Quantum Theory

Please show me how to move from equation 1.30 to 1.31 I tried using integration by parts

I was musing on the life experience of a CMB photon travelling from its source emitter - perhaps some excited hydrogen atom at recombination - to it's absorber which for sake of argument might be a TV aerial. Am I right in thinking that the spacetime interval between these events is zero? And in particular that the photon 'travels' zero spatial distance in zero time (due to Lorentz contraction)? Is there a sense that the photon is sitting for an instant inside some weird tiny spherical(?) surface, in intimate contact with all its possible futures (one of which is said TV aerial), a myriad of even tinier exits to all available absorbers peppered within a matrix …

I was computing an expectation value of kinetic energy. Here the kinetic energy is the square of momentum divided by 2m. But when I square expectation value of momentum, the textbook return Psi unsquared Please see attachment.

How was the equation highlighted in the attachment below simplified. I get the other term but another highlighted term went to zero, how? The hand writing is where I tried using integration by parts. A’ = ih/2m

Hi, I'm new to this forum and I might have a challenge for you, if you respond to what I'm looking for. I'm scouting around the internet to find the brightest professors, PhD level students and overall esperts of physics to form a group. This group will be formed with the aim of, brace yourself, solve the millinium problem connected to the yang mills theory and mass gap. Please, if you are interested contact me, and we will have a little chat to see if you are what this group is looking for. I'm not sure we are going to make it, but I can promise that I'm going to give everything I have to see this project succeed. See ya around ;)

I live in a dark corner of the Solar System and am equipped with a button that I can push which releases an expanding sphere of light in the shape of an individual photon Around me are sited an array of reflecting objects spaced regularly and all at a distance from the point of emission of 1 light.second. What should I expect to see after the first photon has been created ? Can I expect to see the photon reflected back after 2 light seconds from an entirely random region with a probability of this occurring dependent on how much of the 1 light second radius sphere around the point of emission is actually covered by my reflecting objects? I h…

I am wondering what an expert's interpretation of the double slit experiment means for free will. Does the ability of an observer to affect an outcome simply by choosing to observe it mean that the choice had to have been made outside of all universal conditions? I have no belief one way or another, I would just like to ask people more knowledgeable about this stuff than me what they think.

My primary question deals with spin. I understand that there's a formula to calculate the spin of particles and that particles fall within two categories depending on their spin, but I do not understand what the formula is describing though. Is it describing how fast the particle is actually moving? Is it a calculation to determine a specific energy type? Or is it a hypothetical value to help understand a vector energy that's locked in an angular momentum due to color confinement or some force holding the particle together? My next question is about the color force My next tangent is purely a thought experiment which has had me pondering for awhil…

All the typical weirdnesses of QM - the double slit experiment, observation collapsing the wave function etc. - are they still regarded as mysteries that need to be resolved, or is the view now that that's just how the universe is and there is no explanation beyond that?

The quantum entanglement and delayed choice quantum eraser variation to the double slit experiment has given very strange results. So if a particle is detected then the pattern is changed. Does the detected particle communicate with its entangled pair in the past? or there is another explanation to it?

Do photons have mass?

Quantum particles are waves. We are made up of them. So does that makes us waves? Sorry for such a stupid childish question.

I found this a highly interesting article: Retrocausality may sound like science fiction, but it might be the best way to explain certain features of the quantum world, as detailed in a major new paper by physicists Ken Wharton and Nathan Argaman. Published in Reviews of Modern Physics, Wharton and Argaman's paper analyses possible ways to model measurements of "entangled" particles. One reasonable option, they conclude, is to treat the future choices of experimentalists as inputs, using them to explain past events. This isn't quite time-travel, since those past events remain hidden in quantum uncertainty, but it would be a reversal of the usual direction of cau…

I have always read and heard about the quantum theory but have not been able to grasp it enough, what would you say is actually the quantum theory

So I was out running again. Sometime during the run, I discovered my heartrate monitor had fallen off my chest strap. Now I knew when I had last checked it, and this meant it must have fallen off on one of three paths I had run up. So I went back and searched two of paths for it, and didn't find anything. At this point I knew it was on the third path. At this point it also occurred to me that I had measured the position of my heartrate monitor without actually making a measurement or an observation of it. Now here's the giant leap of faith to some relevance. Had I known its momentum before hand, I would have information on both its momentum and position at the …

When we have in diodes electron tunelling it is said that is much easier,when the barrier is slighter and much more covering valence band on p side and conduction band on n side?How is that possible?If we have slighter barrier electron will be much less to go through that barrier?Thanks for the answer.

I just recently found out that Schrodinger made his thought experiment as a criticism of wave function collapse, and tried to illustrate how absurd it was by saying a cat is both dead and alive simultaneously until observed. So when people try to explain uncertainty of something with Schrodinger's Cat, are they using the incorrect analogy to describe the moment of uncertainty? ~ee

If not, is it possible, for instance, to have an infinite number of photons in a given space. Also how can such particle(f.e quarks), then make something that has both mass and volume. Can mass exist without volume?

What does it mean when it is saying representing the actual state of the particle by adding up a bunch of functions? This is in reference to eigenstates. That particle has allowed states called eigenstates. Well it is not that particle is in any one of those states, but you can represent its actual state by combining all of them together. That the part of eigenstates I do not understand. Where a general state of a particle is a mixture of these eigenstates. This is the part I do not understand.

Can anyone explain simply what quantum entanglement is and how it works (with equations). I understand the basic principles, but I found the in depth information a little bit confusing. Thank you.

It is claimed that electrons in graphene are effectively massless at certain points and tunnel "through barriers of any height and width". If they are "massless", what is their De Broglie wavelength equal to? If it is equal to infinity, does it mean they exist "anywhere in the Universe"? https://phys.org/news/2011-11-secrets-tunneling-energy-barriers.html What is the "barrier width" and its difference from the "barrier height"? If electrons in graphene can tunnel through the barriers of any width, does it mean they can completely negate any distances?

Could you comment this one article? There seem to be very few info on this technology. How exactly does it work? Could it really work at any distance? At what efficiency? https://arstechnica.com/science/2017/06/quantum-principle-harnessed-to-create-easier-wireless-charging/?comments=1&post=33496691 https://www.researchgate.net/publication/318092214_Robust_wireless_power_transfer_using_a_nonlinear_parity-time-symmetric_circuit

I am a science laymen. I just saw the Veritasium video about entanglement and Bell (https://www.youtube.com/watch?v=ZuvK-od647c) and have a few questions ... which hopefully will not also be entangled. He says no matter how far apart the entangled electrons they flip "at the same time". How do they know? ... how does one measure both at the "same time"? Can multiple events actually occur at the same time?...or must there be some minimum time difference between any two events (measured events? .. macro? events?) (Is there a 'quantum time' that is different than a 'relative/macro? time'?) Dr. Don Lincoln says (https://www.youtube.com/watch?v=JFozGfxmi8…

Hello, Imagine having exited an electron and it went on a higher energy atom orbit. Is it possible to predict when the electron will emits a photon to lower his energy? If it's hazardous , does it follow a probabilistic model like a gaussian curve or smth like that? ty for your answers!

Introduction to Schrodinger Ensemble Theory Some years ago, I chose to pursue a different approach to the study of the time-independent Schrodinger equation, particularly as it is commonly applied to the following situations: a particle in an infinite potential well, a particle in a finite potential well, the harmonic oscillator, the hydrogen atom. The first group of examples I will discuss are all one-dimensional. The work will generalize when I deal with the hydrogen atom. My concept is simple. For a given potential V(x), suppose \(\psi(x)\) is the solution to the Schrodinger equation in the form: \( (E)(\psi) = …