A New Theory of Everything?

goatherder writes "The Telegraph is running a story about a new Unified Theory of Physics. Garrett Lisi has presented a paper called "An Exceptionally Simple Theory of Everything" which unifies the Standard Model with gravity — without using string theory. The trick was to use E8 geometry which you may remember from an earlier Slashdot article. Lisi's theory predicts 20 new particles which he hopes might turn up in the Large Hadron Collider."

He's to Physics what Slava Pestov is to PLT.

[Anonymous Coward]

Garrett Lisi is to Physics what Slava Pestov is to the study of programming language theory: young blood with new theories that will greatly challenge the status quo. Slava Pestov's Factor programming language is essentially the GUT of the PLT domain. It ties together functional programming, stack based programming, imperative programming, OO programming, and even constraint-based programming into one small, tidy package. In short, it is the one and the only.

For the non-mathematicians

[Lord Byron II]

A set is a collection of things, such as the integers are a set of numbers.

A group is a set with an operation (and a couple of extra properties), such as the integers under addition.

The set of a symmetry group is the set of operations that you can perform to an object and have the object remain unchanged. For example, for an equilateral triangle, rotating it by 120 and 240 degrees leaves you with a triangle. So does flipping it around any of its three axes. Add the identity operation, which leaves the triangle untouched and you have the symmetry set for an equilateral triangle. Add an operation and you have a symmetry group.

The U(1) group is the group of all unitary, 1-dimensional operations that leave the inner (dot) product invariant.

The SU(2) group is the group of all unitary, 2-dimensional operations that leave the inner (dot) product invariant and have a determinant of 1.

The SU(3) group is the group of all unitary, 3-dimensional operations that leave the inner (dot) product invariant and have a determinant of 1.

The Standard Model obeys the symmetry found by combining the three above groups: SU(3)xSU(2)xU(1).

E8 is another group with some special properties. The author of the paper is claiming that E8 contains the Standard Model (SU(3)xSU(2)xU(1)), plus the symmetries belonging to gravity.

Understandable Description

[Ghoser777]

http://aimath.org/E8/e8.html [aimath.org]

I found this site easier to understand than the wikipedia link. I warned my trig students about higher dimensions - wait till I tell them about 8-d vectors, they'll love it!

Re:might be on to something

[Enlightenment]

As I understand it, when we say "gravity," we really mean General Relativity. And when we say "quantum physics," we really mean the Standard Model. Both are the best established explanations for their respective fields. That means once you've unified the Standard Model with gravity in a way that gives the same correct results we knew from General Relativity, you've got a theory of everything.

PDF

[bill_mcgonigle]

Really that's all I wanted [arxiv.org] (complete with useless filename and all - 'An Exceptionally Simple Theory of Everything.pdf' - copy/paste)

here's the abstract for those wondering if they should download it:

Abstract: All fields of the standard model and gravity are unified as an E8 principal bundle
connection. A non-compact real form of the E8 Lie algebra has G2 and F4 subalgebras which
break down to strong su(3), electroweak su(2) x u(1), gravitational so(3,1), the frame-Higgs,
and three generations of fermions related by triality. The interactions and dynamics of these
1-form and Grassmann valued parts of an E8 superconnection are described by the curvature
and action over a four dimensional base manifold.

Although it is chock full of pretty pictures as well. If he's right, somebody is going to do a story about how the Star of David came to be important (Ezekiel's Wheel?) and want to talk to those soldiers who saw the ship in the woods in Britain that was decorated with a complex pattern with triangles in the middle.

OK, enough mindless rambling...

Re:GUT from a surfer dude!

[rminsk]

This "surfer dude" resume:

9/91-5/99 University of California, San Diego
5/99 Ph.D. in Physics
G.P.A. - 3.9

Honors Fellowships - UC Regents fellowship, ARCS Foundation fellowship.

9/86-6/91 University of California, Los Angeles
6/91 B.S. in Physics and B.S. in Mathematics
G.P.A. - 3.9 (4.0 in Physics and 4.0 in Mathematics)
Academic Honors - Phi Beta Kappa, Sigma Pi Sigma, Golden Key.

Graduation Honors - College Honors, Highest Honors in Physics, Highest Honors in Mathematics, Summa Cum Laude, Kinsey Prize for The Outstanding Graduating Senior in Physics.

Not quite your average "surfer dude"

This is most likely BS. Please see here.

[Sarusa]

Please see what a real physicist thinks of this. There's always a chance that he's stumbled onto something awesome of course, but odds are low. Basically he takes some stuff that looks cool and extracts physics from it in various ways.

http://motls.blogspot.com/2007/11/exceptionally-simple-theory-of.html [blogspot.com]

'That's pretty cute! :-) The author is not constrained by any old "conventions" and simply adds Grassmann fields together with ordinary numbers i.e. bosons with fermions, one-forms with spinors and scalars. He is just so skillful that he can add up not only apples and oranges but also fields of all kinds you could ever think of. Every high school senior excited about physics should be able to see that the paper is just a long sequence of childish misunderstandings.'

Re:Huh?

[Anonymous Coward]

It being an "exceptionally simple" theory is a pun.
It's built upon E8, which is the largest, most complicated (i.e. an exceptional case) finite simple Lie group.

Re:FTFA

[Carnildo]

The algebra is 248-dimensional. The universe is still only 3+1-dimensional.

Re:Would've been nicer if you said...

[nuzak]

That would've been far more credible than Einstein... whom, I believe was long dead by the time Norris was conceived.

Chuck's an old dude! IMDB says for Chuck Norris: Date of Birth: 10 March 1940, Ryan, Oklahoma, USA

Wikipedia says for Albert Einstein: March 14, 1879 - April 18, 1955

So we've got at latest a 76-year-old Albert Einstein kicking the ass of a 15-year old Chuck Norris. Aw yeah.

Re:Would've been nicer if you said...

[motomike]

Chuck Norris: born 10 March, 1940.

Albert Einstein: died 18 April, 1955.

Granted, ol' Al would have been 61 years older than Chuck. But geez, is it really that hard to Google something before making an easily-checked claim like, "whom, I believe was long dead by the time Norris was conceived"?

Kids these days.

Re:I don't understand a thing :(

[iabervon]

(I am not a particle physicist or a mathematician of the right sort, but I can kind of follow this sort of thing)

Okay, the context is that you've got particles, and they're fundamentally all the same, but they're "turned" in different ways. Think of a ball with 3-color LEDs inside: you can rotate it around three axes, and move it in three directions, and you can also cycle its color and change its blinking pattern. Particles are like that, except that the topology is weird: it's not back to the same orientation until you turn it around 720 degrees, instead of 360 like normal objects. The "gauge group" is the rules for how you can change things. For example, the total color of the universe is white: if you turn something from red to blue, you have to turn something else from blue to red; but you can also create a pair of a green and a purple (anti-green). They write all these rules up in math, and it's tricky because a lot of the features vary continuously (that is, you can rotate something an arbitrarily small amount). And due to the interaction of the rules for one property with the rules for other properties, there are only certain combinations of properties that you can get. They work out all the combinations that you can have and those are what you see as "different" particles that your experiments show. Of course, we don't know what the rules are, and we're trying to figure that out from what combinations of properties we've seen and which ones we're speculating are impossible. And it's hard and takes a lot of calculation to figure out what a candidate set of rules would even mean as far as results. And people are looking at known results and trying to describe them better than "we've done a billion things, and a billion things happened".

Now, the math of rules for how things can interact turns out to be sort of limited; there are basically 4 normal cases, which are boring, and then there are a few exceptional cases, which are interesting. Of these, the hardest to prove stuff about is E8, and it's just now becoming clear what combinations it allows. It's like one of those puzzles where you press a corner and lights change, and you have to turn off all the lights, but it's got dozens of corners and dozens of lights and every time you press a corner a bunch of things change at once, and there are different kinds of corners and it also matters exactly what angle you're holding it at, so there are hundreds of things you can say about each move.

And the mathematicians working on E8 recently said, "well, you can get positions like this and not like that", where "this" and "that" are big complicated lists. And this physicist read that paper and said, "hey, those lists are familiar; I made similar lists of particle interactions". So the proposal is that particles work like E8 in what kind of rules they follow. And it's a really nice theory, because E8 is essentially the most flexible set of rules you can have without it falling apart into just anything being possible (and some rules or properties just not mattering).

Re:might be on to something

[BlueStraggler]

The quick-and-dirty explanation is that the E8 "object" is a nasty-ass shape that exists in 248 dimensions, and which is notable for various reasons that only mathematicians can really grasp fully, but can be understood by the layman as pertaining to the concept of symmetry. It was discovered in the 1890s, but due to its size was never fully computed until a couple of years ago (the solution is a massive matrix of polynomials taking up 60 GB of storage). Oddly, various aspects of the E8 solution were reminiscent of formulae in the Standard Model, and Lisi has managed to come up with a coherent explanation of why this is. Various aspects of the E8 object's structure appear to explain formerly mysterious facts, such as why elementary particles are grouped into their various families. They also suggest new and undiscovered particles, which may give this theory a very clear set of test cases if it survives that long.

Re:This is most likely BS. Please see here.

[BoChen456]

Thats what unifying physics is all about. Coming up with one theory to explain everything that used to take multiple, completely unrelated theories to explain

By your analogy, he is showing that apples and oranges are really just different types of fruits.

The best example I can think of is Maxwell's electro-magnetism equations. It might seem obvious today, but it was an amazing breakthrough to realise that electrical fields, currents and magnetism were really just two sides of the same coin. Most lay people of that time must have thought it was a childish misunderstanding to relate lightning and what makes a compass work

I can't speak for whether the theory is flawed or not, but I think you're a little too quick to dismiss it based on high school seniors knowledge.

Re:This is most likely BS. Please see here.

[Anonymous Coward]

No offense to the OP, but Lubos Motl is well known by he physics community to be the academic equivalent of a hate monger. Sure, he's done some decent physics work, but he's pretty much impossible to work with and is instantly dismissive of anyone who doesn't follow the same path as him. And no one outside his circle of friends really listens to him all that much since he has a habit of not looking to carefully at the work of those he is criticizing.

So I wouldn't pay attention to Lubos when he says that someone is a crackpot and their ideas aren't feasible. A lot of physicists just look at his comments as free publicity because if Lubos is criticizing it, it usually means that he feels threatened by it, therefore, it could have some promise if it at least got his attention.

Re:might be on to something

[Anonymous Coward]

That's part of the problem. He might impress a layman, but Lubos is dogmatic and has a thoroughly antiscientific attitude - Anything that challenges String Mathematics (it's barely a theory...) has him foaming at the mouth. He's derided Einstein-Cartan theory on specious grounds ("look how few papers there are about it") on wikipedia (E-C theory is an expansion of GR to model spin, it's in fact a mathematical necessity), simply because it's a prerequisite for loop quantum gravity which he hates (it's an alternative to strings...).

But note how this theory has made TESTABLE PREDICTIONS - 20 new particles in a specific pattern. That's more than Lubos can claim after years of "research". The theory might be wrong, but at least it's a scientific theory. Lately, in the (rather rarefied) physics community, Lubos really is used as a sort of contrary guide - if Lubos doesn't like it, you might be on the right track.

Re:This is most likely BS. Please see here.

[quarrelinastraw]

The blog you linked to is a string theorist basically bitching about people who don't like string theory. Basically, someone insulted his religion and he's getting whiney.

Here's what he says about Lee Smolin, author of The Trouble with Physics

Smolin is a mediocre, slow thinker with a bad memory, below-average imagination, bad ability to focus and investigate details, and with kindergarten ideas - it is always hard to tell whether he is just joking when he talks about his childish ideas or whether he is serious - who is unable to learn the state-of-the-art physics at the technical level and who has never written a paper that would remain both valid as well as important among physicists who know their field for more than 10 minutes....

Here's what he says about his beloved string theory:

It's very clear that if someone dislikes string theory, she or he must dislike most of modern theoretical physics, too (Lee Smolin certainly does!). It's because string theory is nothing else than the crown, unification, or culmination of modern theoretical physics and all of its crucial results, insights, methods, principles, and values.

No true academic speaks that way about any idea, whether he disagrees with it or not. That's not science, that's fanboi-ism.

An attempt at a summary

[SirBruce]

Since the 50s, particle physicists have found ways of classifying particles intro groups, much the way Mendelev classified elements into groups via the Periodic Table. When doing this, they discover "missing" particles that fit within a certain group but were not yet known, thus giving such groupings predictive power.

Different groups have different symmetries. E8 is a group in Lie algebra. The group is "exceptional" and "simple" which is why the article is entitled tongue-in-cheekishly "Exceptionally Simple". The power and beauty of the E8 group has been known for a long time, and it's featured in many theories of physics that have tried to provide an framework for explaining the bewildered world of particles and forces that make up the universe.

What this author has done is use E8 in a new way to come up with a potential new theory that unifies all the forces and fields. This is not *strictly* a theory of everything, as there's a lot more that has to be answered, but if true it provides a geometric model that can give us insight into the underlying principles that are involved, just the way the Periodic Table does for elements.

The guy is no kook, but his theory leaves a lot to be desired. One problem is that E8 and other lie algebras and their associated symmetries have been well-studied for decades, and most all of them have run into intractable problems or incorrect predictions, so this may just be another beautiful theory that doesn't fit reality. Lisi uses a little-known method called "BRST connections" to make it all seem to work, which most physicists are unfammiliar with. Another is that his theory actually forces something physicists call as "spontaneous symmetry breaking" into the calculations to make it fit what we know to be true in the "standard model". Many people feel this is putting the cart before the horse; they would prefer a theory where the symmetry is broken in a "nautral" way and the "standard model" of the universe just naturally falls out of it. Lisi's theory doesn't really tell us WHY this is the case, it just says it is, but here's the symmetry that underlies it and which you apply it to.

Another problem is that the theory is still new and doesn't have an quantitative predictions as of yet... there's a lot of math that needs to be done, and it's not clear that such calculation *can* be done given the contraints of his theory. At issue is something known as the "Coleman-Mandula" theorem, which basically says a lot of what Lisi does in his theory doesn't work if there are subgroups in the algenbra that are equivalent to what are known as Poincare groups. Lisi says this doesn't apply to his new theory because it posits that the vacuum of spacetime doesn't have Poincare symmetry but instead is deSitter space. Well, the idea of deSitter space is well-known and has been examined in theoretical physics for decades as well, but there are a lot of problems with it. One is that the "Smatrix", which physicists love so much in making calculations in theories with Poincare symmetries, no longer works and simply becomes an approximation.

The theory also predicts a very LARGE cosmological constant, which is contrary to observation, but there are other theories that explain how this is not actually a problem, so that might not be an issue. Perhaps the largest obstacle of the theory, once the calculations can be figured out, is that it pretty much obsoletes all of String Theory in favor of something like Loop Quantum Gravity. This will make a LOT of string physicists very unhappy.

Lisi's theory will probably not be the last work in physics, but it might bring us a step closer to a real "Theory of Everything". The truth is physicists have been toying with similar geometric approaches and arrange particles in tables and trying to tie in gravity for decades now and every new theory looks great but never quite actually works out. The fact that the universe can *almost* be described via these methods probably tells us we're on the right track, but a true

Re:This is most likely BS. Please see here.

[Anonymous Coward]

Lubos Motl is a "real" physicist? No true scotsman fallacy, anyone? Hell, do your research: Garrett Lisi has a Ph., D. in physics! http://sifter.org/~aglisi/Physics/CV.html [sifter.org] He clearly isn't a "real" physicist, whatever that is supposed to mean (perhaps if Garrett spent more time performing intellectual masturbation and doing things like "debunking" global warming while comparing himself to Richard Feynman, then Garret would become a "real" physicist).

If anyone is interested in Garrett's reply to Motl's ad hominems, here it is: http://www.physicsforums.com/showpost.php?p=1496330&postcount=14 [physicsforums.com]

This is actually a relatively interesting approach, but I'm skeptical about the predictions of 20 new particles Garrett's theory makes. Ultimately it's up to experiment, as opposed to (say) a string of insults a maundering Harvard professor makes, that determines whether or not this theory is false or not.

Re:FTFA

[Anonymous Coward]

Warning: grossly inaccurate and oversimplified.

He's not saying space has 248 dimensions, he's describing the geometry of a polygon. If you read the paper, he's only invoking 3 spatial dimensions and one time dimension to define our universe.

Let's say you've got a cube, and each corner of the cube represents the properties of a subatomic particle. You can have a total of 8 subatomic particles and you can create a direct line between any point on the cube and any other.

E8 is a 248-dimensional set of lines connecting the points of a 57-dimensional imaginary object. What he has done is merge the E8 "object" with the various subatomic particles and used the remaining unassigned points to predict the features of those particles we have yet to detect. In essence, he's created a math representation of a periodic table of subatomic particles.

People with Ph.D's in mathematics aren't expected to understand the theory. People with Ph.D's in particle physics aren't expected to understand the theory.

Quite frankly, there's a serious audience of around one hundred people on the planet that can actually grasp what he's saying, and they seem to be divided about it and its ramifications.

~ J. Barrett

Re:GUT from a surfer dude!

[Dr. Smoove]

How is he a complete whackjob for claiming that hallucinogens (I believe it was LSD in his case) led him to the discovery? Alien abduction stories are wackjob material, but if you've ever experienced a hallucinogen, you'd know why this isn't too implausible.

Think properties, not dimensions.

[pavon]

The 248-dimensions that he is talking about are not like the time-space dimensions, which particles move through. They describe the state of the particle itself - things like spin, charge, etc. The standard model has 6(?) properties. Some of the combinations of these properties are allowed, some are not. E8 is a very generalized mathematical model that has 248-properties, where only some of the combinations are allowed. What Garrett Lisi showed is that the rules that describe the allowed combinations of the 6 properties of the standard model show up in E8, and furthermore, the symmetries of gravity can be described with it as well.

Now, there are other valid combinations of properties within E8 beyond the ones that represent the particles in the standard model, and these combinations would represent new particles that we have not seen before, if the model is correct.

Re:Wikipedia link to E8 - Still makes nooooo sense

[ajs]

http://en.wikipedia.org/wiki/E8_(mathematics) [wikipedia.org]

Holy crap! - I can read all the words, but none of it makes any sense. It's like the took regular English words and gave them all different meanings. I haven't felt this uncomprehending in a loooong time - and even the dumbness felt from quantum chemistry pales to this.

Well, a lot of it falls out of this:

http://en.wikipedia.org/wiki/Group_theory [wikipedia.org]

Which then gets you here:

http://en.wikipedia.org/wiki/Symmetry_group [wikipedia.org]

Once you get those two, you can hit:

http://en.wikipedia.org/wiki/Differentiable_manifold [wikipedia.org]

and you're very close to a general understanding of the shape (no pun intended) of what E8 is all about, and can dive into:

http://en.wikipedia.org/wiki/Lie_group [wikipedia.org]

Re:Wikipedia link to E8 - Still makes nooooo sense

[Garridan]

If it's any encouragement, I'm just finishing up my BS in Math, and currently taking a graduate course in algebra. And I don't get about 50% of the article. (note -- the wikipedia article has *nothing* to do with physics, it's just algebra & geometry) All I can say is, if you want to understand this stuff, grab a pencil and write down every definition you see. Every time you see a term whose definition you can't rattle off instantly, read it again.

Re:PDF

[Burz]

For those who may be interested, an interview and a couple of online discussions with Garrett Lisi participating:

http://www.physicsforums.com/showthread.php?t=179527 [physicsforums.com]

http://backreaction.blogspot.com/2007/08/garrett-lisis-inspiration.html [blogspot.com]

Re:GUT from a surfer dude!

[Billy69]

No, they're not. In the UK all undergraduate Batchelors degrees are 3 years, excepting medicine, vetenery science and dentistry, and all can cary honours within those 3 years. You can take a year in industry to make them 4 years in total. Some (very limited) courses called 'Undergraduate Masters' take 4 years, but end with a Masters-level qualification (MMath, MEng, MGeol, etc...) and with a year in industry this would take 5 years. There is no extra 'honours year'.

Re:Wikipedia link to E8 - Still makes nooooo sense

[swestcott]

Here is a video by NewScientist that tries to explain it to I hope this is not a dupe

http://uk.youtube.com/watch?v=-xHw9zcCvRQ [youtube.com]

Re:GUT from a surfer dude!

[Gropo]

Just FYI, LSD is disassociative and carries the risk of negative psychological response you're worried about. DMT is the real deal, widely regarded as 'psychologically safe' and no reported lingering after effects (flashbacks). Negative responses to the experience generally stem from 'not being ready for the message' rather than pre-exsisting temporal neuroses/psychoses as with LSD. Essentially, if you're free minded--the type of person who can 'just enjoy' an amusement park ride without constantly feeling the pings of imminent danger--you'll respond well to DMT.

That said, the reason I believe entheogens can foment scientific breakthroughs as discussed is attributable to two factors brought about by the process.

1) The manner in which these serotonin receptor 'confusers' suppress (or amplify, again LSD) our everyday neuroses. The immediate and lingering effects of 'clear headedness' allows for purer thought. Often, when the person taking entheogens is a mush-melon who goes in to the experience trivially to 'get off' their 'pure thought' afterglow leads to far fetched conclusions. Take the same molecule and apply it to molecular biologist or highly trained Buddhist and truly remarkable work can be accomplised.

2) On an individual level, entheogens can be described as agents for allowing the subject a unique perspective temporarily removed from their primary and secondary socializations (as described in sociology), that is to say the scripts that define your personality are removed to a certain degree. This is often described as 'ego death.' This is also a primary goal of Buddhist and Taoist meditative ritual. Even a little taste of 'ego death' can inspire mountains of unencumbered thought.

This can manifest itself in realizations such as "Jesus why am I so weak about smoking cigarettes? Where does that come from? It's so clear now how to turn it off" or "There's absolutely no reason why a DNA template subset can't be exponentially amplified using heat-stable DNA polymerases." ;)

Re:I don't understand a thing :(

[stonecypher]

I am not a particle physicist or a mathematician

Why do I get the feeling that that's the reason you're the only person in here both trying and succeeding to make this material available to the lay ministers?

it's not back to the same orientation until you turn it around 720 degrees, instead of 360 like normal objects

I've found that a variation on the Flatland theme really helps people come to terms with this - it's easier for us to look down then map back up when we're trying to understand things outside our physical experience, at least in my opinion. The one I've been using is a sphere on an axis, painted identically on two sides, and a very young child observer. Generally speaking, the toddler won't be able to tell the half-rotation from a full rotation. Following that, I usually invoke the toy ball with the second ball suspended inside in a thin fluid, and posit that it rotates at precisely half the speed of the exterior ball, and revoke the identical side-to-side painting. If the outer ball is only slightly transparent, a young child won't notice that after a full rotation, the interior sphere has only rotated halfway - then you mumble something about an analog clock or a car gearing down, depending on your audience - and point out that only an adult would notice that it takes two rotations to get the state back.