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Questions tagged [string-theory-landscape]

This tag applies to questions which deal with investigations of the string-theory landscape (defined as the space of solutions to the dynamical equations of string-theory) by physical, mathematical, or statistical methods.

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Questions about the landscape in string theory

If I understand correctly, the string theory landscape is the totality of possible Calabi-Yau manifolds to make up the compact factor of space in string theory, in which there are of the order of $10^{...
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1answer
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Have string theory and brane cosmology the same landscape?

Has any of these hypothetical theories a "higher" number of possible universes or has string theory landscape the same type of possible universes than brane cosmology?
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Strings 2018 takeaways [closed]

What are the main takeaways from the Strings 2018 conference? What are the main announcements, discoveries or directions emerging from this event? To my knowledge, one is the result by Vafa and ...
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1answer
103 views

Pick a specific solution of string theory?

This is a conceptual question. One popular criticism against String Theory is its high number of solutions, around $ 10^{500} $. Is it true that each solution is corresponding to a specific possible ...
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1answer
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Light branes and swampland/landscape

Following a talk by Cumrum Vafa, I understood that light branes are important as he quoted the formula: $$m\sim \exp(-\alpha M/M_P)$$ and then, he stated that light massive particles AND extended ...
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1answer
551 views

Can AI solve the string theory landscape problem? [closed]

According to current ideas about String Theory, is that the standard model is but one vacuum in millions of the theory. It strikes me that to find the correct vacuum and search through all the ...
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1answer
109 views

Are the possible universes in brane cosmology embedded in string theory landscape?

String theory has a landscape of possible universes. Brane cosmology is related to string theory because it needs extra dimensions, but are the possible different universes of brane cosmology ...
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Specific coupling constants, fermions and string theory

Can string theory answer why the Yukawa couplings or the v.e.v.s.have the values they have in our Universe? I mean, why can string theory answer( and EXPLAIN) the question of why the top coupling to ...
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Why do people say that the string length is on the order of the Planck length?

As I understand it, string theory has only one fundamental dimensionful quantity - the string tension $T = 1/2 \pi \alpha'$, where $\alpha'$ is the Regge slope (in units where $c$ and $\hbar$ equal $1$...
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1answer
118 views

Definitive form of M/String theory and AdS/CFT role

What is the principal/more actual strategy in order to find the definitive form of M/String theory? I mean, you have a (for example) $10^{500}$ string theory possibilities landscape (given by the ...
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1answer
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Variations in which feature(s) of string theory give rise to so many possible Universes?

The string theory landscape comprises $10^{500}$ (give or take some) different Universes. What feature(s) of string theory you have to vary to "go" from one Universe to the next?
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How many string theories are there?

In Zwiebach's book, in the first chapter it was written, "The lack of adjustable dimensionless parameters is a sign of uniqueness of string theory: it means that the theory cannot be deformed or ...
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1answer
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Would a rational Bayesian agent reject String Theory as a model for particle physics?

One thing people often criticise about String Theory as a model for particle physics 1 is that it has a lot of parameters (infinitely many?), i.e. there is not just one vacuum, there is a whole ...
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Why is energy minimized over the string landscape?

As understand it, the 4D string landscape is a function that assigns an energy to every possible compactification of the 6 small spatial dimensions. We expect our universe to lie in a local energy ...
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205 views

What laws are the same in all string theory compactifications?

In the string theory landscape, the set of particles we observe, their masses and interaction strengths originate from one of many different possible compactifications. What fundamental physical ...
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Are the fundamental constants of nature independent?

Background: I am a layman and I just watched the video "Infinite Worlds: A Journey through Parallel Universes" (http://www.youtube.com/watch?v=OO4uzgiRHkE) featuring a discussion with Andrei Linde, ...
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1answer
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Brane polarisation (Myers Effect/Polchinski-Strassler/KPV)

I have a question about brane polarisation. In the most famous cases I know of--the original giant D2 brane of Myers, the Polchinski-Strassler resolution of the $\mathcal{N}=1^*$ IR singularity, and ...
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String Theory Landscape [duplicate]

I have seen multiple times that physicists used a formula to find the number of vacua in string theory, What formula was used to calculate the number of vacua in string theory? How did they arrive at ...
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What experiment would prove string theory?

The conceptual model of multidimensional vibrating strings provides an incredibly rich and diverse "language" that almost certainly is encompassing all of known physics as a singular point somewhere ...
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2answers
297 views

How “unnatural” is the universe? [closed]

Looking to read up on the impact the discovery of Higgs boson has on the String Theory I came upon these two paragraphs in an article about the Higgs boson Nobel Prize: One possibility has been ...
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1answer
96 views

Do all vacua in the string theory landscape have a different cosmological constant?

Or can two vacua with the same energy differ in other ways?
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417 views

BICEP2 and string theory

Can anybody elaborate on the implications of the BICEP2 result for string theory? The discussion here What experiment would disprove string theory? suggests that refuting string theory is rather ...
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1answer
123 views

Theoretical String Landscape Question

Could it be plausible that the same theoretical string "shape" occurs twice. As in two or more universes with the same amount of dark energy and string shape. The term "shape" I'm defining as based ...
7
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1answer
362 views

Determining the Hodge numbers of some orbifold examples

I'm currently reading about complex geometry in order to get a feeling of how to determine the Hodge numbers, e.g. of certain orbifold constructions. Since I'm a physicist with no deeper mathematical ...
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Moduli Stabilization in 6D Einstein-Maxwell theory - Fluxes and O3 planes

I'd like to do the maths for the moduli stabilization of 6D Einstein-Maxwell Gravity $$ S= \int d^6X \sqrt{-G_6}(M_6^4R_6[G_6]-M_6^2|F_2|^2), $$ where the 6D metric is specified by $$ ds^2 = g_{\mu\...
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2answers
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How does the full string theory potential look?

Is the full stringy potenetial (for which it is claimed to be 10^500 vacua) written down explicitly somewhere? Any references? Thanks, Dave
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Extra dimensions and the big bang [duplicate]

If there were extra compact dimensions,and at the big bang all dimensions were compact,my question is why the big bang failed to expand those presumed extra dimensions like it did with the 3 spatial ...
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Why does string theory have such a huge landscape?

I was browsing through Foundations of Space and Time, a compilation of essays on various theories of quantum gravity. The following passage in the introduction intrigued me: Each compactification ...
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Poincare recurrence and the multiverse

In this paper Susskind claims that a stable de Sitter universe is problematic (among other things) due to the existence of Poincare recurrence, which happen because of finite entropy. I disagree that ...
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1answer
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String theory and the SM spectrum [closed]

Long ago, I realized this: (super)string theory can NOT give a well-defined/unique prediction of why the electron (muon, tau) or the neutrino (any flavor) masses have the masses we measure. String ...
3
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1answer
417 views

What precisely, is the string theory landscape in 10 dimensions?

I was reading this Physics.SE thread. The OP said, (changed the last word to type HO) For D = 10, there are 5 vacua. Or maybe it's more correct to say 4, since type I is S-dual to type ...
3
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1answer
147 views

G(2) lattice and the M-theory landscape

In a previous question (Calabi-Yau manifolds and compactification of extra dimensions in M-theory), I was told that the $G(2)$ lattice can be used to compactify the extra 7 dimensions of M-theory and ...
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2answers
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How can string theory work without supersymmetry?

This question is inspired from reading Mitchell Porter's nice answer here to a question asking why supersymmetry should be expected naturally. Among other things, he explains that since weak scale ...
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2answers
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Are the $10^{500}$ different string theories being whittled down?

An example of a test: Ask each variant whether its estimate of the electron mass lies within $\pm\,x\%$ of the known value. This surely can't take long per theory. Although $10^{500}$ is huge, ...
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Does the ensemble of effective Lagrangians in the String theory landscape mostly include gauge theories?

String theory false vacua can be described by effective Lagrangians at low energy. Is there generally a correspondence between these effective Lagrangians and SU(N) gauge theories? Or do the effective ...
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How seriously do string theorists take the “landscape”

The string theory landscape seems to this outside observer to be an intermediate step in the intellectual progress toward a more robust theory that explains why our one universe has the particular ...
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1answer
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Why doesn't the anthropic principle select for N=2 SUSY compactifications with an exactly zero cosmological constant?

The party line of the anthropic camp goes something like this. There are at least $10^{500}$ flux compactifications breaking SUSY out there with all sorts of values for the cosmological constant. Life ...
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Does a complete theory of quantum gravity require anthropic post-selection?

Does a complete theory of quantum gravity require anthropic post-selection? Certainly the black hole complimentarity and causal patch conjectures highlights the essential role of observers, at least ...
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String landscape in different dimensions

For D = 11 large (uncompactified) spacetime dimensions, the only "string theory" vacuum is M-theory For D = 10, there are 5 vacua. Or maybe it's more correct to say 4, since type I is S-dual to $Spin(...
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1answer
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Interplay between the cosmological constant and “microscopic” properties of string vacua

As far as I understand, string phenomenology is usually concerned with compactifications of string theory, M-theory or F-theory in which the uncompactified dimensions form a 4-dimensional Minkowski ...
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Are there stable string theory vacua with non-minimal cosmological constant?

Naive reasoning suggests that a string theory vacuum with cosmological constant Lambda1 is always unstable as long as there is a string theory vacuum with cosmological constant Lambda2 < Lambda1 ...