It seems a gravitational field does not alter the electromagnetic field strength. Is this correct?
My reasoning:
With no gravity, field strength is:
F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu
Introduce gravity:
\partial_\mu A_\nu \rightarrow \nabla_\mu A_\nu = \partial_\mu A_\nu +...
We know that photons (light) are massless but they have momentum. Now suppose I am in the space far away from planets/stars that there is no external force exerts on me, if:
1- I turn on a flashlight (torch), would I be pushed in the opposite direction which the flashlight is facing (Newton's...
In A.P. French's Special Relativity, the author said the following,
As I understand, photons are massless, so I don't think the last equation above applies to photons, but then, when deriving it, he used an equation proper to photons (##E=pc##).
So in which context is ##m=p/c## valid?
According to the 2nd postulate of Special Relativity, speed of light in vacuum is the same in all inertial reference frames.
If I take a beam of photons and see the other photons in the beam from a frame of reference of a single photon, do they look stationary or moving at the speed of light...
Suppose one measures the position of a photon without destroying it. From my understanding, the wavefunction of the photon should collapse, and will return to a more spread out state over time. How would one calculate this, specifically the rate at which the wavefunction spreads out from the center?
I'm not an expert in this matter, and at best only aware of some superficial facts and a layman's understanding of them. So please forgive me for any ignorant mistakes in my thoughts, and kindly point them out to me.
Going by the Lambda-CDM model, the expansion of the Universe will eventually...
Summary: massless particles (or at least photons) are attracted to other photons and to matter, but which is most attractive, and why ...
Summary: massless particles (or at least photons) are attracted to other photons and to matter, but which is most attractive, and why ...
I am really...
Hello,
I have some trouble understanding how to construct the matrix for the beam splitter (in a Mach-Zehnder interferometer).
I started with deciding my input and output states for the photon.
I then use Borns rule, which I have attached below:
To get the following for the state space...
The problem says: A radio station emits electromagnetic wave with a frequency of 100MHz (102*106 Hz).
a)What's the energy of this radiation's/glow's photon? (Solved, i found 6,63*10-26 J)
b)Compare your calculation with the energy of another visible radiation/glow, with a wavelength of 600nm...
Homework Statement
The laser cavity is formed by two mirrors separated by 15 cm. One of the mirrors has an ultra-high reflectivity and the output mirror has the much lower reflectivity of 99.5 %. How many photons are there in the cavity?[/B]
The power of the laser is 1mW and the wavelength is...
Homework Statement
Suppose two polarization-entangled photons A and B in the following Bell state:
\begin{equation}
\Phi=\frac{1}{\sqrt{2}}\bigl(\left|H_{A},H_{B}\right\rangle + \left| V_{A},V_{B}\right\rangle\bigr)
\end{equation}
1. What is the state if the photon A passes through a...
I understand the concept of stimulated emission and how it works as light amplification, but a certain technicality in its process eludes me. How is the inciting photon actually interacting with the electron that falls to a lower energy level?
In every physical interaction that I know of there...
Hi,
I have come across the word coupling a few times looking at surface plasmons and surface plasmon polaritons. I was wondering if anyone could give me a better understanding of what it means for something like a photon to couple to a plasmons to creating a plasmon polariton. From what I'm...
Simple question. Are photons reflected as is from a surface like a mirror, or is the reflecting surface atoms capturing the photons and re-emitting them?
After I read Martin_K's post of 4:14 Oct. 30 on the frozen image of an object just before it fell through a black hole's event horizon, the next few minutes I was jumped by a handful of related ideas.
First, the frozen image scenario is illustrative because when photons are frozen in place...
So I'm kind of confused. The way I understand it, an electromagnetic field is just a regular electric field viewed from a relativistic point of view, meaning that since we see the charges moving relative to us, we feel like the particles and the fields created by them come closer together (I...
In the last paragraph of these notes, https://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2016/lecture-notes/MIT8_04S16_LecNotes3.pdf, it says how a state with large number of photons is not classical. Why is that? I thought quantum mechanics' laws were most applicable when we...
Can an on board laser be used to propel a solar sail space craft if the laser is pointed at the sails ?
Would Newtons third law affect the laser and maybe prevent the ship from moving ?
Thank you for answering my very ignorant questions.
NineNinjas911
The way I understand this is that Relativity says space-time is like a field that's affected by the way mass moves through it. Photons are massless so is this why the speed of light is the same in all reference frames?
In basic electrostatics any charged particle will produce an electric field at every point in space, and will have electric filed lines spreading out radially.
E = kQ/r^2
The Standard model of particle physics says that the Photon is the force carrier for the Electromagnetic force, just like...
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...
General question regarding how images are formed. As you move your eye "detector" around a illuminated room. The is image of lets 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...
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
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...
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
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...