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Papers to prove and disprove string theory/ M Theory? 
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#1
May212, 07:38 AM

P: 4

Hello,
My name is Holly... I'm new here.... so i have no idea weather I put this in the right section! D: ... Sorry if so :3 Basically, I have been put to the task of writing a paper on String Theory and weather or weather not String Theory/ MTheory (i can do either one, will do the easiest one! ) truely can be "The Theory of Everything"/ the ULTIMATE theory. Problem is, in preparing, I have to come up with 4 papers for both proving and disproving this statement. So my question is, where do I look? I've checked Google Scolar. However, I'm finding it hard to find them! So, I am asking everyone here, with the pure kindness of my heart, does anyone know where i can look, or know of any papers that I can access, or any ideas at all, I would be so grateful! However, if that fails, is there any other topic I could easily argue in a paper to do with the Standard Model or similar topics of Physics, where there is a good argument to be had with plently of papers around?? Thankyou to everyone that helps Holly Alice Jess Spencer PS: I realise that I have used the wrong "weather"... I have forgotten the...other spelling! 


#2
May212, 08:00 AM

P: 534

You have to mention what level of review papers you are supposed to do... is this for junior/senior undergrad course or graduate course?



#3
May212, 08:09 AM

Sci Advisor
P: 5,446

Let me ask some questions:



#4
May212, 08:42 AM

P: 5,632

Papers to prove and disprove string theory/ M Theory?
There is a general description of String theory here:
http://en.wikipedia.org/wiki/String_theory with sources and links which may be of use to you. Two fundamental issues I know about: The other issue is that no testable predictions have yet been made by string theory. So given these two problems, no one is quite sure where string theory will lead. You should probably also check out superstring theory and m theory in wikipedia for an overview. None of the three theories have been completed. 


#5
May212, 08:59 AM

P: 5,632



#6
May212, 11:40 AM

Astronomy
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PF Gold
P: 23,227

"Dark matter versus modified gravity". There are plenty of papers arguing for each of the two sides, I can help locate them if you want. The issue is pretty simple. You know what spiral galaxies look like. The stars in them are slowly going around the center. Like very big solar systems where the stars act like planets, and orbit the center of the galaxy. In all or nearly all systems we look at there does not seem to be enough mass to hold the thing together. The stars seem to be orbiting too fast, especially the ones farther out. Using the best methods we have to account for all the visible matter in the galaxy we come up with estimates of mass which are not enough to hold the stars in their orbits, given the speeds they are traveling. This conflicts with our familiar law of gravity. According to the law we know, the pull of gravity gets weaker in proportion to the SQUARE of distance. COULD THIS LAW BE SLIGHTLY WRONG AT VERY GREAT DISTANCES? According to the law we know, if you go out to a planet 3 times the distance, the pull is 9 times less. If you go out 5 times the distance the pull is 25 times less. If that law is exactly right, then the pull out at the edge of galaxies would not be strong enough to keep the stars curving around in orbit. Unless the galaxy is a lot more massive than we reckon from what is visible. So either there has to be a lot of invisible matter that has collected in galaxies, along with visible matter. Or else the familiar law needs to be modified so that way out there where the pull is weak it does not fall off quite as rapidly with distance as our familiar law says. The issue is fairly clear cut and there are people arguing on both sides. The standard cosmology model is called "LambdaCDM" and that depends on assuming roughly 5 times as much dark matter (DM) as there is ordinary. The people on the other side often refer to "MOND" which stands for modified Newtonian dynamics. "dynamics" means the laws of various kinds of motions of things. MOND is a formula by which the pull does not diminish so rapidly with distance, after it gets very weak. You could say it is familiar standard gravity with a little "fudging". But maybe that is not a nice way to put it. The MOND people say that the standard cosmic model LambdaCDM has actually been invalidated because people keep looking for DM and don't find it. And some MOND people have made measurements looking for extra mass in our part of the galaxy and they don't find any sign of extra mass. But that could just be a fluke. Maybe we are in a kind of empty pocket where there does not happen to be much DM extra mass. It is somewhat combative and provocative of them to say LambdaCDM has been invalidated because most cosmologists use the standard cosmic model in all their work. To fit data to and make calculations etc. Nobody likes to hear that the mathematical model they use every day for work has been invalidated. It is a majority versus noisy minority situation. I'll get a few links, just in case you want to keep an alternative issue on the back burner. Look at this guy's papers! http://arxiv.org/find/astroph/1/au:.../0/1/0/all/0/1 If you click on any of those links you get a summary or "abstract" of the paper. That in turn will have a PDF link to see the whole paper, if you like the short "abstract" summary. for example one of Pavel Kroupa's 200 papers is called The dark matter crisis: falsification of the current standard model of cosmology That one just came out last month, in April. It is #4 on the list, which shows the most recent papers first. There is an online video of Kroupa debating Simon White, a prominent cosmologist who adheres to the standard LambdaCDM picture. They are polite, even cordial to each other, but the issues do come out rather clearly. If anyone wants I will get the link to the video. 


#7
May212, 12:15 PM

Astronomy
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PF Gold
P: 23,227

http://arxiv.org/abs/1204.3919 No evidence of dark matter in the solar neighborhood C. Moni Bidin, G. Carraro, R. A. Mendez, R. Smith (Submitted on 17 Apr 2012) We measured the surface mass density of the Galactic disk at the solar position, up to 4 kpc from the plane,by means of the kinematics of ~400 thick disk stars. The results match the expectations for the visible mass only, and no dark matter is detected in the volume under analysis. The current models of dark matter halo are excluded with a significance higher than 5sigma, unless a highly prolate halo is assumed, very atypical in cold dark matter simulations. The resulting lack of dark matter at the solar position challenges the current models. Click where it says "PDF" over on the upper right corner of the page, to see the whole article. However, for a rebuttal, and defense of the standard model, one could look at this blog post by cosmologist Sean Carroll http://blogs.discovermagazine.com/co...04/20/puzzles/ He gives a lot of links in two short paragraphs. That could help find papers citing evidence in support of DM. Holly, if the technical articles (written by scientists for scientists) are too hard you can always get into topics like this at the level of the online science news magazines, and the blogs. Sean Carroll's blog is a good example. Another example is Nature.news. Have a look at this: http://www.nature.com/news/surveyfi...system1.10494 Nature is a respectable outfit and the journalism here is easyread. This might be the kind of article you are looking for. 


#8
May212, 02:39 PM

P: 4

Thankyou very much for your swift replies!
However: Even if this isn't graduate level, this piece needs to be high level, University level if you will: the science needs to perfect and each case argued out. I need a good mark on this piece as it is 30% of the Overall grade. I do apoligise for the way I write, I am dyslexic and find it hard to express myself in words sometimes, although I do reassure you I do love physics and do know what I am talking about, even if occasionally.. I may not be making... sense! I believe I do know what each one is, however, I could be misled ;) I am going for the presumsion that when you say "prove" something you have significant evidence that a law or theory works and when you disprove, you find evidence where you find a... *forgets word*.... scenario or result which goes against what the theory/ law/ idea predicts. For example (Yes I know this was turned out to be wrong due to certain things but is a good example) Neutrinos travelling at the speed of light, if it was repeated many times, by different companies/ scientists and the papers were peer reviewed and they came to a conclusion that yes  Neutrinos travel faster than light then that would be disproving the theory that dictates that they cannot travel faster than the speed of light. However, if say one experiment was to say that they travel faster then the speed of light then that wouldnt be disproving as it is only one group claiming this. As for knowledge on string theory/ M theory, I know the basics, i know the fundamentals but havent gone into details.. yet... If I were to be given a week or so, I could easily pick up quite a lot, I can be like a sponge when I want to be! I would know more on string theory if I generally had the time  I have to take 12 GCSES right now, but after that (in 1 month) i have 12 weeks of pure nothingness *bliss* so I will catch up on reading textbooks in the local field and not to mention Cheltenham Sicence Festival is happening so there are lots of talks on such topics going on! 


#9
May312, 03:09 AM

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P: 4,612

Sakurai, the review
http://xxx.lanl.gov/pdf/hepth/0212114v1.pdf contains arguments both for and against strings, which is something you might need. 


#10
May312, 05:41 PM

P: 5,632

You will not be able to definitively answer whther M theory can be the theory of everything..but you can define the things that must be fixed in the theory before we can find the answer.
If you decide to stay with string theory, consider reading two Chapters in Lee Smolin's THE TROUBLE WITH PHYSICS....THE FIRST SUPERSTRING REVOLUTION AND REVOLUTION NUMBER TWO...The prior chapter PREPARING FOR A REVOLUTION has some useful background explanations about string theory....a used paperback is not expensive... In the first revolution Smolin mentions another problem beyond the the two I already posted: 


#11
May412, 12:14 AM

Sci Advisor
P: 1,685

Not exactly. In both cases, there is a resultant spacetime as an output, and strictly speaking there is no input unless you insert one in for some physical problem (like computing the analogue of a Cauchy problem). In fact, the problem is essentially isomorphic between string theory and GR.
For instance, an uncountable infinity of solutions that the Einstein field equations spits out, are unphysical. It is always the case that you need to input extra physical criteria (picked by hand) to somehow select a physical spacetime. Eg a requirement on the matter content, or some symmetry principle, or a cosmological principle (like homogeneity and isotropy) etc. In some sense, the problem and conceptual challenges with quantum gravity is that it chooses the worst features of both quantum field theory and GR, and keeps them. The nonuniqueness and preponderance of solutions that is part of the baggage of GR, carries over into string theory. The great problem with string theory, unlike GR is that there is no obvious physical criteria that is known that selects out the physical spacetimes in a simple manner. What lacks is the analogue of the symmetry principle or the cosmological principle, such that it selects out the physical part in a clean and efficient manner. We don't even know what we should be looking for really. This actually gets at a rather important point that is often overlooked when laymen discuss QG and what a theory 'ought' to output. So for instance when people say they want GR as a low energy. What they really mean is they want GR as a low energy limit + some extra conditions on the boundary conditions, residual symmetries and matter sectors. A priori, one really wants a TOE to be able to say something about that. So I mean, it would be nice if string theory (or some other theory of QG) could give a general energy condition and restriction on the form of the low energy physics and explain the homogeneity and isotropy of cosmology (or rather, the exact details of the inflaton) 


#12
May412, 12:32 AM

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P: 5,446

Even more pressing is the fact that in a fully developed quantum theory all classical solutions plus perturbations will contribute (e.g. in a path integral). So we expect that all string theory vacua are of some relevance and that one cannot a priory select the relevant one(s) by hand.
If string theory shell exclude certain vacua from physical amplitudes there must be a principle emerging from string theory itself (superselection rules, dynamical supression of tunneling, topological effects, ...) not something put in by hand (look for a vacuum looking similar to MSSM and believe in its relevance). But this is impossible as long as string theory does not provide a unified language for all its sectors. And this is  as usual  my conclusion: string theory as of today is not a coherent, complete theory; it does not even have a small set of defining postulates and equations. 


#13
May412, 01:35 AM

Astronomy
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PF Gold
P: 23,227

http://blogs.discovermagazine.com/co...04/20/puzzles/ and in it he gives three further links to his own blog posts about dark matter. http://blogs.discovermagazine.com/co...04/20/puzzles/ http://blogs.discovermagazine.com/co...tfinethanks/ http://blogs.discovermagazine.com/co...edarkmatter/ Maybe these aren't technical enough (he's a respected cosmologist but its only blog). I will look for some more. Here is an astronomer blogger who in a sense "balances" Sean Carroll because he is moderately sympathetic to the antidarkmatter side. he concludes "dark matter (probably) isn't dead (yet)." http://galileospendulum.org/2012/05/...yinshambles/ He doesn't think cosmology is in shambles (which Pavel Kroupa said) but he gives some weight to the criticisms. He examines some 3 or 4 areas of evidence. I'll try to find some actual technical papers tomorrow. It's midnight (bedtime) here. 


#14
May612, 12:39 AM

P: 1

Holly,
Before you review papers you should become very familiar with String Theory. I recommend reading Brian Greene's latest book "The Hidden Reality Parallel Universes and the Deep Laws of the Cosmos". Has a nice chapter on String Theory, the progress it has made and what he believes still needs to be done. I also recommend Peter Woit's book "Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law". He is probably the most vocal opponent of String Theory and also has a website with discussions on String Theory.  tony 


#15
May612, 04:24 PM

P: 4

[Links Removed]
Yes, I am familiar with String Theory and I do believe I may have read a bit of Greenes book,  the name rings a bell! I shall look into Peter Woits book as well! Thankyou 


#16
May1412, 12:23 PM

P: 4

Thankyou very much! i shall have a gander :D Thankyou, I do recognise the name of that book, I usally read the first chapter of those books on the ol' Kindle for free :3 I shall have a gander again!! I would like to apoligise for this late reply, It seems my last one never got moderated or posted! Holly 


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