Photon Definition and 1000 Threads

Is this statement correct: ? "The effect of making this observation is to force the photon entirely into the state of parallel or entirely into the state of perpendicular polarization." * I don't see how you can talk about how the polarization of a photon changes if the photon gets absorbed...

Which theory explains the complete behavior of photon, Quantum mechanics, Quantum field theory, String theory or Quantum Gravity? Like in young's double slit experiment, photon will go through 1st slit or 2nd slit.

Hi. Does anyone know the probability of an energetic photon interacting with ions in free space if we know the ion gas density and the photons wavelength? I'm trying to find out if the energetic photon is treated like a particle where its size is relative to it's wavelength. In other words, is...

Let's say we have a transition from ##J^P = \dfrac{1}{2}^+## to something like ##J^P = \dfrac{5}{2}^+##. It radiates a photon with some energy ##E_\gamma##. How does one know the parity of said photon? How does conservation of parity work here?

What is the longest wave-lenght of a photon particle in the nature and can it be longer?

This school page goes over the basic math of calculating the photon energy and wavelength emitted by an electron in a hydrogen atom. It comes to one photon near 490nm. Is one photon always emitted by atoms? Why can't it be two or more photons at lower energy? Has a fraction of photons ever been...

According to relativity, from a photon's frame of reference time is instantaneous, correct? So in an instant a photon would, to its frame of reference, experience being absorbed immediately after its creation, as well as hundreds of years of travel through space in the same instant. Say...

This concept is rather interesting : "Excitation of two atoms by a propagating single photon pulse" -- http://arxiv.org/abs/1411.3445 . They say that, in principle, one can tailor an optical pulse so that it will excite two atoms from the ground state (i.e., the |gg> state) so it ends up in any...

I am curious on what is meant by amplitude in an EM wave. From all the searching I have done the amplitude has something to do with the density of photons in the EM wave, and the frequency with energy of the photons. The part I am confused about is the fact that the wave is oscillating. I...

I'm confused because the James-Cummings model of an EM field interacting with a 2 state atom uses fields of "n" photons of frequency "omega" But, a pulse of time , t = pi/(2*coupling) creates an equally superimposed state, |superimposed states> = 1/(sqrt2) (|1> - i*|2>) . My questions are...

Not quite sure how to ask this, but here goes: I think I understand how a photon impacting an atom can increase the energy level of an electron in the atom. When I read about "light pressure", I thought, is there a way for, say, a stream of photons to accelerate an atom by continually impacting...

Hi there, I have some simple questions concerning a thought experiment about photons. Set-up: There are two molecules in the universe and in between them there is empty space. A photon of light is emitted from molecule A and is absorbed by molecule B. From the perspective of the photon, does...

Has electron recoil due to photon emission ever been confirmed by experiment? cause I can't find any reference to electron recoil being measured anywhere I look. If it has been measured, what methods do they use?

From my understanding, photons travel at the speed of c in the straightest line possible. Say I take a photon and send it off to the right toward a mirror. It hits the mirror and is deflected in the opposite direction in relation to the angle of incidence. My question is is the photon that is...

I hear that the interaction between a photon and an electron is introduced by the local gauge invariance in the quantum field theory. On the other hand, I know that an decelerated electron emits a photon. Are these two saying the same thing? Or how these two are related?

Hi. I have three questions. I'm not asking anyone to prove it, no debating :), but am merely interested in your interpretation of QM regarding the absorption of photons in the radio wavelength region. Although I'm sure your answer would remain the same regardless of wavelength. Question 1: If...

The QED theories merely state that a photon has spin and momentum. Are there any reasonable mechanistic descriptions, perhaps in terms of variations of E and H beyond the infinite plane wave (which is also not helpful)?

I see that a photon is said to be its own anti-particle. How is that possible? For example, how is it consistent with the idea that a particle and its anti-particle annihilate each other leaving only energy? PS. The links to other questions about this don't seem to answer the question, at least...

Just wondering if there's a precise definition of what it means to be an elementary particle. I had assumed it was related to not being able to convert it into multiple "smaller" things, but then a photon is called elementary when it can be converted into smaller energy positrons and electrons.

Are photons emitted from the stationary protons in a dipole antenna? The protons don't accelerate at any point but their electric field does contribute to the electromagnetic wave.

I have read some of the stuff on this website but am still puzzled. I understand that E=mv^2 refers to the rest energy of the photon which presumably would be nil if the mass is nil. However, we never find photons in this state as they travel at the speed of light and at this speed they do have...

Wikipedia standing wave noun Physics noun: standing wave; plural noun: standing waves a vibration of a system in which some particular points remain fixed while others between them vibrate with the maximum amplitude. _____________________ As a Photon gains or looses energy it's maximum...

Homework Statement I am trying to solve problem 5.4(a) in Peskin & Schroeder. I am requested to calculate the decay rate of a ##1S_0## positronium state into two photons. Obviously, we have to sum over all photon polarizations eventually to get the total decay rate. However, I do not understand...

I read about the wheeler experiment been done in Australia. But one thing I don't understand. If the particle (but let's use a photon) goes through the two slits (or one) and the screen is removed after it already went through, how is it measured? Does it stop after the measurement? My...

I have read that the elementary particles of the Standard Model have dimensions 0. Is this the case or not? I have read on this site relevant answers to similar questions, but have not found them to be very clear. If it is the case, surely much of quantum weirdness is thereby explained: after...

I'm reading the Wiki article below to say the invariant mass of photons in an expanding volume of space will decrease. I thought invariant mass of a photon was always zero and the energy of photon changed due to the expansion of space. So where did I go wrong? Quote from Wiki General...

according to einstine energy and mass both are euivalent it means mass can be converted into energy and energy can be converted into mass. it means photon is a kind of energy particle with velocity is equal to velocity of light if we condense the energy of photon the we will get the mass of it...

I was wondering if there is any way to electrically charge photons?

Hi! I would like to ask some general question about IR spectroscopy. During absorption of IR photons two quantities have to be conserved, energy ##\hbar \omega_{photon} = \hbar \omega_{phonon}## and momentum ##\hbar k_{photon} = \hbar k_{phonon}##. Wouldn't these two quantities be conserved at...

What is the experimental outcome of a single photon or electron double slit experiment under the constraint that after each detection the detector material is reset to the original state ie, in the limit it is substituted by another detector sheet, or photographic plate. Of course that the...

Title should be: Are photon energies constant along null geodesics? [Mentor's note: Title corrected] As I understand it in general relativity the paths of light rays, given by null geodesics, are scale invariant. Is that correct? Now Maxwell's equations in flat Minkowski spacetime are also...

Hi there, my question is the following. If an electron and positron annihilate, how can they result in ZZ? The issue I'm having is that due to charge conservation, the exchange particle can't be W- or W+. It also can't be a photon since the Z's don't have electrical charge to couple to. It...

Homework Statement (a) Show ##a = \frac{a_0}{\gamma^3}##. (b) Find proper acceleration of rocket (c) Find speed as a function of time. (d) Find acceleration of second rocket. Homework EquationsThe Attempt at a Solution Part(a) 4-vector acceleration is given by ##\gamma^2 \left[...

Is there a way to change a photon of visible light to a radio wave? I know scattering and doppler effect can reduce frequency but is it possible to reduce the frequency enough to get in the radio wave range?

Does a photon have a mass?

Homework Statement A sodium lamp emits light at the power P = 130 W and at the wavelength λ = 570 nm, and the emission is uniformly in all directions. (b) At what distance from the lamp will a totally absorbing screen absorb photons at the rate of 1.00 photon /cm^2s? Homework Equations 1...

Homework Statement The schwarzschild metric is given by ##ds^2 = -Ac^2 dt^2 + \frac{1}{A} dr^2 + r^2\left( d\theta^2 + sin^2\theta d\phi^2 \right)##. A particle is orbiting in circular motion at radius ##r##. (a) Find the frequency of photon at infinity ##\omega_{\infty}## in terms of when it...

Please tell me,why can't a photon transfer it's energy completely to a free electron?

This is the second time I've asked this question, I thought I'd add some extra details. Consider a single accelerating electron, this electron emits a single photon wave which radiates out spherically in a superposition, What direction and what time does the electron recoil if there is no...

For a photopolymer, the heuristic goes that longer wavelengths of UV light penetrate deeper than shorter wavelengths of UV light. For example, the UVA spectrum penetrates more deeply into the photopolymer than the UVC spectrum. What is the best way for this to be explained?

Hi All, Kindly find here 2 questions, i was wondering about: 1) Will (helium cooled) Mono C-silicon be able to absorb a high intensity laser of about 900-1100 nm ? 2) How can Ultra-violet and visible light cause rise in material temperatures. Thanks.

I always have some interesting on the photon. after I read the oscillator expansion of the electromagnetic field in a finite volume, I find photon is more a mathematical concept in theoretical physics than real particle. not like electrons, number of photon is a representation of the energy...

Hi there, I've been reading a textbook on Physics as applied to nuclear medicine, in particular focusing on how photons interact with matter. The textbook states (without reference) that "there are nine possible interactions between photons and matter, of which only four are of significance to...

Can a photon with higher energy than ionization energy stimulate atom?

when I say one atom, I mean literally just one atom isolated and if so how would you measure it?

I have thought for some time that it is physically correct to treat photon source as time evolving rather than photon state (i.e. using Heisenberg picture rather than Schrodinger picture) so I was glad to find this picture in Feynman's book (QED: The Strange Theory of Light and Matter): In...

I want to ask about the differences between a photon rocket and a rocket which uses conventional propellant. A conventional rocket shoots exhaust matter out the back end, resulting in impulse and acceleration. A photon rocket shoots photons out the back end, resulting in impulse and...

Homework Statement A stationary atom releases a photon when it goes from excited state n to lower state n. Delta(E) is the energy difference between initial state En and final state En', consider kinetic energy of recoiling atom. Apply conservation of energy and momentum and solve for the...

I know that a photon traveling from the Sun takes around 8 minutes to get to Earth, but, how long does the photon "think" {if it had a stopwatch} it took to get from the Sun to Earth ?

I read that a wave function of the photon does not exist in coordinate space. But, when I read Feynman's "QED: the strange theory of light and Matter", for instance, when the photons travel through the glass, it seems like wave functions of photons. How it is with this?