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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6
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1answer
165 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 ...
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2answers
85 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.
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1answer
65 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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6answers
9k views

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 ...
3
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1answer
134 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 ...
1
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1answer
70 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 ...
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
89 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 ...
0
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1answer
88 views

Swampland conjectures and $f(R)$ gravity

Why the swampland conjectures should be satisfied even in backgrounds with the $f(R)$ gravitational model, if the gradient energy (or the kinetic term of the scalar fields) are negligible for the ...
3
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0answers
61 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_{\...
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1answer
75 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-...
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1answer
70 views

In the string theory multiverse, is every universe fated to collapse in a Big Crunch?

This is what I understand of the multiverse of the string landscape: the "laws of physics" reside in a 100-dimensional string landscape, which has ~$10^{500}$ minima. Each of the minima corresponds 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 ...
8
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1answer
238 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 ...
0
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1answer
87 views

If there exists a universe with other than 3+1 dimensions, could we quantum tunnel to it?

Section of Wikipedia article on the possibility of universes with space & time dimensions other than 3 and 1 respectively. If one of these other universes exist, could we in principle quantum ...
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1answer
60 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?
3
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1answer
136 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^{...
1
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1answer
110 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?
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 ...
4
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1answer
148 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 ...
-1
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1answer
107 views

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 ...
0
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1answer
842 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
163 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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0answers
86 views

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 ...
3
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1answer
329 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 $1$...
11
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1answer
389 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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1answer
145 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 ...
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?
3
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1answer
935 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 ...
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1answer
214 views

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 ...
7
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2answers
217 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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2answers
217 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 ...
5
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0answers
251 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, ...
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 ...
1
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0answers
56 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 ...
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 ...
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
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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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 ...
0
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1answer
126 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 ...
8
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1answer
425 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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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\...
6
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2answers
400 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
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0answers
61 views

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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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 ...
7
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0answers
480 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 ...
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1answer
567 views

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
456 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
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 ...
12
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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 ...