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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Why can't we search string vacua by computer?

I am imagining this: A database of Calabi-Yau manifolds. More can be added when more are found. The software picks a random CY manifold, assigns random fluxes etc. It looks at the low energy sector ...
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Do all string theory vaccua have the same vacuum energy?

Of the $10^{500}$ or so vaccua in string theory. Do they all have the same energy? i.e. are the vaccua degenerate? Or do they have different energies? (If this is even possible.) It is said that the ...
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From where does the fact that there are $10^{500}$ possible compactifications in string theory? [duplicate]

I have heard for quite a few times that there are $10^{500}$ possible compactifications in string theory. And in one of his lectures, physicist Leaonard Susskind explains that, this comes from the ...
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What experiments could be done *in principle* to help down-select between different versions of string theory?

I understand that string theory (broadly defined) is a solution to quantum gravity. That is, it is a unified theory the explains both quantum phenomena (such as the particles of the standard model ...
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Is there an analogue of string landscape in condensed matter physics?

Possibly not every quantum field theory can be viewed as an effective theory of string theory, and possible effective theories are called the landscape. It's natural to guess that something similar ...
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Branes with any number $n$ of dimensions and their relation to the laws of physics?

I had a few questions about this paper by Nima Arkani-Hamed, Georgi Dvali and Savas Dimopoulos (https://arxiv.org/abs/hep-th/9907209) which is closely related to the concept of branes (https://en....
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How many different vacua really are there in the string theory landscape?

How many different vacua are there in the string theory landscape? Different sources give different estimates: some sources talk about the number $10^{500}$, others $10^{272\ 000}$, still others say ...
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4 votes
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Are orbifolded 10d E8 GUTs valid low-energy EQFTs of string theory? Or swampland?

AdAMP recently proposed a string-reminiscent E8 GUT (digest, full) where 6 extra dimensions are compactified on a $\mathbb T^6/(\mathbb Z_3\times\mathbb Z_3)$ orbifold to yield the 4d Standard Model. ...
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2 votes
3 answers
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Why do string theorists seem to ignore cosmology?

Related and sort of a follow-up question to: If string theory is inconsistent with observations, why hasn't it been rejected yet? From the answer to that question, string theorists are aware the ...
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Realistic String Theories without Supersymmetry

In a podcast with Cumrun Vafa (https://www.youtube.com/watch?v=yppqz12ngbM&t=654s with the relevant part from 35:30 to 35:50), Vafa mentioned that there exists string theories that can describe ...
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Definition of Multiverse

From the viewpoint of physics, what is the difference between Multiverse, understood as an infinite number of island Universes (bubbles), possibly with different values of fundamental constants/...
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How Strings move from 1 CY manifold to another?

M-theory says that there's a Calabi-Yau manifold, representing $n = 7$ extra spatial dimensions (here simplified to $n = 3$; check out animated video) curled up and compactified inside every 3D Planck ...
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Have any "toy models" of detecting string theory in other universes been identified?

Someone could publish a paper tomorrow saying, "This choice of Calabi-Yau manifold recovers the physics of the observed universe, and implies this feasible way to detect how the universe's string-...
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Does multiverse theory obviate the need for fine tuning?

I recently read the book by Max Tegmark, The mathematical Universe, where he expounds upon the multiverse and how if ANYTHING can happen, will happen, because of all the ways things can be arranged. I ...
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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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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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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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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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34 votes
6 answers
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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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3 votes
2 answers
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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 ...
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1 vote
1 answer
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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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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^{...
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2 votes
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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 ...
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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 ...
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4 votes
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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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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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-1 votes
1 answer
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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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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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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 ...
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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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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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3 votes
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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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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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3 votes
0 answers
104 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 ...
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4 votes
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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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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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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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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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0 votes
0 answers
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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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5 votes
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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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13 votes
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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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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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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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4 votes
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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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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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7 votes
2 answers
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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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7 votes
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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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5 votes
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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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2 votes
1 answer
254 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 ...
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1 vote
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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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