Photon Definition and 1000 Threads

Am I right when I say that you can orbit the photon sphere and still be not pulled towards the Event Horizon but you need to orbit (In your spaceship) at the speed of light?

Photons with smaller and smaller wave lengths have a higher and higher energy and these engeries have an increasing Schwarzschild radius r_s. Consequently i can ask when half the wave length \lambda/2 is equal to r_s, such that one wave length fits into the sphere of the Schwarzschild radius. I...

Hello all, I have a few questions and a few thoughts I think I understand that according to einsteins theory of relativity, wavelengths can be perceived differently when traveling at different velocities comparatively to when it was emitted. i.e. if something traveling close to the speed...

How an electron transition from lower energy state to higher energy state in hydrogen atom emits a photon?

I'm thinking about photons of low frequency as would be produced by a radio transmitter. How would a transmitter have to be set up to transmit just one photon? The smallest transmission I can think of would be to move 1 electron from one end of the antenna to the other. I would think that would...

Homework Statement http://puu.sh/brbpb/3c7573fa32.png Homework Equations E = (mc^2 +K + mc^2 + K) P = E/c E = mc^2 The Attempt at a Solution The book says that the momentum/kinetic energy of the electron and positron produced in a pair production is so small that it can be...

From what I understand, the little group for a particle moving at the speed of light, has 3 generators. 2 generators generate gauge transformation, and 1 generator rotates the particle about its axis of motion. I have 3 questions: 1) Do all particles moving at the speed of light (not...

So when it encounters a linear polariser, and is transmitted through , what actually happens to the photon. Has it stopped vibrating in the plane perpendicular to the polariser, when it emerges? This would be my obvious conclusion. Since putting a second perpendicular polariser...

I'm quite confusing with the theoretical method to estimate photon flux in a media. The method I knew is use the density of photon multiplied by the velocity of photon. Considering the solid angle distribution, for a certain direction only a part of π/4π can be delivery, therefore the...

Dear all, If I have the value of photosynthetic photon flux in unit [ micro mole per meter square per second] as an output for ultra violet sensor. How can I know the corresponding wavelength of that radiation ? and can I know from that wavelength what is the type of the ultraviolet...

When the two polarizers are set 60 degrees apart, for example, QM prediction is 25% correlation. It is already different than what is believed to be classical or "expected" result. So what is the point of testing more than one angle in a single experiment? And what difference does it make when...

Can you explain please! thank you.

An M.I.T. Physics lecture mentioned B and E crossing over the x-axis as lowest energy state/position of the wave(s). Along the x axis, path of photon, is photon momentum here the lowest also? Does momentum vary? For a tiny target, if a photon collides at this exact point is there no momentum...

Equations of state for photon gas and relativistic electron gas This entry develops equations of state that are useful in calculations about cosmology and about the insides of stars. The first calculation is for a photon gas and the second is for a 'relativistic' gas of particles with mass...

Initial assumptions : 1. An unpolarised photon has 50% chance of being transmitted through a linear polariser. 2. When a photon meets a polarizer we subject it to an observation. 3. The effect being that we have forced it to collapse from being in the superposition of the vertical and...

Dear mates: During ionization with radiant energy there is a photon emission (see http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html). I know photon emission occurs by a decay of radiant energy from a excited state and what is confusing to me (I can't find a logical conection) is that...

I am trying to understand what is meant by the phrase 'absorbed and emitted bosons'. Is it the same as destroyed and created? Suppose we have an electron in an atom at energy-level1. The electron 'absorbs' a photon (its kinetic energy) and is put into energy-level3. Does the photon still exist...

Are lower energy electron orbitals always closer to nucleus than higher energy orbitals? Is this energy proportional to the inverse square law and Coulomb's law? When an electron jumps down to a lower energy orbital, is potential energy not just converted to kinetic energy, and so where does...

Imagine a theoretical universe which contained only two photons with the same energy. Imagine that each photon began at approximately the same point and traveled in exactly opposite directions. I believe that general relativity predicts that photons exert a gravitational force on each other...

Hello, I read the Feynman's QED book, where I learned that a photon has a intrinsic property called frequency. This property affect, for example, the interference profile when we have a lot of photon together. Ok. Now, thinking on an conventional antenna. When we have a 100kHz signal on...

Hello, I am wondering about a photon absorption/emission by an atom. We have been told at the university an electron is excited up in Bohr's model if an atom absorbs an energy in a form of photon. What cause an electron release an energy and falls down in Bohr's model? Does not an atom...

Hi guys! I have come across a problem I can't seem to wrap my head around. I've learned that E.M. radiation can be propagated by discrete packets of energy , photons. Is the energy of each photon discrete, or can it have a continuous range of energies depending on its frequency? I would be...

I am curious what a photon looks like if we could observe it pass through space. It's also supposed to be oscillation of electromagnetic field. I don't understand what that means. Is it the field gets stronger and weaker and stronger and weaker, or spreads out and shrinks etc etc? Or if it's...

Hi, I have a thought experiment I'd like to share along with a couple of quotes. First, we consider the moment when a body goes from have exactly zero charge to a +Q charge. At that moment, by definition of E field a distance r from point charge q, we have a field propagating from point...

I have question on my own understanding.. So please correct me.. 1. It is said that mass of photon is zero; Or it is so small that it can be neglected without any problems. 2. An object cannot surpass speed of light, because as it approaches to light speed, it's mass increases, and it require...

Definition/Summary A photon sphere is a spherical surface round a non-rotating black hole (or other extremely compact spherically symmetric body) containing all the possible closed orbits of a photon. All such orbits are circular and unstable. The radius of the photon sphere is 3M...

In a real double-slit experiment, the kind of pattern obtained will be different as an observer (which may or may not be human) is or is not present, transversely placed in relation to the path of photons. My questions: 1. How can we make this observation? This is: How can that observer (human...

A textbook presentation is given by Purcell: "Electricity and Magnetism", Appendix B, "Radiation by an Accelerated Charge". He carefully shows how the changes in the Coulomb field of a quickly decelerated electron propagate outward with velocity c. Since the field was moving past the observer...

Hi Everyone This may sound like a question with an obvious answer but with my current knowledge, it is not obvious to me. Can one photon interfere with another photon or can each photon only interfere with itself? Most people on this forum will know that Young's Slits produces interference...

I need help with something that i seemed to remember was fairly easy, but just can't seem to find the simple formula for: I have an amount of hydrogen atoms at a temperature of 10000 Kelvin. What percentage of them are ionised and what percentage of them are in the n=2 excited state...

I am not a student. I am a retired Chemical Engineer and a retired IT Auditor (ex-ISACA member). My questions are a product of my thoughts about Physics and the Cosmos and my talks with a closer friend. Please answer me. Imagine an atom in a position P in the Universe and n observers, all them...

When I think of frequency, I think of something happening per second or per unit time. When light is a wave, I can understand that it has a frequency, but when it is a particle like a photon, what is the interpretation of its frequency? What is occurring per unit time? Or do we associate a...

I suppose this is a 2 part question. I saw a neodymium YAG laser being used for UV experiments at University of Portland a long time ago. They put the yellow-green light of the YAG through a piece of (I believe if memory serves me well enough) calcite crystal and it emerged as UV. Does the...

How does the blackbody radiation prove the existence of photons or quanta as Planck described it, I've understood how the photoelectric effect proves the existence of photons, but the blackbody radiation seems quite vague to me. I would like a basic explanation for this, thanks in advance.

1. A 2.5m aperture telescope obverses a star through an R filter. Assume that there is no noise associated with the detection system. The CCD has a full well depth of 20,000 counts and a gain correction factor of 1.00000. a. On average, the telescope detects 3 photons/sec from this star. What...

Hello to everyone! I cane across this problem and since I have no training in SR I can't solve it on my own, That is why I would very mutch apprecitate any help I could get. The problem: A photon and a spaceship simultaneously start at planet A and the travel in paralal towards planet B. The...

The situation I am considering is that of a single photon directed at a target (say a photographic plate). My understanding is that the wave function for this system (determined by the whole context of the experiment: photon properties, nature of the target, boundary conditions etc.) gives a...

I read somewhere that gauge symmetry prevents the photon from acquiring a mass. The argument seems to go that the 1-loop correction to the photon won't contain a term independent of the external momentum due to gauge invariance, so there is no need for a bare mass counter-term. So should that...

How do transmitters convert electrical signals into photon energy?

The title was too long, original question was: Why is the relative biological effectiveness (RBE) of photon and electron the same ? I was suspecting the charge of electron to possibly have some effect... Also, in biological matter, would there be a difference between photon damage and...

So I'm trying to figure out something I don't understand about the direction of radiation when a charge is accelerated. I know that when a charge is accelerated it gives off EM radiation, which I kind of picture as the electric field of the charge 'wiggling' spherically all around it. If that...

Photon is the sub-atomic particle that light is made of. The properties of Photon: Mass = 0, Charge = 0, Spin = 1. According to Einstein's relativity, light travels fastest at 300,000 km / sec. When any other object travels at the speed of light, the universe shrinks to zero distance. But...

Greetings. I thought about how/ why light propagates slower trough matter than vacuum. Generally it is excepted that it happens because photons are absorbed and then emitted by the atoms and it kinda makes sense. But I see other possibilities. I propose and experiment: How about shining...

We can view the amplitude vs time variation of an EM wave using an oscilloscope with the needed bandwidth. Such a view shows us the shape of the wave (sinusoid or other), the number of cycles contained in a given burst, any modulating signal etc. Though it wouldn't be measured with an...

We know the equation E=pc or P=mc both of them are avaliable for photon.But photon is a massless particle.How can that be possible ? Thanks

Dear All, I have read many posts on this forums about the interaction of photons with the atoms of transparent materials. The point that I was searching for in particular was "why is the speed of light in transparent material less than c". The explanations given by many about the absorption...

Hi to everyone! I'm searching information about evidences of photons existence. It seems like the photoelectric effect isn't for itself a proof of photons existence. Some people tried a semi-classical discussion of this effect (Lamb - "The Photoelectric effect without photons"). I'm...

Homework Statement A photon, a packet of electromagnetic radiation, carries both energy and momentum. Consider a photon with a wavelength of 428 nm in vacuum. A) What is the frequency of the photon? 7.01×1014 Hz CORRECT B) What is the energy of the photon? 4.64×10-19 J C) What is the momentum...

I don't completely understand why an electron positron pair cannot be created from an isolated photon. I understand it must have something to do with 4 momentum conservation, but I really can't see a problem given the photon has enough energy for the mass to energy vice versa conversion.\ The...

Homework Statement Consider the following. (a) For a hydrogen atom making a transition from the n = 4 state to the n = 3 state, determine the wavelength of the photon created in the process. (Already solved this, 1.86x10^3 nm) (b) Assuming that the atom was initially at rest...