Bee's interview with Garrett. BLAM It connects.

[marcus]

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

my candidate for the greatest ever physics blog interview

 

[Chronos]

A disarmingly charming exchange. Einstein played the violin, Garrett rides waves. I like chess, but am not gifted. The geometry is compelling and beautiful.

 

[marcus]

A disarmingly charming exchange. Einstein played the violin, Garrett rides waves.

Chronos! you have inspired me with an idea. What if Einstein had had a blog?[/color]

 

[arivero]

"Sorry for the delay, E8 got stuck in PI's spam filter" :-DDDDD

 

[neutrino]

Einstein would have known that it was useless having blogs. Instead he would have spent time coming up with a unified theory[now that he knows about the other forces also].

 

[ccdantas]

Well, I spend a minimum amount of my time in my blog. I'm always intrigued on how "heavy" bloggers find time for writing so many posts, sometimes quite elaborate posts. I can only conclude that at least one of the below must be true:

- they do not have a family or a family "life" to care of;
- they have very flexible jobs, if at all;
- they carry their notebooks *everywhere* and are able to write anywhere they happen to be;
- they often have good internet access (specially those who are able to include a link for almost every word they mention in their posts);
- they sleep only up to 5 hours per night; :zzz:
- etc... (I've certainly forgot several possibilities)

I would speculate that, if Einstein lived in our time, he would not blog, or if so, he would spend a very little amount of time with it.

Christine

 

[jal]

Marcus … I did a picture search for E8 and E8 root system.
http://aimath.org/E8/
Mathematicians Map E8

and the best image
http://homepages.wmich.edu/~drichter/images/splashphoto_small_073106.jpg
because it shows the shadow of E8
second place
http://en.wikipedia.org/wiki/Image:E8_roots_zome.jpg
This is a Zome model of the E(8) root system

I also got other interesting pages such as
http://www.amsta.leeds.ac.uk/~rjm/parade/R3R1.html
E8 singularity Equation: x^3-y^5-z^2
http://www.sukidog.com/jpierre/strings/mtheory.htm
SUPERSTRINGS! M-theory

I got a different question.
What is the total length of the connections?

 

[marcus]

Hi Jal, Christine, Alejandro, Neutrino et al.

Jal I don't know the total length you are talking about. Maybe someone else with a better understanding of E8 can discuss this.

Christine, I seem to remember hearing that A.E. was something of a ladies' man. So even when he was not busy playing the violin and thinking physics, he would probably have been too busy chasing women and having affairs. Blogging might have come very low on his list of priorities.

So I generally agree with you and Neutrino, but in later life I think Einstein did very much like to write letters! He corresponded with many people, not all of them physics colleagues. Perhaps because he liked to explain ideas, express opinions, and enjoyed writing. Would he have joined the discussion at Peter Woit's blog *Not Even Wrong*? Someone with more knowledge of what the man was like can guess better than I.

 

[garrett]

jal:
I've been talking with David Richter, and I used a paper of his to build this animation of the E8 root system projected into 2D:

http://deferentialgeometry.org/talks/FQXi07/video/e8anim.mov

(caution, it's 100MB.)

 

[garrett]

Christine:
I'm not a heavy blogger, but I satisfy all five of your requirements. ;)

 

[jal]

You're fun to talk to. LOL
The link did not work for me.
Since E8 is such a monster it never the less has a fixed number of conection point and a fixed pattern of conections. I was just wondering if this was true since the different picture imply this conclusion.
Be nice to me ... I'm not a mathematician.
jal

 

[garrett]

Hmm, wonder why the link didn't work. Can you play quicktime movies?

The E8 root system isn't that monstrous -- it's just 240 points in a finite lattice in 8D. Each root is the same distance from the origin, and each has 56 nearest neighbors. To make the E8 polytope (classified as P421), one draws in these links to the nearest neighbors. The pretty pictures, and the correspondence to the standard model quantum numbers, come from projecting this root system into lower dimensions.

 

[turbo]

jal:
I've been talking with David Richter, and I used a paper of his to build this animation of the E8 root system projected into 2D:

http://deferentialgeometry.org/talks/FQXi07/video/e8anim.mov

(caution, it's 100MB.)

I don't know what that animation is showing us, but it's beautiful, especially when the nodes line up in 2-D and resolves to a much simpler-looking object.

 

[arivero]

Marcus, the point with E8, and much of the amateur approximations we do here, is that from the point of view of high academia they fall in the category "tried without success, not PhD will be produced from here". Or, Also near of Feynman's analogy about boxes and keys, "did you try this number?".

The problem is that one must have a natural method to break E8 into the standard model. (And Garrett wants gravity too!). In the same sense that string theoretists have a lot of vacui to choose from, GUT theoretists have a lot of breaking patterns to choose. The only fundamental (*) advantage of string theoretists over GUT theoretists it that the later do not have a fundamental reason to break the group at all, while the former must do it to go down to four dimensions. BTW, Lumo uses this fact to claim that "Standard Model has been proven to be a consequence of compactified heterotic string theory back in 1985, I mean by Strominger Horowitz Witten Candelas". Fortunately the preprint of this paper is readable online http://ccdb4fs.kek.jp/cgi-bin/img_index?8504007 so you can read and check. As far as I remember, four 27-generations with N=1 supersymmetry and E6 gauge group is not the Standard Model. Yet.

(*) they also have to have one technical advantages, better control of V+A interactions, and one half-fundamental one: justification of the high energy cutoff.

 

[arivero]

Incidentally, the last parragraph of Strominger Horowitz Witten Candelas suggests to try to break E8 into O(10) by using some other kind of undiscovered manyfold. Most probably this possibility has already been settled as negative, has it?

 

[garrett]

Thanks Alejandro, this is a good description, and the KEK link was helpful.

Indeed what I have been doing is GUT + gravity. It came as a surprise to me, three months ago, that the Lie group I had built up to over the years was E8. This has been very exciting, and I'm now playing with many of those symmetry breaking patterns. The difference is, as you say, I'm including gravity in there with the other GUT gauge fields.

I can make this more clear, and fun, by starting with a simple question:
"What is the rank of the standard model and gravity, as a Lie algebra?"

 

[arivero]

I can make this more clear, and fun, by starting with a simple question:
"What is the rank of the standard model and gravity, as a Lie algebra?"

I can not tell about clarity, but I agree it is funnier.

 

[jal]

Hi garrett!
How would you explain to someone who has never heard of extra dimensions ( more than 3 dimensions)?
Where would you start? (Without using compactification)
This must be a challenging communication/teaching situation.
Would you, For example...
Assume that there is another direction (a fourth) from the corners of a cube...
240 points
8d
56 neighbors
240/4=60 (one extra direction on each corner of a cube)
60/6=10cubes
That does not seem to work

or ...?
jal

 

[garrett]

I can not tell about clarity, but I agree it is funnier.

Ha! Would you be able to make sense of what the hell I was asking if I told you the answer was 6?

 

[garrett]

jal, we have to be careful here. There are several different spaces we're dealing with at once when we work with a principal bundle. (This is probably why Sabine said YM is not so simple.)

We have the spacetime we move around in.

We have the 248 dimensional E8 manifold, which serves as the fiber or "internal space."

And we have the 8 dimensional vector space that the 240 E8 roots live in, that describe the structure of E8.

If you want to think about Yang-Mills theory the same way people think about Kaluza-Klein theory, then you have to imagine the 252 dimensional "entire space."

Or, if you don't want to think about extra dimensions at all, you can just think of all this as the familiar four of spacetime and a bunch of algebra.

 

[jal]

LOL
You covered all the bases. Gramma would happily go back to her knitting.
For a simpler question.
Can you pull out the LQG tetras from E8?

 

[garrett]

"Can you pull out the LQG tetras from E8?"

No, this has to come out of a spacetime quantization framework. But, once people figure out how to do this for a so(1,3) connection, the theory should be qualitatively the same for an e8 connection. Of course, the prospect of calculating 10j symbols for E8 is terrifying...

 

[arivero]

Ha! Would you be able to make sense of what the hell I was asking if I told you the answer was 6?

Er, 6 mod 8? Or (-)2 mod 8? (not the real answer about Lie algebras, but funny how one can wander thinking in the low numbers and get lost in the forest)

 

[garrett]

Heh, yah.

OK, here's what I'm talking about. The rank of E8 is 8. This is the dimension of the Cartan subalgebra -- the largest number of mutually commuting Lie algebra generators. For the standard model and gravitational gauge fields, the mutually commuting generators are in:
strong su(3) -> 2
electroweak su(2) -> 1
electroweak u(1) -> 1
gravity so(1,3) -> 2
So there are 6 total, which is the rank of the standard model and gravity, treated as one big Lie algebra. Make sense now?

 

[jal]

strong su(3) -> 2
electroweak su(2) -> 1
electroweak u(1) -> 1
gravity so(1,3) -> 2
So there are 6 total

Everybody knows that I'm stupid ...so it does not bother me to ask a stupid question.
Why do you want to add them up? Why not stay at 2?
jal

 

[garrett]

Because we're looking at the big picture, jal.

 

[jal]

gramma is laughing and knitting

 

[ccdantas]

Christine:
I'm not a heavy blogger, but I satisfy all five of your requirements. ;)

Hi Garrett!

Yeah, the reverse is not often true!

BTW, I very much enjoyed Bee's interview with you. Not everyone has the courage or the talent to follow a more free life style, doing what they really want to do in life. It's not easy, because at a certain point there are basic necessities in life that must be paid for, I mean, there is not much escape from the necessity of having some amount of money to live in minimal conditions. Otherwise you have to turn yourself into an indian or something, right?

From Sep 2004 to May 2007 I had a very difficult time in my life because of my job. I didn't want to work in software engineering -- but that was the situation I found myself in! -- and the conditions for doing research were almost impossible. Because it was a permanent position, it was very difficult to leave that job for something completely uncertain. (Some people would never understand why that job was so terrible for me, but it was). I was very stressed and depressed! That was not what I wanted to do with my life. Since when I was a child I wanted to be a physicist or an astrophysicist, so things were getting very difficult everyday. Then, with a lot of luck, I was able to get a transfer to the materials division of the institute, where I'm now back to physics.

In any case, I almost had the impetus of doing something like you did...


Christine

 

[ccdantas]

I think Einstein would certainly like to exchange emails with colleagues and make heavy use of the internet, like most researchers do nowadays. I don't know whether he would like to comment in blogs, specially in more polemic ones... We will never know...

 

[hossi]

Hi Marcus,

Thanks for the link Yeah, Garrett's suggestion to make it an interview instead deserves a Nobel prize. I'm hoping to re-animate the inspiration series maybe in interview-style. I didn't like putting deadlines for contributions, so some people who agreed to write something never replied.

Hi Christine,

Regarding your list: well, you know that I don't have much of a family life, at least not in Canada. So this is probably true. Interestingly, I've been asked that question repeatedly, so a few words about it. What I write on the blog are things that have been on my mind anyhow, they are not specifically blog-designed. (There are exceptions to this, e.g. the whole inspiration series.) My writing is mostly finished before I sit down and actually type it. I don't have to carry my laptop around to do that, and it doesn't take much of an internet connection to upload a textfile to blogger.

(The most annoying part is how much time it still takes me to write in English, and then it's never quite as fluid as I think it would have been in German.)

The comment section is a completely different problem.



B.