Photons Definition and 1000 Threads

Hi there. I am attempting to do calculations for my own project, the question being what is the attenuation necessary to reduce the number of photons in a beam to single-photon levels. N approximately 1 or 2. The laser in question is a 650nm 5mW laser. I have solved the energy per photon...

I was reading Diagrammatica by Veltman and he treats the photon field as a massive vector boson in which gauge invariance is disappeared and the propagator has a different expression than in massless photon. After some googling, I found that this is one way to formulate QED which has the...

P=mv *momentum equals mass X velocity. Light particles or "photons" are said to be "massless". And yet they have momentum. How is that possible? (p.s. I used to know the answer)

Hello, I am a student who started studying MCNP. I'm not used to writing in English, so I'd appreciate it if you could understand even if there were grammatical errors in my thread. I want to check the energy of gamma rays from neutrons reacting with matter. So, I wrote this in the content of...

Tentatively, I ask in this forum for a qualitative pointer to what end effects one might expect when a gamma energy photon energizes an atom of a substance, and causes fluorescence. It relates to a practical endeavour about using a PIN diode as an X-ray detector, where the device considered...

Can someone please explain the four classes of fundamental particles? (Just the basics) I came here because I never learned any chem or physics in school so please explain like I’m five :)

My understanding is that the repulsion between two electrons is mediated by the exchange of virtual photons – virtual meaning not lasting long enough to be detected. But suppose one of the electrons is in the sun and the other on Earth. There should still be a repulsion because the...

Consider the following experiment: A photon hits a beam splitter, then a non-linear crystal (nichtlinearer Kristall - sorry, prepared the image in German) on each path that does parametric down conversion, splitting the photon into a signal and an idler. The idlers proceed to two detectors (D1...

if we assume each photon of light as a very very light piece of matter (by famous E = mc^2 and then: m = E / c^2) and sum up all photons that have been made from the creation time of a galaxy (also considering limitation of speed of light) and also photons that accidentally passing throw that...

We can analysis a static EM field into Fourier serie. Then we can consider a static EM field as a superposition of many running EM wave. So why we could not consider static EM field as a superposition of many photons(maybe virtue photons)?

Assume we have a photon pair prepared just so they are suited for a two photon interference. Let's call the corresponding beams A and B. Then we run each beam individually through a 50:50 beam splitter such that we get beams A1, A2, B1, B2 such that we can symbolically write the state of the...

[This](https://youtu.be/9l6VPpDublg) is a lecture by Persinger where he postulates that photon entanglements and the Earth's magnetic field can facilitate telepathy. (See from 20:00 to 30:00) Links to the study he cited...

Hi! So I know about the electron-photon interaction but what about photon-photon interaction? I mean, I do know there is a very small chance for them to interact, but how else do they transfer energy in order to get from Sun to Earth, for example? When it comes to sound waves I get it, for...

So (wildly simplistically) lasers work by photons being reflected between mirrors gaining energy on each trip through the medium until they break through the mirror on the output end. How many trips does that typically result in? 10s, millions? And thus the total distance is that count * the...

Summary:: Hello I am a writer and presently working on treatment for a science-fiction story. So I am not a scientist, just a neophyte interested in science and wanting to write a fiction that would not be too far-fetched and that would make some sense for everyone, including the scientific...

I am still so totally confused about the ultimate source of the photons of the CMB. I am getting really confused by online sources, who are either not very clear, or seem to contradict each other. I feel like I have narrowed it down to two sources; 1. The early universe was full of high...

One Major question I have about wave-particle duality of say a photon... Could we describe it like a rock falling vertically into a still pond. Around this point of contact we establish a circular wall which detects the contact of the wave. Two things are evident here: the rock keeps on moving...

But then I learned a photon can be split into two or even three photons (red-shifted, energy is conserved), and also photon can lose energy and still be a photon (Raman effect, inelastic scattering). Now, I am not sure what it means when it is said photons are quanta of light (smallest unit of...

I've tried to solve this by calculating the number of photons. I've done this by calculating the energy of one photon, taking h*c divided by lambda. h*c is 1240 eV*nm and lambda is 10 nm. This gives me 124 eV. I then divide the total energy by the energy of one photon, 50 keV/ 124 = 403 photons...

Entangled photons are generated, for example, by parametric down conversion (SPDC). The ordinary photon beam has polarization 0° and the extraordinary photon beam comes with the polarization 90°. Each photon leaves the source in a cone of light. Both cone shells intersect in two beams, which are...

Black holes suck things in and the current explanation is that they bend spacetime. I have my own hypothesis though. If electrons shoot out photons when they switch positions in the atom that would mean that at the very least electronshave photons in them. Atoms always try to have the right...

If an atom were made to release a Photon, then a number of the components of the atoms nucleus were theoretically extremely quickly removed. would the previously emitted photon change wave length?

Correlation between polarization measurements of entangled photons at angles less than 45 are greater than classically statistically possible. No set of hidden variables can be preordained to explain the 75% correlation of photon measurements at 30 degrees and complete anticorrelation of...

My question relates to the physics of the emission line of Ca II which originates in the solar chromosphere. My understanding is that ionized Ca which lacks a single electron in its valence orbital interacts with free electron in the chromosphere milieu to form Ca I (nonionized). The captured...

in classic electromagnetism, two plane waves with the same frequency and -1 phase difference can cancel each other. due to conservation of energy, I assume that photons (that so far we have treated as sort of EM energy chunk traveling through space) can't truly cancel each other. then, what...

The photon and the gluon in the Standard Model do not interact with the Higgs field and are hence massless and travel at the speed of light. Is there a simple explanation why these two elementary particles are the exceptions?

Special Relativity tells us - the faster things travel their time is slower relative to a stationary observer. Do massless particles, like photons traveling at the speed of light, experience zero time and in their frame of reference travel "instantaneously".

Is there a smalless wave packet of EM wave corresponding with photons?I read on Internet saying that EM wave consist of many random wavetrains.(Although it seems to me that this wavetrain can be divided into two parts example in double slit Young experiment)

First I'll explain my understanding, because I'm not very confident in it. The main point is that the electrons are ejected and then accelerated to a very high kinetic energy. Then they start smashing into the anode. Most will go through a series of collisions before completely stopping, so that...

I'm trying to understand the Energy-Momentum relativistic relationships for a light particles. It is commonly said that the Energy of a photon depends on the observer by the relationship ## E = - \mathbf{p} \cdot \mathbf{u}## where p is the 4-momentum of the source emitting light particles and u...

Why do we know the velocity of all photons are the same as the velocity of light?Can we deduce this or we must have experiment test?What is the experiment test?

Correct me if I am wrong. I understand that if ##\vec E## and ##\vec B## are solutions to Maxwell’s equations then ##\Psi= \vec E + i \vec B## is a solution to Schrodinger’s equation. Is there an easy way to calculate the statistical distribution of the number of photons, or at least the...

Hello , Why does an incoming photon can only scatter from an electron if the electron is not bound top an atom ? Because from what I know a bound electron can absorb a photon then be excited to a higher energy level and then re-emit a photon while transitioning back to it's previous energy...

I am wondering if one of the prerequisites of the double-slit experiment, when done with electrons, is that the beams must be in a dark vacuum tube so as to not destroy the interference pattern. I am trying to learn if the beams will lose their interference pattern because the particles of the...

My question is about how the interference patterns work in a double-slit experiment when firing individual photons through either slit. Classic - there is 1 photon - it has nothing to interfere with. Quantum - even with a photon going through each slit at the same time, the likelihood of them...

Filament in a vacuum Take a quick look at this! Now, can the glow be explained in any other way than concluding that photons are being emitted from somewhere other than directly from the filament? i.e. is it not obvious that photons are being emitted from points of origin other than the...

Hello, I have this question whether it will be possible to generate electricity by heating up a suitable metal (conductor). We know from the photoelectric effect that high energy photons (of visible light; probably with frequency closer to that of violet) can knock off the outer electrons from...

It seems a gravitational field does not alter the electromagnetic field strength. Is this correct? My reasoning: With no gravity, field strength is: F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu Introduce gravity: \partial_\mu A_\nu \rightarrow \nabla_\mu A_\nu = \partial_\mu A_\nu +...

I am not understanding how to think of photons and wavelength in ultrafast optics. An ultrashort pulse is the summation of many wavelengths. So, if you refract an ultrafast pulse it will actually spread out spatially? Can you define a wavelength as sort of an average wavelength? And most of the...

Spectrally generated photons I get: electrons "fall down to a closer orbit" and a photon is created. I don't understand however how the photons from black body are created. I have searched extensively for this without finding answer. Can someone enlighten me?

So if i have a photon of some energy and i want to find the magnitude of the momentum, i can get the right answer but the units don't make sense. So i derive p = E/c since i know the energy of the photon and i used f=E/h and substituted this into p=hf/c This means for units of the equation p...

I often read of photons manifesting different levels of energy. I know that energy increases as wavelength decreases and frequency increases. Are there other ways particles gain or lose energy? As water boils heat energy is transferred to the water causing water molecules to move faster and to...

photos are in the speed of light which means that the fasts change in photons energy would take infinite time for the outside observer so does it means that the photons can't spin or interact with each other or have any kind of change

1) Photons have momentum. So if an atom emits a photon it ought to recoil to conserve momentum. This recoil will change the kinetic energy of the atom (by an amount dependent on the initial momentum). Does this mean the energy of the emitted photon is the difference in energy levels (of the...

I got one book by Cohen-Tannoudji, that is, Photons and Atoms. It is hard to understand for me now. What books are the prerequesites to read for understanding Cohen's this book?

We know that photons (light) are massless but they have momentum. Now suppose I am in the space far away from planets/stars that there is no external force exerts on me, if: 1- I turn on a flashlight (torch), would I be pushed in the opposite direction which the flashlight is facing (Newton's...

Considering a Delayed Choice Quantum Eraser experiment such as the one in the picture above: It is said that paired photons arriving at the detectors A,B,C,or D, reach the detectors after the entangled pair has reached the interference screen. Are we actually able to measure the time interval...

This is probably a common questions, but I can't find it answered anywhere... It is of course well known that the average number of thermal photons in a mode can be calculate from from the B-E distribution: <n>=\frac{1}{e^{hf/k_BT}-1} The usual understanding of this is that what we are...

Hi. I am reading quantum optics by Marlan Scully currently. Although the book has devoted a whole section to explain the photon concept, I am still confused about some nature of photons. First, how do photons distribute in space? For example, there are ##n## photons for a Fock state ##\left | n...

In the prompt 4c in this problem set: https://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2013/assignments/MIT8_04S13_ps1.pdf. We are asked to find out how d, D and w will change (where d is the slit width, D is the distance from the slits to the screen and w is the distance...