which shows that only keratin is impervious to whatever brings about the dematerialization. The source for this information is the travelogue he wrote after the voyage. It
also shows that what we see is an illusion sustained by the mind, is no more
substantial than a hologram and can be turned off like a hologram if that’s
what one wishes to do.

• Aleister Gates says:

dolt

• truthseeker says:

It aint easy, but something immaterial affected the “Robe of Turin”.

• anotherview2 says:

Ha, ha, Dreamworks abound in the ozone layer.

9. GMcDowell says:

String theory is nothing but fantastical mathematics. It does not in any way, shape or form describe the universe we inhabit. It is a real disservice to continue writing articles about a discredited mathematical theory as if it has merit in astrophysics when it clearly does not. Please let this be the final posting about ST.

10. GMcDowell says:

If you knew anything about the early universe, you’d know that:
1. There was no light.
2. There never was a deity other than the mythical kind.
Do grow up.

• Sal says:

Unless God lives in a different universe and our universe is his “fish tank”?

• truthseeker says:

Of course! God is the being that changes the water!

• jefferis says:

You have insufficient evidence for assertion 2, and you misunderstand the sequence of #1. Darkness was first: “In the beginning… the universe was without form and void, and darkness was upon the face of the deep” (Gen 1:1,2) and then there was a Big Bag (Light) v. 3.

You know there is a very wise saying you’d do well to remember.

“Those who attempt to find answers to matters of science with religion
as well as
Those who attempt to answer matters of faith with science.
TRULY UNDERSTAND NEITHER

12. A.R says:

wait…so i do exist or I don’t exist? This is so confusing…I’m going to go eat a burrito.

• daniel_rey_m says:

It’s weird that someone should mention boorreetoes here. Last year one of them vanished from my plate as I read a magazine. I looked up and it wasn’t there anymore. This happened again about three weeks later. It’s additional proof for the Hologram Universe Theory. Please see the blog at [Blog promotion not permitted – buy advertising!] and leave a comment.

13. Luboš Motl says:

Dr Koberlein, I don’t understand where the obsession of people like you to write about topics you have clearly no clue about comes from.

The Universe *is* a hologram, quite literally. It is not made of the same “films” as the holograms on our credit cards but it follows the same principles: the actual physics may be described in terms of fields on a manifold which has one dimension less than the final “product” – the location of the objects in the new, emergent, holographic dimension is encoded in the wavelength of the interference patterns. This is true both for the real-world holograms on credit cards as well as the holograms in quantum gravity. Every consistent theory of quantum gravity has to respect it – the holographic principle is *not* dependent on any intrinsically stringy arguments (even though a “consistent theory of quantum gravity” and “string theory” are likely to be synonyma at the end). After all, ‘t Hooft and Susskind started the holographic principle independently of string theory.

AdS/CFT has surely not been “just a conjecture” for at least 15 years. Your claim that “it is just a conjecture” is as dumb as the creationists’ claims that “evolution is just a theory”. And there is *no* evidence against string theory and lots of circumstantial evidence supporting string theory, exactly the opposite of your wrong claims.

Whether the simulation by the Japanese guy is really important isn’t clear to me yet – but what is clear is that your obsessive desire to talk down quantum gravity, holography, and string theory only shows your incompetence and bias.

14. Allannaa Lassevanta says:

So wait… People took the word “holographic” in this context to mean the sci-fi version of an object projected in 3D? … Sometimes I wonder how we ever managed to walk upright to begin with.

15. Jihm says:

In my opinion, the only sort of non-infinite reality possible is a simulation.

• stig781 says:

That’s an artificial technological concept.

16. anotherview2 says:

Thank you for putting this twist of theoretical physics (string theory) in an understandable context.

17. David Gillies says:

The idea of operations on a manifold being equivalent to operations on a contour embedded in that manifold is hardly new. That’s Stokes’s Theorem, and it’s first year undergraduate physics. What I’d like to know is whether Maldacena’s work is a restatement, an amplification or merely analogous to Stokes.

18. magnus.nyborg says:

Yeah, but then god supposedly introduced the talking snake, and that’s where one should realise the idiocy…

19. Mark_2674 says:

I know I read that information about a black hole is derivable strictly from its surface (google it). The point is that this idea has apparently been applied successfully in a number of areas.

20. Mark_2674 says:

Does a hologram universe imply that all information about a person, there internal physiology, life history, etc, can be determined by examining their external surface?

21. Art Riechert says:

People who have NDEs describe them in terms that corroborate the holographic universe theory and that sound like they were on the holographic film rather than the projection from that film. They say things like “I literally felt like I was everywhere in the Universe at once” and “I felt an overwhelming sense of oneness and connectedness” and “it seemed even more real than normal” or “realer than real” which refers to Craig Hogan’s statement that there is a certain inherent blurriness or fuzziness in a holographic projection and since they were on the original film rather than living on the projection which is what our Universe is supposed to be it makes sense that it would be “realer than real.” They also say things like “I had all knowledge” which is a reference to the connectedness of a piece of holographic film.

• jameskrug says:

That’s a very creative connection to make. Science tends to shy away from things deemed “paranormal”, but I think there are certainly very relevant, scientifically eye-opening explanations for almost all of these phenomena, which could greatly expand our knowledge of the universe if taken seriously.

22. magic3499 says:

Geez, after reading the comments, I hope there’s no sequel.

23. IVAN3MAN_AT_LARGE says:

“boorreetoes”? You mean burritos. Your dog probably ate it!

• daniel_rey_m says:

Ivanman, I’m sorry but you had better find another explanation.
I have no pets, other than several corner spiders in a dusty, unruly household full of cardboard boxes that looks more like a warehouse. Over the years I’ve managed to develop an efficient way of feeding them, and THIS, TOO, IS RELEVANT for the said theory. One must use a big jar to capture certain
insects, like cloth moths, mosquitos and big flies, and a small one for the tiny flies, which come in three varieties. If you’re lucky you’ll find them resting on a wall. It’s almost impossible to trap them on the wing as they fly back and forth, no matter how large the mouth of the jar, especially in the case of the moths, whose movements are too quick and erratic when they’re airborne. Once they’re safely in the jar, shake it until the thing is groggy but not knocked out. This is essential since 1) most spiders will reject a dead body, and 2) if you don’t shake, the bug will escape when you open and try to drop it onto the web. There are more complications but I can’t go into this more deeply. All I will say is that, having shaken cautiously as explained, you might open the jar AND FIND NOTHING IN IT, as though the animal had slipped through a portal straight into the twilight zone. I challenge you to explain that without
involving the dogs this time around.

Wow, thanks for explaining it (and disappointing the [Deleted.] out of me, lol). But it’s also reassuring, because the thought of not being real is a hard thought to sit and bare.

I’m curious though, does the “life is a simulation” theory as a whole apply to this paper? Or was this paper simply not proof of that particular theory at all? It seems like the theory hasn’t been disproved, simply that they completely misled you in the title. They made you believe it was about the “life is a simulation” theory or the “simulation hypothesis” I think it’s called, but this seems almost entirely unrelated.

edit: When I say paper, I don’t mean your article, but the paper/s you’re talking about.

25. jameskrug says:

I find it a tad ironic that there are now hundreds of thousands of credible UFO reports from around the world, spanning decades. Yet this idea is still generally scoffed upon by mainstream science. Yet, there is still zero observational evidence of string theory, and yet it is pursued with vigor. You stay consistent, scientific method!

26. Caihlyn says:

Biological life forms are limited by their three spatial dimensions plus linear time. If there was a way to peer into the higher dimensions I think many mysteries would be explained.