String Theory: How Close Are We?

[Curious6]

How Close Are We To...

How close do people on this forum think string theorists are to a full complete non-perturbative description of string theory? Do you think it is a question of months, years or decades before scientists will be able to fully describe the theory? My point on this is that I have just read an article on M. Kaku's website where he states that when a full non-perturbative description of string theory will be made, it will automatically provide evidence for the theory as it can boil down to other simpler theories for which there is already a lot of experimental evidence. Also, I am asking this question because I don't really know the current state of research in string/M-theory and if any progress is really being made. Thanks for any answers!

 

[marcus]

this assessment of progress (and near term prospects)
was made last year
http://arxiv.org/abs/hep-th/0303185

he developed some checklists and did a parallel comparison
of progress in string approach and in LQG approach
Smolin has published string research papers as well as LQG
so it is from the perspective of someone who's had a hand
in both lines of development.

Your topic question, curious, is "How close are we..."

Smolin's title begins "How far are we..."

he has some progress charts, you might find his perspective interesting

 

[Curious6]

OK, thank you very much marcus, your response has been very helpful!

 

[Tom McCurdy]

Many people have high hopes of the new Particle accelerator CERN finding sparticles (super symmetery) or the graviton at moment of escape-- if they are able to do this this would be huge for string theory-- then there are those who are looking at the sky for evidence of expanded macroscopic strings that were around during the creation of the universe and expanded. However whatever happens it will take at least a few more years miniumum to ahve even a rough final draft.

 

[sol2]

My point on this is that I have just read an article on M. Kaku's website where he states that when a full non-perturbative description of string theory will be made, it will automatically provide evidence for the theory as it can boil down to other simpler theories for which there is already a lot of experimental evidence.

If you include gravity, then this statement would be true.

It's just how you decide to look at it from that "point". Everything "underneath it/planck length" then would make sense. That's just my "point", though. Not the big one, but the small one.


... .. .. ..

 

[arivero]

Your topic question, curious, is "How close are we..."

Smolin's title begins "How far are we..."

Terry Prachett tells that Darwin had got a different appreciation if his book had been titled "the ascent of man" instead of "the descent..."

On topic, my opponion has moved a little during the last year, and I thing that "how close..." is the right estimate, but that perhaps the road is hidden across a hill and we will walk for miles without noticing it. As I see it now, the role of LQG is to provide a sound justification to quotient (not to compactify) towards four dimensions, and the role of string+supergravity is to provide the particle content... Prediction of masses in plain LQG will be impossible, and people will not be happy without it.

 

[Curious6]

If you include gravity, then this statement would be true.

It's just how you decide to look at it from that "point". Everything "underneath it/planck length" then would make sense. That's just my "point", though. Not the big one, but the small one.


... .. .. ..

Doesn't string theory already include gravity naturally? I thought that this was one of the strong features of the theory.

 

[sol2]

Doesn't string theory already include gravity naturally? I thought that this was one of the strong features of the theory.

When we examine how the relative strengths of the strong force and electroweak force behave as we go to higher and higher energies, we find that they become the same at an energy of about 1016 GeV. In addition the gravitational force should become equally important at an energy of about 1019 GeV.

http://www.sukidog.com/jpierre/strings/unify.gif

The goal of string theory is to explain the "?" in the above diagram.

http://www.sukidog.com/jpierre/strings/why.htm

It is very important to understand where this is located and from what perspective gravity is included.

For me, trying to comprehend Quantum gravity is to comprehend how we can quantize those gravity waves and this tells us about the events taking place in high energy considerations.

But I am looking for how this effect, is spoken too, in our current state of affairs. A look at the current universe. Why is gravity such a weak measure at this point?

So most definitely your point is well mark question, and from the layout, it should spark some recognitons for people to understand how this is so. You must understand the energy relation here to particle reductionism.

What relationship would you find to such particle and at what energy levels to discern it specific nature? Each energy determinatin has a resulting effect in what we perceive of gravity, and this is where my comprehension is failing.

Yet at such particle scale and energy considerations, there is a direct comparison to the state of affairs in the epochs of our universe. So looking back to the early universe you are also understanding the evolution of our standard model from a reductionistic point of view, but at this point , Planck length, we find the energy and gravity very extreme.

So I have given the two points of weak measure and high gravitational consideration here as a scale so that we can look at our universe.

By using this method, I can look at the Q<->Q measure and tell that this feature is scalable in relation to the way in which we percieve gravity. A length measure, from the high energy considertaions to the weak field measure of our current universe.

M1 to M2 and we learn to comprehend the metric field in which this measure extends and the dimensional significance of the length measure. This allows one to understand early universe events, and photon coupling in regards gravitational considerations. How would this reflected in this length measure?


http://theory.uwinnipeg.ca/physics/circ/img41.gif

You would have to know something about that gravitational field. This is the first clue to understanding dimensions and the hyperdimensional reality for me.

I tried a way to conceptualize this in my mnd, and what I found is the relationship I saw to displacement in mass measure. This would be like stepping into a bathtub and seeing how high the water rises, we have this indication.

But imagne if you were able to fit inbetween these spaces of water constituents and the water level did not rise ( this statement is support by a perspective that I have long held and have quoted numerous times)?

As absurd as this sounds, I was tryng to find a way around the current measure thinking in regards to fm measure(m1 to m2) currently assumed. This is a failure for consideration, so it must be approached from a different angle and why I thought of displacement.


I am always open for corrections. I did not get this far without them.

 

[arivero]

I am always open for corrections. I did not get this far without them.

Happy to hear it: 10^16 and 10^18 instead of 1016 and 1018 could do a good start

 

[marcus]

Happy to hear it: 10^16 and 10^18 instead of 1016 and 1018 could do a good start

Alejandro at SPS in the list of threads "particle content" is about 20th from the top and the date of the latest post is said to be August 23.
But if one actually goes to the thread, one finds that the latest post was September 3.
the listing threads is supposed to be ordered by latest post
but this feature seems to be broken or inactive.

 

[arivero]

Perhaps I sent the message Aug 23; it is a moderated newsgroup after all

 

[sol2]

Happy to hear it: 10^16 and 10^18 instead of 1016 and 1018 could do a good start

Corrections appreciated and I would have spoken to this. I just assume the validation would have helped in that regard by reference. Tidiness for sure, and if the html language was eadily available or easily translated here I would have made this correction and others with Marcus.

Ex. 10₁₆ 10¹⁸ http://wc0.worldcrossing.com/WebX?14@156.Sv2EcIybEs4.2@.1ddf4a5f/122

Marcus did provide link(another time) and I am assuming he is referencing this, although I have not yet gone looking.

I am constantly translating between this forum and other html friendly sites so this would be one more I would have to add to the library. I haven't seen anybody else use this forum language in their journals like I have.

I will try latex here. 10¹⁶ to 10¹⁸
Guess not.

Arivero and Marcus,

If you are going to reference a site then right click on the "thread"(Particle content) and hit "copy shortcut" Come back here(right click mouse and paste. On a post, the number in the corner and do the same.

It seems to me that the particle content of string theories is not so arbitrary as sometimes we are told.

If I get it well, there are two basic sources of particle content in the theory. On one side, the compactification of the kaluza-klein background should give place to the force fields of the theory. On other side, the vibrational modes of the string should be the matter content. Is it?

Thus from the 10-dimensional restriction of background we should have a total number of 6 gauge fields, should be? This is independent of the background we choose. It is room enough for U(1)xSU(2), but not for QCD gluons. Thus either I am being too naive, or QCD is got from other aspect of strings, or string theory has already been falsyfied and nobody told me.

The matter content comes from the string itself, and it provides us both the elementary fermions and their SUSY partners, does it? Here it does a bit better, as we can expect to see only the fermions for oscillation modes corresponding to the non-compactifyed dimensions. There are 4 of such dimensions (ie usual space-time), and there are 4 different kinds of elementary fermions. So strings could be scoring here. But there is the issue of the scale of the susy partners, and why do we see only the fermions and no one of the corresponding bosons.

I am right in this view? I have never heard any string theoretist arguing that there are four fermions because there are four non-compactified directions for the string, even thought it seems a very positive argument for the theory.

Yours,

Alejandro

https://www.physicsforums.com/showthread.php?t=39870

This would then add credence to what had already been posted and commented on.

If your post is translated over into sci strings, it will have label across the top. If your post is not accepted and accepted here in forum, then it will stand as is. It is heavily monitored as you say and sometimes the delay can be days, or not at all, and the moderators will respond to your email if they feel it is not appropriate for there board.

This time delay sometimes loses the flavour of reaction to posts generated as it will have gone by in the moment and sometimes this may be good. As one reads sometime later adjustment can be made but on google, not so.


So anyway thanks for paying attention to the detail.

 

[marcus]

Perhaps I sent the message Aug 23; it is a moderated newsgroup after all

quite true.
As a comparison, I looked at SPS on google and saw that there the threads were sorted by
date of acceptance of the latest post
so that several threads where you have contributed, like "particle content",
were visible at or near the head of the list.

on google-SPS, whenever a thread grows, it calls attention to the fact.
By contrast, at the PF version of SPS a thread can be growing and yet remain down in 20th place where one rarely looks, thus giving no sign of its activity.

I shall begin checking SPS on google, to get a better idea of what's happening there

 

[sol2]

quite true.
As a comparison, I looked at SPS on google and saw that there the threads were sorted by
date of acceptance of the latest post
so that several threads where you have contributed, like "particle content",
were visible at or near the head of the list.

on google-SPS, whenever a thread grows, it calls attention to the fact.
By contrast, at the PF version of SPS a thread can be growing and yet remain down in 20th place where one rarely looks, thus giving no sign of its activity.

I shall begin checking SPS on google, to get a better idea of what's happening there

You should read my post in regards to time passage and moderated posts. It will make sense then

 

[marcus]

I saw your post about time delay, sol, but couldn't respond till now. Thanks. The picture is getting clearer about that, I think. You also were trying to make superscripts

I will try latex here. 10¹⁶ to 10¹⁸
Guess not..

there are two alternative ways of doing supers
1. with LaTex and the ^ mark
as in 10^18

2. without LaTex and saying [zup] except replace zup by sup
as in 10[zup]18[/zup]
which if you replace zup by sup will be 10¹⁸

If I take your sentence
10¹⁶ to 10¹⁸
and decide on method 2. then I just erase the word "tex" and it is
10[]¹⁶[/] to 10[]¹⁸[/]
and erasing the unneeded [] clutter it is
10¹⁶ to 10¹⁸

 

[marcus]

How close do people on this forum think string theorists are to a full complete non-perturbative description of string theory? ... Also, I am asking this question because I don't really know the current state of research in string/M-theory and if any progress is really being made. Thanks for any answers!

Fraid its partly my fault we got off topic. Does anyone have very uptodate information on string developments?

there was a survey of string research at the American Physical Society conference last week at UC Riverside. APS-DPF ( division of particles and fields)
Peter Woit gave links at Not Even Wrong
http://www.math.columbia.edu/~woit/blog/

I tried downloading the plenary talk on string and it took my computer over 20 minutes because the PDF was full of visuals---colored diagrams and the like. It was "Current Trends in String Theory" by Cliff Johnson of USC.
dated August 31 2004---perhaps a little too upbeat

for balance, one could read the exchange of comment between Serenus Zeitblom and Thomas Larsson in
http://www.math.columbia.edu/~woit/blog/archives/000076.html

 

[sol2]

Well Marcus,

Looking at the ideas that would have been generated in string theory, vaildation indeed has to understood in regards to gravity.

So I wanted to draw your attention this http://wc0.worldcrossing.com/WebX?14@118.DMiCc56HET4.2@.1dde9178/35 I made in 2002. This
http://wc0.worldcrossing.com/WebX?14@119.hRN7cMTgEkl.0@.1ddf4a5f/123

http://www.sciencewatch.com/may-june2001/savas-dimopoulos-big.jpg
Savas Dimopoulos

For all its successes, the standard model is nevertheless unsatisfying. There are 18 or so free parameters, such as the electron mass, that seem arbitrary: they have to be determined experimentally. What is the origin of the masses of the fermions? How can the strong and electroweak interactions be unified? And what of the gravitational force, on which the standard model is silent?

http://www.sciencewatch.com/may-june2001/sw_may-june2001_page3.htm

One has to understand what extra dimensions means, and by showing Sava I am pointing you in this direction. Sometimes one has to consider what one has been doing since two years have past, to get to where they are with the research they had been doing. Has one gained a good foothold on the comprehensions that are easily undertsood by those who have been engaged in this process?

I started this post to show you how important the Q<->Q measure is in relation too?

So I'll finish this post to prepare for others to follow. If you do not follow this history, you will never understand what Nima Arkani-Hamed, Sava Dimopoulos, and Gia Dvali been doing with extra dimensions. There is a conceptual feature here that I have spoken too in regards to gravity that few understand.

I have responsed to Lubos "request" but he likes his crystal palace and to confront him on the question of what Nima likes, he swaggers

When you conisder the extra dimenisons how shall we percieve this?