String theory and M-theory and Kaluza Klein theories predicts additional extra dimensions(adsbygoogle = window.adsbygoogle || []).push({});

at least 2 recent papers proposed tests these predictions of extra dimensions

String theory phenomenology and quantum many body systems

Sergio Gutiérrez, Abel Camacho, Héctor Hernández

(Submitted on 24 Jul 2017)

The main idea in the present work is the definition of an experimental proposal for the detection of the number of extra{compact dimensions contained as a core feature in String Theory. This goal will be achieved as a consequence of the fact that the density of states of a bosonic gas does depend upon the number and geometry of the involved space{like dimensions. In particular our idea concerns the detection of the discontinuity of the specific heat at the condensation temperature as a function of the number of particles present in the gas. It will be shown that the corresponding function between these two variables defines a segment of a straight line whose slope depends upon the number of extra{compact dimensions. Resorting to some experiments in the detection of the specific heat of a rubidium condensate the feasibility of this proposal using this kind of atom is also analyzed.

Comments: 6 pages

Subjects: General Relativity and Quantum Cosmology (gr-qc)

Cite as: arXiv:1707.07757 [gr-qc]

and

Signatures of extra dimensions in gravitational waves

David Andriot, Gustavo Lucena Gómez

(Submitted on 24 Apr 2017 (v1), last revised 21 Jun 2017 (this version, v2))

Considering gravitational waves propagating on the most general 4+N-dimensional space-time, we investigate the effects due to the N extra dimensions on the four-dimensional waves. All wave equations are derived in general and discussed. On Minkowski4 times an arbitrary Ricci-flat compact manifold, we find: a massless wave with an additional polarization, the breathing mode, and extra waves with high frequencies fixed by Kaluza-Klein masses. We discuss whether these two effects could be observed.

Comments: v1: 21 pages + appendices, comments welcome! v2: few minor additions

Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

DOI: 10.1088/1475-7516/2017/06/048

Cite as: arXiv:1704.07392 [hep-th]

and

Exploring extra dimensions through inflationary tensor modes

Sang Hui Im, Hans Peter Nilles, Andreas Trautner

(Submitted on 12 Jul 2017)

Predictions of inflationary schemes can be influenced by the presence of extra dimensions. This could be of particular relevance for the spectrum of gravitational waves in models where the extra dimensions provide a brane-world solution to the hierarchy problem. Apart from models of large as well as exponentially warped extra dimensions, we analyze the size of tensor modes in the Linear Dilaton scheme recently revived in the discussion of the "clockwork mechanism". The results are model dependent, significantly enhanced tensor modes on one side and a suppression on the other. In some cases we are led to a scheme of "remote inflation", where the expansion is driven by energies at a hidden brane. In all cases where tensor modes are enhanced, the requirement of perturbativity of gravity leads to a stringent upper limit on the allowed Hubble rate during inflation.

Comments: 29 pages, 7 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Cite as: arXiv:1707.03830 [hep-ph]

and

Strong gravitational lensing --- A probe for extra dimensions and Kalb-Ramond field

Sumanta Chakraborty, Soumitra SenGupta

(Submitted on 18 Nov 2016 (v1), last revised 30 Jul 2017 (this version, v2))

Strong field gravitational lensing in the context of both higher spacetime dimensions and in presence of Kalb-Ramond field have been studied. After developing proper analytical tools to analyze the problem we consider gravitational lensing in three distinct black hole spacetimes --- (a) four dimensional black hole in presence of Kalb-Ramond field, (b) brane world black holes with Kalb-Ramond field and finally (c) black hole solution in f(T) gravity. In all the three situations we have depicted the behavior of three observables: the asymptotic position approached by the relativistic images, the angular separation and magnitude difference between the outermost images with others packed inner ones, both numerically and analytically. Difference between these scenarios have also been discussed along with possible observational signatures.

Comments: Revised version; 29 pages; 11 figures; 4 tables; published in JCAP

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Journal reference: JCAP 07(2017)045

DOI: 10.1088/1475-7516/2017/07/045

Cite as: arXiv:1611.06936 [gr-qc]

performing these experiments and finding evidence of extra dimensions would validate string/M-theory.

what if,

what if performing these experiments, and others, rule out extra dimensions. obviously there will be peer review, and perhaps more experiments, other explanations might be proposed.

but what if these 2 experiments, and possibly others, rule out Kaluza Klein theories, string theories/M-theory

what-if

these experiments are only consistent in 3 spatial dimensions and 1 time dimension and rule out any additional real dimensions

how would this affect the credibility of string/M-theory?

in light of previous discussion

and mitchell porter said: ↑The problem with those methods of quantization is not just that they are "nonstandard", the problem is that they don't connect with reality in any way! These authors may start classically with known field theories, but when they construct the quantum theory, they do it differently; and the way they do it does not reproduceanythingfrom known physics, not even qualitatively. String theory may usually predict a lot of things we aren't seeing, and a lot of quantities we would like to test remain impossible to calculate; but at least it exhibits qualitative continuity with established physics. All the new phenomena that came with the revival of quantum field theory in the era of the standard model, like anomalies, instantons, you name it, have their counterparts in string theory. On the gravity side, string theory has a classical limit, and it also reproduces theoretical phenomena of semiclassical gravity.

Loop quantum gravity, on the other hand, seems to provide a recipe where you start with a set of fields that includes general relativity, then you follow their special quantization procedure, and you end up with various equations that the resulting wavefunctions have to satisfy, and maybe you can prove one or two things. But these results are entirely abstract and algebraic, and do not give you back anything like quantum fields in space-time, despite the starting point. So this recipe can certainly produce research papers, but the resulting papers are radically disconnected from ordinary quantum field theory, from classical gravity - and from string theory.

Once I concluded that the divide is really that great, I became perplexed by the size and persistence of the loop quantum gravity literature. I can see one person, or a handful of people, stubbornly persevering in a research program that disdains lots of established physics, due to an idiosyncratic investment in particular ideas. But loop quantum gravity is dozens of people over decades. I was especially troubled by the lack of historical precedent for this.

But I'm happier now because I did find a historical analogy: algebraic quantum field theory. It's not an exact analogy, but it is another example of a research community developing over decades a mathematical formalism which is largely disconnected from what physicists were actually doing. Algebraic quantum field theory starts with a few ideas drawn from real physics, but describes either fields that don't interact, or a few special interacting field theories in lower dimensions. Meanwhile, real physicists were using effective field theory, the renormalization group, and the lattice. Similarly, loop quantum gravity started with some real things, but its subsequent development has diverged from everything in gauge theory and quantum gravity that actually works.

Returning to the idea that some sort of standard but nonperturbative canonical quantization of supergravity might help with the formulation of M-theory, well, it might help just because it would be in that same mainstream of quantization methods, and would therefore actually be relevant to M-theory. But I think that at best it would still only give you a new perspective on what's missing in supergravity. In the end you should find that you need new heavy states, the branes. The best guide might be AdS/CFT in the case of AdS4/CFT3 and AdS7/CFT6, where known CFTs are believed to be entirely equivalent to M-theory in the dual AdS spaces.

what becomes of string M-theory and Urs Schreiber and mitchell porter observations and objections if on experimental grounds, using experiments and observation, extra dimensions are completely ruled out, and that experiments are only consistent with 3+1 dimensions? Urs Schreiber said: ↑There is a whole list of reasons why this is overly naive.

First, the idea that a choice of coordinates on phase space (e.g. Ashtekar variables) should affect the outcome of quantization is in contradiction with basic facts of physics. On the contrary, everything ought to be independent of artificial choices of parameterizing phase space, even if maybe one choice of coordinates may make some aspects more transparent than others. But if you find yourself with a would-be quantization that only works in one set of "variables" but not in another, then something went wrong.

Second, gravity is not fundamentally a gauge theory as Yang-Mills theory is, even if you write it in first-order language in terms of a vielbein and a spin connection. The spin connection is an auxiliary field that serves to implement the torsion freeness constraint, but the genuine field of gravity is encoded in the vielbein. Mathematically the statement is that a field configuration of gravity is equivalently encoded in a variant of an affine connection, yes, but the full structure is that of a Cartan connection This is a plain affine connection plus extra data and constraints. Glossing over this point is the source of much confusion in the literature.

....

what would be the most promising approach to quantum gravity 3+1 dimensions should experiment and observation rule out Kaluza Klein dimensions if it's not loop quantum gravity?

bonus - what would be the most promising approach to quantum gravity 3+1 dimensions should experiment and observation rule out Kaluza Klein dimensions and supersymmetry if it's not loop quantum gravity?

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# I Testing string/m-theory extra dimensions prediction

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