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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6answers
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If string theory is inconsistent with observations, why hasn't it been rejected yet?

I'm no expert on string theory, but I've been reading about it. I've been quite surprised because of how it appears to be inconsistent with observations, but hasn't been rejected yet. Examples: On the ...
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2answers
3k views

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 ...
11
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1answer
391 views

Do all $\mathcal{N}=2$ Gauge Theories “Descend” from String Theory?

I'm thinking about the beautiful story of "geometrical engineering" by Vafa, Hollowood, Iqbal (https://arxiv.org/abs/hep-th/0310272) where various types of $\mathcal{N}=2$ SYM gauge theories on $\...
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2answers
2k views

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 ...
8
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1answer
428 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 ...
8
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1answer
248 views

How do we know the laws of physics remain the same in different dimensions?

Section on Wikipedia dealing with the possibility of different dimensions. When reading this section it feels like there's a giant elephant in the room that is not addressed. For example, here's a ...
8
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0answers
179 views

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\...
7
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2answers
8k views

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 ...
7
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2answers
849 views

What is the current status of the swampland?

What is the current status of the swampland? Have people expanded the list of swampland criteria? If let's say I wish to figure out if the Standard Model belongs to the swampland, are there any ...
7
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2answers
219 views

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 ...
7
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0answers
485 views

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 ...
7
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2answers
221 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 ...
6
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2answers
402 views

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
6
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1answer
192 views

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 ...
6
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1answer
196 views

How's string theory phenomenology doing these days (2021)?

I've seen one paper that says finding string theory vacua with particular low-energy properties is totally intractable, from a computational complexity standpoint. I've also seen people saying that ...
6
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1answer
134 views

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 ...
6
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0answers
141 views

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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0answers
252 views

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, ...
4
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1answer
149 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 ...
3
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2answers
843 views

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, ...
3
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1answer
148 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 ...
3
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1answer
954 views

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 ...
3
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1answer
461 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
137 views

Alternatives to the String Landscape?

Many people criticize string theory for being very speculative and far fetched (since it requires extra dimensions). Nevertheless, the string landscape is often invoked to have many variations of ...
3
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1answer
137 views

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^{...
3
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1answer
343 views

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 $1$...
3
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0answers
64 views

Tadpole cancellation condition for $C_4$ in Type IIB Supergravity theory

In the following I use Polchinski's notation. Type IIB Supergravity action (with non-vanishing fluxes & $\rm{D3}$-branes) contains \begin{align} S_{\mathrm{IIB}} &= S_{\mathrm{NS}} + S_{\...
3
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0answers
101 views

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 ...
3
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0answers
87 views

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 ...
2
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2answers
480 views

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 ...
2
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2answers
320 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 ...
2
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1answer
250 views

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 ...
2
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2answers
90 views

How many different vacuums are there in the string theory landscape? [closed]

Different sources give different estimates, from $10 ^{100}$, $10 ^{500}$, $10 ^ {20,000}$, while others write that there are infinitely many of them.
2
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1answer
102 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?
2
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1answer
258 views

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 ...
2
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0answers
58 views

Why does the perturbative ($\mathcal{N}$=8, d=4) supergravity and type IIB closed string compactified on $T^{6}$ spectrums coincide?

The observation is that the perturbative spectrum of $\mathcal{N}$=8 supergravity in four dimensions is exactly the same as the type IIB closed superstring spectrum after dimensional reduction on $T^{...
2
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0answers
91 views

Absence of topological phases in quantum gravity and the BFSS matrix model of $M$-theory

McNamara and Vafa have recently conjectured in their paper Cobordism Classes and the Swampland that any vacua in string theory can be reached from any other one (possibly by a process that require an ...
2
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0answers
436 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 ...
2
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1answer
366 views

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 ...
1
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1answer
78 views

String Landscape, De Sitter vacua and Broken Supersymmetry

If we assume that the swampland conjectures, etc. regarding de sitter vacuas existence in the string / F-theory landscape turn out to be incorrect (and therefore we can assume the problem is well-...
1
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1answer
75 views

Black holes are excellent scramblers, but can they scramble points in the string-theory landscape?

Consider the usual derivation of Hawking radiation, using quantum field theory (QFT) in the spacetime of a collapsing star. At late times, long after the event horizon has formed, Hawking radiation is ...
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1answer
75 views

Swampland and Weak Gravity Conjecture (WGC)

I think I've understood the general idea of the WGC (proposed in https://arxiv.org/abs/hep-th/0601001). From a more recent review, I quote: In a consistent effective field theory (EFT) coupled to ...
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1answer
60 views

String Landscape and Extremal / SUSY Black Holes

I should preface this question that I am new to understanding the string landscape and swampland program and F-theory, so I apologize if my question is obvious / unclear! Recently I was reading some ...
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1answer
62 views

Does the string theory landscape apply to M-theory?

I had read about "string theory" having a large number of solutions (~$10^{500}$). Does this apply to the 11 dimensional M-theory or only to it's five 10-dimensional limiting cases?
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1answer
147 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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0answers
21 views

How many fields are there in most flux compactifications?

Quoting from this paper: At first sight, the most striking thing about these compactifications is how many fields they have compared to the Standard Model. While the particle physicists of the 1930s ...
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1answer
111 views

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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0answers
57 views

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 ...
0
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1answer
849 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 ...
0
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1answer
53 views

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?