Theory Definition and 1000 Threads

Hello! If the Library of Babel has 10^(2,000,000) books, does anyone think that it is possible to create a quantum state (with a quantum computer) that represents this Library? I think that in a classical way it is impossible, but in a quantum way? I find it quite interesting! What about you? :)

What exactly is the usefulness of formal logic theory? And how much useful is it? I believe that most of us have an intuitive sense of logic, which has to be very useful throughout our lives and just about for every situation we can think of. Given that, I came to wonder what more does formal...

Is the Theorey of relativity that there is no absolute movement, only movement of one frame relative to another or that there is absolute movement but we cannot measure it ?

Dear Community, I am trying to figure out what is happening in this article (https://journals.aps.org/prb/abstract/10.1103/PhysRevB.29.130) when they are calculating the Fredholm Determinant (Section IV). The basic idea is that you want to solve $$ k = |\frac{det(1+h_0)}{det'(1+h_0+v)}| $$...

Hi everyone. As a graduate student in statistics, I had taken a graduate course in measure-theoretic probability theory. In a conversation with the professor, he had remarked that if I wanted to pursue further research on some of the topics covered, it may be wise to do background reading or...

I’m often not sure what science writers mean when they use the word “observe.” I was recently re-reading Einstein’s book on relativity and it’s “observe” this and “observe” that, in a very simplistic sense. What’s “observable” to me is blue and green and red, etc., and the apparent spatial...

Consider a place where General Relativity is the appropriate theory, but suppose we consider just a tiny volume, so to speak, of space-time.. which is to say we are observing a phenomenum for a very short amount of time and the "laboratory" is also very small in space. Under these circumstances...

Homework Statement Homework Equations All needed are in the picture above (i hope so) The Attempt at a Solution to me it is extremely difficult because it is so complicated with many notations. Also, I actually don't know how to read the question properly to answer it Is E(beta) is the...

Homework Statement Find the known pythagorean triangles with sides of integers lengths, given the area of the pythagorean triangle is 60. Homework Equations Pythagorean triangles are right angled triangles. a primitive pythagorean triple is of the form: x=2mn y=m^2-n^2 z=m^2+n^2 gcd(m,n)=1...

I have found a general result for certain exponential integrals that may be of interest to those involved with using path integrals. I am not certain that I am applying it correctly but it appears to work, and I can reproduce results quoted in various textbooks , using it. This may however be...

As I understand it Horava Lifschitz theory breaks lorentz invariance at high energies. Does this mean we should see photons from gamma ray bursts leave a signal of varying speeds of light for different frequencies?

Hello, everyone! I am a lover of physics, specifically that of the quantum type. The very specific question I have is the exact scientific definition of "information" pertaining to string theory. Any insight is good insight!

Hello! What makes a theoretical model stand out compared to others. I was thinking about the Higgs mechanism and the fact that there were quite a lot of other models (proposed in the 60's-70's) to explain symmetry breaking, which (I assume based on the fact that they got published) were...

Homework Statement ##\mathbf A##.Joules heating Consider a metal in a uniform temperature in a static uniform electric field E.An electron experiences a collision, and then after a time t, a second collision. In the drude model , Energy is not conserved for collisions, for the mean speed of an...

[Moderator's note: This thread is spun off from another thread since it was dealing with a more technical point that is out of scope for the previous thread. The quote that starts this post is from the previous thread.] I feel the same about transformations of Dirac matrices and Dirac field...

What is the best theory why our vacuum may be in the edge of metastability? Is it possible there are many false vacuum separated by energy barriers and the reason why our vacuum may be metastable is so that it is easier to cross the different false vacua (not necessarily to the true vacuum)?

I believe this could be interesting to many people here who are interested in quantum theory but are not (yet) professional physicists: http://lanl.arxiv.org/abs/1803.07098

The theory of electroweak temperature says that when you have a plasma of particles at energy above the electroweak phase transition (100 GeV). The Higgs field would turn from nonzero vev to zero and the electroweak forces would unite and the electroweak bosons would become massless. What...

Hello! I am reading some things about representation theory for SU(n) and I want to make sure I understand it properly. I will put an example here and explain what I understand out of it and I would really appreciate if someone can tell me if it is right or not. So for SU(2) we have ##2 \otimes...

Could someone please check if these are right?

I'll start by saying I'm posting this in Beyond the SM just because we have no elementary spin-3/2 particles in the SM as far as we know, though I was also considering posting it elsewhere. If you feel it's more appropriate in another area just let me know. As for the question itself, I'd like...

I calculated the energy density of capillary waves with Debye method (pretty much Debye model in 2D), and I assumed there is a frequency cutoff for capillary waves as well. However, when I checked my work with solution I was quite surprised that the solution suggests there is no such a cuttoff...

Homework Statement : [/B]This is a general conceptual doubt, not a numerical based doubt. We were taught that when an electron(or any charged particle) moving with uniform velocity enters a magnetic field(perpendicular to its direction of motion), then a force acts on the electron which makes it...

In his second lecture of the QED series (see below), Prof. Richard Feynman explains the phenomenon of reflection from a plane mirror, and then the working of a diffraction grating with his theory of arrows (probability amplitudes), and we see that how the new theory, which is much moved from the...

Can someone at least gives a summary of the constrains in the E8xE8 heterotic superstring theory? Many sources are mostly outdated that was written decades ago when not much research were done yet in superstring theory. So is E8xE8 already refuted? Or to what degrees and what constrains? I need...

By "The Force" I mean from "Star Wars". https://aeon.co/essays/cosmopsychism-explains-why-the-universe-is-fine-tuned-for-life The author seems to say that the Universe is an active sentient agent that has fine-tuned itself so as to make the fundamental forces of nature be such as to allow for...

The Godel theorem shows that the standard Peano axiomatization or arithmetic is undecidable. However, there is an alternative Presburger's axiomatization of arithmetic, which is decidable. Similarly, the standard ZFC axiomatization of set theory is undecidable. For instance, the continuum...

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Renormalization Continue reading the Original PF Insights Post.

Hello, I have begun to teach myself Control Theory. I am looking for a book that is focused for mechanical engineers. I do not mind examples in electrical engineering, but they bore me (no offense). Also, I find some books begin with Laplace Transforms. Yet I found this online lecture...

So if string theory is to be correct it must be able to come up with the observed value for the energy density of empty space which is pretty close to zero? A naive understanding of the compact spaces of string theory tells me that an "energy audit" of the highly curved compact manifolds of...

Homework Statement Derive, using the canonical commutation relation of the position space representation of the fields φ(x) and π(y), the corresponding commutation relation in momentum space.Homework Equations [φ(x), π(y)] = iδ3(x-y) My Fourier transforms are defined by: $$ φ^*(\vec p)=\int...

Hi! Can anyone recommend a good introductory book for measure theory? I've found Terence Tao's online book to be a good start, but would I be asking too much if I wanted something even more introductory? Ultimately I'm working toward Ergodic theory (and probability theory along the way) with...

Hello, everyone! My name is Hannah Taylor and this is my first time contributing to a forum so bear with me while I figure everything out. In the meantime let me share a few facts about myself with all of you.. I was born and raised in a small village called Cowden, we have about 650 people &...

I am practicing for my math exam next week and I came across this problem: A set has 200 elements in it. It is partitioned into three subsets so that the second and third subsets have the same number of elements. If four times the number of elements in the second subset is three times as many...

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Interacting Quantum Fields Continue reading the Original PF Insights Post.

I have been reviewing GR lately because as a mentor I find myself now answering more of those questions. I learned GR years ago from Wald and other sources, but since then have been exposed to the symmetries of the Standard Model. What struck me during this review is I now have a different...

Hi. Maybe you can help me clarify the ideas a little. I've put in google the following. rebuilding.quantum It seems that there are scientists interested in founding quantum theory on bases that harmonize with simple criteria. After more than 100 years of elaborating and debugging quantum...

Hi, I was watching a really interesting old video from Richard Feynman who was talking about how precise/accurate the predictions of quantum theory agree with observation. The number of decimal places it agrees he said is astounding. He likened it to measuring the circumference of the Earth to...

Hello everyone. I have a question about the fact that there is no drag in the thin airfoil theory. I have read that it comes from inviscid and incompressible flow (potential flow) but what i can not understand is why there would be no drag from pressure differences ? The skin drag is of course...

http://arxiv.org/abs/1801.04083 UV completion of a theory of Superfluid Dark Matter Andrea Addazi, Antonino Marciano (Submitted on 12 Jan 2018) We show that a model of superfluid dark matter, modifying the Newtonian potential and explaining galactic rotational curves, can be unitarized by the...

There is a relationship between each of the mathematical values in each of the paradoxes with regard to each observers. There is obviously also a relationship between every situation we study in the Special Theory of Relativity. The Lorentz Transformations obviously prove this. So, I began to...

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Free Quantum Fields Continue reading the Original PF Insights Post.

I'm currently applying for grad schools in string theory with an interest in AdS/CFT but am open to fundamental formalisms in string theory. I was trying to decide on a few universities to apply to. I am currently considering University of California Davis and University of Illinois Urbana...

This is probably extremely wrong I just want to know how. If photons don't experience time doesn't that mean they are every where at once, and if that is true doesn't part of quantum physics say before a particle is observed its in all the states it can be in? So doesn't that apply in that sense...

So in string theory at each point of Minkowski spacetime we might have a 3 dimensional compact complex Calabi–Yau manifold? We can have curved compact spaces without complex numbers I assume, what is interesting or special about complex compact spaces? Thanks!

Greg Bernhardt submitted a new PF Insights post Mathematical Quantum Field Theory - Quantization Continue reading the Original PF Insights Post.

A scalar field theory with potential $$V(\phi)=-\mu^2\phi^2+\lambda \phi^4$$ is spontaneously broken and as a consequence, for the ground state, $$\langle \phi(x) \rangle \neq 0$$. However, the path integral, which should give ground state expectation values, looks to be zero by oddness of the...

Suppose we want to solve the Hamiltonian ##H=H_0+\lambda V## pertubatively. Let ##E_1,...,E_n## be the eigenvalues of ##H_0## and ##S_1,...,S_n## the eigenspaces that belong to them. In order to do that, one usually choses an orthonormal Basis ##|\psi_{i,j}>## of each ##S_i## with the property...

<< Mentor note -- posts broken off from an Insights comment thread >> Ok, this is where I show my ignorance, but all this is theoretical and why I get lost with these academia discussions. Time is just a mathmatical construct to measure the motion of two or more objects relative to each other...

Einstein's theory states that curvature of space (created by a celestial body around itself) determines the orbital path of other celestial bodies around it within that curved space by a constant lateral force acting towards the centre upon that revolving body. Then why is that a similar force...