The speed of light is a fundamental universal constant that marks the maximum speed at which energy and information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.
Questions tagged [speed-of-light]
2860 questions
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The speed of light also applies for 'distance' materials?
The question is hard for me to put into one sentence so please try to completely read the example :
If I had a stick that is $1000 \ \mathrm{Km}$ long and I would push it forward with $1 \ \mathrm{mm}$ in lets say... $10 \ \mathrm{ms}$ (I have…
user2547
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Does Cosmic Expansion cause everything to travel faster than light, relative to almost everything else?
Under Cosmic Expansion, everything beyond the Hubble Sphere is traveling away from Earth faster than the speed of light, which implies most of the Universe is traveling away from Earth faster than the speed of light, under a flat-space (or almost…
wave
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Can an object appear to travel faster than the speed of light?
An object cannot travel faster than the speed of light.
But given a video of an object travelling at $0.5c$, could one speed the video up so that the object appeared to be travelling at $1c$, $2c$ or more?
Or would something prevent this?
Tim
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The hyppothetical 299792458m wand
This is an impossible scenario, however I would like a physical explanation of what should happen if such a scenario occurred.
Considering that:
Light speed in vacuum is 299792458m/s.
I have an hypothetical wand of 299792458m.
The wand is almost…
Greg7000
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When 'speed of light' changes, is it because the pendulum moves slower or the transition of caesium-133 gets more sluggish or?
I am a layman thinking about the speed of light. Say we measure the speed of light as:
number of Bohr radii the light covers per pendulum swing
number of Bohr radii the light covers per 9192631770 caesium-133 hyperfine transitions
and that the two…
frt132
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Can we watch the light travelling in slow motion?
If light travels 3 lac km in 1 second we cannot see it moving and it seems to be continuous. Everything in our lives are far slower than this.
Like we cannot differentiate between the different images that make a movie clip if it changes 60 frames…
Anupam Rekha
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What is the relationship between the speed of light and virtual particle production
What is the actual basis of the speed of light? Why is the transfer of information limited to it? Virtual particles that arise and disappear within a certain timeframe, is There a relationship between how long those particles appear before they…
Todd Burkett
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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 100 stars in the sky because the light from…
Ravi R
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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 the time the camera reaches Mars, we obviously…
Dargscisyhp
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If you had a ridiculously bright laser, and you were positioned at a point far enough away, could you see the light move through space?
Just a question out of pure curiosity that I can't seem to find an existing answer to. Let's say you are at an empty point in space, and your friend has the universes strongest and brightest laser 10 light seconds in front of you and to the left. If…
mascott75
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Speed of a body in circular motion has different points of the body travelling with different speeds
If I take a dumbbell with one end on the radius of a circle ( and a little away from the centre) and the other other end also along the same radius and rotate the dumbbell about the centre. Let the speed of the nearer end be c/9 then there may be a…
Harsh Anand
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Can someone shoot down these ideas for measuring the speed of light in one direction?
I recently saw a Veritasium video on how we aren't able to measure the speed of light in one direction - only in two. He claims that there's no way to know whether light travels at what we think of as "c" in both directions or at c/2 in one…
jss367
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Understanding that nothing can go beyond the speed of light
Possible Duplicate:
Is the “How to break the speed of light” minute physics video wrong?
Radius of the moon - 1737 km.
Thus circumference of the side that can been seen from earth - pi * 1737 = 5457 km.
Speed of light - 300 kmps
So if I point a…
tusharmath
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Could light be considered considered a type of gas?
I propose this question largely due to this video (see 4:19) and how it describes light going through polarized lenses. The effect described there could be explained if you consider light to function like a gas, in that it fills whatever space it is…
Nicholas Summers
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Do we know why speed of the light in vacuum is exactly 299792458 $m/s$?
I know similar questions were already here, but anyway, do we know the reason why the measured speed of the light is exactly 299792458ms? Why it is not twice more or half of it? Is there something braking the light in the vacuum down? I mean…
Fis
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