Photons Definition and 1000 Threads

There are two polarization filters, A and B. Polarization filter A has angle of 0° and B has an angle of 30°. A photon is in superposition, so it doesn't have a definite polarization axis. The likelihood it's passing through a filter is depend on the difference between angle of the...

Ambient for lack of a better term... I'm reading "Beyond The Cosmic Landscape". Perhaps out of date, but a very understandable explanation of QED. Am I right to deduce that the air which surrounds us is jam-packed with electrons emitting photons? Thanks...

Hi. If we have 1 million entangled photons separated from their "entangled partner". We send all those photons (without their "entangled partners") through a polarizer. Each photon has has 50% chance of passing through the polarizer. So 50% of the photons will pass through the polarizer and...

Hi everyone, I do experiment in field of quantum optics and I want to calculate the mean of the number of photons (MNP). In the most of papers, MNP can be calculated by using average power which is measured by power meter. But my power meter is defective. For now, I have only the avalanche...

Homework Statement Discuss the concept of the wave-particle duality for electrons and photons and include an equation which connects the wave like and particle like properties. Homework EquationsThe Attempt at a Solution So I am having trouble with how to word this question and generally...

It’s written almost all physics books and courses that entangled photons can’t be used for faster than light communication. The question about used entangled photons to communicate faster than light has been discussed before, but I didn’t get exactly why faster than light communication with...

Solar sails use the push of photons on a mirror. Would it work to use the push of photons in the atoms in fiber optic cables so the question is would there be push and how much on 1 mile of a space train 50 feet wide with 1 foot thick of fiber optics. Here's how I think it would be nearly...

When we look at the cars on the road, it appears like where they are driving is random, their directions appear as random. But the drivers don't drive into random directions. It appears random to us because we don't know the thoughts and intentions of the drivers. If we knew almost everything...

This question has been bothering me for decades: Imagine a point source in space that emits one photon per second. Would the photon expand in a globe in all directions until it strikes an object or would the photon shoot off in a random direction? Suppose you have one target ten meters away...

given a complete vacume.(Excluding the photons) given a volume. given a temprature. given a wavelenth. work out the number of photons in the vacume?

General question regarding how images are formed. As you move your eye "detector" around a illuminated room. The is image of let's say "a book" is in every position in the room at a given time correct--even before you "look" at it? The photons reflected off the book have formed an image of the...

If you have two similar coherent sources which are separated from each other by a barrier. Now one source sends particles one by one into one slit and the other sends particles into the other in a double slit interference experiment. Now, the photons are always undistinguishable, so they should...

Can a photon ever change frequency? What I mean is, can say a photon of red light ever become a photon of green or yellow light?

We're told that all electromagnetic radiation consists of photons. But you never hear them mentioned when discussing low-frequency radio waves. Why not? I get that, due to the low frequencies, the energy of each individual photon would be very small, so there must be lots and lots of them flying...

I know little about QED, QCD, and whatever the corresponding theory for the weak force is, and of course virtually nothing about the quantized theory of the gravitational force, which mostly doesn’t exist, so the following arguments and questions may be somewhat wrongly based where they refer...

Consider a box whose walls are mirrors. Suppose we trap a bunch (yes, it's vague) of photons inside the box. They will not escape, or assume that a major part of them will not escape the box. Now suppose we have a way of decreasing the size of the box at our will, but possibly obeying the laws...

<< Mentor Note -- thread moved from the technical forums, so no Homework Help Template is shown >> Let's say you have a laser cavity with two mirrors at either end, one is considered 100% reflective, the other 99.9%, so that a wave beam is emitted through this lower reflectivity mirror. I know...

If photons are light particles, and they lack mass, how is it possible that they are affected by gravitational pull from a black hole? Super sorry if this has been asked / answered before, I couldn't find it on this forum if it has... Caveat No.2: My physics knowledge was limited to high school...

Hi. Maybe you can help me understand something. Two identical photons travel parallel in a vacuum. I want the lines of their trajectories to be as close to each other as possible. 1. If each photon could observe the other, what would it detect? 2. Is there a minimum separation necessary to...

I'm trying to understand the time delay induced on each photon when several individual photons travel in an open space from a sender to a receiver for example in the application of Quantum Key Distribution. So what I understand so far is light(photon) travel around 299,792 km (186,282 miles) per...

What's the interval between photons in stimulated emission? In stimulated emission one photon induces the emission of a second photon whose coherence length, energy, polarisation and direction of travel are all identical to its own. There must be a delay between the two photons, see below, so...

Other than relativity is there any theory, proof, experiment, etc. that tells us a photon has no mass? i.e. Is the concept of zero mass solely derived from relativity

Let's say I feed the same electrical signal into the opposed windings of a contrawound toroidal coil, and that this results in their individual electromagnetic fields cancelling to "zero". Can someone explain what in turn happens to the virtual photons associated with those canceled fields? For...

When I look at certain experiments involving entangled photons generated by spdc, for example quantum eraser experiments, it seems to me that each observed pair of entangled photons is propagated in a horizontal plane. However, aren't the entangled photons generated randomly in all planes...

When why sey that light is electromagnetic wave i understand this. But what i do not understand is where photons come into picture ? can somebody explain me the relationship between those two . My knowledge in this respect is not great so I would ask that the answers be adjusted .

from wiki "Although the photoelectric effect and Compton scattering strongly suggest the existence of the photon, it might alternatively be explained by a mere quantization of emission; more definitive evidence of the quantum nature of radiation is now taken up into modern quantum optics as in...

Homework Statement Homework EquationsThe Attempt at a Solution As frequency is decreased to threshold, no. of emitted electrons will remain same, but their maximum kinetic energy will decrease. So, the current should decrease slowly. For frequency less than the threshold frequency, no...

Me and my friend have recently (half a year ago) had a huge debate, between ourselves, about the wave-particle duality. We took sides in light being a particle or a wave. I was for particle he was for waves. At the end of a hot-filled week of arguing, the debate ended up with the acceptance of...

Homework Statement Make a very rough estimate of the probability that two high energy photons with an invariant mass of 126GeV are decay products of the Higgs. Use information found elsewhere (so I need to find this info preferably on the internet). Homework EquationsThe Attempt at a Solution...

On the following link https://physics.stackexchange.com/questions/183961/modified-double-slit-experiment-two-electron-sources-instead-of-two-slits there is a discussion of the modification of double-slit experiments where two electrons sources are put in place of the slits. The conclusion is -...

Hi everyone! Sorry for the bad English! Please, I learned that a wave is something the photons "surf" on, like, in one electromagnetic wave, can have many photons. So, is this true? Like, I though that one gamma ray and an infrared photon would ride different waves... More: the light from the...

Hi, Can someone please explain as to why light beams attract or repel each other even when they don't have charge. Seems like it behaves like two current carrying parallel wires. There is very little material about this which goes completely above the head. Thanks

If there were dark photons in the dark matter sector.. should it be described by gauge symmetry.. in other words.. should the dark photons be gauge bosons? or nongauge bosons just like the higgs?

I've read that a particle's position can be measured by firing a photon at it, but how does one actually determine the position of the particle by doing this? What is the maths behind it (is it calculated from momentum conservation)? Furthermore, I've read that increasing the energy of the...

Homework Statement According to the Big Bang model of cosmology, the universe has been expanding since some initial time (call it t = 0) when the temperature was infinite. At early times, the temperature T scales as t^1/2 . The current temperature is about 3K. Consider the part of space which...

If we (a detector) are moving toward a star that emits a single photon (due to its distance) and that photon hits our detector, it will be blue shifted. My question is why. If the color of a photon is a reflection of its energy level and since the speed of the photon is always coming at us at...

Some will claim that RF energy being composed of photons can only be accepted on faith because there is no experimental evidence and there probably will be no experimental evidence due to the comparatively long wavelenghts of RF waves. But the technique of NMR (nuclear magnetic resonance)...

Photons contain kinetic energy. When you entangle photons, do you change the properties of the kinetic energy which forms the wave energy? Kinetic energy is proportional to temperature... Kinetic energy is also proportional to relativistic mass.(in Special Relativity) So is the mass of...

What is the interpretation of the fact that photons have spin zero? Does it has do to with the fact that their proper time variation is zero? Or let's go a bit deeper into the math. If it's possible to write down an eigenvalue equation for photons as it is possible for electrons, then we should...

If you search for "does a photon experience time", almost every other link says that they travel at the speed of light and so STR tells us that its clock doesn't tick at all. However why do they use the arguments for special relativity which was developed for massive particles moving close to...

I heard that you can never really touch anything. I also heard from an article that the reason why your butt doesn't fall through your chair is due to forces. Here is a short excerpt: "Cracking like lightning through the void, all the specks of electrons and the specks of nuclei are constantly...

Relative to the observer, objects shorten when approaching the speed of light exponentially. Does this rule also apply to the wave function? Does this rule also apply to massless particles like Photons? Or am I just simply forgetting something?

In classical physics, EM waves propagate this is one of the main features of all waves in general. Usually for mechanical waves the elements (like molecules) that vibrate do some little motion. For example a string can move up and down, but the waves travel further through propagation. The...

I'm having trouble understanding how simple particles can be received and then with that information translated into a song on the radio or a program on television. Any help?

Is there more to our universe than what we can observe? If so, does that mean that photons from the CMB are traveling towards us from beyond our cosmological horizon?

Hello all. I am trying to determine what is the effect of having photons that are distinguishable undergoing a quantum interference process. To do that, I try to generalize the Hong-Ou-Mandel effect, and try to determine what are the terms that appear as a function of the product of the creation...

If one was to create an array of X amount of mirrors tracking the sun and shining on a targeted spot in the sky to create ions at specific elevations similar to a ladder, could this cause an ion column to create a continuous charge of energy from the upper atmosphere to hit the ground? Lets...

Hello all, I came to know that electric(electromagnetic in general) force between charge particles is mediated by photons. At first I just wondered what are photons doing here? I mean till what I know is that photons bundels of energy for em radiation and that they are massless but have...

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...