- #1
Drbazz
- 9
- 0
What makes light travel so fast? Is light its own energy?
It doesn't check baggage.Drbazz said:What makes light travel so fast?
...for those who waits on Earth (not for the one who travels).mgb_phys said:If you want to travel around the universe the speed of light is annoyingly slow.
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!Drbazz said:What makes light travel so fast?
Do You know that some theories predict possible velocities for undiscovered particles as much as 1000 000 of the velocity of light?Drbazz said:What makes light travel so fast? Is light its own energy?
Minich said:Do You know that some theories predict possible velocities for undiscovered particles as much as 1000 000 of the velocity of light?
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.
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).minich said:As Einstein wrote all is relative. Even the speed of light.
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.jtbell said:Can you provide a reference?
I agree. It is very usefull unit.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).
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.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.
Excuse me, I see that You misunderstand me.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.
Minich said:I want to say that in acoustic we can define speed of sound that will be invariant.
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.Minich said:We know experimentally that the speed of light depends (ie it is not a constant) on gravitational field.
Yes, it is textbook explanation for beginners. We don't need even experiment to verify obvious conclusions.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.
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.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.
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.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.
Drbazz said:What makes light travel so fast? Is light its own energy?
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?
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?
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!
Sorry, I can't grasp what you mean; light's speed is not relative to the frame of reference.quantumducks said:In conclusion, how we feel about the speed of light is relative to the frame of reference.
lightarrow said:Sorry, I can't grasp what you mean; light's speed is not relative to the frame of reference.
Ok, got it! (Sorry, I'm not very smart in english language )quantumducks said:Yes, but the keyword is "how we feel about the speed of light".
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.
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.
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.
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.
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.