# E8 — A secret of the universe?

Discussion in 'Physics & Math' started by Tiassa, Nov 16, 2007.

1. ### TiassaLet us not launch the boat ...Staff Member

Messages:
35,715
So ... how significant is it that a surfer with a PhD has allegedly cracked the secret of a 57-dimensional object, thereby revolutionizing the scientific view of the Universe?

The thing is that many are taking a cautious approach. While Georgia Institute of Technology's David Ritz Finkelstein notes, "Some incredibly beautiful stuff falls out of Lisi's theory ... This must be more than coincidence and he really is touching on something profound", others, such as Oxford University's Marcus du Sautoy points out, "The proposal in this paper looks a long shot and there seem to be a lot things still to fill in."

American theoretical physicist Lee Smolin, according to a colleague, is said to be "betting on a very, very long shot". Perhaps most tellingly, Lisi himself says the theory is "very young", and would "assign a low ... likelihood to this prediction", and expects that LHC experiments will more likely "see some of these particles than ... superparticles, extra dimensions, or micro black holes as predicted by string theory".

This all sounds cool as hell to me, but I'm neither a physicist or mathematician. Even the Wikipdia entry on E8 escapes my comprehension. But it is beautiful.

___________________

Notes:

Highfield, Roger. "Surfer dude stuns physicists with theory of everything". Telegraph.co.uk. November 14, 2007. See http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/11/14/scisurf114.xml

Messages:
10,296
It's very, very early in the game but appears that he may may well be on to something. Keep in mind that math IS the primary tool of the theoretical physicist and has always served very well in the past. I could easily list a dozen or more names to make that point clear - people like Lorentz, Planck, Eddington, Einstein - but I'm sure you understand the importance of it.

Let's give this lad some breathing room and time and see what comes out of his work. Indeed, it may be a long shot but it certainly looks more promising than anything that's come along in a great while. Note that it ties in well with string theory which so far hasn't been able to construct tests to verify it. And THIS may well provide it with some needed tests.

5. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
Tiassa---

This paper has been over-hyped quite a bit. I've only given it a cursory glance, but it looks like he's embedding the symmetries of space and time into the large group E8. Basically, you can think of E8 as a collection of 8 by 8 matrices with special properties. There are a few technical problems with the work. I object to it being called a theory of everything'' because he doesn't fully explain gravity---that is, as far as I can tell, he doesn't solve the main problem of quantizing gravity.

If anyone is interested, there is a somewhat technical discussion of this topic at another discussion board, physicsforums.com, lead by a moderator (who I hate) called marcus and Garrett Lisi himself. If you can get past the fact that marcus carries an open bias agains anything resembling string theory, then you may want to join in the discussion there.

There has also been a lot of attention in the blog-o-sphere. Lubos Motl (a string theorist from Harvard, now working in Pilsen) doesn't particularly like the paper, which is no surprise, as he hates anything that isn't string theory. Sabine Hossenfelder I think was the first to report. She is a very bright physicist who is at Perimeter Institute in Waterloo, and works on testing quantum gravity. Finally, Peter Woit has given the paper a good once over as well. I don't think he does much physics beyond criticizing string theory (which has made him quite famous), but he has some semi-permanent position at Columbia University.

To me, the paper feels a bit like numerology---sort of like if you add up all the protons in the universe you get roughly the same number as the distance from the Sun to Alpha Centauri in pennies, or something. But you shouldn't take this as a well informed opinion

7. ### ReikuBannedBanned

Messages:
11,238
Where is my posts i made here?

8. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
I deleted them because they were off-topic.

====

To all: I will do my best to keep serious threads like this one free of trolling.

9. ### sniffyBannedBanned

Messages:
2,945
If this theory becomes accepted does it mean curtains for string theory?

Messages:
11,888

11. ### sniffyBannedBanned

Messages:
2,945
I believe it not.

12. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
Perhaps. I think Lisi showed that the group E8 contains a subgroup which is SO(3,1). SO(3,1) is the Lorentz symmetry in four dimensions, so this theory definitely predicts a four dimensional space-time.

13. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
Well, yes. But the E8 in string theory comes with 10 space-time dimensions. This E8 lives in four dimensions.

Messages:
2,945
Hmmm.

15. ### NickelodeonBannedBanned

Messages:
10,581
What is that picture supposed to represent?

16. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
I am not sure actually. Remember I said that E8 is a collection of 8 by 8 matrices with certain properties? There are a finite number of such matrices, 240. I think each little black dot in the diagram is an 8 by 8 matrix, and the lines connecting them are some multiplication rules, or something.

Everybody puts this picture up, but nowhere have I seen an explanation of it.

17. ### ReikuBannedBanned

Messages:
11,238
eerrr.. Oli...

There are only 8-time dimensions in a 57 dimensional configurate...
DUH

18. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
There's NO time dimension. The 57 dimensional thing is a representation of E8, I'm sure.

19. ### ReikuBannedBanned

Messages:
11,238

If there is't AT LEAST one time dimension, the this whole thread has been a farse, from a quantum and relative veiwpoint.

20. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
Well, I disagree. The time dimension lives in SO(3,1), which lives in the E8. The E8 breaks to stuff x SO(3,1). SO(3,1) has spinor and vector representations, which explains why we have fermions and bosons.

21. ### ReikuBannedBanned

Messages:
11,238
yu wot? Chinese mate... i understand some of it... not all.

22. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

Messages:
8,967
Well---the Lorentz symmetry is SO(3,1). A symmetry of nature is basically an operation that you can do on something, so that something is left unchanged. The space'' of space-time'' has a three dimensional rotational symmetry. This means, for example, that if you were floating in space and had no way to identify directions, you could turn about three different axes and have things look the same. The other example is a sphere. IF you have a solid, unmarked sphere, you can turn it about the x, y, or z axes, and still end up with things looking the same. This group of rotations is called SO(3).

Time kind of fucks everything up, but suffice it to say that you can define rotations in time---to us they look like a displacement in space. Doing htis, you can show that space-time looks like SO(3,1).

What Lisi has showed is that SO(3,1) lives inside the larger group E8. And presumably he's shown how to break the larger symmetry of E8 up into smaller bits, each of which describe our universe.

23. ### ReikuBannedBanned

Messages:
11,238
Well, SUFFICE to say, in relative format, a 57 dimensional coordinate against the ratio of geometry, it WOULD NEED an 8-dimensional configuration.

Why don;t you just ask one of your physicist professors instead of acting like an immature scientist by deleting my posts.