The speed of light is a fundamental universal constant that marks the maximum speed at which energy and information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.

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Is it possible to apply force to a light particle?

I know, the universal speed limit is the speed of light $c$. So, is it possible to apply more force to a light particle? What would happen to it if we could?
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18 views

Thunder Clap Armageddon [on hold]

In a superhero setting a thunder clap is where someone claps with superhuman strength causing damage such as broken windows and burst eardrums. What I want to know is, taken to the extreme of the ...
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0answers
41 views

Travelling at a relative speed greater than the speed of light [duplicate]

I've wondered about this since I was a kid. I've been told the speed of light is a constant ($c$), which would mean that light always travels at the same velocity. Now, here's what interests me: if ...
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1answer
95 views

Doppler effect and light

Approaching the speed of sound in an aircraft is relatively difficult, because the closer you get to Mach 1, the denser the pressure is around you (sound accumulates causing vibrations). Is there a ...
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24 views

Relativity and observable universe

Will cosmological horizon "expand" for an observer approaching the speed of light (at least in the direction of observer's motion) ?
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4answers
766 views

Can internet speed be faster than speed of light?

We send email in order to transfer information and, over time, the technology used to send email improves to send email at faster rate. Since we use the Internet to send information from one place to ...
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1answer
309 views

Theoretically if you passed the speed of light in a medium, would there be a sonic boom equivalent?

I know that it is technically impossible to reach the speed of light in vacuum since the mass of the object traveling would reach infinity. However in a medium, would there be some sort of theoretical ...
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1answer
50 views

What would happen to the human body if we went almost at the speed of light? [duplicate]

If we were to travel almost at $299\,792\,458~m/s$, or the speed of light, what would happen to the human body? Would we be fine or would there be consequences? Would our body shut down? I've been ...
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49 views

Is it possible for someone traveling at the speed of light to see at all? [closed]

I know that the speed of light is the same for all observers regardless of your speed, But this question is really worth thinking about. If someone let's say managed to reach the speed of light, ...
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3answers
121 views

How is it possible for the wavelength of light to change in a medium?

So my physics class has just finished a long unit on optics while at the same time I've been trying to teach myself relativity. I admit my understanding is probably rudimentary, but I figured all the ...
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1answer
46 views

Camera on the ground vs camera in a train

A couple days ago my history teacher was explaining special relativity with the train example, where you are in a train close to light speed and you see a clock on the train terminal and the clock ...
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2answers
70 views

Is speed of light is impossible, even for light in nature? [closed]

im not a student, teacher, researcher in fact I've never even taken a physics class. But I Love to argue!, i spent a day proving (in my mind anyway) that, 1. a photon does have mass. 2. its ...
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4answers
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Does a photon in vacuum have a rest frame?

Quite a few of the questions given on this site mention a photon in vacuum having a rest frame such as it having a zero mass in its rest frame. I find this contradictory since photons must travel at ...
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1answer
55 views

Light speed time distortion

From my understanding objects moving close to the speed of light experience a time distortion in that time moves slower and slower as they get closer to the speed of light. If that is the case ...
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1answer
42 views

Traveling near the speed of light

If I travel near the speed of light, form a stationary observer perspectives, I will take 1 year plus to travel 1 light year, but in my perspective, would I take less than 1 year to travel to that ...
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1answer
56 views

Is Lorentz transformation applicable of light itself?

I've just studied Einstein's Special Theory of Relativity and have followed most part of it. I was just wondering that whether the equations of Lorentz transformation are applicable on light? i.e. can ...
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1answer
31 views

Filming light in slo mo

So I was thinking of a cool video I could make when I thought of filming a video of me turning on a light. I thought that if you film yourself turning on a light and slo mo that video enough times ...
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3answers
59 views

Our speed and direction by comparing the speed of light?

If the speed of light is constant no matter the speed of the source, shouldn't we be able to know the direction and exact speed we are going relative to the absolute 0 in speed? If a photon is sent in ...
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1answer
23 views

Do the mediums decrease or increase the speed of light? (source to target) [duplicate]

If sun is the source of light then is it possible that the speed of light might increase depending on the mediums its going through or its not possible.
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0answers
92 views

Question on “new CNGS/OPERA measurement of neutrino velocity” (hep-ex/1212.1276)

A "new measurement of the limit on muon neutrino velocity with respect to the speed of light " by the OPERA neutrino experiment in collaboration with CERN has become public recently, as preprint ...
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9answers
1k views

Would it be possible to develop special relativity without knowing about light?

My understanding of special relativity is that it is fundamentally based on the constancy of the speed of electromagnetic radiation - that this speed is a physical law (or derivable from physical laws ...
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0answers
16 views

When light changes medium, does it decelerate, or instantaneously change speed? [duplicate]

The velocity of light changes between mediums, but does light specifically decelerate when it enters a denser medium, or is the change is speed instantaneous?
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1answer
51 views

Light coming from distant stars

As we know, light travels with a constant speed and the Universe is ever-expanding and endless. Considering this fact, is it possible that the sky we see should change everyday? Let's say today we see ...
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25 views

The speed of light sets a lower limit to the rate at which a reference frame can pass through time. Is there anything that sets an upper limit? [duplicate]

Is there any "slowest" velocity that sets a cap on how fast a reference frame passes through time, or can you pass through time infinitely fast given a "slow" enough velocity?
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1answer
62 views

Will the Velocity of an object change if it moves fast,close to speed of light?

If an rocket moves with a speed of 0.5c. So, the speedometer in that rocket will show 0.5c. But there will be time dilation when someone sees it from the earth. Then it's Time dilation will be So, ...
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2answers
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Speed of light and perception

So I'm reading a book called "The Elegant Universe" and here is a part of it Imagine two countries that have been at war are sitting down to sign a treaty ending hostilities while traveling aboard a ...
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18answers
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Is it possible for information to be transmitted faster than light by using a rigid pole?

Is it possible for information (like 1 and 0s) to be transmitted faster than light? For instance, take a rigid pole of several AU in length. Now say you have a person on each end, and one of them ...
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2answers
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What would we see back on Earth if we shot a camera off into space and watched a live-stream?

I'm curious as to what we would see if we shot a camera off into space at, say, 50,000 mph and watched a live stream. Clearly in the beginning we'd be seeing things in more or less real time. But by ...
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1answer
41 views

Relative motion at almost the speed of light

My title might not be precise but I didn't know how to decribe it better. I've been reading about the special and general theories of relativity for a short while and I started wondering. First, ...
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2answers
156 views

If you shine a light away from the center of a Schwarzchild black hole, will it stay still?

$$ A $$ Light is travelling away from the absolute center of the Schwarzchild black hole (i.e. none of that spinning/stretching field) at $\ C $, and so shouldn't $\ \Delta C$ need to be greater than ...
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0answers
93 views

What happens when light is reflected from a surface moving in a medium with a huge refractive index?

Imagine a mirror is moving away from a light source in a substance through which the speed of light is very slow -- so slow that the speed of the mirror is close to being the same as the speed of the ...
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3answers
128 views

Is it true that all particles that have a speed less than the speed of light must also have mass?

I've previously learned that massive particles cannot achieve the speed of light. But recently I read that, concerning the gels that refract and bounce light within around enough that it can travel ...
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3answers
85 views

Which is more fundamental,''constancy of speed of light'' or ''space-time''? [closed]

My friend asked me,''which is more basic or fundamental? constancy of speed of light which makes space-time behave dynamically OR dynamical behavior of space-time that makes light to travel with ...
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5answers
319 views

Detecting absolute motion inside a box

This is not a contradiction and I know it is impossible but still consider a thought experiment by me and point out if something is wrong. See the following picture and then the explanation follows. ...
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1answer
95 views

Is there any limit on movement of space itself?

According to special relativity, c is the maximum speed at which all matter and information in the universe can travel. [IN SPACE] But the inflationary hypothesis says the space itself expanded ...
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1answer
305 views

What would happen to electronic circuits when traveling near the speed of light?

Imagine a space ship, loaded with all sorts of computer systems, traveling near the speed of light. Electricity itself is very fast, and can reach speeds close the speed of light. (up to 99% ...
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1answer
46 views

How fast would you have to go to claim you saw the red light as green due to the Doppler Effect?

Driving toward it, I suspect you would have to be going at relativistic speeds. Calculating this, it appears to be around 1/6 the speed of light when driving directly at it, but since you are on the ...
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4answers
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In superluminal phase velocities, what is it that is traveling faster than light?

I understand that information cannot be transmitted at a velocity greater than speed of light. I think of this in terms of the radio broadcast: the station sends out carrier frequencies $\omega_c$ but ...
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2answers
42 views

What--is the Ultimate Limit of heat based off c? [duplicate]

As heat goes up, molecules start moving at a faster rate. A gas molecule, if unhindered, could speed across the United States in three hours. I don't even want to know about plasma. But if heat ...
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4answers
73 views

Photon: speed and mass

Is it correct to think that the speed of light does not depend on the speed of light source because photons have no mass, so they have no the kind of inertia that is associated with mass, so they can ...
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2answers
97 views

To what fraction of the speed-of-light has any multi-atom molecule (or polyatomic ion) been accelerated?

Of course photons go $c$ in a vacuum, and seems there's data on electrons getting to $0.999999999976c$ and protons to $0.99999912c$. For the twins paradox to be plausible, one of the twins must ...
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4answers
9k views

Why doesn't light, which travels faster than sound, produce a sonic boom?

I know that when an object exceeds the speed of sound ($340$ m/s) a sonic boom is produced. Light which travels at $300,000,000$ m/s, much more than the speed of sound but doesn't produce a sonic ...
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2answers
149 views

Does the speed of light have a range of speeds due to medium-dependency?

An EM particle-wave propagates in a vacuum at a constant speed $c$, independent of the source/receiver but dependent on most mediums it moves through. Since the vacuum is a medium, and if logically ...
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3answers
191 views

How can light travel at a speed greater than the speed of light

I was reading John Rennie's answer here, Can light travel faster? I now know that the sentence ''the speed of light is always constant in vacuum'' is just an oversimplification, for example light ...
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1answer
47 views

Would we see the past if we look to a mirror 1 light year away? [duplicate]

What would we see if we place a mirror 1 light year away? Would we see the present or the past?
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0answers
31 views

What is the speed of gravity? [duplicate]

Hypothetically, let`s say that one day our Sun is suddenly removed from the galaxy. For us, on earth, would take up to 8.3 minutes to notice that the sun was removed, since the distance from the earth ...
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0answers
22 views

Relative speed and time [duplicate]

There is a notion that travelling at the speed of light is impossible for a matter. But what if the there are 2 objects that are coming towards each other with half the speed of light. Thus relatively ...
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3answers
494 views

Why does red light travel faster than blue light?

I know that light of all frequencies travel at the same speed in vacuum. But I wonder why their speed differ in any other medium, why does red light travel faster if it has less energy than blue ...
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2answers
131 views

Special Relativity - Distance Not Increased?

I just watched the movie Interstellar and the question was asked of why/how high-speed travel would slow time within an area. Curious as I am, I watched several YouTube videos to quickly 'educate' ...
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Speed of light yes or no? [closed]

First off I am not a physics student: I am more of a science enthusiast. My question pertains to time and the speed of light: According to Einstein, no mass can travel at the speed of light. Now, ...