Theory Definition and 1000 Threads

Hello, I am new to this. As I understand it, the difference between the quantum field theory and string theory is that in the former, physical field is considered as the fundamental reality, while in the latter it is believed that everything comes out of strings. My question is, by everything do...

There seems to be a lot of conflicting research on nuclear winter theory, especially since the 1990s. Carl Sagan famously predicted that the Kuwaiti oil well fires from Operation Desert Storm would result in a small global winter, but the effects turned out to be more localized and less severe...

Hello! I read some stuff about "attempts" to test some aspects of string theory at LHC and I was wondering if there is any deep reason behind the conservation of energy in general or it is just based on the fact that it holds in all the experiments (excluding uncertainty principle arguments)...

This question is directed to all the professors who have supervised PhD students in high energy theoretical physics. What attributes have you noticed (during your years as a supervisor) among PhD students who later went on to have great careers in high energy theoretical physics and made a name...

Homework Statement STATEMENT ##\hat{H}=\int \frac{d^3k}{(2\pi)^2}w_k(\hat{a^+(k)}\hat{a(k)} + \hat{b^{+}(k)}\hat{b(k)})## where ##w_k=\sqrt{{k}.{k}+m^2}## The only non vanishing commutation relations of the creation and annihilation operators are: ## [\alpha(k),\alpha^{+}(p)] =(2\pi)^3...

Hi everyone, So I recently read a chapter in a math book that vaguely describe how connections on bundles occur in particle physics, but they are very cryptic about the physics part and I just want to know a little bit more about it. So I'll tell you what I read and then follow up with some...

Homework Statement hello, I have this graph and i have to figure out these so to speak characteristics. 1) find incidence matrix 2) arrange peak according to rank and layers 3)draw new arranged graph 4) find new connection matricies of peaks and arcs Homework EquationsThe Attempt at a...

so this is the question: let a and b be real numbers such that 0<a<b. Suppose that a3 = 3a -1 and b3 = 3b -1. Find the value of b2 -a. initially my line of thinking was that just solve the equation x3 - 3x +1 = 0 and take the roots which are more than 0 and then after that i got stuck ok that...

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Firstly an apology...I don't know what level my question should be aimed at and what forum it should be set in and I think that level A and Quantum Physics are as good as guesses as any. Moderator please moderate if necessary. It's about constructor theory, something that I wouldn't normally...

Let us consider a classical field theory with gauge fields ##A_{\mu}^{a}## and a scalar ##\phi^{a}## such that the Lagrangian is gauge-invariant under the transformation of 1. the gauge fields ##A_{\mu}^{a}## in the adjoint representation, with dimension ##D_{\bf R}##, of the gauge group...

Hi all, I am struggling the question, please see attachments. Thanks a lot Devise an algorithm which, given a (directed) friendship graph (in the xkcd format), finds the optimal seating arrangement. Your algorithm should include the following:  a description of the required input format...

Hello! I read several books and took courses on quantum mechanics and particle physics and I understood the topics. However I feel that I have only pieces of informations without a global image of what is going on. For example in the particle physics classes we were given Feynman rules without...

Hello people, I'm really interested in non-mainstream physics but so far i can't find a place./forum where i can discuss or share theories. I've tried doing it in the Quantum Physics section, but my thread was rejected because personal theory developments are not allowed here. So far it's ok...

Is it possible to associate electric and magnetic fields with the vibrating string that is thought to represent a photon in string theory? Thanks!

Homework Statement The problem consists of 2 parts,the first one(I have done it) is on the following website: https://www.physicsforums.com/threads/transition-probability-from-two-states.804343/ Q1: I calculated the desired result p(t) = sin^2(Ut/h). However,I don't understand why <1,t | 2 >...

What happened to the membrane bound organelles that were present in the eukaryote that gulped the primary endosymbiont (that is, the eukaryote that gulped a prokaryote), after the secondary endosymbiosis.

The textbook proves that ##x^a x^b = x^{a+b}## by an induction argument on b. However, is an induction argument really necessary here? Can't we just look at the LHS and note that there are a ##a## x's multiplied by ##b## x's, so there must be ##a+b## x's?

In classical field theory, translational (in space and time) symmetry leads the derivation of the energy-momentum tensor using Noether's theorem. From this it is possible to derive four conserved charges. The first turns out to be the Hamiltonian, and thus we have energy conservation. The...

Hi everybody, I have a question: is an abelian group can be isomorphic to a non-abelian group? Thank you everybody.

I have been attempting to unravel Abbe’s theory, of the role of diffraction in microscopic vision, in a ‘nuts and bolts’ sort of way, meaning in terms that I can understand: diffraction, interference and so on. While Fourier transforms are clearly at the heart of the process the assertion that...

Instead of the 10,11, and 26 dimensions proposed by various theories, could there be, let's say 10 positive dimensions, existing of 9 of space and one of time, but also 1 negative dimension? This is just a random theory. I have no idea what a negative dimension would hold, but I think it would...

Good afternoon people; recently I decided to give a study break from control engineering; now I'm back. I'm studying again control theory and I see some good results. By the way I got stuck in a topic called root locus method. Now my issue is not about how to sketch the root loci graph (BTW I...

Lightcone gauge is ##X^u=\tau=1/\sqrt{2}(X^0+X^{D-1})## (1) The mode expansions are: My book says 'it is possible to solve for one of the oscillators in terms of all the others' with this relation. What is a oscillator? Is this any of the ##X^{D}## coordinates, what exactly does ##n##...

Are there anything new in String theory?

In mechanical engineering we have various courses in strenght of materials, and I've noticed that graduate students learn the Theory of Elasticity. I've researched a little bit about it, and I know that the Theory of Elasticity is more general than strenght of materials. But I have some doubts...

The question is about to derive an approximate expression by regular solution theory, It is difficult for me to find relevant source on this question. However, the question to me is so vague that I do not know how to answer. What I have tried is to search what the interaction parameter is...

So I did this lab on momentum on jets and the theory is that "a force is applied on the plate due to change of momentum" the jet both impacted on a flat plate and on a hemispherical plate; now i understand that the greater the angle of deflection of the water jet, the greater the change of...

Hi all, I have an offer to do an MSc in QFFF at Imperial or an MSc in Mathematical Physics at Edinburgh, or (with luck) an MSc in Theoretical Physics at Kings College London (KCL). Technically, QFFF is the best (i.e most reputable) course - but I have heard very bad things about how it's...

Homework Statement Hi, In some of the diode analysis examples that we did in class, we often end up with circuits like the ones shown here. I'm quite confused because sometimes I understand them and other times I just don't know how these voltages are coming from. It really makes me question...

Homework Statement [/B] Use Max Planck's quantum theory to explain the following behavior of photoelectrons. i) Low-intensity light does not release any photoelectrons. What will happen if the light is made brighter? Explain your reasoning. ii) Low-intensity light releases photoelectrons...

I have an acquaintance who maintains that in quantum field theory, primarily the cgs system is used. OK, I know it's not really important, but I was under the impression that everyone had switched to SI. (My book on quantum field theory has very few actual quantities with units outside of GeV...

I am looking for an accessible textbook in group theory. The idea here is to use it to learn basic group theory in order to take up Galois Theory. My background includes Calculus I-IV, P/Differential Equations, Discrete Mathematics including some graph theory, Linear algebra, and am currently...

The thread https://www.physicsforums.com/threads/qft-operators-time-space-asymmetry.906369/ contains the first recommendation I have seen in these forums for Klauber's book, and instead of hijacking that thread I thought I might ask a question here. I find the book more readable than many for...

Homework Statement A cylinder containing an ideal gas is in vertical position and has a piston of mass ##M## that is able to move up or down without friction (Fig. 13.2). If the temperature is increases, ...Fig (13.2) (a) both ##p## and ##V## of the gas will change. (b) only ##p## will...

Here's an interesting article from Quanta magazine: https://www.quantamagazine.org/20170223-bootstrap-geometry-theory-space/ and some backstory: https://en.wikipedia.org/wiki/Bootstrap_model

Hey everyone, So I'm writing the script for a Youtube show I'm making, and it's pretty heavy on the science/physics side in terms of exposition. So before i jump into what i want to ask let me just briefly explain the story. A Time traveler and his time traveling machine go back 30 years in...

The Special Theory of Relativity is based on the observations of an outside observer on a system traveling at the speed of light. There is no single point of reference to determine speed. So speed is determined relative to another object. This being the case an Apple traveling at the speed of...

Find a function g from {0,1} to B\A such that f^-1(g(x)) = x +2 for x∈{0,1}. Present it in the 2-row form. A = {{1},2,3} and B = {∅,1,{2},3} I know that B\A = {∅,1,{2}} and f is a bijection from A to B\A how do I find such function g? It obviously can't be bijection, how do I match one value to...

Let's talk about the function ##f(x)=x^n##. It's derivative of ##k^{th}## order can be expressed by the formula: $$\frac{d^k}{dx^k}=\frac{n!}{(n-k)!}x^{n-k}$$ Similarly, the ##k^{th}## integral (integral operator applied ##k## times) can be expressed as: $$\frac{n!}{(n+k)!}x^{n+k}$$ According...

Homework Statement [/B] How are we able to go from the first line to the second line and then the second line to the third? Homework Equations Euler Identity: e^j(theta) = cos(theta) +jsin(theta) The Attempt at a Solution This problem is more about preliminary theory in my opinion so I tried...

what is the current consensus on inflation, as recent article in SciAM https://www.cfa.harvard.edu/~loeb/sciam3.pdf the 3 authors are highly respected physicists in the field they conclusion inflation is internally inconsistent and inconsistent with best measurements from PLANCK CMB...

Hello, here there are 2 things (one about hologramic universe and the other about a quantum physics test similar to the slit lamp. The first one is about the Bohm and Pibram as well as one about Alain Aspect 1982 study: articles about their theories...

I had heard of adinkras but didn't realize that they were meant to play this role. Nor did I realize that the representation theory of supersymmetry is mathematically underdeveloped.

Are interpretations that are non linear with respect to the wave function (eg. GRW, transactional) compatible with string theory?

Why the center of Newton's ring is dark? though I am thinking the path difference in the center is zero between two reflected rays... so,I will be glad if you give the correct information about that...

Gravitons are particles believed to be the cause of gravity but can anyone tell me their principle and how they work

I need details on this topic ,this is my assignment but my solid state physics is not so good,and don't know much about it but i have to do this assignment ,i have material on reciprocal lattice but for only including in assignment ,not for my understanding,so i directly need any material on...

Anyone familiar with possibility theory and possibilistic analysis? I came across it during my own research on expert human reasoning/decision making. Here is a brief description of possibility theory from a recent article behind a paywall. As I see it, possibility theory offers a novel way...

Hello everybody! I hope you are having a great day ! My question: is the strings theory a REAL theory ... is it really the final answer to the relationship between relativity and quantum mechanics! ? [emoji54]