Light Definition and 1000 Threads

I keep hearing that the relative speed of light remains constant because time and lengths change with speed, what I believe is called the Lorentz factor. At slow speeds the Lorentz factor is extremely small, so what do people believe accounts for the rest of the change? If I travel...

We know light made up of photons which is massless, but why it can absorbed by black hole? Is it becuz the Einstein's relativity about every object can curve time space

The Lorentz factor shows how fast one frame will judge speeds in another frame to be taking into account the relative motion between the two frames. The speed of light is a factor in the Lorentz factor but I have heard that this is not because the speed of light is fundamental to it. So...

Hey :) I measured the transmission of blue visible light (350-550nm) through lithiumdisilicate ceramics with an ulbricht ball and an spectrometer. The light source was a led dental curing unit (bluephase style). The light guide was positioned direct on the ceramics. Now I wanted to test...

What happens to an object when you negate the Higgs field to give an object zero mass? Does it behave like light and travel instantly without force (or is there a gap here?) I heard if you took away mass from something like a baseball it would just float. How does this reconcile with the...

When light enters an ocean, the photons scatter elastic with water molecules yet the presence of opaque particles causes the depth to be limited. Is this scattering Rayleigh scattering? (like the scattering in our atmosphere) https://en.wikipedia.org/wiki/Rayleigh_scattering

The question is: The General Relativity Ideas were confirmed by the position of Mercury by Eddington. How could they be certain that the light deviation was due to gravity rather than the lens effect the Sun's corona may have had? What process was used,if any,to remove the effect of the...

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...

Is it feasible to design and develop a Smartphone torch app which can display light in different colors selected by the end user? Thanks & Regards, Prashant S Akerkar

Lets assume: emissivity of a human=0.91 T=310K Surface area body: 1.60 m^2 If we use the Stefan-Boltzmann Law we can find a value for the rate of emission of light by a human. Rate emission=762 J/s Given this rate of emission, why don't humans glow in the dark?

If two light bulbs have the same voltage but one with a lower current does it make one dimmer than the other? I’m confused why lights in parallel circuits don’t get dimmer even tho there is less current. Thx for replying

Consider the traditional thought experiment of moving train observers, the "stationary" observers, and the flash of a lightning strike at the midpoint of the train. It seems that the stationary observers would expect the train observers to see different flash intensities (due to different...

If the speed of light would change in the universe without any other natural constant changing, would all clocks be affected in the same way by this? This is implied by Einstein in this paper on page 368 http://myweb.rz.uni-augsburg.de/~eckern/adp/history/einstein-papers/1912_38_355-369.pdf...

I've been reading Feynman's (classical) derivation of the refractive index and I wonder if there is a more quantum mechanical description in terms of complex number field vectors - one vector for that part of light that goes straight through and another for that part of light that goes through...

Hi all, I have two questions about light in Special Relativity. (I'm going to pad these questions out with a few statements about my understanding of length contraction and time dilation, so you can see how I currently think about it and clear up any misconceptions if I've got the basic idea...

I am a laymen. I just thing that if the speed of light is constant then all acceleration should be measured against it. It doesn't move. Everything moves through it. Is that how it works? This has been making me anxious.

I have seen thought problems with an observer on a train or in a station, etc., but I have not seen ones with the observer traveling at relativistic speeds. It seems to me that at sufficient speed he would observe himself exceeding the speed of light due to the slowing of time. This seems like...

Homework Statement If the frequency and intensity of a light source are both doubled, show that the saturation photo-current remains almost the same. 2. Relevant Graph https://cnx.org/resources/e73bf218926bd39de4a52bafe3a82d04bbf73542/CNX_UPhysics_39_02_photoexp1.jpg The Attempt at a Solution...

I have been working a project of creating a simulation of thin-film interference in a 3D modeling program, Blender, to be able to create materials that would use its effects. While uncommon, I would love for it to be able to correctly calculate reflectance and transmittance when the incident...

I'll get into the details why I need this for below but first I'll explain what I'm looking for. I basically need a flat sheet of aluminum or any plastic in grey or black color that doesn't provide specular reflections, yet is smooth enough to not have any noticeable texture when looking with...

Earth is moving through space. If I throw a ball straight up, it falls down to me and is not left behind. This is obviously because it already carries the momentum of Earth's movement. But if I fire a photon straight up, does it also carry a velocity component in direction of Earth's movement...

How would the world be if light didn't travel in a straight line? I was wondering how it would affect life.

I was away for a few months and thought I might pose this thought I am working on, on this forum when I return. There was a very help full person who assisted me in the finer explanation of the Lorenz transformation a few months ago, and I really learned a lot about SR and GR. A few weeks ago, I...

1. At pg.212, Hartle book (2003) writes equation 9.81 as an approximation of 9.80, directly. 2. $$ΔΦ=\int_0^{w_1}\frac{(1+\frac{M}{b}w)}{(1+\frac{2M}{b}w-w^2)^\frac{1}{2}}dw$$ equation(9.80) $$ΔΦ≈\pi+4M/b$$...

I have both my iPhone and desktop computer set to a "night light" mode, and obviously my eyes appreciate the warmer colors at night. But what I'm wondering is this: Do they actually work? Here's what got me thinking: I have a pair of Elvex glasses rated to block all blue wavelengths, and I...

Hello. Today I've thinking about limit velocity and speed of ligth. We know that material particles can't achieve that speed, also when the speed of particles increases your own clock walks slowly. In the particular case of ligth your speed don't move anything. This it a explanation of why...

Hello forums, I'm kind of new nice to meet you guys and girls, Could someone please explain this to me? D=S * TTherefore Distance = Speed of light * TimeAnd then Distance = Speed of light + 7 * TimeWhat is Distance and what is time?

I am trying to get a better understanding about the constancy of the speed of light which is a well-established axiom of current day physics. for the start i want to understand how it is experimentally established and how these results are interpreted. My difficulty here is that this seems to be...

Since more distant objects are older, and the farthest objects we receive light from are billions of years old, or rather, their light is billions of years old, in what way, or how different would the distant universe be, if we could see the light it generates today? For that matter does light...

im trying to figure out if there's a way i can see the FULL flame from my torch (MAP) without having to be in an potentially unsafe dark environment as yall may know MAP gas burns a very light blue<teal colour that's very hard to see in normal light levels using the interwebs, all I am finding...

Homework Statement Homework Equations Minimum/Maximum occurs when the first derivative=0 GM≤AM: ##~\sqrt{xy}\leq\frac{x+y}{2}## The Attempt at a Solution [/B] If the sum of squares of the distances (setup 2) in an arbitrary point is bigger than the sum of the squares of the shortest...

Blackbody radiation spectra of hot light sources ( stars in this case) should have the full visible light spectrum and still stars less massive than the Sun emit reddish light while stars more massive than the Sun emit blue light. How is the blackbody radiation spectrum altered by the star mass?

Interference pattern made by light shows the wave nature of light and photoelectric effect shows particle nature of light. So, what is light? According to the photoelectric effect, light consists of photons with energy E and momentum ## \vec p##. According to the interference pattern, we...

Where in this though-experiment do I get it wrong? Even though no mass can travel faster then c, maybe information can? And I'm not talking about quantum entanglement etc. Consider a pipe, filled with balls that are very tightly arranged. If I push the outermost ball on one side of the pipe...

Hi people! May be this could be an historical question. Before Einstein, it is suppoused that speed of light in ether is always the same, I´m right? I mean, if observer O is at rest respect ether and observer O´ is moving respect ether and O´ send a photon to O, the speed at which that photon...

Theoretically, squeezed state can be generated using a process called 'parametric down conversion'. I was going through the literature and found that people performed 'second harmonic generation' before doing 'parametric down conversion'. Can anyone tell me why simple harmonic generation is...

I am studying hailstones. I have set up an experiment to pass colored light through hail, one color at a time for the colors of the visible spectrum, Red, Orange, Yellow, Green, Blue, Indigo and Violet (ROYGBIV). I have measured the dominate wavelength for each color with a photo spectrometer...

I just had the thought that atoms emit light at quantized levels but that would seem to imply that only certain energy levels could possibly exist instead of a complete spectrum. But, if light is traveling down or away from a gravitational field the frequency gets shifted. Would this make it...

Does light traveling through a fiber optic cable generate any sort of detectable electromagnetic field? Please forgive the stupid question. It’s something that popped into mind recently and google hasn’t adequately answered for me. I’m not a scientist or physicist. :blushing:

It is said that photoelectric effect of light proves that light has particle nature, but which property is shown by light in the photoelectric effect which is also the property show by things having particle nature? Even in the photoelectric effect the energy is transferred in the form of wave...

Recently I read something in NASA Tech Briefs about an instrument that could measure phase differences as small as .001 degree in light. I would like to create an instrument that could do this for every pixel in a picture, even if it was only a few hundred pixels (such as a 20x30 pixel array)...

Homework Statement If you create a 1 ms light pulse by turning a flashlight on and off, how long will the pulse take to reach the other side of the room 20m away? (in air at standard T and P) what is the length, in m, of the pulse? I realize that light has a wavelength and when you pulse it...

In this article, researchers have used electrons to image light as both particle and wave at the same time. https://phys.org/news/2015-03-particle.html

If you were to travel alongside a train, as fast the train, to you the train would seem stationary. I read that if you were to travel along a photon of light, as fast as the speed of light, that photon would not seem stationary. Is this true? If so, why?

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...

Hello, Recently, a solar power tower plant was founded next to where I work. Since it's the tallest object in the area, it's quite hard to miss it. But apart from that, every morning the reflected light is arranged in a hyperbolic- like way, as you can see in the picture. Does anyone have a...

Homework Statement Monochromatic light of wavelength, λ is traveling in air. The light then strikes a thin film having an index of refraction n1 that is coating a material having an index of refraction n2. If n2 is larger than n1, what minimum film thickness will result in minimum reflection of...

Homework Statement Suppose you wanted to be able to see astronauts on the moon. What is the smallest diameter of the objective lens required to resolve a 0.60 m object on the moon? Assme the wavelength of the light is near the middle of the visible spectrum: 550 nm yellow light. (in m) A...

I have seen many articles lately regarding planned manned missions to the moon and Mars but the question of radiation protection constantly comes up. Engineers keep proposing various shelter designs that use local materials (regolith) as a concrete base to absorb harmful radiation so that the...

How does the expansion of space cause light to lose energy?