Theory Definition and 1000 Threads

I came across the following paper by Christian Arnold, Matteo Leo & Baojiu LiRealistic simulations of galaxy formation in ##f(R)## modified gravity https://www.nature.com/articles/s41550-019-0823-y From what I have read on Wikipedia about the chameleon theory, it only left one question: How...

Summary: There is some thing i did not get about Multiple History theory Summary: There is some thing i did not get about Multiple History theory I am reading big answers to the big questions from Stephan Hawking. He has mentioned very little about Multiple History theory. I could not...

There are two related Lemmas in Schaum's Outline of Group Theory, Chapter 4 that seem excessively convoluted. Either I am missing something or they can be made much simpler and clearer. Lemma 4.2: If H is a subgroup of G and {\rm{X}} \subseteq {\rm{H}} then {\rm{H}} \supseteq \left\{...

Have there been any recent developments in the attempt to unify the standard model of quantum theory with General Relativity? It appears the no progress has been made recently in string theory or loop quantum gravity.

[Moderator's note: Spin off from previous thread due to topic change.] Recent experimental confirmation of the quantum trajectory theory: https://www.quantamagazine.org/how-quantum-trajectory-theory-lets-physicists-understand-whats-going-on-during-wave-function-collapse-20190703...

Reading the interesting book "Groups_and_Manifolds__Lectures_for_Physicists_with_Examples_in_Mathematica", in the introduction it is stated: (...) we have, within our contemporary physical paradigm, a rather simple and universal scheme of interpretation of the Fundamental Interactions and of...

I have this theory; gravitation is a result of the right composition and amount of elements, combined with the right temperature with a flux of course. This means there are many possibilities to create gravity, and anti-gravity if switched 180 degrees. Am I far out? what's your thoughts?

Hello! In Griffiths chapter on Time independent perturbation theory, he has a problem (9.20) in which he asks us to calculate the first order contribution to the electron Hamiltonian in an atom if one takes into account the magnetic dipole/electric quadrupole excitations, beside the electric...

Full quantization of gravity is a big issue, but that's not what I'm asking here. I'm asking about quantum effects that involve any form of gravitation (Newtonian or GR) but that don't require a full quantization of GR or anything like that. Things like gravitational neutron interference or the...

I am writing an introduction to a first course in elementary number theory. The topics are linear Diophantine equations, modular arithmetic including FLT and Euler's Generalization, quadratic residues and Non - linear Diophantine equations. How can I write an introduction to this showing linkage...

Hi. Are these two books complementary, or do they have too much in common? https://www.amazon.com/dp/1107034264/?tag=pfamazon01-20 www.amazon.com/Quantum-Field-Theory-Standard-Model/dp/1107034736/ My problem is that I still don't quite understand the difference between university courses in...

Hello, I am an undergraduate who has taken basic linear algebra and ODE. As for physics, I have taken an online edX quantum mechanics course. I am looking at studying some of the necessary math and physics needed for QFT and particle physics. It looks like I need tensors and group theory...

If one considers the kinetic theory of gases, can a first order estimate of thermal transfer be performed by considering momentum exchange at the container's surface? I understand the basics of explaining and calculating pressure with the kinetic theory of gases, but if we assume energy is...

I get new notification from new scientist usually about some virus or some weird anthropology theory. Once in a while a physics subject and this time I got this "https://www.newscientist.com/article/mg24132220-100-schrodingers-kittens-new-thought-experiment-breaks-quantum-theory/" Can somebody...

Hello, I have some questions related to the Penetration Theory proposed by Higbie (1935). I carried out laboratory experiments in a bubble column of 1.3 m filled with water and saturated with oxygen. Air bubbles were rising and the liquid was stagnant (its motion was just due to the rise of...

Hi, I am very new in Graph Theory, and am currently trying to figure out it's potential to solve my research problem. Here it goes: I have a large physical network (10000 nodes, around 14,000 edges), it can be represented by an undirected weighted graph. Many portions of the network might have...

I have a problem about Heisenberg model.When applying mean field approximation,why does the average of spin flip terms be zero(<S+>=<S-> = 0 )? Thanks

Hello, I have two questions into one. First I would like to know what books are considered the best to introduce the theory of quantum dots, so for example with the k.p method, tight-binding, empirical pseudopotentials, and other techniques, analytical derivations, optical properties, band...

Summary: Does the "problem of time in quantum mechanics" go for Lorentz-invariant quantum mechanical theories like QED? Everything I read about "the problem of time in quantum mechanics," i.e. absolute time in QM clashing with relativity's relative time coordinate and relativity of...

Hello everyone, for quite some time I am struggling with the following question: If we consider the action for a single particle in Classical Electrodynamics $$S[x(\tau),A(x)]=\int - m\ ds - \int d^4x\ A_{\mu}(x)j^{\mu}(x) -\frac{1}{4}\int d^4x F^{\mu\nu}(x)F_{\mu\nu}(x) $$ with $$ds=...

My Problem: Given a Graph G = (V,E), where the number of vertices is less than or equal to the number of edges, use induction to prove that the graph contains at least one cycle (the graph is not required to be completely connected). My attempt: For my base case, I used only one vertex with one...

Error correction can be performed on 1010101 after reception, i need to find the right code <br> i know that the polynomial for the received code is $$x^6+x^4+x2+1$$ when i try to find the error pattern,by long division, $$r(x)/g(x)$$ the remainder is $$z^2+z^2+1$$ xor $$z^2+z+1$$ so the...

The fundamental building blocks of the universe is thought of super strings, if proved can solve the mysteries of the universe but if proved than how? And how can it solve the mysteries of dark energy &dark matter and black holes?

Hi All, Considering a set of many many small hard balls which start colliding inside a box. The velocities of these balls being mostly greater than c/2. Is it possible, in this case, to speak of convergence to a thermal state in the same sense of ordinary thermodynamics (i.e., using...

Not sure if this thread belongs in this section. I was thinking who could give a better advice than the teachers themselves? Please do move the thread if it does not belong here. Thank you. I am first year non-physics student. I kind of never had any experience with physics. I have about 3...

Is there any theory in physics that can be modeled in any type of space (Hilbert space, Euclidean, Non-Euclidean...etc)? And if yes, could that theory also contain/be compatible with all types of (physical) symmetries?

Dear All, I am a second year Natural Sciences (the course incorporating the Physics courses) student at the University of Cambridge. I definitely want to specialize in Theoretical Physics next year, but the years spent at University, and the time in the vacations between terms, seems so long...

Are the Hohenberg-Kohn theorems insanely more powerful than the Fermi liquid theory? At first glance it looks like I'm comparing apples to oranges. But here is my reasoning. The Fermi liquid theory describes well the normal state (i.e. non superconductive and other exotic behaviors) of metals...

Goldrei's Propositional and Predicate Calculus states, in page 13: "The countable union of countable sets is countable (...) This result is needed to prove our major result, the completeness theorem in Chapter 5. It depends on a principle called the axiom of choice." In other words: the most...

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Schaum's Outline of Group Theory, Section 3.6e defines {{\rm{L}}_n}\left( {V,F} \right) as the set of all one to one linear transformations of V, the vector space of dimension n over field F. It then says "{{\rm{L}}_n}\left( {V,F} \right) \subseteq {S_V}, clearly". ({S_V} here means the set...

Hi I am sitting with a homework problem which is to show if I can actually integrate a function. with 2D measure of lebesgue. the function is given by ##\frac{x-y}{(x+y)^2} d \lambda^2 (x,y)##. I know that a function ##f## is integrable if ##f \in L^{1}(\mu) \iff \int |f|^{1} d \mu < \infty##...

Has anybody ever heard of this? I learned about it in a discrete math class in grad school, and I've never heard of it anywhere else !? For example, logical disjunction (OR) and set-theoretic UNION are isomorphic in this sense: 0 OR 0 = 0. {0} UNION {0} = {0}. Similarly, logical AND & set...

How does one go about finding a matrix, U, such that U-1D(g)U produces a block diagonal matrix for all g in G? For example, I am trying to figure out how the matrix (7) on page 4 of this document is obtained.

I need to give an option talk about elementary number theory module. I will discuss how it is study of positive integers particularly the primes and give some cryptography applications. What is a good hook to stipulate in this talk regarding an introduction to elementary number theory?

I need to give an option talk about elementary number theory module. I will discuss how it is study of positive integers particularly the primes and give some cryptography applications. What is a good hook to stipulate in this talk regarding an introduction to elementary number theory?

hi, I'm currently taking a classical field theory class (electromagnetism in the language of tensors and actions and etc) and we have just encountered the gauge symmetry, that is for the 4 vector potential we can add a gradient of some smooth function and get the same physics (if we take Aμ →...

There is a statement on page 26 in Elliott Mendelson's book of "Introduction to Mathematical Logic" as shown: What I got from the statement above, which is obvious, I guess, is that in the sequence of \mathcal{B}_1,\mathcal{B}_2,...\mathcal{B}_k there are "SOME" well-formed formulas (wfs)...

I am struggling to answer questions about gasses. In this case the only way i can think of is, it has to do with the change in atmosphere right? because if we think about the formula P/T=P/T as the temperature decreases the pressure should increase. But in this case we have a smaller pressure...

In 1933 Enrico Fermi published a paper on his theory of beta-decay. He describes it as a contact force, which means he didn't think there was a mediator as there was for the electrodynamic forces. Somewhere along the line, there must have been someone who suggested a mediating particle such as...

M-Theory is a theory of membranes which are the fundamental objects of the theory (M2 and M5 branes), however these objects are considered solitons, solutions of supergravity. How can membranes be "fundamental" if they are solitonic solutions of supergravity? Or am I missing something? And is...

Can you help me I don't remember a theory The name was something like Theory ok kamp (Kemp? ) Something like this This theory is about magnetism, more precisely about how two sources shield and influence the field) Do you know the name thank Jacky Thank you

I have been browsing this book, and it seems a quite interesting one. The traditional Statistical Mechanics is quite traditionally treated (so only average) but then, the linking of Statistical Mechanics with QFT, and the exact solutions in Conformal Field Theory, are quite nice. But I do not...

From here: From here: Peres writes on p.11: And on p.58: Note that Peres says that these issues are not yet fully understood! On p.63, Peres writes: On p.424: And on the next page: The footnote quoted by Peres says: And on p.25, where Peres introduces ensembles, he says (like Gibbs...

Hi all, I've been looking at de Broglie-Bohm theory and more recent attempts at Bohm-like models that are relativistic and attempt to reproduce QFT. What I'm not clear on (non-expert) is how the vacuum is modeled in these cases? If we have a set of infinite quantum harmonic oscillators...

What activities can one use in explaining collision theory to secondary level students?

What are some good solid state/condensed matter theory schools in Europe ?

How the repulsion between electrons occurs in String theory and in the loop quantum gravity? The electrons will also create electrostatic fields, or will it be the another mechanism?

I am going through this book, and on page 38, there is LEMMA 3.15 Let K be a subfield of C, f an irreducible polynomial over K, and g, h polynomials over K. If g divides gh, then either f divides h or f divides h. OK, so I have proven that f must divide over g or h - i.e., if f doesn't divide...

Hermann Minkowski (Einsteins math instructor and a mathematical physicist himself): The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth space by itself, and time by itself...