The speed of light is fundamental universal constant that marks the maximum speed at which information can propagate. Its value is $299792458\frac{\mathrm{m}}{\mathrm{s}}$.
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2answers
177 views
Refractive index inside a fibre
The refractive index $n$ of a fibre is calculated as;
$$
n = c_0/c_m
$$
Where $c_0\approx 300000km/s$ is the speed of light in a vacuum, and $c_m$ is the speed of light in the fibre in question. How ...
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3answers
185 views
Could some Red and Blue shifts be the result of light passing through “dark matter”?
As i see it, light behaves in certain ways, as the Double Slit experiement shows,
So when light comes into contact with dark matter, it becomes both a wave and a particle, the wave is bent around the ...
4
votes
2answers
413 views
Is 2.5x speed of light possible between two objects?
These news are in Finnish:
http://www.hs.fi/ulkomaat/Kaukaisin+havaittu+galaksi+et%C3%A4%C3%A4ntyy+maasta+valoa+nopeammin/a1305618680897
The main excerpt is:
"Distant galaxy moves away from us as ...
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3answers
157 views
Difference in velocity of light in change in medium
It is often seen that according to physics the light changes it's velocity according to the medium through which it is traveling. So can it be explained that why so happen?
2
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2answers
151 views
Is there any law that prevents an object with mass to become massless?
I got into a discussion with my physics teacher about the speed of light and I asked
What if an object with mass was to lose mass as it gained speed-- would that allow for an object to eventually ...
2
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2answers
197 views
Another faster-than-light question
Imagine we have something very heavy (i.e supermassive black hole) and some object that we can throw with 0.999999 speed of light (i.e proton). We are throwing our particle in the direction of hole. ...
10
votes
1answer
603 views
How realistic is the game “A slower speed of light”?
The game "A slower speed of light" from MIT claims to simulate effects of special relativity:
Visual effects of special relativity gradually become apparent to the
player, increasing the ...
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1answer
112 views
Time dilation $t'=(1-\frac{v}{c})t$ instead of $t'=\frac{1}{\gamma} t$
Suppose we have a train moving. When the origin of train's frame coincides with the origin of observers frame; the the time is set to zero. At that very instant, a photon is emitted from train towards ...
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2answers
548 views
If nothing in the universe can travel faster than light, how come light can't escape a black hole? [duplicate]
Possible Duplicate:
How does gravity escape a black hole?
If nothing in the universe can travel faster than light, how come light can't escape a black hole? I mean, Einstein's relativity ...
3
votes
1answer
158 views
Does $\lambda\nu = c$ hold for all the waves in the universe?
Are all waves in the universe the same as electromagnetic waves?
Basically, my question arises from an equation I found in my chemistry textbook:
$$\lambda \nu ~=~ c.$$
This states that the ...
1
vote
1answer
147 views
Speed of light and virtual particles
After becoming extremely bored while studying for an Afrikaans exam, I started thinking about virtual particles. So, can light (photons) interact with virtual particles (even though they only exist ...
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1answer
85 views
Faster than light due to reference position [duplicate]
Possible Duplicate:
Travelling faster than the speed of light
Please try to follow and clarify me I've been curious about this for a long time as it seems a bit paradox due to the rule that ...
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2answers
165 views
A light and magnetic mirror paradox?
If light is an electromagnetic wave and lightspeed is constant (we ignore spacetime or gravity for this question) why can't we slow down light with a few dozen wellplaced magnets and electricly ...
15
votes
3answers
740 views
What is the length of 1 second in meters
If time is treated as a fourth dimension of spacetime, what is relation between length and time units?
Or in other words, how can I convert time units to length units, for instance seconds to meters?
...
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1answer
68 views
does force affect light's path?
Say If I'm running to north at a very high speed. And as I'm running, I'm shooting a beam of light toward west, will the light go completely west, or it will have some degree toward north too?
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2answers
218 views
Is it possible to reduce speed of light? [duplicate]
Possible Duplicate:
What really cause light to appear slower in media?
This came to me as a question from one of my friend while I was convinced that the answer is NO. But I have read in ...
1
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2answers
306 views
Faster Than Light Communication Using Gravity?
Suppose two parties $A$ and $B$, some distance apart and at rest relative to each other both had control of one massive local object each.
If party $A$ lifted their local object upward relative to ...
0
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0answers
79 views
Are we always going to measure lightspeed at 3*10^8 no matter what? [closed]
We know light from the sun takes about 8 minutes to reach earth. Now let's imagine a reality where light is twice as fast so it takes 4 minutes to reach earth.
What would be our measure of lightspeed ...
2
votes
0answers
42 views
Reaching the speed of light, rockets [duplicate]
Possible Duplicate:
Double light speed
Someting almost faster than light traveling on something else almost faster than light
Well I've been wondering quite a long time about this ...
3
votes
5answers
320 views
Measure absolute speed
Currently I'm 17 years old, going to secondary school. So, my ideas might be totally wrong...
I know that everything is relative. In the example of speed, the earth moves, and the galaxy moves, etc.
...
1
vote
0answers
243 views
What happens with photon when it is slowed down substantially?
In a dispersive media light's velocity can change substantially. Imagine we can slow it down to near 0 what the wave would look like?
Frequency of light does not seem to change even at v=0 (at least ...
1
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2answers
173 views
What happens when atoms speed up to extreme velocity?
The title might be misleading, but my question is in regard to what happens when we reach temperatures close to absolute zero (Kelvin). I've found different quotes as to what happens on the low end of ...
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2answers
126 views
Is a compact universe consistent with the results of (for example) the Michelson-Morley experiment?
If the universe is compact then there is a twin paradox that is resolvable only by selecting a preferred inertial reference frame (arXiv). I was under the impression that the lack of a preferred ...
6
votes
1answer
193 views
drift velocity of electrons in a superconductor
is there a formula for the effective speed of electron currents inside superconductors?
The formula for normal conductors is:
$$ V = \frac{I}{nAq}$$
I wonder if there are any changes to this ...
3
votes
2answers
127 views
When traveling close to the speed of light
I hope this isn't a stupid question for you guys but here we go.
As you travel close to the speed of light, it is to my understanding you gain mass.. does this also apply when the brain sends ...
1
vote
2answers
298 views
Light speed in space-time. is it really constant?
I am by no means an expert in this field, however something puzzles me about the speed of light and the relativity of time and space (space-time).
Is is universally acknowledged that the speed of ...
4
votes
6answers
243 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 ...
4
votes
4answers
717 views
What happens when a photon hits a mirror?
When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity ...
6
votes
1answer
641 views
Has the speed of light changed over time?
Could someone judge my (stoner) hypothesis that the speed of light has changed over time -- ie. as the universe has expanded in volume light has slowed down, perhaps going so far as back to the big ...
3
votes
1answer
150 views
How would be tv reception in a spaceship travelling close to speed of light?
My little brother has made me a tough question (specially for a computer science engineer).
Imagine that there is a spaceship orbiting earth close at nearly speed of light (say 99%).
Someone in earth ...
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votes
2answers
211 views
What were the intention/conclusions for Michelson-Morley experiment?
Which of the following were the intentions of M&M?
to disprove the existence of aether.
to show that the aether has no effect on matter and energy and therefore is as good as non-existent.
...
0
votes
3answers
165 views
If a star were to suddenly dissapear, would it still have gravity?
I am wondering whether or not literally anything can travel faster than the speed of light. For example, if gravity from a star immediately ceases to have an effect if it suddenly and magically ...
0
votes
3answers
272 views
Why do photons travel?
Photons travel at the speed of light.
Is there a known explanation of this phenomenon, and if yes, what is it?
Edit:
To be clearer, my question is why do photons travel at all. Why do they have a ...
0
votes
1answer
330 views
Two trains at the speed of light [closed]
Okay. Two trains travelling towards each other at the speed of light. So, from one train (let's call it train A), the other is moving towards it at the speed of light. The other train shines a torch. ...
0
votes
1answer
111 views
Galileo's dictum and how light cannot violate it
Okay. So I've been told that the speed of light is constant and cannot violate Galileo's dictum, but even if it weren't constant (in a vacuum), how would it violate it anyway?
Say you are on a train ...
0
votes
3answers
968 views
How is light affected by gravity?
Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass and gravity only affects objects with mass.
On the other hand, if light does have mass then ...
0
votes
5answers
211 views
Is it possible to build an instrument which can travel faster than light? [duplicate]
Possible Duplicate:
Accelerating particles to the speed of light
I have heard about atomic rockets in novels which have the capability to travel faster than light. I have also heard about ...
2
votes
5answers
423 views
Special Relativity Second Postulate
That the speed of light is constant for all inertial frames is the second postulate of special relativity but this does not means that nothing can travel faster than light.
so is it possible the ...
1
vote
2answers
161 views
Why does the (relativistic) mass change & why?
I studied that when an object moves with a velocity comparable to the velocity of light the (relativistic) mass changes...but I am really eager to know how does this alteration take place....If anyone ...
2
votes
1answer
158 views
Could the Higgs boson field be responsible for the dramatic mass increase when an object begins to travel close to the speed of light?
could the Higgs boson field be responsible for the dramatic mass increase incurred when an object nears the speed of light?
2
votes
4answers
336 views
Why are objects at rest in motion through spacetime at the speed of light?
I read that an object at rest has such a stupendous amount of energy, $E=mc^2$ because it's effectively in motion through space-time at the speed of light and it's traveling through the time dimension ...
8
votes
2answers
617 views
Does the speed of light vary in noninertial frames?
The speed of light is the same in all inertial frames.
Does it change from a non-inertial frame to another? Can it be zero?
If it is not constant in non-inertial frames, is it still bounded from ...
1
vote
1answer
194 views
What is the speed for an object that travel close to the speed of light?
I have some questions regarding Einsteins theory of Relativity that should be fairly easy to answer. Lets say we make an experiment where we have a rocket (with an astronaut inside) that travels very ...
2
votes
1answer
352 views
Rotating mirror - Foucault's measurement of light speed
Some time ago I came across a secondary web source on measurement of light speed in water made by Foucault around 1850. I append its redrawn scheme below (light is reflected from the rotating mirror ...
0
votes
1answer
96 views
Is the acceleration and deceleration of a wave instantanious?
When an light travels in free space, it has a velocity of propagation equal to the speed of light.
However, then the light enters a medium with a refractive index of n, the velocity of propagation ...
2
votes
2answers
180 views
How do I adjust the kinematic equations to avoid reaching speeds faster than light?
I like some 'science' in my 'science fiction', so I started crunching out the kinematic equations for some of the scenarios my characters are getting involved in, and ran smack dab into an issue. ...
1
vote
1answer
211 views
Relative Speed vs speed of light [duplicate]
Possible Duplicate:
Travelling faster than the speed of light
Someting almost faster than light traveling on something else almost faster than light
I've got two questions which are ...
-1
votes
3answers
166 views
Does the Lorentz transformation not apply to light?
Since you would know that light always travels at the constant velocity with respect to all frame of reference ....according to relativity whenever we are traveling at speed of light our time with ...
-6
votes
1answer
195 views
Speed of light is not fixed?
In my research, I found that the speed of light is not fixed. IS it true?
Namely, We know that light refracts when the medium it travels through changes. Actually, light travels in the same medium ...
10
votes
5answers
1k views
How do photons travel at a speed that should be impossible to attain?
If it requires infinite amount of energy to travel at the speed of light then how photon attains this speed? Its source is never infinitely sourced.
