This is really annoying...

[SiriusCG]

I don't frequent this forum too often, but I'm going to comment anyway...

Usernames like )??(??(J?E)??)??( and SU(3)xSU(2)xU(1) are really annoying. I guess I'm supposed to disregard the "cutsy hacker style" junk and discern this users name is "Joe" and the other is... ???

C'mon mods, there has to be some limit to what is acceptable for a username and what isn't...

Thanks.

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

SU(3)xSU(2)xU(1) IMO is a perfectly acceptable username for this forum, at least as much, if not more so than SiriusCG.

Perhaps you need to educate yourself just a little in physics (in paticular, "string theory") before your next visit.
I suggest you start: HERE and HERE, and HERE.

[SiriusCG]

Ah, a little research show you to be a (somewhat rude) 14 year old kid... 'nuff said.

[t00fri]

SU(3)xSU(2)xU(1) IMO is a perfectly acceptable username for this forum, at least as much, if not more so than SiriusCG.

perhaps you need to educate yourself just a little in physics (in paticular, "string theory") before your next visit.
I suggest you start: HERE and HERE, and HERE.

"Joe",

while it is remarkable that you are able to associate SU(3)XSU(2)XU(1) to (Particle) Physics at an age of 14 , this word is NOT particularly related to String Theory. It rather denotes the Lie symmetry group structure of the so-called Standard Model of Elementary Particles (involving quarks, leptons, and the various gauge bosons, i.e. the gluons, W,Z bosons and the Photon) . This name and meaning existed MUCH before string theory was invented.

Fridger

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

while it is remarkable that you are able to associate SU(3)XSU(2)XU(1) to (Particle) Physics at an age of 14 ,

I must be a child prodigy!
No, seriously, any average 14 year old knows how to GOOGLE.

this word is NOT particularly related to String Theory. It rather denotes the Lie symmetry group structure of the so-called Standard Model of Elementary Particles (involving quarks, leptons, and the various gauge bosons, i.e. the gluons, W,Z bosons and the Photon) . This name and meaning existed MUCH before string theory was invented.

Fridger

Thanks for the clarification... I of course meant "Gauge Theory", not "String theory".
Although, correct me if I'm wrong, but isn't Gauge Theory loosely related or precursor to the field of String Theory?

ie. Gauge Theory -> Supersymmetry -> String Theories -> Superstring Theories

(Oops, I think that's exactly what you already said above )

To over-simplify it, I thought String/Superstring Theories were just a new way of looking at elementary particles (the same things Gauge Theory is concerned with). The older Gauge Theory thinks of them as "particles", whereas the newer String Theories think of them as "vibrations".

... and if I understand correctly, these new theories have implications on theories about the fundamental structure/topology of the Universe, eg. multiple dimensions, branes (M-Theory), etc...

... which, I suspect, is right up your alley.

[t00fri]

while it is remarkable that you are able to associate SU(3)XSU(2)XU(1) to (Particle) Physics at an age of 14 ,

I must be a child prodigy!
No, seriously, any average 14 year old knows how to GOOGLE.

this word is NOT particularly related to String Theory. It rather denotes the Lie symmetry group structure of the so-called Standard Model of Elementary Particles (involving quarks, leptons, and the various gauge bosons, i.e. the gluons, W,Z bosons and the Photon) . This name and meaning existed MUCH before string theory was invented.

Fridger

Thanks for the clarification... I of course meant "Gauge Theory", not "String theory".
Although, correct me if I'm wrong, but isn't Gauge Theory loosely related or precursor to the field of String Theory?

ie. Gauge Theory -> Supersymmetry -> Superstring Theories

(Oops, I think that's exactly what you already said above )

To over-simplify it, I thought String/Superstring Theories were just a new way of looking at elementary particles (the same things Gauge Theory is concerned with). The older Gauge Theory thinks of them as "particles", whereas the newer String Theories think of them as "vibrations".

Of course, it was obvious that Google was helping in your post...still...

Since you were asking:

String Theory embeds all known Gauge theories including gravity such that all Gauge Theories are recovered when the "string tension" (= a free constant that may be adjusted) is made very large!

Therefore, String Theory has been phrased "The Theory of Everything" by it's defenders. But before this can really be substantiated, there is a long long way to go...The main problem is that it is very hard to experimentally falsify String Theory, since it does not make a single testable prediction (unlike the Gauge theories that it incorporates).

The role of Supersymmetry in the context of String Theory is under debate. This may well be clarified to some extent, once the gigantic Supercollider LHC at CERN in Geneva/Switzerland has started it's operation towards the end of this year.

Enjoy this video about the LHC:
http://www.youtube.com/watch?v=rgLdIly2Xtw

Fridger

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

The main problem is that it is very hard to falsify String Theory, since it does not make a single testable prediction (unlike the Gauge theories that it incorporates).

Is the reason that it is un-testable: because the physics we have access to is "stuck" in 3+1 dimensions and therefore we don't have experimental access to the other dimensions that the theory predicts?

So it cannot be proved or dis-proved because it's impossible to conduct an experiment?

[t00fri]

The main problem is that it is very hard to falsify String Theory, since it does not make a single testable prediction (unlike the Gauge theories that it incorporates).

Is the reason that it is un-testable: because the physics we have access to is "stuck" in 3+1 dimensions and therefore we don't have experimental access to the other dimensions that the theory predicts?

So it cannot be proved or dis-proved because it's impossible to conduct an experiment?

Yes that is correct. String theory basically lives in 10 dimensions. At some high energy scale, a "dimensional collapse" called "compactification" is assumed to take place, where our familiar 3+1 dimensions remain and the rest curls up into 6 dimensional tiny spheres that one my paraphrase "space-time foam" . The problem with lacking predictions is due to the fact that this dimensional compactification may happen in a HUUUUUUUUUUUUGE number of inequivalent ways. Which one was chosen, we don't know. Each time the predictions in 3+1 dimensions differ drastically...

Fridger

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

The main problem is that it is very hard to falsify String Theory, since it does not make a single testable prediction (unlike the Gauge theories that it incorporates).

Is the reason that it is un-testable: because the physics we have access to is "stuck" in 3+1 dimensions and therefore we don't have experimental access to the other dimensions that the theory predicts?

So it cannot be proved or dis-proved because it's impossible to conduct an experiment?

Yes that is correct. String theory basically lives in 10 dimensions. At some high energy scale, a "dimensional collapse" called "compactification" is assumed to take place, where our familiar 3+1 dimensions remain and the rest curls up into 6 dimensional tiny spheres that one my paraphrase "space-time foam" . The problem with lacking predictions is due to the fact that this dimensional compactification may happen in a HUUUUUUUUUUUUGE number of inequivalent ways. Which one was chosen, we don't know. Each time the predictions in 3+1 dimensions differ drastically...

Fridger

Now THAT is annoying.
I guess we might have to call on Douglas Adam's pan-dimensional mice to conduct the required experiments!

Thanks for the explanations.

I hope your username passes inspection. Those 2 zero's could be controversial.

[t00fri]

I hope your username passes inspection. Those 2 zero's could be controversial.

Yes, t00fri is not an entirely clever choice, but it is in some way a historical professional left-over... Most people use my first name that is very rare but easy enough...

Fridger

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

I had a thought...

One way to find evidence for a specific topology might be to look for some "predicted effect" in 4 dimensional space.
This would have to be an effect which has no other explanation.

(This of course assumes that the extra dimensions have an interaction with our dimensions in the first place)

Disproving these theories might be more difficult as the absence of evidence does not disprove the theory. It could be just that there is no evidence....

[SiriusCG]

"Joe", Let me give you a practical demonstration of why your user name is unacceptable...

This is result of searching, or trying to search, for Celestia forum posts using your current user name using the search box in the upper right hand corner:

No posts were found because the word ?ae(j?e) is not contained in any post.

and for "t00fri"

Search found 1520 matches: t00fri

Evidently t00fri "passes inspection"...

[t00fri]

and for "t00fri"

Search found 1520 matches: t00fri

Evidently t00fri "passes inspection"...

You findings are strange, indeed. Firstly, in the 7.5 years of being a member of this forum, I wrote 7753 posts NOT just 1520. Actually, the top three posters are

1 selden Wed Sep 04, 2002 4:21 8629
2 t00fri Fri Mar 29, 2002 14:53 7753
3 chris Mon Jan 28, 2002 21:21 3933 Site Admin

according to the forum statistics. As a check, of your result, I also used the forum's search engine with input 't00fri'. Unlike you I got the correct result, however.

Then I used the search engine with the username of "Joe" ()??(??(J?E)??)??(). Also here everything is fine, the name is accepted and 7 posts are reported!

Fridger

[SiriusCG]

Interesting, I just ran the same test terms as before and got the identical results as I first posted... Firefox 3 in Xubuntu LINUX, but that shouldn't matter. Who knows.
Oh well, I guess that there are more important things in life to be concerned about...

Cheers.

[t00fri]

I had a thought...

One way to find evidence for a specific topology might be to look for some "predicted effect" in 4 dimensional space.
This would have to be an effect which has no other explanation.

(This of course assumes that the extra dimensions have an interaction with our dimensions in the first place)

Well in a sense this is being done. For instance does one expect in certain scenarios a deviation of the famous Newtonian law of gravitation at short distances < 20 micron, say.
This modification might arise as a left-over from the fact that the underlying theory was formulated in more than 3+1 dimensions. Yet only in CERTAIN scenarios, unfortunately.

Nothing has been found so far, actually.

Fridger

[t00fri]

Interesting, I just ran the same test terms as before and got the identical results as I first posted... Firefox 3 in Xubuntu LINUX, but that shouldn't matter. Who knows.
Oh well, I guess that there are more important things in life to be concerned about...

Cheers.

Perhaps you entered t00fri into the wrong place?

Fridger

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

"Joe", Let me give you a practical demonstration of why your user name is unacceptable...

This is result of searching, or trying to search, for Celestia forum posts using your current user name using the search box in the upper right hand corner:

No posts were found because the word ?ae(j?e) is not contained in any post.

There is nothing wrong with the search function. You've tried to do a partial match without the required wildcard characters. (A search for "Sir" will also return nothing.)... Do you know what a wildcard character is?
I suspect you've also used the basic search rather than the advanced form which allows you to search for Authors.
(Did you click on "Advanced Search" and enter the search term into the correct box ? )

For example, a search for ")*ae*" or "*(j*e)*" in the Author box works perfectly.

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

I had a thought...

One way to find evidence for a specific topology might be to look for some "predicted effect" in 4 dimensional space.
This would have to be an effect which has no other explanation.

(This of course assumes that the extra dimensions have an interaction with our dimensions in the first place)

Well in a sense this is being done. For instance does one expect in certain scenarios a deviation of the famous Newtonian law of gravitation at short distances < 20 micron, say.
This modification might arise as a left-over from the fact that the underlying theory was formulated in more than 3+1 dimensions. Yet only in CERTAIN scenarios, unfortunately.

Nothing has been found so far, actually.

Fridger

OK, thanks for that. The jury remains "out"!

[LordFerret]

This is all way out of my field, but I do recall reading somewhere that our only hope of 'seeing' a superstring would be to observe its 'shadow'. So, if you choose to believe what you see in shadows..........

[)ÎÆ(÷×(JØE)×÷)ÆÎ(]

Fridger,

Thanks for the video. Interesting, but like most programs of that nature it seemed to be pitched at a mainstream audience, so didn't really go into the details of the actual physics, still, I learned a little from it.

I was quite amused by Alvaro de Rujula's comments...

Alvaro de Rujula: "If the LHC is lucky enough... to penetrate inside these points that contain extra dimensions, then a complete new field opens up of possible new discoveries."

Presenter: "But, what if we don't find it..." (referring to the Higgs boson)
Alvaro de Rujula: "That would be fantastic, because that would mean that we really haven't understood anything!...and that is the best situation in science, the one that precedes big revolutions...is when we realize that we had in fact understood nothing!"

It seems to me he's seriously hedging his bets.
-- Success == "A complete new field";
-- Failure == "we really haven't understood anything!...and that is the best situation in science"
( A cynic would say he's a forward thinking physicist contemplating the future justification for further billions/trillions of funding in the event of either outcome. )

Here's an article about the search for the Higgs boson;
http://www.newscientist.com/article/mg19325934.600-higgs-boson-glimpses-of-the-god-particle.html?full=true

For SeriousCG:
A justification for why my user name is acceptable, is that it exhibits "Super Symmetry":
)??(??( J?E )??)??(