How does light travel so fast?

In summary, light travels at a constant speed due to the nature of our universe and the ratio of electric and magnetic fields. This speed is considered slow for those who want to travel around the universe, but it is a necessary constant. Some theories propose the existence of particles that can travel at speeds much faster than light, but this is still being studied. The speed of sound is not a good comparison to the speed of light, as the latter is always constant and not relative to the observer's velocity. It is possible that the speed of light may vary in different environments, such as in gravitational fields, but this is still being researched. There is also the possibility that the speed of light may be affected by nuclear forces, but this has not been
  • #1
Drbazz
9
0
What makes light travel so fast? Is light its own energy?
 
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  • #2
same thing that makes all waves move at the speed they do. if you tighten a spring it will carry waves faster. space itself has a certain 'stretchiness'. in fact it has 2. one for the electric field and one for the magnetic field. I think its the ratio of these 2 factors that determines the speed of light in any medium.
 
  • #3
Drbazz said:
What makes light travel so fast?
It doesn't check baggage.

Anything with no mass has no choice but to travel at the speed of light, the actaul value is set by the nature of our universe. If you want to travel around the universe the speed of light is annoyingly slow.
 
  • #4
mgb_phys said:
If you want to travel around the universe the speed of light is annoyingly slow.
...for those who waits on Earth (not for the one who travels).
 
  • #5
Drbazz said:
What makes light travel so fast?
Hey, you are the first one in ages who is not annoyed by the fact that light's speed is too low! You should win a prize! :smile:
 
  • #6
Drbazz said:
What makes light travel so fast? Is light its own energy?
Do You know that some theories predict possible velocities for undiscovered particles as much as 1000 000 of the velocity of light?

So the velocity of light is about the velocity of hand keystroking.

As Einstein wrote all is relative. Even the speed of light.

What does God think about it and about absolute restrictions?
---------------------------------------------------------------------
The only real power comes out of a long rifle. Joseph Stalin.
 
  • #7
Minich said:
Do You know that some theories predict possible velocities for undiscovered particles as much as 1000 000 of the velocity of light?

Can you provide a reference?
 
  • #8
granpa said:
space itself has a certain 'stretchiness'. in fact it has 2. one for the electric field and one for the magnetic field. I think its the ratio of these 2 factors that determines the speed of light in any medium.

Not quite- it's the reciprocal of their product.

minich said:
As Einstein wrote all is relative. Even the speed of light.
Actually, that's not true. His point was that the speed of light was always, always constant, and he didn't like the name "relativity" for this reason; he's said to have wished it was called the principle of invariance. (The term "relativity theory" is said to have been coined by Max Planck).
 
  • #9
jtbell said:
Can you provide a reference?
I think i can. I need to find some articles on my shelves, thow it can take some time, there are about 6000 books plus journals in paper (nonelectronic) form.

By the way the simplest case is http://www.google.ru/search?num=100...=0&ct=result&cd=1&q=tachyon+particle&spell=1" of Arnold Sommerfeld, George Sudarshan, Olexa-Myron Bilaniuk, Vijay Deshpande and Gerald Feinberg.
 
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  • #10
muppet said:
Actually, that's not true. His point was that the speed of light was always, always constant, and he didn't like the name "relativity" for this reason; he's said to have wished it was called the principle of invariance. (The term "relativity theory" is said to have been coined by Max Planck).
I agree. It is very usefull unit.

So does the speed of sound in the air. And the Mach number for supersonic velocities.

Some physisists believe that there is the physical vacuum for quantized electromagnetic fields. Can such physical vacuum flow? How can we measure the velocity of vacuum flow and how can we control or change it's velocity?
 
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  • #11
Minich said:
I agree. It is very usefull unit.

So does the speed of sound in the air. And the Mach number for supersonic velocities.
You're missing the point, this isn't about 'convenient units'. Muppet's point was that the speed of light in vacuum is invariant, i.e. it is not relative as you seem to think.
 
  • #12
There's a fundmental difference between the constancy of the speed of sound and that of the speed of light though (which I assume is what you meant by "so does the speed of sound"?). An observer moving at 100 miles an hour away from a source of sound will measure the speed of sound to be about 240 miles an hour (that constant speed measured relative to the source, less the speed of the observer). But an observer moving away from a light source at 0.9c will still measure light from that source to be traveling at c.

EDIT: Short and sweet, Hoot.
 
  • #13
Hootenanny said:
You're missing the point, this isn't about 'convenient units'. Muppet's point was that the speed of light in vacuum is invariant, i.e. it is not relative as you seem to think.
Excuse me, I see that You misunderstand me.
I want to say that in acoustic we can define speed of sound that will be invariant.
We also can have several definitions of the speed of sound invariant or uninvariant under some transformations of the coordinate systems. There are such varieties of gas dynamics description (lagrangian, euleur,...).
We know experimentally that the speed of light depends (ie it is not a constant) on gravitational field.
Is it possible to consider, that the speed of light depends on nuclear forces? Were there experiments defining speed of light in nuclear matter?
 
  • #14
Minich said:
I want to say that in acoustic we can define speed of sound that will be invariant.

That line interests me profoundly. How can you define a speed of sound that will be invariant?

If I measure the speed of sound in the source's rest frame, I might get a figure of 343 m/s. If I then travel away from the source at 300 m/s, won't I always measure it at 43 m/s? If I travel faster than the speed of sound, I will never hear it. I can't therefore measure it. And so it can't be invariant under velocity transformations. Which is the whole point of special relativity. The invariance of the speed of light under velocity transformations. This leads to all the lorentz transformations as the true velocity transformations. Or have I misunderstood?
 
  • #15
Minich said:
We know experimentally that the speed of light depends (ie it is not a constant) on gravitational field.
No it doesn't! The physical speed (i.e. experimentally measured speed) is always c. However, the coordinate speed (which is not a physical quantity) may be greater than c in a gravitational field. To repeat, if one correctly measures the speed of light (even in a gravitational field) the speed will always be c.
 
  • #16
muppet said:
There's a fundmental difference between the constancy of the speed of sound and that of the speed of light though (which I assume is what you meant by "so does the speed of sound"?). An observer moving at 100 miles an hour away from a source of sound will measure the speed of sound to be about 240 miles an hour (that constant speed measured relative to the source, less the speed of the observer). But an observer moving away from a light source at 0.9c will still measure light from that source to be traveling at c.

EDIT: Short and sweet, Hoot.
Yes, it is textbook explanation for beginners. We don't need even experiment to verify obvious conclusions.
About invariant speed of sound i already gave the answer.

My supervizor in laser project Oleg Kolosovski liked to question:

What is the difference between physisist and engineer?
Engineer never measure quantity, if the result is supposed to be obvious.
It is obvious, that there (our laser apparatus) we must have 30000 volts. Let us take voltmeter and measure the voltage now...
 
  • #17
If this thread doesn't get back to addressing the original question, then it will be locked. If you want to discuss SR beyond what is contained in standard textbooks that is of no help to the OP, then please do it elsewhere.

Zz.
 
  • #18
Hootenanny said:
No it doesn't! The physical speed (i.e. experimentally measured speed) is always c. However, the coordinate speed (which is not a physical quantity) may be greater than c in a gravitational field. To repeat, if one correctly measures the speed of light (even in a gravitational field) the speed will always be c.
Is it? I was not interested in gravitation for many years. In student time we derived equation for light propagating in gravitational field. It was analogous to propagating in ordinary matter with varing effective n(x,y,z)>1, so the speed of light couldn't be equal to c.

Gravitational lensing in geometrical optics approximation.

And there were the results of Venera laser location, that showed the retardation of signal when it passes near the Sun.

Can You give the reference if i am wrong?
 
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  • #19
Minich said:
Is it? I was not interested in gravitation for many years. In student time we derived equation for light propagating in gravitational field. It was analogous to propagating in ordinary matter with varing effective n(x,y,z)>1, so the speed of light couldn't be equal to c.

Gravitational lensing in geometrical optics approximation.

And there were the results of Venera laser location, that showed the retardation of signal when it passes near the Sun.
If spacetime were flat, then you could say that light's speed varies in a gravitational field; but spacetime is not flat in GR; it's for this reason that a light beam is never bent and never changes its speed.
 
  • #20
Drbazz said:
What makes light travel so fast? Is light its own energy?

Light is not its own energy, light is energy, though that isn't the reason why it travels fast. It travels "fast" because given the laws of our universe it need travel fast, do it's mass-less-ness.
 
  • #21
Minich said:
Is it? I was not interested in gravitation for many years. In student time we derived equation for light propagating in gravitational field. It was analogous to propagating in ordinary matter with varing effective n(x,y,z)>1, so the speed of light couldn't be equal to c.

Gravitational lensing in geometrical optics approximation.

And there were the results of Venera laser location, that showed the retardation of signal when it passes near the Sun.

Can You give the reference if i am wrong?

You're talking about coordinate speeds, which aren't necessarily physical speeds, while Hootenanny refers to physical speed. All observers that physically measure the speed of light measure the same speed, even if, for example, they're inside a black hole.
 
  • #22
Minich said:
Is it? I was not interested in gravitation for many years. In student time we derived equation for light propagating in gravitational field. It was analogous to propagating in ordinary matter with varing effective n(x,y,z)>1, so the speed of light couldn't be equal to c.

Gravitational lensing in geometrical optics approximation.

And there were the results of Venera laser location, that showed the retardation of signal when it passes near the Sun.

Can You give the reference if i am wrong?

time slows down in a gravitational field so light does slow down but so does everything and everybody else. so no observer wall measure the speed of light in a vacuum at has own location to be less than c.
 
  • #23
lightarrow said:
Hey, you are the first one in ages who is not annoyed by the fact that light's speed is too low! You should win a prize! :smile:

In conclusion, how we feel about the speed of light is relative to the frame of reference.
 
  • #24
quantumducks said:
In conclusion, how we feel about the speed of light is relative to the frame of reference.
Sorry, I can't grasp what you mean; light's speed is not relative to the frame of reference.
 
  • #25
lightarrow said:
Sorry, I can't grasp what you mean; light's speed is not relative to the frame of reference.

Yes, but the keyword is "how we feel about the speed of light". :wink:
 
  • #26
quantumducks said:
Yes, but the keyword is "how we feel about the speed of light". :wink:
Ok, got it! (Sorry, I'm not very smart in english language :smile:)
 

What is light and how does it travel?

Light is a form of electromagnetic radiation that is visible to the human eye. It is made up of particles called photons that have no mass but carry energy. Light travels at a speed of approximately 299,792,458 meters per second (or 186,282 miles per second) in a vacuum. It travels in a straight line until it is reflected, refracted, or absorbed.

Why does light travel so fast?

Light travels at such a high speed because it has no mass. According to Einstein's theory of relativity, any object with mass cannot reach the speed of light. Since photons have no mass, they are able to reach this ultimate speed.

How do we measure the speed of light?

The speed of light is measured using a device called a "speed of light apparatus." This device uses a laser beam and a rotating mirror to measure the time it takes for light to travel a specific distance. By dividing the distance by the time, the speed of light can be calculated.

Can anything travel faster than light?

According to our current understanding of physics, nothing can travel faster than light. The speed of light is considered to be the universal speed limit, as it is a fundamental constant in the universe. Any object with mass would require an infinite amount of energy to reach the speed of light.

How does light travel through different mediums?

Light can travel through different mediums, such as air, water, and glass, at different speeds. This is because the density and composition of the medium can affect the speed of light. For example, light travels slower in water than in air because water is denser. When light enters a new medium, it can be reflected, refracted, or absorbed, which can also affect its speed and path of travel.

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