Photon Definition and 1000 Threads

We know lepton conservation law, that means multiple neutrinos can not be consolidate to big single neutrino. But photon is boson not lepton, no need of conservation, does that mean it is possible to combine or fuse a bunch of photons into ONE big photon, or say, more energetic photon, i.e...

Everyone speaks of entangled photons and entangled states as if entangled photons were rare in nature, products only of our investigations into the quantum weirdness. With the intent of confirming whether or not this is true according to modern physics, can someone explain how truly "untangled"...

I am a student . My question is that in what way we can accelerate a photon , is this possible ? I am a student . My question is that in what way we can accelerate a photon , is this possible ? what if i pass the light to a medium of varying refractive index,containing lots of biprism at...

I have wondered how a photon could be massless, given E=mc2. I have seen explanations involving treatment of the situation through consideration of momentum. It seems to me my own explanation is valid, and I ask for comments. Actually E= m’c2 =gmc2, where g=1/sq rt{(1/[1-(v2/c2)]}. Photons...

It is known that wavefronts of internal OAM photons travel slower than light but I wonder what happens if you accelerate such a beam. This should be possible under gravity.

Hi all! I've checked Wikipedia and a related thread regarding experimentally measuring an upper limit for the photon rest mass: https://en.wikipedia.org/wiki/Photon#Experimental_checks_on_photon_mass https://www.physicsforums.com/threads/photon-rest-mass-0-wasnt-proven-experimentally.792583/ I...

We know that the photons are massless particles. The traveling speed of the photon is equal to the speed of the light(C). The Einstein's law of relative mass is says when a particle travels at the speed of light, then it's mass becomes infinity (i.e. highly increases). The photons are also...

follow up from responses in old thread. https://www.physicsforums.com/threads/why-does-attenuation-coefficient-decrease-with-increased-energy.569981/ I have seen in my experiment using a saline media ( some oxygen bubbles) that an increase in Incident PFD is showing an slight increase in the...

Hello, first post. I recently became interested in quantum physics and its mysteries. To my understanding, In the double slit experiment, the photon or electron will scatter and behave like a wave when both slits are open and neither slit is measured. Over time their cumulative scattering mimics...

I've recently been reading about entanglement between two spatial modes of a single photon. It's a little over my head and there is one aspect about it that I'm particularly unclear on, which I was hoping someone here might be willing to shed some light on it. The basic setup is described with...

Dear, I am going into quantum physics the past days specifically the dual slit because it boggles my mind. You can find the Wikipedia here https://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser And this is the picture...

It's been a while. But I have always received the help I needed on this forum. I had this question in my head, When a particle accelerates, it creates an oscillating electric field, and a photon. How much does this effect, affect the energy of the particle itself? Say I had a particle...

Hello! I am a bit confused about the decay of a photon into a electron-positron pair. In the center of mass of the photon, isn't this decay violating the energy conservation?

I read somewhere that an electron travels forward in time and a positron travels backwards.And when a photon hits the electron the direction of time for it reverses and it becomes a positron.Does an electron really turn into a positron when hit by a photon? why?

Hi. I have a rather silly question. When speaking about a single photon? What do people mean when they speak of the polarization of a single photon. For instance, in classic electromagnetic theory, this would be the direction in which the electric field of the wave is oscillating . But does...

Hello all, Is this a thing? I understand that a theory of quantum gravity is necessary to explain the physics at the core of a black hole, but it seems a black hole is the only environment energetic and dense enough to ignite a mass-energy feedback loop where colliding photons release the...

Basically, I found the energy of a photon using its frequency ((6.8*10^15) and E=(3.6496394*10^-16)) and so I then used "p=E/c" to find the momentum and got 1.2173887*10^-24 however I don't know the measurement of the momentum. Is there a better equation to use to find momentum, and what would...

Let a photon of a definite wavelength (hence a definite momentum ) start it's journey at time 0. After 8.3 minutes it hits a detector on earth. So it's position is exactly known (in fact it can be predicted for any time less than 8.3 minutes). So we have particle with definitely known momentum...

Is the velocity of two photos of same radiation(light) with different energies same ?? (also in Same medium) Will energy alter the velocity of photon?

Is there a theory that explains the mechanism under which photons exceeds the speed of light? It should refer to cases including photons generated in an oscillating charges, dipoles, inhalations, different kind of excitation, accelerated particles, scattering phenomenons etc. Please note that...

Basically, I'm asking about loosely-bound electrons, e.g. everyday static electricity. Can their combined wavefunction evolve to a low-energy state "at once", so that they emit a single high-frequency photon, rather than multiple photons of energies suggested by the potential difference? If...

Homework Statement , 2. Homework Equations , 3. The Attempt at a Solution : [/B] If an electron and photon have the same energy, the electron will have a shorter wavelength, and a larger momentum. The shorter wavelength makes it useful for electron microscopes, outperforming optical microscopes...

Hi all, and thanks in advance. I am an old guy learning GR for fun. Reading Weinberg's "Gravitation and Cosmology". PhD in math 1998, so I read all books like I read math books: every character, every word, every line, every page extremely carefully. I am stuck on the stupidest thing. On p.72...

Homework Statement A certain molecule has a characteristic rotational energy of 8.81x10-4 eV. What is the energy of the decay photon towards the state with angular momentum quantum number l? Homework Equations E = Erot (L(L+1)) The Attempt at a Solution Why would this not be 12 multiplied by...

If I shine a laser beam through a calcite crystal, the beam is split in two, as shown below. Are the photons in the split beams in an entangled state?

Hi all, Whew, last question for a while: I think I already know the answer, but want to confirm (e..g, I think this thread basically answers the question, https://www.physicsforums.com/threads/propagation-of-wavefunction.152053/) As an example, let's say I have an electron (in free space or...

Despite some effort I still don't understand how Coulombs law can be used for experimental search for mass of photon. From wikipedia: If a photon did have non-zero mass, there would be other effects as well. Coulomb's law would be modified and the electromagnetic field would have an extra...

A few quick questions I'd like cleared up:1) Alkali metals are said to have a really low threshold energy, enough for visible light to cause the photoelectric effect. Does this mean if I aim a flashlight (turned on) at a piece of sodium, I could ionise it? Simply flashing a light over a piece of...

Can a beam of light be objectively in a specific photon number state (Fock state), let's say ##|2\rangle##? Or is it (the specification of the state) detector/observer dependent? I.e. we can only say that a beam of light is in a Fock state, but which exactly is detector dependent (detection time...

Hi, I'm a high school science teacher. Most textbooks classify EM radiation as kinetic energy. But this doesn't seem right to me. As a photon is massless it's hard to see how it can have kinetic energy which is 1/2 mv^2. It could be said that it has energy hf and therefore mass hf/c^2. Then its...

I am interested in what the average photon densities are within galactic environments due to non CMB sources. In extra galactic environments, the CMB certainly dominates, however as you enter more dense and luminous areas (e.g. , the galactic disc) broad spectrum photon densities from local...

Homework Statement A photon beam is incident on a proton target (at rest). Particle X (and nothing else) with rest mass M=1.232GeV/c2 is then produced. Use m_p =0.938GeV/c2 as the proton mass. a) What is the energy of the photon beam, in terms of GeV? b) What is the momentum of the moving...

I know photon is considered a point particle, so it means it has no physical dimensions, if I'm not wrong. Plus, it has a probability wave function associated to it. It also interacts as a wave which consists of an electrical and magnetic field perpendicular to each other and delayed by a...

Hi guys, I am looking for a formula which I am sure exits but I cannot locate it. The problem is that a quantum dot absorbs a photon of wavelength λ0(dot is semiconductor or could be any other material). Assuming that it reemits a photon, what is the probability that this emitted photon will...

Electrons have spin 1/2 and interact with a magnetic field. Since photons have spin 1, I suppose they also feels a force on a magnetic field. So that means that light can be deviated from its original path by a magnetic field?

I successfully created the fringe pattern at home with a simple laser light and a black plastic sheet with two thin cut as double-slits. I then used two mobile phone cameras at two sides in hope that the wave function of light will be collapsed. But nothing happened i.e. the fringe remained...

Hello, I'd like to know which book or papers I'd read to understand, possibly without too rigorous mathematics knowledge, how do photons like X-rays or gamma ones reflect off surfaces and attenuate through solids or generally speaking, facts about how do they interact with the real world. So...

When one reduces the intensity of let's say, an incandescent bulb (by varying the resistance, as seen in many homes), which decreases more, the photon frequency (not related to wavelength, but the time interval between photon emissions) or the areal density of the photons? To what extent does...

Homework Statement Figure 1.1 shows an equilateral glass prism illuminated by a 100 W laser beam of wavelength λ = 600 nm. The refractive index of the glass of the prism is 1.50 at λ = 600 nm. The path of the light in the prism is parallel to the base of the prism. The momentum of a photon is...

I was informed I might get a better response by posting to this forum, so sorry for the double post. Hello all, I am currently attending a service course for a PET/CT system for my employer. We have been covering the physics behind the function of detectors and my instructor said something...

[Moved from https://www.physicsforums.com/threads/if-a-photon-were-trapped-between-two-perfect-mirrors.880490/ because it's a different question] Hi, ed. Could you explain what you mean by interference between photons? Is there a wavelength smaller than 0.1nm for EM radiation?

If a photon were trapped between two perfect mirrors perpendicular to its axis of motion, and they were gradually brought together until they were touching, so that the distance between their faces was 0m, would the photon be "trapped" between the mirrors? Without space in which to move, how...

Homework Statement I'm trying to derive an analytical expression for the photon backscatter flux in finite turbid media using the diffusion equation and the method of images. What I want to write is: for a given volume (x,y,z), where a coherent light source is incident on the x-y plane and z is...

Is it possible that the reason the delayed choice two slit experiment outcomes occur is because for the photon, traveling at the speed of light, the past, present and future are all as one, and therefore it "knows" what is going to happen and therefore always "makes the right choice" at the...

Let's say here are two ways for a photon to go between point A and B and a detector at B detects photons with some probability based on interference. Mathematically, it's calculated by carrying phases along each path and then adding them up regardless of how much time it takes to travel along...

Can one shed light on the velocity of the photon through the fourth dimension x4 using limits? To begin with, please study the mathematics from Brian Greene’s book An Elegant Universe. The upshot is that the faster an object moves through space, the slower it moves through the fourth...

What is the velocity of the photon through the fourth dimension x4? Photons are real, physical entities. The fourth dimension is a real, physical entity. Therefore, photons must have a relationship with the fourth dimension. They must have some velocity relative to it. What is the velocity...

As far as I understand, phonons are just thermal vibrations of atoms in a lattice and blackbody radiation is just the radiation emittied due to thermal oscillations accelerating the atoms back and forth. Is there any example of a derivation of the Planck equation from considering black body...

Is it possible (and has it been observed) where a single high energy photon is emitted, but then is received as multiple lower energy photons?

Hi Guys and Gal's In answering a question in general physics I came across the following which explains at a reasonably basic level what a photon is, spontaneous emission etc at the level of basic QM with a bit of math: http://www.physics.usu.edu/torre/3700_Spring_2015/What_is_a_photon.pdf...