Photons Definition and 1000 Threads

I have heard that photons are attracted by gravity. Does this apply to electrical or magnetic fields?

Homework Statement Show the Lorentz-Invariance of the following spatial statement: Two photons are traveling parallel to each other. The relative position vector of the two photons is orthogonal to the velocity and has length d. Homework Equations / The attempt at a solution[/B] The first...

In a pure crystal structure of some semiconductor compound each molecule is usually bound to other four by covalent bonds, in other words each of the four valence electrons of each molecule is in a covalent bond with another molecule. At 0K all electrons remain in these covalent bonds, but as...

I need this information for a simulation I am working on that involves optical photon detectors. Specifically, I need a rough figure for how many photons a photon detector would register per second if I were to place it in ambient light from the sun. I realize that this number depends on the...

I was wondering, how does a photon look like? What does it look like? I'm taking modern physics at the moment and I'm able to calculate lots of things quite well. Like DeBroglie wavelengths, I'm able to utilize the Schrodinger equation and the Heisenberg uncertainty principle and what not but I...

Are photons massless? They have energy and can be affected by gravity, so don't they have mass? I've heard plenty of people say that photons are massless, does this just mean that they have negligible mass? Also, if only light/photons can move at the speed of light, then wouldn't everything be...

Imagine a stream of photons moving from the sun to the Earth (A, B, C, D, E, F, G, etc.). Now imagine 2 different men measuring the speed of the photons, and (somehow) recording which photon is hitting them. They are in the same position, but one is traveling 1/2 the speed of light (relative...

From what I understand Einstein was the person who decided length contraction would indeed occur in the vector of velocity, more so as you approach c. If it were possible to accelerate a particle to c, would the length would become 0? If the length were to become zero, would the notion of mass...

Hi, so I'm a first year neuroscience student at Carelton University in Canada. I had a little bit of a "revelation" with this topic recently after I understood it a bit better and I think this is really interesting. (If I understand it correctly!) We're learning about Kekule structures...

If I am not wrong, Feynman is claiming that photons can pass through each other. Isn't it? This thread is started with the interest of the thread "Does electron has definite path?": https://www.physicsforums.com/threads/does-electron-has-definite-path.780047/page-2#post-4905563

Why is light viewed as both wave energy and particle motion, whereas other forms of electromagnetic radiation is only seen as waves? Light is just a small part of the spectrum, so, surely all electromagnetic radiation should be viewed in the same way.

i have the following questions: Bell inequalities use spin 1/2 matrices and experiments use photons. Is then the electric field horizontal or vertical after the measurement with a polarizer in other words can we assimilate the orientation of the field with a vector in the hilbert space ? How...

Homework Statement Given the maximum possible number density of stars in the present universe, assume that they have been radiating light for 10 billion years at a solar rate of ##3.9 \times 10^{26} \ W##. Photons emitted all have a restframe wavelength of 500 nm. Find a crude upper bound for...

Hello all, I have been looking at the arXiv account of the quantum imaging experiment but there are certain features of the theory I am trying to get a better understanding of. The main thing at the moment is the relationship between the signal and idler photons. Consider those idlers that are...

I was always thought that photons were electromagnetic wave-particles. What if they were only EM waves and not particles at all. You are probably going to ask. What about polarization? And if there were 2 spaces intertwined at 90 degree angle. You probably have played with polarized glass and...

A mode of frequency ##\nu## has energy ##E_n = h \nu##. In terms of photons, the interpretation that I have read several places, is that this correspond to ##n## photons of energy ##h \nu##. Furthermore, it is stated that the probabilty of finding ##n## photons at frequency ##\nu## is given by...

Could we split the beam of light in the Hanbury Brown and Twiss effect setup into 3 equal beams each, with each beam having a detector, and measure three photons arriving at nearly the same time at all three detectors? Thanks for any help!

Is there gravity between two photons?

Greetings, I am interested in conducting a retro-causality experiment to send a bit of data back in time. I would like to delay how long it takes one of a pair of entangled photons to reach a part of the experiment for an extended period of time such as an hour. What ways are there to keep...

When the light from a distant star comes to our eyes...as the photons transverse the distance...are they traveling as a particle or as a wave? ie Are we being bombarded by millions of photon bullets or millions of waves? tex

hello everyone I have a question , that is like a story " I talking with my friend about Neutrino and ... " I had written about it at wikipedia and they said that the speed of Neutrino not more than Photons , but I had read that they are faster than Photons speed. which one is true?! I am...

Everyone learns the picture associated with e.g. the Balmer series in Hydrogen: a photon with a precise energy flies in and is absorbed by an electron which is excited into a higher energy state, which then decays to the ground state, re-radiating a photon of that precise frequency. If we...

Hello, I'm thinking about the wavelength of a freely propagating photon vs. a freely propagating electron. For the photon, we have the classical picture of oscillating E and B fields perpendicular to the direction of propagation, and we call the wavelength of the photon, which can be...

Since photons are bosons and do not follow the pauli exclusion principle, does this mean that two photons can be at the same place at the same time? Is it meaningful to talk about a photon 'colliding' with another photon? I mean, suppose we send two photons of the same color towards each...

The photon is the force carrier of the electromagnetic force, I'm not talking about photonics but hasn't the effect of every electric current dc or ac ever been due to photons acting only? In theory couldn't we have an electron-less current due to only photons but still with the same effects?

Hello, Schrödinger's Picture: Researchers Take An Image Without Ever Detecting Light which speaks about the article from nature Quantum imaging with undetected photons" Normally by the entangled it is not possible to transfer information :rolleyes: Patrick

Can someone please tell me the name of the theory describing the interaction of photons with charged particles eg electrons, protons? Can you also suggest a good introductory web page describing that theory at First Year University level for self study? Better still, a good VIDEO lecture on...

Which gases have to capability to absorb light and emit photons of equal frequency?

If a gas is bombarded with light will the atoms absorb the light and emit photons of an equal energy level?

if photons bounce into each other at a frequent rate, and photons bouncing off of each other may result in large change in direction of motion... then why don't we see "junk" photons? photons that enter our eye not because they bounced off a surface, but instead bounces off of another photon?

Here's an experiment using weak measurements on photons in a "nested interferometer." They conclude: In conclusion, we have performed direct measurements which shed new light on the question: Where were the photons passing through an interferometer? The main results are presented in Fig. 2B...

In Feynman's famous book QED, he repeatedly reminds us that we must include the possibilities of photons traveling faster than light and slower than light to get the right answers. At least for short distances, short times. For longer distances, longer times, those possibilities cancel and the...

Why photons can't go any slower than the speed of light, in vacuum? Or if they could, then why they don't?

Hi all, I'm currently studying pair production by two photons (a high-energy one traveling in a isotropic field of low-energy ones), and I'm trying to understand the energy range of the electron created by this phenomenon. For this, I'm studying an old paper from Aharonian 1983...

Does the intensity of light mean increase no. of photons?

What is the current thinking about the waveform of photons? How can finite signals in the time domain produce a discrete frequency response in the frequency domain? As anyone who has worked with signal analysis remembers, the Fourier transforms of time signals in the real world always produce...

Good evening. Usually we say that during light-matter interaction, energy of light should be transferred piece by piece, rather than continuously, with each piece equals hbar*ω. But in photon echo experiment, we say atoms are excited into a "superposition state" of ground state and 1st...

Is there a resonant frequency of light? I was just wondering because the higher the frequency of light, the higher the energy. Or is there an optimal frequency?

Experiment: Imagine the dalayed time quantum eraser experiment, except the pair of "idler" photons(which would normally pass onto the detectors d1,d2,d3,d4) instead fall into a black hole. Would d0 detect interference or not? It seems commonly accepted that the information of...

I thought that it would be possible to get a single photon to a double slit which would be sufficiently coherent to create an interference pattern. You would use entangled photon pairs, which I realize is not coherent light to start with. And use the Alice stream to herald the Bob stream. But...

Hi Everyone There is a problem that I have with understanding what happens when photons are emitted "one-at-a-time" in the Young's Slits experiment. However, I think I may have come up with a solution to this problem and would be very grateful for your thoughts. Let's say a single photon...

I deliberately wrote that heading not quite accurate, as a photon is more of a probability thing, and so might not have an electric field at all. But what I'm getting at is, we know a photon doesn't have a well defined amplitude, but it does have a frequency. So what I wan't to know regarding...

According to my understanding of SR, a light photon traveling at c, of course, relative to me "experiences" no time. In other words, it is not traveling through, at least, the time dimension I am traveling through. A neutrino, say, moving close to c does, but it is traveling very slowly...

Hi there. I have a couple of questions regarding the derivation of the Boltzmann equation in Dodelson for photons when given scalar overdensity perturbations to the FRW metric. To start with, let ##\Theta(\vec{x})## denote the temperature perturbations to the Bose-Einstein distribution of the...

I have seen many 'photoelectric effect vs compton effect' Questions in this and other forums, but i am still not convinced. I can see how photoelectric effect points to the particle nature of light. But i don't see how compton effect as a separate experiment is needed to confirm this. The only...

Hello everyone, I have a question about the process of spontaneous parametric down conversion (or SPDC). This process is used to create two entangled photons in the visible regime by shining a laser through a beta-barium borate (BBO) nonlinear crystal. My question is, can this process be...

I'll describe what I "think" a photon is and once any misunderstanding I have has been corrected then any problems I have following the correction should probably be ignored as I will have to re-evaluate from that point. So here goes. Its an electromagnetic wave that's emitted from an atom...

What actually are photons, means are they packets of energy or some sort of matter.

If two photons ( A and B ) are traveling in opposite directions from a point in a vacuum will the relative speed of photon A to photon B be grater then C?

i have read that existence of photons as a mass less particles came from the energy momentum equation. E^2 = (mc^2)^2 + (pc)^2 and that since when m = 0, there is still an energy = pc but, sunce momentum defined as m*v, and mass is absolute quantity, then why that m = 0 which we were...