Physical Definition and 1000 Threads

In particular I'm studying the paper "Theory of dynamic response functions of periodically modulated physical systems" by Lovesey et al. and "modulated system" are mentioned many times. My thesis advisor recommend to me reed this paper but is very confuse, any reference you can give me in...

I know I have to use λ=xd/L. But I don't know what any of those variables (except lambda) mean. If you assume that 0.59 is x times d, you can get an answer that is close. 0.59/100 = 5.9*10^-3. Can someone explain the solution and meanings of variables using a diagram? (The answer to the...

Summary: The key to unifying the theories of the very large and the very small is asking if the object in question is physical Uncollapsed(stateless | unphysical) Quantum Waves + State(Matter Field or wave collapse) = Physical Matter Is a Matter Field state change the same thing as wave...

What is the physical meaning of ##\psi_1(x)\hat{A}\psi_2(x)##, where ##\hat{A}## is an observable and, ##\psi_1(x)## and ##\psi_2(x)## are arbitrary wavefunctions?

Hello, I am freshly retired and enjoy going back to the fundamentals. I followed the wonderful courses by Alain Aspect on Coursera on Quantum Optics 1 and 2 . The quantization of Electrodynamics is really easy stuff. Just follow the correspondence between Poisson brakets and Commutators ... and...

Sorry in advance if this question doesn't make sense. Anyway, I am reading a paper about quantum field theory and the Whitman Axioms (http://users.ox.ac.uk/~mert2060/GeomQuant/Wightman-Axioms.pdf), and it describes a field (Ψ) as Ψ:𝑀→𝑉⊗End(𝐷) where 𝑀 is a spacetime manifold, 𝑉 is a vector...

Hello, I am having trouble understanding the two friction force terms from the ball rolling on page 4 of this physical model: http://www.dewtronics.com/tutorials/roulette/documents/Roulette_Physik.pdf What is the reason for the cos\theta term ? I think the frame of reference is made up of the...

Here's my understanding. Please let me know what I'm missing or what I've misunderstood. <x> represents the average of position measurements on some N, identically prepared particles. If those measurements are thought of as a distribution, then that distribution's form should match the wave...

I'm master physics student looking for books in physical chemistry for stuff like born Oppenheimer Approximation and more. Most books give hand-waving proofs and I'm looking for a book which is more rigorous. Thanks

Summary: Could MWI (Many Worlds Interpretation) create universes with fundamentally different physical laws? Physicist John Wheeler proposed along with Hugh Everett and Bryce DeWitt the 'Many Worlds' Interpretation of Quantum Mechanics (although he expressed some doubts about its validity) I...

Please take a look at my first thought experiment: You have 2 coins to place on the table. The distance between them may be between 0 (inclusive) and 1 meter (exclusive). So if you want to store the number 15 you simply set the distance to 0,15m. You can later read the information by measuring...

Hi, are there any attempts to make a machine readable definition of most common rules and actions (or a causal model) of physical world? I'm looking more a logical level of modelling, at the same level that human common sense works. I have some experience on semantic tecnologies and ontologies...

Hi All, I have VMWare Workstation Software to use VMs . When I create a machine I am asked to load an OS into the new VM: Is it possible to load the Physical PCs OS into the VM:

I'm trying to understand the various different ways in which we can 'formulate' theories in physics and I am finding it somewhat hard to obtain a bird's-eye view. I hope someone here can help clear up some ambiguities. I apologize in advance for the 'sketchy' ways I put matters in my...

Were the universal physical constants already in place at the instant of the BB? Things like Planck's constant, the speed of light, the various mass of particles, the various force values. Was it possible that the early universe ( the first couple of billionths of a second or so) existed without...

Is it not fascinating that you can feel eye contact on such distances we do? What is it that we actually detect? I understand that the eye absorb light, it may be the starting point for the explanation?

While viewing a recent lecture on Einstein’s Field Equations, the presenter made the association between the various quantities like mass, energy, momentum and pressure directly to the four dimensions of spacetime. Depending on which derivation of the FE he was explaining, he would make an...

Many asteroids and planets have undergone enough heating so that they were at some point completely or partially melted. What physical mechanisms are in play here? I'm assuming a solar system such as our own. Thanks!

The gradient of a function gives a vector perpendicular to it's surface. So the equation reads electric field is the negative of the vector perpendicular to the equipotential surface. I know electric field and understand potential but I can't physically make sense for the above sentence how LHS...

I am wondering what is the physical evidence that Cooper pairs are indeed the ones responsible for superconductivity. These pairs consist of two electrons with opposite momentum, forming a boson with null momentum. But what about pairs that would consist of, say, 6 electrons (or even more)? Of...

I have used Laplace transform during my EE studies to solve differential equations and in control system analysis, but we were taught that as a tool kit to make the math easier. The physical meaning was never explained. I know basic time and frequency domain concepts (thanks to Fourier series)...

Is there any physical quantity having two different units or can it be possible that a physical quantity have two different units?

Hi everyone, I'm trying to derive DC motor differential equations. I have some doubts: I have a viscous friction coefficient in terms of N*m*s. Is it possible to express it in terms of N*m*s/rad? And how? Some exercises show this value in Newton-meter-second and others in...

Hi everyone, this is my first post on PhysicsForums. Thank you so much in advance for your help! My question is the following. Let us suppose we have an event A in a curved spacetime which, for definiteness, is the spacetime curved by the bodies of the solar system. Adopting a coordinate system...

I am able to solve the problem however if x was position and t was time how is this problem interpreted? I know, for example that ##\frac{dx}{dt}## tells us how the position of something changes as time changes (or instantaneous change) and an integral gives a net change so to speak.

Hello everybody. I am currently on my last year of Computational Physics education. More and more I am interested in Machine Learning and Neural Network. Time has come for me to choose diploma work thesis, so I am searching for interesting ideas where I can merge my interest in neural networks...

I have a couple of basic questions/statements which I'm not sure about because I can't find a simple and comprehensive description of some of the basic stuff regarding the physical layer. (I've read the relevant chapters in a couple books like Tanenbaum's, and Kurose & Ross's one, but I couldn't...

<mentor: moved to homework forums - no template okay in this case> Please I need help with this one! Drawing a Quaternary deposits’ profile The purpose with this practical is to understand how a map showing Quaternary accumulations is built up and how it may be interpreted. The information is...

I have started hosting a "scence open mic" and the first one last month was very successful so I'm doing it again. We had about 30 people show up and 5 presenters including myself giving up to an 18 minute talk on anything science. It was a great experience and I encourage others to try it in...

I'm a hobbyist physicist and I just started studying QM through watching Leonard Susskind's lectures on the Stanford Youtube channel. I get the idea of it being impossible to precisely know both a subatomic particle's position and momentum, but is this actually a physical limitation? Or is it...

I already know the fact that angles are physical quantities, but sin, cos of some angles are quantities? Quantities are those things, which can be quantified, are sin, cos, tan be quantified through measurement, if yes then other mathematical functions should also be categorised as physical...

I've been reading a book called hyperspace by D.R Michio Kaku. In this book he talks about unifying all the fundamental forces of nature (gravity , electromagnetic force , weak and strong nuclear forces.) My question is, what if they are not unified and we are just trying in vain. I don't...

I’d like to know if anyone has formulas for calculating the spring constant (k) of coil springs, from their physical dimensions. I bought a coil spring, suspended a 0.6 kg mass to it, observed its oscillation period at very close to 0.6 seconds, and so believed the spring constant “k” to be...

I want to visualize the concept of divergence of a vector field.I also have searched the web.Some says it is 1.the amount of flux per unit volume in a region around some point 2.Divergence of vector quantity indicates how much the vector spreads out from the certain point.(is a...

I'm trying to understand the physical implications of electron temperature (Te), vibrational temperature (Tv), rotational temperature (Tr) and translational temperature (To) of a plasma. I am reading often that Te > Tv > Tr ≃To, in terms of what is happening inside the plasma what does this...

Bead sort is a not practical sorting algorithm that suppose to have a time complexity of ##O(\sqrt{n})##in the real world. I thought it would be great if a device that can take numbers from the computer,then turn it into analog stuff that the device can read,drop the beads,and return it...

Hello My name is Joseph I am a physics student, I am new to Fortran, I know how to write a code for solving differential equations, but now I have a physics equation for evolving star rotation as a function of mass. and I do not know how to evolve (using any numerical method, such as Euler) so...

I’m understanding that QM superposition in which, for example, a single electron acts as a wave in a double slit experiment and interferes with itself by passing through both slits simultaneously (when there are no detecting devices priorly measuring either slit) presents a result which is...

So, I am confused about the following.I learned in high school and in my first year of university that there is something called time dilation that observers observe that time is slower for objects that are moving faster. As in if there were two initially synchronized clocks that you could...

Let us say that we have a dispersion relation curve and associated instability curve as shown below for a magnetised plasma, which have been formulated through kinetic theory. The frequencies and growth rate have been normalized w.r.t. cyclotron frequency of proton. My question is: what does...

Consider the classical scenario a stone falling in the Earth gravitational field. Classically we attach a Potential Energy to the stone and using the law of conservation of (mechanical) energy we are able to evaluate the dynamic of the falling stone. This model assume a stone in a "external"...

There has been studies showing that high testosterone protects against cortisol. Is that why there's also a correlation between height and income? Because extremely competitive high level jobs would easily destroy a normal person's health unless they have high testosterone to protect against...

Hi friends, I'm just thinking, in some video games, the characters have a double jump mechanical. What's the physics concepts behind this? I mean, it's really possible explain it? I saw a brazilian video about science in games in which the author talks about air resistance. It's a curious...

I had heard an opinion from my high school teacher, but I can't understand?? "An experimental record of a French scientist. He heats the diamond and sublimates it. After cooling, it turns back to solid barbecue carbon. In this case, although there is a physical transition, the substance seems...

First time in this forum, so greetings to everyone! I am currently working with some physical models in the field of natural ventilation and I came across the following 5th order polynomial equation (quintic function): $X^{5}+ C X - C =0$ This is the steady state solution of a physical system...

Is there scientific studies that confirm that a race or ethnic group is physically superior to any other? I think we can examine sports records can make some judgement on what type of groups of people are superior in each type of sports. But I don't know how you would go about judging who is...

Im carefully studying Deep Inelastic Scattering and I have the doubt if valence quarks are real physical entities or if they are just a way we can think hadrons are built. I understand that inside hadron we have the Parton Distribution Functions that say that there are an infinite number of...

Time dilation can be shown mathematically but what is the physical phenomenon due to which it occurs?

So I recently picked up 40 of 10.525 GHz Microwave RADAR transmitters: I opened up one out of curiosity and had something like this (image attached) . I noticed some parts of the PCB aren't even connected to anything. How do the different shapes and sizes of the PCB interact with each-other...