There’s a lot of buzz about Surfer dude stuns physicists with theory of everything. Basically a physicist who had been working on a Grand Unified Theory that didn’t involve string theory finally came up with a way to correlate all the known particles and fields with a special mathematical object called E8 which was also generating some buzz earlier this year for finally being solved by mathematicians. Besides a particular form of E8 working just so to describe some of the peculiarities of various physics equations, as well as tying together gravity with the other forces, it also predicts a few new particles and fields and so should be testable.
A few questions:
Despite the “exceptionally simple” title, and although the paper does indeed to be fairly simply written, it still uses a bunch of terms and symbols that go beyond this layman’s knowledge of physics. Anyone out there in the physics field capable of summarizing the findings without math or symbols?
Besides the physics stuff, the lynchpin of AESTOE seems to be this big pretty spirograph thing called E8. The wiki page is particularly obtuse. It seems that there is this called a Lie Group, and there are exceptional ones, and simple ones, and E8 is the largest simple exceptional one. Can anyone explain what a Lie Group is, and what makes E8 so special?
Some new particles and fields are predicted. It’s suggested that some of the particles might be detected by a new hadron accelerator. Does the description of these particles put them within the domain of this new detector? The paper also suggests that some of the particles may have been or be difficult to detect because they are massive. Why wouldn’t a more massive particle be easier to detect? And what exactly are fields in this context?
The elementary particles are correlated with the 240 roots of E8, but it seems from table 9 of the paper there are either 60 or 63 particles. What am I missing? Also, is g a graviton? It seems to be the only particle that’s alone in it’s own group. How is that explained?
What’s the buzz in the physics community so far? How legit is this?
Well, Lee Smolin is quoted in your link as saying, “It is one of the most compelling unification models I’ve seen in many, many years”. That’s enough to make my ears prick up.
In order to detect a particle, you first have to generate it. When it comes to these kinds of particles, energy = mass. So you need to have sufficient energy inserted into the colliding particles in order to generate a massive new particle. the LHC will be the world’s highest energy collider, with each proton having an energy of 7 TeV (tera-electron-volts). Thus each collision will have 14 TeV and any resulting particles could have masses up to that value.
Is he proposing that the shape of space-time itself is of this geometry? If so, is this at the Planck Length?
Also, they’re saying that this is an elegant and simple TOE that tidy all the forces up without having to result in the multi-dimensions of string theory. But then they go on to say the E8 shape having 57/248 dimensions. How does this differ from the dimensions proposed by M Theory? (I understand the structure has 248 points… but don’t understand where the 57 dimensions come in.)
Chronos? Stranger on a Train? Mathochist? Someone?!
I don’t understand any of this physics stuff but I thought this was amusing. If Lisi turns out to be right then “Holy crap, that’s it!” will be immortalized right alongside Archimide’s “Eureka!”
I haven’t looked over this in detail, yet. But from a quick skim, it looks like all he’s found is that a lot of the groups associated with various physical phenomena can be found embedded as subgroups of E8. Which is not really all that surprising, in itself: The groups used in physics are mostly pretty simple, and E8 is very large and complicated. I’d be more surprised if it didn’t contain all of the interesting physics groups as subgroups.
The meaty part is the claim that there’s some significance to the way these subgroups are embedded, and that the relationships between the subgroups says something about the relationships between the theories the subgroups represent. That, I would need to look in a lot more detail before passing judgement.
One very good thing about this idea, is that he’s able (or at least, so he claims) to determine masses for some of these “new” particles, and that some of them might fall into the range of the LHC. If he (or others working on this) can make predictions of such masses, they’ve got themselves a testable hypothesis, and when the LHC is turned on, we’ll be able to say whether they’re right or not. In this respect, at least, they’re far ahead of the String Model, which can’t really make any substantive testable predictions: Whenever a string model test comes up negative, there’s so far always been some way to tweak the parameters of the model so it’s still consistent with the results.
Doesn’t this just make string theory “a very neat idea” instead of a valid hypothesis? I mean, if you can explain away any inconsistencies, why even consider that it would be valid?
A group is a set G together with an operation * that takes two elements of G and produces another one. There are a few properties that have to hold[ol][li]a * (b * c) = (a * b) * c[]There is an element e in G such that for any element a, a * e = e * a = a.[]For every element a in G, there is an element b such that a * b = b * a = e.[/ol]Note that we don’t require that a * b = b * a, although it’s always nice to work with groups where that does hold. [/li]
Take the real numbers together with addition. It’s easy to verify that this is a group, but it has one other really nice property: the operator * has a derivative. That’s basically what you need to make it a Lie group (pronounced Lee, by the way), although the definition is a little bit more general.
I need a little bit more notation to explain what it means for a group to be simple. If g is an element of G, and N is a subset, then gN is the subset you get by taking every n in N and replacing it with gn. Similarly, Ng is the set you get by replacing every n in N with ng. If N is a group, g is an element of g, and h satisfies gh = e, gNh is a group as well.
If it turns out that no matter which g you pick, gNh = N, we say that N is a normal subgroup of G. Normal subgroups are pretty important in group theory, so you spend a lot of time talking about them. In particular, you might be interested in knowing which subgroups of a group G are normal. If it turns out that the only ones are G itself and {e} (which is a subgroup of any group), we say that G is simple.
The interesting thing about the finite simple Lie groups is that all but a finite number of them follow one of a few patterns. The ones that don’t are called exceptional, and E8 is the largest of them.
