Photons Definition and 1000 Threads

I've been reading about the photoelectric effect, and something got me thinking. If the frequency of light shone onto the metal is below the threshold frequency, no electrons are liberated from the surface of the metal, since electrons absorb quanta of energy, so if that light is shone for a...

I've looked up this question on the web, and I've gotten seeming conflicting answers. According to Feynman's path integral - to find the probability of a photon being at A at time 1 and B at time 2 can be determined by taking an integral of the photon traveling over all possible paths. I...

Hello all, I was driving down the road yesterday, and I realized that I don't really have a solid grasp on how frictional forces cause infrared radiation. Can anyone explain, or direct me to a resource that explains, how this happens at the atomic level? I am thinking that the work done...

Two photons arrive at a hypothetical 50:50 Beam-Splitter with no phase shift between reflected and transmitted modes. One enters the Left side and the other the Bottom side of the BS as shown in Fig.1 of the link below: https://drive.google.com/open?id=0B5JsDLKoUSA5emk5Qk9nUHVIelE Each photon...

Does GR allow for photons to be in a stable orbit around a massive body?

I have read that photons do not experience time... If that's the case then if a particular photon is emitted by a body then that should exist in every time relative to us i.e that same photon should be there at exactly the same point forever.

The wave-particle duality of light was demonstrated first with Thomas Young's 1801 Interference Experiment...and then more clearly with the Double Slit Experiment. Both of these were done with light (so photons). My question is -- How did we come to understand the same of electrons? Did we...

In an effort to understand how an electron and proton attract each other in the QFT picture, I am wondering if there any differences at all between photons (virtual or whatever) emitted by electrons and photons emitted by protons? For instance, do photons from protons have a different spin or...

What are currently the best cost-effective ways to temporarily store a photon and preserve its phase? Or, at least, to slow down light? A fiber optic cable is definitely cost-effective for the latter, but not practical for intervals longer than 1µs due to absorption losses and length.

Putting a soft photon in vacuum will result in a zero energy vacuum state. Despite the zero energy, has this state vacuum fluctuations? Putting more of these photons will result in more vacuum states. Would they have vacuum fluctuations as well resulting in more vacuum flctuations? A total...

Homework Statement Calculate the mean number of photons in a cavity at temperature T and the mean energy per photon. Homework Equations In the large volume limit, the log of grand canonical partition function is: ##log(Z_g) = \frac{gV}{h^3}\int log(1-e^{(E-\mu)/kT})dp^3 ##, with g - spin...

When looking at a night light with almost closed eyes, I notice that the light becomes a vertical line. When tilting my head 90 degrees, the line becomes horizontal. Can this be explained by Heisenberg's Uncertainty principle? This question has been asked in another thread : "Squinting at...

This a really simple question: If I have, say, 2 ions close to one another, and measure their repulsion very precisely, is the force constant, or is it a series of little pushes caused by individual virtual photons? I know there are many misunderstandings about virtual particles, but I'm not...

I have heard a virtual phton as used in QED defined as being forced carriers between two fermions which last for very short periods of time. A couple of questions about this: 1) how do we know these are photons and not some other force carrier if we cannot detect them directly? 2) can...

Hi, I got the following question in my textbook: [translated]"Compare the wavelength of a photon and an electron where the photon and the electron have the same momentum". My thinking is the following: Firstly, pp (photon) = pe (electron). My textbook briefly mentions the extention of the...

hi everyone. i'm only 16 so please beer that in mind. I've been doing some reading around and have come across the idea that light slows down in an dense medium as a result of the photons moving tough other particles with a slight delay however they retain all factors about them selves apron...

All these videos and articles about the Double Slit Experiment say that if we "look" where the single photons go, they act like particles and if we don't "look" they act like waves, creating the interference pattern... BUT What does it mean to "look"? We're not using our eyes or any camera...

Does anybody know what a photon is? Light used to be known as electromagnetic wave till 1900, but then it's particle was made justified by photoelectric effect, Compton effect. And we know about diffraction, interference, etc. And it has no mass.

Xiao et al say the following here: https://arxiv.org/pdf/1703.03818.pdf Is this correct? I'm finding it hard to believe that there is a probability that some irreversible events will occur that would ultimately result in heating up the mask (screen with slits). I mean, we could always make the...

Homework Statement (a)Estimate the number of photons per second emitted by a 100-W lightbulb, assuming a photon wavelength of 550nm.(b) A person can just see this bulb for a distance of 800m, with the pupil dilated to 7.5mm. How many photons per second are entering the pupil? Homework...

The photoelectric effect is usually presented as an example disproving classical electromagnetism as viable model for interaction of light with matter and as evidence of quantization of energy in the electromagnetic field, i.e. the existence of photons. I would like to discuss a thought based on...

If two observers on Earth in different locations around the globe, were both viewing the CMB with their equipment pointing at the same point in the sky, and charting the fluctuations in it, would they correspond or vary from each other greatly. In other words, if you made a graph of the CMB and...

Is there a single optical component that will do the following? Do nothing to the horizontally polarized input, but rotate the vertically polarized input by 90 degrees, so that both beams finally emerge with the same polarization? I am looking for a single element that will replace the...

can light collectively or individual photons act as a medium for propagation of sound waves?

https://en.wikipedia.org/wiki/Very-high-energy_gamma_ray Wikipedia says this about Very-High-Energy Gamma Rays: This is approximately equal to wavelengths between 1.24 × 10−17 and 1.24 × 10−20 meters, or frequencies of 2.42 × 1025 to 2.42 × 1028 Hz. Such energy levels have been detected from...

I understand that laser is based on the phenomenon of coherence. But I wonder how, say, two photons could be said to be located at the exact same spot when their locations could not be precisely defined due to the principle of uncertainty. To specify, which between the following two would be...

Gabriela Lemos and her team successfully entangled photons. Would it be possible to explore the interior of a black hole by letting one of the entangled photons enter beyond the event horizon and observe the impact on the other?

What if I replaced the half transparent mirror in a laser cavity with a 100% reflective mirror? -would all photons escape due to the quantum tunneling effect? -would the mirrors melt? Thanks :biggrin:

Like every wave, light has a frequency and an amplitude. So far, I know that the frequency equals to the photon energy and the amplitude to the amount of photons. My question is: how big is that amplitude and does it matter? Thanks for every reply :wink:

Are two entangled photons described by the same wave function or wave function shape? Heres an example... Say for example, we have a laser in TEM01 mode that is shooting individual photons (this mode as two distinct maxima). Then the individual photons are going through a BBO crystal to become a...

I understand that in the standard model, photons are the carriers of the EM force. Does that apply to a normal bar magnet? I.e., when you sprinkle iron filings near a bar magnet and the filings align along the field lines, does that mean that photons are being exchanged between the magnet and...

Hi at all! I need one more help from you. 1. Homework Statement 123.4 eV photons ionize further a rarefied gas of ##B^{2+}## ions. A small fraction of electrons emitted in this process is immediately captured by ##B^{3+}## ion, going to occupy the states 2p, 3p, and 3d. Calculate the minimum...

It is known that particles with rest mass cannot travel at the speed of light. Can we also say that particles that travel at subliminal velocity, like these OAM photons do, have mass? It has been demonstrated [1] that these beams can be thought as made of photons that posses intrinsic OAM, and...

Homework Statement A ##\pi^0## meson decays predominantly to two photons. Suppose the energies (E1, E2) and angle (##\theta##) between the emitted photons are measured. Find an expression for the ##\pi^0## mass in terms of E1, E2, and ##\theta##. Homework EquationsThe Attempt at a Solution...

My understanding is that the wavelength or frequency of an individual photon cannot be reliably measured. For example, if a beam of monochromatic light is filtered so that only one photon at a time enters a spectroscope, each photon may land anywhere on the screen. Only when a statistically...

Why does the energy of a photon increase when falling into a gravitational field ? If we use the equation E=hf, then the energy of the photon increases, but I understand that we also need to add the potential energy to find the total energy. Et=Ep+hf. The potential energy decreases by the same...

Photons are prepared in a vertical state (90º), split in a crystal and sent to Bob and Alice. Both Bob and Alice will measure 100% vertical and 0% horizontal. Photons are prepared in a 45º state, split in a crystal and sent to Bob and Alice. Both Bob and Alice will measure 50% vertical and 50%...

Quantum electrodynamics "states that any particle (e.g. a photon or an electron) propagates over all available, unobstructed paths and that the interference, or superposition, of its wavefunction over all those paths at the point of observation gives the probability of detecting the particle at...

Homework Statement Earlier my teacher put this equation on the board, π_0 --> γ+γ It appears to work until you consider spin. Homework Equations a quick google search reveals that the spin of a photon is +1 and the spin of a pi meson is 0 The Attempt at a Solution This appears to work for...

This question came to mind from the thread... https://www.physicsforums.com/threads/can-a-photon-be-accelerated.901484/ Knowing... 1) Strong gravitational fields create strong curves in spacetime 2) Light traveling through strong gravitational fields get curved along the spacetime 3)...

1 - Huygens-Fresnel principle states that every point in a light wave is itself a wave source, 2 - light is made of photons, 3 - photons have a wavelength, they are QM objects. Hence my question : are photons the actual wave sources in Huygens-Fresnel principle ? Or are those two...

Hello, This has been bugging me for some time now, so I would be interested to see what I have been missing so far. Imagine a single ray of light (made up of many photons) hitting a perfectly non-absorbing (for this wavelength of light) spherical dielectric object, which has finite mass. The...

When computing the probability distribution of bosons, why is A = 1 for photons? Does this not imply that photons will have an increasingly high probability of being present as E approaches 0? What is the significance of such a situation?

Because they are massless, could you theoretically fit an infinite number of Photons into a small space? There is probably an equation that proves this wrong but I'm curious.

Hello, Ok, so I’ve been searching about this for a while and there seems to be a difference in explanations that confuses me. What concerns me is the exact detailed physical mechanism that makes particles cause a scatter of a photon and an emission of a photon. The Wiki page about scattering...

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...

i know that the total energy density of a blackbody radiation is E= 4 segma/C * T^4 so how i can use this to find the number of the CMB photons in 0.25 litre?

Are photons(when described as a particle) considered objects? You can't see them on an individual level, but they hit you and interact with gravity. Might be a silly question, but was just debating it with a friend.

Let me start off with a reference: http://www.lithoguru.com/scientist/lithobasics.html This is an article about the field of lithography and microlithography. Before anyone dismisses the importance of this technology , let me point out that it is used to make EVERY integrated circuit and...

So according to QFT, fundamental particles are just excitations in their underlying fields. So the photon would correspond to an oscillation of the EM field. But it takes energy to excite this field. And E=mc^2. So therefore the photon should have some mass. Energy was put into create it. That...