# photon

1. ### B Does time exist for photons?

Do photons, I'm not sure how to express this, "experience" time? Since they move at the speed of light does time not exist for them? If time does not exist, how is it possible for anything to happen to them. If interacting with matter requires a change in their condition, how can a change in...
2. ### B Detecting a photon passing through a slit without destroying it?

I cannot see how a photon can be detected and yet remain the same photon. I am thinking that the description "If a detector is place at each slit so that we know which slit the photon passsed through, the interefence patten does not form" is sloppy and in error.
3. ### I Photon Bell Experiment, what happens in a single case?

I am wondering what happens in the case of 100 entangled photons with a polarization angle of 0 degrees (or 0 and 90) that interact with Alice at 22,5 degrees and Bob at 45 degrees in a Bell Experiment. Do I get a count of 85 for Alice and 50 for Bob, which means a maximum coincidence count...
4. ### I Is the energy of a burst of light the sum of the energy of each photon?

In A.P. French's Special relativity the author said, The mass and length of the box are irrelevant here. He said the momentum of the radiation is $E_{radiation}/c$. We know that the momentum of a single photon with energy $E_{photon}$ is $p_{photon}=E_{photon}/c$. So is...
5. ### B Tachyon's existence

A tachyon or tachyonic particle is a hypothetical particle that always travels faster than light. Most physicists believe that faster-than-light particles cannot exist because they are not consistent with the known laws of physics. - Tachyon definition The photon is a type of elementary...
6. ### B Position of a particle and photons

Once I have read that we can’t know a actual position of a particle because to see the particle we need to send photons and when we send photons it colides with the particle and change it’s position. Is this true?
7. ### Find the photon energy in the center of mass frame and vice versa

I tried to use the Lorentz transformation: $E^{*}_{\gamma }=\gamma _{cm}E_{\gamma }-\beta _{cm}\gamma _{cm}p_{\gamma }$ We have a photon, so it becomes: $E^{*}_{\gamma }=\gamma _{cm}E_{\gamma }(\beta _{cm}-1)$ Unfortunately, the solutions say that the correct way is to use the inverse...
8. ### I Mach-Zender-Interferometer with polarizers

I have a question on how exactly polarizing filters would influence interference in a Mach-Zehnder interferometer. To explain, I'll show some configurations and what I would expect to happen - please tell me if I am incorrect anywhere. Here is the standard MZI configuration with no filters and...
9. ### Poisson distribution and Shot Noise

My setup: I have the an LED (LED370E) in front of a photodiode (S12915-16R). The photodiode is connected to an ADC (DT5751) which has a counting functionality. The way it works is that it counts how many times the signal goes above a certain threshold and makes a histogram out of it. I know...
10. ### Calculate the energy release of an atom

First of, I have no idea what I'm supposed to do with the neutrinos and the photons. Can somebody explain how to handle these? The rest of what I tried is quite straight forward \begin{align*}\Delta E &= 4M_p - M_{He} - 2 M_e + E_{\text{Neutrino and Photons}}\\&= 4M_p - (2[M_p+M_n]-E_B) - 2...
11. ### Energy of a photon

So i'm a chemistry student here in the UK - and i'm feeling a bit like a fish out of water on a physics forum but... i'm having trouble with a derivation that seems simple but i can't for some reason seem to understand. I know that the energy of a photon is given by E=hc and that c=lambda*v...
12. ### B But WHY do antimatter and matter annihilate on contact?

Everyone knows that matter and antimatter annihilate upon contact. But exactly WHY this should happen is not at all obvious, at least to me. So what exactly happens when two such particles encounter one another that leads them to disappear in a large release of photons? And for that matter...
13. ### What happens to a light photon when it hits glass?

Homework Statement Using quantum mechanics, what happens when a photon of light hits glass? Homework Equations Momentum= Mass x velocity The Attempt at a Solution I am not sure of my answer but suffice to say the following: Assuming the collision between the photon particle and those in the...
14. ### B What is the size of a VHF photon?

I read that electromagnetic radiation behaves both as particle and as wave, in what is called wave–particle duality. Given that the radio waves of VHF television have wavelengths from one to ten meters, what is the size of a "VHF photon"?
15. ### B Photon solar deflection

For a photon passing close to the Sun, Newtonian physics predicts a deflection of 0.85o. GR gives the correct 1.7o. Can the true value alternatively be obtained via 1) a Newtonian model, and 2) gravitational time dilation: the photon's slower speed near the Sun leads to it spending more time in...
16. ### Relativistic momentum of two photons from a decay

Homework Statement Homework Equations (1) E2 = p2c2 + m02c4 (2) E = γm0c2 (3) E = Eγ1 - Eγ2 (4) p = E / c (5) E = hf (6) λ = c / f The Attempt at a Solution a) Using eqn (1), rearranged p = (E - m0c2) / c , I obtained 2.9 MeV c-1. Not sure if I have the right answer here as I...
17. ### B How to determine the wavefunction of photons?

Hi, I'm sorry if this question has already been answered somewhere and I'm just too incompetent to find it, buuut: As the title already says, I really do not get that part of quantum physics (if you can even say I'm getting ANY part at all...). As I searched all Google for an answer I just...
18. ### B What happens to the wave function if...

The question is; In an experimental small universe, a photon is released from a source. It continues its path as a probabilistic wave function. if it interacted with mass, we could say the wave function collapsed and observe a particle photon hitting an object. But what happens when the photon...
19. ### B Is our Universe a single point for a photon?

I have come across a questions which reads "Why does even photon travel?". After reading special and general theory of relativity, this one bugs me all over. For a particle moving closer to speed of light, clock slows down and the space around it contracts. I see a photon travel and I see things...
20. ### Relative speed of two photons

Homework Statement What is the speed of a photon with respect to another photon if: the two photons are going in the same direction. they are going in opposite direction? 2. The attempt at a solution I think the answer to the first question should be zero and to the second one be 2xC; C⇒speed...
21. ### B Do photons experience time?

As far as I know, a object will experience time slower when its speed is close to the speed of light. But photons themselves moves at the speed of light, does that mean that they experience no time?
22. ### B In night vision equipment, how does 'information' transfer?

So I read a couple of explanations of how night-vision equipment works. Unfortunately I don't remember the sources but my recollection/understanding is that infrared light is converted into electrons and then in to visible light. So my question is how does the information by which I mean (the...
23. ### I Still have questions about photon mass

Just read the FAQ post "Do photons have mass?" and I'm still confused. The post says that all of the photon's energy is in the pc term of the energy-momentum equation. (1) But isn't p equal to mv, implying there is mass? (2) The post also says there is no inconsistency with E=mc^2 but doesn't...
24. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 1: Introduction

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
25. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 2: Introduction to Classical Field Theory

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
26. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 3: Quantization of Real Scalar Field - 1

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
27. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 4: Quantization of Real Scalar Field - 2

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
28. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 5: Quantization of Real Scalar Field - 3

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
29. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 6: Quantization of Real Scalar Field - 4

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065
30. ### Quantum Field Theory by Dr. Prasanta Tripathy (NPTEL):- Lecture - 7: Quantization of Complex Scalar Field

Copyright reserved to Prof. Tripathy and NPTEL, Govt. of India. Duplication prohibited. Lectures: http://nptel.ac.in/courses/115106065/ Syllabus: http://nptel.ac.in/syllabus/syllabus.php?subjectId=115106065