Light Definition and 1000 Threads

OK, going to ask a question that I sort of know is going to be shot down but at the moment I can't make sense of this. If I send a machine/robot with a particle that is quantum entangled with another particle that is left on earth. When one particle is blue the other is red. The machine also...

When light, traveling through a rarer medium, gets reflected off at an interface with a medium of higher refractive index, it suffers a phase shift of half-wavelength. Now if it was normal incidence, the phase-shifted light would retrace its path. Does that mean the wave would cancel out?

a prism is supposed to scatter light rays and separate it into rainbow,then why in a prism periscope the prism send light rays to a particular direction instead of scattering?

Brachistochrone problem’s original proof by Snell’s law and a story of Newton.

I Dont understand how light polarized along a certain axis in a prepared state can then pass through a second polarizer that is at an angle to the first. The experiment I’m trying to understand starts with unpolarized light which then passes through a first filter which vertically polarizes the...

I was wondering if I placed an infinite number of light polarizers in an array, each rotating an infinitesimal amount from the next, would I be able to get 100% of the photons shun thru them on the other side?

Ok very much amateur here, appreciate any advice. So, the guy at home depot suggested the ballast was the reason my flourescent kitchen light goes out occasionally. The light worked well for the first 3 years of ownership. Now, it doesn't buzz or flicker, it just occasionally doesn't work...

Hi, We talk about single-mode and multi-mode fiber and I assume they talk about the way of sending just one modes (TEM or TMmn or TEmn). Which mode is generally used for single-mode fiber? Is this set by the geometry of the single-mode fiber (especially the opening)? Also, this means that the...

My question is about the speed of light. Our current understanding of light says that light is constant for all observers, and uses time dilation to explain this. Have we proven this? The speed of light emitted from a stationary object is equal to C. The speed of light emitted from a moving...

It's come to my attention that if we were to travel in a spaceship at 0.5c directly away from our sun, I would observe that the light from the sun as being red shifted. What I would also observe was that this red shifted electromagnetic wave would in fact travel away from me in the spaceship...

I've read that UV light cannot "penetrate" the atmosphere as easily during winter. But what does this exactly mean? My hypothesis is that due to rayleigh scattering, since light with smaller wave lengths scatter more, the UV light doesn't end up reaching the surface of the Earth (i.e. gets...

Hi all, I would like to calculate light intensity of a bulb from 0.5 meter. Which formula shoul i use? I have a PV. Dimensions are 12x12 cm. Bulb is 100 Watt. Thanks

I've been a semi-pro photographer for a long, long time. I know the value of having a polarizing filter in my camera bag. I also wear polarized sunglasses for driving during the day. You can't beat 'em. I know some people who are complaining about these LED head lights from oncoming cars...

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?

Okay, first of all so I'm in no way educated in the concepts and especially the notation of quantum physics; my knowledge is confined to a very simple superficial understanding. However, if someone could educate me about why faster than light communication is impossible in the scenario I'm...

I recently started reading Feynmans book QED. There are a couple of questions I have regarding his theory on the percentage of light that is reflected of two surfaces of glass. My question is as follows, A piece of glass in fact has four surfaces. The front of the glass the back side of...

I have read in several popular physics texts that general relativity predicts that gravity deflects light, but that Newtonian mechanics, in contrast, predicts that the trajectory of light is not affected by gravity. However, I am very skeptical and confused about this result. We of course have...

Has anyone read the book of this author? What is your opinion about this topic? https://www.google.de/search?q=tired+light+lyndon+ashmore&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjbo_exj5vfAhXK2qQKHdHsD6AQ_AUIDygC&biw=1280&bih=623

From, https://flipboard.com/topic/crystals/freezing-fog-creates-rare-light-pillars-in-wisconsin-on-sunday/f-ca02faf45c%2Faccuweather.com For physics see, https://www.nytimes.com/2017/01/06/science/light-pillars.html

I would like to discuss the topic of light (photons) being emitted from stars potentially being the source of dark energy and dark matter. Photons have mass and velocity; therefore they will affect space time, and their impact could have an effect on objects causing acceleration. Would love to...

Hi, I am wondering if anyone could point be to any references for gradient optics. The current literature seems a little haphazard. The model I am looking for would need to consider the following. Single medium whose optical density (index of refraction) is some gradient index of refraction...

Hi, As I understand it the theory that the universe is expanding is in part based off the red light shift. My question is could atoms in space, dust etc cause the red light to travel faster. I realize that space isn’t a medium, but could the aforementioned atoms and dust exist in such...

I know that special relativity is based on the postulate that an object that travels at the speed of light with respect to one inertial observer must travel with the speed of light with respect to all inertial observers. This postulate implies that no two inertial frames can differ by a relative...

I am looking for some resources describing the following content: A light with wavelength ##\lambda## is propagating in flat spacetime. The light redshifts as its wavelength gets larger and larger. In quantum field theory, this causes an infrared divergence of the field. What I want to know...

In the big bang theory, inevitably we have the end of space. Expansion ratio is same everywhere in space. The end of the universe moves from us at the very high speed, but there space also hardly expands(Ho << 1). Then what happens to the light that arrives at the end of space? Will it stop...

hello, i am a near light runner at 3000000 km from us there is a mirror to start the run , my friend turns on a very powerful lamp and i start running toward the mirror me and my friend will see both the light coming back after 20 seconds?

Considering that infrared is what we call heat, and we can feel it. Also considering that UV is what causes sunburns, why aren't we also being burned by normal visible light? It's not like as if we're transparent and all of that light passes right through us. Visible light has a higher radiation...

Is the average nonlocal speed of light the same for travel out from the Sun and travel back to the Sun over the distances the Voyagers are now located?

Homework Statement Hi everyone, I'm a high school teacher and every time I teach the concept of polarization, students ask me the same question and I can't answer it. I show students this picture. The red lines show the electric field vibrations. After passing through polarizer 1, the...

Hi, Will there be interference if I point the laser thru one of the openings of the double slit aperture only while the other one is open? And is the interference more pronounced or the same if I shine it thru both the apertures at the same time.

I came across someone in the lighting industry who insists that because of Gauss's divergence theorem and Maxwell's Laws that when light is emitted from a surface that it is only emitted orthogonal to the surface. I have tried to point out numerous real world examples that contradict the...

I can't see how the textbook produces the following relationships between angles: $$ \theta = \phi + \alpha \qquad (1)$$ $$ 2\theta = \alpha + \alpha ' \qquad (2)$$ My thinking is that the exterior angle theorem for triangles was used to create expression ##(1)##, but I am unsure as to how...

In the ray model of light we learn that two light rays don't interfere with one another. That is one crosses the path of the other and both follow their path as they were doing before. In terms of quantum theories could we say that in this situation the electromagnetic field is not interacting...

Elliptically polarized light strikes a glass surface (in air) with refraction index n at Brewster's angle. What is the polarization of the reflected ray? How does it change if now the glass surface is partially submerged in water? And if the glass surface is fully submerged in water? How...

I was curious, is the speed of light in a vacuum really constant to all observers no matter their speed or movement? Is it possible for someone to somehow see light travel slower?

My question is - is all light a wave until observed, then wave function collapses and behaves as a particle? This is far fetched (and i don't subscribe to it!), but theoretically could light from a distant object passing through a double slit experiment and exhibiting a particle pattern be...

We know that light of a specific colour has a specific frequency. Suppose we have a torch emitting white light, and we place a, say, red cellophane paper, in front of it. Now we would have red light. So does this mean the new beam we get has a new frequency? How?

In his GR youtube talk ( , starting 24:30), Susskind shows that a light photon on straight path in a stationary frame has a curved path in an accelerated frame. Concluding, as did also Einstein, that gravity deflects photons. But exactly the same argument applies to massless particles. Meaning...

For instance, if you put a big "magnifying glass" above the atmosphere in the shadow of a total solar eclipse thus blocking out light from the "surface of the sun", could you heat an object to a temperature hotter than the surface of the sun? Applying the Second Law, one can't raise the...

I know the technical details of why light bends towards "the normal" when meeting a more refractive medium must be complicated. But I was thinking about it in a more lay fashion. I was thinking if the bending can be explained using Christiaan Huygens' principle in that a light front is made of...

For class I conducted a experiment where I made sugar solutions, poured them into a glass prism container and used a laser pointer to find the refractive index. However, while typing in my results I realized I found the angle of deviation instead of the minimum angle of deviation since I didn't...

A question regarding the redshift of star light being proportional to the star's distance from us. I suppose there were other, competing explanations for this when it was first observed (e.g. that light somehow loses energy/frequency extremely slowly over large distances), in addition to the...

Good afternoon, I have read that light changes it's wavelength when it enters a different medium because it's speed changes but then I read that the speed of light doesn't change (it's always c) and it just takes longer. So, it is the "observed" wavelength that changes or some such? Any help is...

Could it be possible for light to not move at all but remain still while space and time moves past it? The light would just exists as the continuum of space time moves past light.

is it possible, i mean can we hold it at a certain distance we want ?

Homework Statement When unpolarized light passes through a polarizer, what happens? A.The light emerges polarized in the polarizer axis direction with about 12the intensity of the incident beam. B.The light emerges polarized perpendicular to the polarizer axis direction with about 12the...

Hi all Today I came home to find very discrete lines of colored light on my living room floor. Can anyone help me to explain this phenomena? I am familiar with dispersion but am wondering how the combination of glass and blinds is creating this effect. When I rotate the shutters as you can see...

Per the maxwell equations, we know that em waves travel at the velocity of light, but that is not a sufficient condition to say that electromagnetic waves are light. How do we know that electromagnetic waves are light? They could just be something that has the same velocity as light. Any...

How would a gel with index of refraction 1.33 (~same as water) effect the velocity/frequency of incoming light assuming the material is a scattering medium with a scattering coefficient greater than zero?

Hi, I am trying to model the distribution of the light emission from a material when excited with neutrons in MCNP. I have been searching literature and found not many things. Could anyone provide me with sources from which I can get info? Thank you in advance.