Light Definition and 1000 Threads

Note, it possible to determine if the speed of light varies depending on direction, with the use of a single clock. Simply send a beam and reflect it back, but on the return trip introduce a medium to slow the beam. Three cases, T1, T2, T3 are total travel times. T1: assume light is the...

First, I am way out of my field of understanding here so please keep it simple. I watched some videos on E=MC2 which led to how light reacts differently than matter at high speeds causing time to slow down when moving fast. My question is, if I was to shine a flashlight perpendicular (90...

Hello there.The question is as stated:does light curve spacetime?We know that bodies with mass do curve spacetime but does a massless particle or wave like light curve spacetime?Thank you.

Is it really possible for light to travel at different speed in opposite directions? This video seems to say that this is assumed as a fact (with of course Einstein being the one to make the assumption), and that since it is impossible to measure the speed of light in one direction, we really...

This is not for a homework or anything, I'm just a curious person who was wondering... that: how small is the smallest hole in an opaque material that would still allow to see the "world beyond it", using your eye or any kind of existing or prospective technology? (English is not my mother...

Visualize the following scenario. A star such as the sun, and a planet such as Earth are located in a solar system. A photon travels from sun (x0) to Earth (x1), and a satellite is in the midway observing the photon. This is relates to Einstein's special relativity. I ask this since it take...

I let E1 be the event where source 1 emits the photon and E2 for the second source with the respective coordinates in O as $(x_1, t_1$) and $(x_2,t_2)$ such that $t_2=t_1 \because$ simultaneous and $x_2-x_1 =D$. Using Lorentz transformation I obtained that in O', $$x'_2-x'_1 = \gamma...

Does this video even make sense? And if so, is it right or wrong?

Hello ... I had a question about the capabilities of the two-stage light gas guns which are used to study the effect of small meteors on spacecraft shields ... is it theoretically possible to achieve velocity above 7 km / s for a projectile of about 16 grams weight and 15 mm diameter using a...

Does anyone know of any products that would allow me to install a battery operated light switch and ceiling light? This would save me a lot over tearing down all the sheetrock, replacing sheetrock, painting, etc.. I'm thinking a switch with a faceplate. A simple button cell would go behind the...

The polarization referes to the direction of the electric field of a light wave which is to be one direction. The unpolarized light interacts with a material in various ways such as reflection, scattering, refraction. and each of which can transform an unpolarized light into a vertically or...

Before to open this topic, I found this there. It's quite similar, if not the same, but I'm a little confused, so I'm here. The situation is represented in this image. From optical geometry, ##\theta_{incident} = \theta_{reflected}## The four-momentum in ##S'## is the following one...

I am asking this question because I dint find a source that explain why the light go in straits line Let say that a light go near very big mass that bend it ,and then the light escape it . would the light change his angle after it band like that the red part is the range where the mass effect...

I have a question regarding Kugelblitz black holes. I know that they are purely theoretical, and I am perfectly fine with the matter-energy equivalence so I have no problem in assuming that concentrating a sufficient amount of energy in a certain radius might generate an event horizon. However...

Hello, just some general questions I have been thinking about 1. So as you approach the speed of light time slows down, but why not at everyday speeds like walking around? I know people are going to say time slowing down only matters at extremely high speeds. However, shouldn't time dilation...

I drew the red and green tangent lines and I found that the angles in blue are equal to theta 1. Also , as the BCD triangle is equilateral, theta 2 = 30. With this I can calculate the side of this equilateral triangle as a function of the radius R of the circumference. After that, I can't go on...

Hi, I am doing high voltage testing (20-35 kV or more) where I am trying to capture corona discharge. My DUT is in a dark test room with no light. I am using a Canon EOS T7 (2000D) DSLR to capture the corona. What I would like to know is the wavelength of the corona so I can do further...

If you want to detect a particle in the 2 slit experiment on a detector. And we state that the electron is traveling as a wave so there is a wave front...that must mean that the wave front hits the detector at the same time in more than one place where there is constructive interference. But...

for example the car headlight would look faster then c speed. (it speed would be the speed of light +the speed of the car) to observer in front the car. because the light come from the car so the speed of the car would connect with light speed (like when you walk on a train) . so does the light...

I am trying to capture corona discharge on metal conductors. I am using a Canon DSLR and it works pretty good. I think there may be light from outside of the visible spectrum being emitted during these discharge events so I would like to see if it's possible to capture this light and actually...

This may sound dumb.. We know metals reflect microwave. One way to look at this is considering an eddy current formed inside the metal that cause the reflected EM Flux. When glass reflects light, does something similar happen? Can we have eddy currents (or something analogous) with light since...

Hey there, I'm aware this is a bit of a stupid question, and I think that I understand the principle fundamentally, however, my intuition is still having a little trouble catching up, and I'm trying to figure out if it is because of an important detail that I have missed/misinterpreted. I think...

I've read that speed of light for a Rindler observer is not constant. I wasn't sure why and I tried to do this as an exercise for myself, I think I came with the correct answer, but I'm not sure, is the following argument correct? Let's describe the (flat) space-time using Rindler coordinates...

if I would look through a window on darker area I would see my reflection instead of the outside world . but if the other side of the window is light then the light may pass through the window does the light outside effect the window and make the refraction disappear ?. or the light always...

If sound (or any wave) was transmitted in a medium whose density was vanishingly low , would that wave propagate in the same way as em radiation in a vacuum? And vice versa does em radiation propagate in the same way as ,say sound so long as it is in a dense enough medium? In other words...

Hi, can i use a light clock made out of mirrors a distance appart to measure whether there is length contraction in different regions of spacetime? If the clock speeds up then the distance between the mirrors decreased. If the clock slows down the distance between mirrors increased.

https://www.physicsforums.com/attachments/269029 Lightning strikes A and B simultaneously in the Embankment frame. M' sees the flash at B before the one at A. But if the flashes are simultaneous in the Train frame, does M' still see B before A?

If the answer is yes then it seems that Einstein's second postulate was not so revolutionary.

This probably has been asked before but i had a thought about the speed of light and time dilation. First off all i know the speed of light is constant and that it is the max speed anything can be but hear me out. So let's say a jet are traveling from point a to b in space with let's say 0,8c...

The light comes from glass to boundary of glass and soap film, then there will be light which is reflected and transmitted. The reflected light has no phase shift and the transmitted light will hit the boundary of soap film and vacuum and the reflected light from this boundary will also has no...

Summary:: Need help with LDR's, experiments/ investigations I need to do an Investigation on Light Sensitive Devices, what 3 experiments could I do with similar aims that are somehow related, also does anyone know how different filters on light - frequency changes affect LDR's or where I could...

for example the blue light wave have frequency of about 450Thz and the yellow wave have frequency of about 508thz (I found this data in the internet) , so if this two wave would get closer to each other we would observe them as green wave which have frequency of 526Thz . so my question is...

Just wanted to confirm whether or not the images formed by light shining through hexagonal slits are hexagons rotated by 90 degrees. In the solutions, a hexagon was not rotated 90 degrees.

I heard somewhere that light in the visible spectrum that we see interacts with matter the most? Is that true, and in what ways?

Hubbles law states the rate of recession of galaxies increases proportionally with distance, and the cosmological horizon is where distant galaxies recede away at the speed of light. Does this not violate the rule of faster than light speed travel?

Does cardboard absorb or reflect UV from indirect sunlight? does it go through the cardboard and hit the plastic and rubber items inside the shoe box with UV?

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...

Is there a way to modify a thin overhead LED light fixture that fits over a ceiling box to make the direction of the light easily adjustable? Perhaps add some sort of adjustable shade to it? In remodeling a bedroom, I'd like to install ceiling boxes ( e.g...

C= mirror center O = vertex I don't know if the design is right, if someone can show me the correct one. I also don't know how to proceed in geometry Solution: Lf / ( L - f( 1 + d/D))

UV causes dryness of plastic and rubber and lights have UV so keeping it in the dark away from light inside boxes prevents this but notice this photo where the box where the arrows are marked the clarity q enters this region of the closed box is enough for the long term the UV of this clarity...

I wanted to filter out reflections from glass. So I bought a camera with a "circular polarizing filter." It filters out polarized light, adjustable for orientation. The result confuses some cameras, so it also has a second stage which induces circular polarization. The results were...

In optical communications, one of the modulation methods is to control the optical power (Simplest case, for example, bright = bit 1, dim = bit 0). I learned that we can achieve this by a Mach-Zehnder modulator (MZ modulator). Simply speaking, the principle of MZ modulator is to split the input...

Refractive index of a medium is defined as : n = c / v; v is speed of light in medium. I believe n is never measured directly as here is no way to directly verify c / v. So what I guess is that all refractive index values are experimentally measured using n = sin α₁ / sin α₂. But then there is...

I have written a Javascript/HTML5 app that simulates a Light Clock as a way to understand the kinematics of relativity. It shows special and general relativistic effects, and how they are related. I would appreciate any feedback on the app, it's correctness, and it's usefulness as a learning...

if you put a light on object you will see shadow in the shape of the object . it would looks like the following picture the blue part is the object. but if you point a laser or light on specific object you will be able to observe it from differences angles like in the following picture the...

Question 1; The conditions for total internal reflection are: -That light is traveling from an optically denser medium (higher refractive index) to an optically less dense medium (lower refractive index) - That the angle of incidence is greater than the critical angle. Therefore, I conclude that...

Why does neutral gas before reionization block the flow of light, and how does ionization help the flow of light?

Dear Physics Forum, I need help with this problem. In the diagrams above I try to show my difficulty. My main problem is working out how shadow will fall on a completely flat surface with the light source at more or less a 0 or 180 degree angle (depending on how you want to look at it) ...

Approaching for the first time to these "higher level" topics is mind-blowing, and indeed I cannot understand why is the speed of light a constant... why doesn't it vary relatively to the emitter state of motion? And isn't it affected by gravity(I know it is affected in the sense of a spacetime...

Hello! My kid asks if this is theoretical idea is correct and I just don't know this stuff very well: It is impossible to travel at light speed but not impossible to travel just below. So the highest theoretical speed should be: "The distance light has traveled in one second" minus "One Planck...