Speed of light Definition and 1000 Threads

Lets say we manage to build a spaceship 30miles wide and long that is capable of reaching to 99.99% the speed of light. Now inside this massive spaceship we have a particle accelerator. The spaceship is now traveling just a fraction under the speed of light when we decide to fire up the particle...

Can someone help me with speed relative to different objects! Nearly everything in everything in everyday life is relative to the earth, however if i was traveling a little be slower than the speed of light, relative to the earth, why am i not traveling faster than the speed of light relative...

Does a photon gain speed if it travels in "free-fall" toward the earth? A particle of mass gains speed as it free-falls to the earth, and yet, mass is just another form of energy. Light is energy. So, does light gain speed?

Could the speed of light be variable? (not always travel at the same speed)

kindly be descriptive

Homework Statement Assuming you are traveling at 9.80665 m/s in space, how long would it take to reach light-speed? My teacher told us the question was in-part a trick; we can never truly reach the speed of light, only get very close. She told us to simply give the percentage of the speed...

Suppose I hold a pencil by its tip and turn it around 20°, around the axis which goes through the pencil's length. The pencil's base, at the other extremity, a few centimeters away, will also turn by 20°. Now suppose this is a huge pencil which stretches from the Earth to the sun. By turning its...

Highschool physics student here with a thought experiment I would like some input on. While learning about Newton's Third Law (are reactions are immediate and there is no delay) I had a thought about the speed of light and relativity. Imagine You have a stick with a length of one light-year...

If we use the basic relativity equations on the speed faster than light we would get(in calculating differences in time on the Earth and on the spacecraft )an imaginary number.So does that mean that maybe by traveling faster than a light we would end back in the past,or that would just mean...

hi all, this is a very basic question. apart from maxwell's equation, why else is the speed of light a universal constant?

I have been doing research lately. And I wanted to know if anyone could tell me what exactly in relativistic mechanics makes us not able to achieve the speed of light?

I was having a discussion with my physics teacher the other week (I'm an A-level student) about the speed of light. We were doing some questions about black holes sucking in light. Long story short, we both got confused about relativity. I put forward the idea that massive objects can move at...

I have been engaged in several different threads, all relating to comments that I have posted regarding Einstein's second postulate that the one-way speed of light is c in all inertial frames. Rather than continue different aspects of these conversations in these different threads, I have...

Im a 3rd year physics major. I understand the equation E=mc^{2}. But i don't understand why mass and energy are related by the number c. How are mass, energy, and the speed of light so inextricably related that we can describe their relationship with one simple equation?

Three preconceptions for our thought experiment: 1. Gravity's effects propagate at a rate faster than the speed of light. This is demonstrated by the fact that the Earth is not thrown out into space due to the constantly shifting position of the Sun and an 8.3 min delay of "gravity waves"...

Hello there, and I apologise if I do something wrong, I'm new to the forum and have a general interest in physics. I was thinking back to something earlier (as sparked by a post I happened on in the 5 light year long stick thread) and got to wondering about whether how I understood physics and...

When I think of what happened in the big bang theory and in today's world when we look through telescopes and look at distant objects it raises the question of how far back in time can we actually see with more and more powerful telescopes? One thing that I find confusing is that at the time...

I was wondering if the speed of light (c) can be derived from Planck's constant (h) or the opposite way. I know that they are both fundamental constants, but I'm sure they are connected somehow. Saying it on a different way: if Planck's constant would be different, would the speed of light...

I know Einstein said it is impossible to travel faster than speed of light as the mass would get infinitely large. But if black holes exist and even a beam of light would be pulled back by gravity. Then Newton's 2nd law of motion, F=ma suggest faster than speed of light is possible. can...

Are there any consistent theory in which the speed of light is infinity, but the space-time is curved? Let us imagine a history of mankind in which GR is invented before special relativity (SR).

Hi everyone, I recently read an essay by Isaac Asimov called "Figure of the Farthest", which discussed the ideas on size of the universe across history. One of the basic ideas of that essay was that, since objects move away from us at increasing speeds the farther they are, then when you...

I see a lot of places, "The speed of light is the same in all inertial reference frames." But is it the same in non-inertial reference frames too? For example, your reference frame/observer is accelerating according to someone else holding a flash light, at the moment they meet, the other...

I understand that modern day Physics allows for travel into the future, but not the past. I understand that time slows down the closer and closer you get to the speed of light, so that you never exceed that limit. But what if you meet it? I know because of the laws of Physics, you couldn't meet...

Suppose I have a stick whose length is infinite, then the stick was rotated at one end. Despite playing with a small angular velocity, but should have a linear speed of the other end of the stick (which is at infinite distance) will be very high considering the formula of linear velocity =...

If one were to travel towards a star at the speed of light, and the spaceship beamed to Earth a continuous video stream of the voyage with an on board camera running not @ 25 FPS but at 300,000,000 FPS; Then what will the person on Earth watching the streaming video see as the voyage progressed...

It is known that in a medium of refractive index 'n' , the speed of light becomes c/n. So if we can make a medium of high refractive index, then the speed of light will be substantially less in that medium. Then it can be possible to accelerate particles inside that medium at speeds greater than...

From what I understand, we can never reach the speed of light because it would require infinite energy, because our momentum would be infinite. But if that is the case, wouldn't light have infinite momentum and therefore infinite energy? Or am I an idiot and 'the speed of light' is just a term...

This is one thing that I cannot understand no matter how much I search about it. I read that it has something to do with mass becoming infinite or something like that. How does that happen? Can anyone give me a detailed explanation on why we can't reach it? What will happen if we...

I recently read http://www.google.co.in/search?source=ig&hl=en&rlz=&=&q=speed+of+light+in+caesium+vapors&btnG=Google+Search" that speed of light is faster in cesium vapors. It is described as leaving the cesium container even before it has entered it, claims that light travels 310 times faster...

Can anyone explain what restricts the speed of light to about 186,000 miles per second? Why can't it travel faster?

Mathematically you can prove the speed of light is a constant, but I also read from a book by Brian Greene that seemingly there is a rather logical, other than mathematical understanding of it, an explanation regarding time scale change of an observer in motion. Does anyone else know it?

I'm wondering if the speed of light in a medium other than vacuum is well defined. I explain myself: Say I am underwater and I create a laser pulse. I know that at any given time, the speed of the photons constituting the light is always c. However I also know that photons will get absorbed...

Deleted Deleted

Light has mass, and it travels at the Speed of light, so a massless object... I'm new to this entire field, and I know I'm probably wrong, and someone has already debunked this years ago, and if so, please either 1. correct me or 2.Add something. Since Photons have mass and when they comein...

Let us examine the speed of light in relation to the Equivalence Principle . Let me first state the Equivalence Principle: "At every space-time point in an arbitrary gravitational field it is possible to choose a "locally inertial coordinate system" such that,within a sufficiently small...

Okay, you experts, please explain this one to me.. LOGICALLY. I am traveling in my UFO along highway 40 at .75 times the speed of light. I am 1 light second (Ls) away from a speed limit sign. I know that I am traveling at that speed because I can see the speed limit sign coming at me at what...

I haven't studied this very much, but how do EM waves behave in noninertial frames? Do photons have an acceleration in order to maintain constant speed c in the noninertial frame? What happens to the Lorrent'z force in non-inertia frames? A charge moving in a magnetic field is equal to a...

if you have an idea on how to exceed the light barrier please post.

I understand that Shrodinger's wave equation describes the probability that a particle will be found at any certain location in space upon its observation. I'm wondering if these 'movements' adhere to the speed limit of light (and if so, why is this okay). For example, if a particle is...

Hello, this is my first post here and I'm sorry if I say a dumb thing. Something is bothering me for a long time... I have read that if you break the speed of light you will go back in time. Ok... So what if when a star explodes, and creates a black hole, the energy released from the explosion...

hey guys i just saw a weirdo on TV claiming that the speed of light is not constant...since that is a direct attack on Einstein's postulate of relativity is there any truth in that statement?

since i have always have been interested in combat sports i was just wondering what would happen if some one in the octagon or in the ring punches his opponent at the speed of light(i bet chuck norris has already done that) i mean will the fist time travel or something?

Hello, I just had a weird thought and would like some clarification. Keep in mind I'm only 15 years old, and I have had NO courses in physics. I'm VERY ignorant and would like an explanation. If light is constant, then how do we know the true speed of light? If Earth moves at x speed this way...

Spherically symmetric infinitesimally thin shells can be described via the well known junction formalism of Israel. The equation of motion of thin shells is (G=c=1): (dr/dtau)^2 = (mg/mr)^2 - 1 + (2mc+mg)/r + (mr/2r)^2 This is an energy balance equation, where r is the...

Is there any situation in the world of physics that speed of light > (c=3*10^8) or can it be? IS there any possibility?

Why is the speed of light the fastest anything travwling through space can move?

Dont want to read all of this, then just read the last paragraph. If you still mixed up then read all of it. Why does einsteins theory of general relativity deal with c, the speed of light in a vacuum, the speed of light can take on many different forms when traveling through mass. But...

How is it possible that the universe expanded faster than the speed of light during inflation when this is the "cosmic speed limit"?

What is the speed of light at 2.7 degrees K.If it`s less than C,you know what my next question is. Empty space is not empty i am told, so we don`t have the classical definition of a vacuum so photons are passing through something that should slow the photons down? At cryogenic temperatures on...

If light travels at a certain speed through fiber-optic cable, would the light get to its destination faster if the fiber-optic cable was actually a liquid, and the liquid had a substantial velocity in the same direction as the light?