# Thread: The Speed of Light

1. ## The Speed of Light

If the spped of light is always a constant
without respect to the velocity of the object emitting the light

then it is a logical contradiction.

read it HERE

2. Interestingly enough, we're doing this in physics right now.
For some background, here is a little demonstration:
For those that don't know much about physics, I'll start with this example. Let say you're on a truck going 70kmh on a highway, and throw a ball forward at 10kmh. Someone on the side of the road would see the ball going forward at 80kmh. If you throw the ball backwards, they'd see it going 60kmh forward.

But the weird thing is, light doesn't do this. Let's say you're going 100, 000km/s on a freeway, (You're REALLY in a hurry ) and you shine a light frowards. We're going to assume this is a vacume with no air, making the speed of light 300, 000km/s. Based on what we've just seen, you'd tihnk that an observer would see the light going 400, 000km/s. But it doesn't. The observer sees it going 300, 000km/s, no matter what you do to the truck.

A good analogy is this: Imagine you're in a hover boat that has no wake at all, and have a friend on the beach. If you dip you're hand in to make a little wave, your friend sees it going 2 meters/second. If you then crank the speed boat up to full power, and go by your friend while splashing your hand in the water, your friend will still see the waves at 2 m/s. This makes sense: Why would the speed of the boat change the waves? Light is the same way, it travels through space as energy, and isn't affected by the object emitting it.

Just thought I'd type that up to give a little background.

3. WTF is embankment? I got lost there.

4. embankment

NOUN
1. The act of embanking. 2. A mound of earth or stone built to hold back water or to support a roadway.

embanking

TRANSITIVE VERB
Inflected forms: -banked, -bank·ing, -banks
To confine, support, or protect with an embankment.

5. Originally posted here by Dr Toker
WTF is embankment? I got lost there.
The chapter in the link was in the middle of a book.
Earlier, he had described a hypothetical "railway embankment"
with a railway carriage travelling on it.
This was not really clear. sorry.

6. Hmm,
Very interesting concept, but there are a couple problems with it. Light is a constant c, he is trying to manipulate that constant by adding the relativity of another object with velocity to that constant. His theory is rather easily disproved by that of saying, light is not effected by the relative velocity of two objects, neither positive nor negative velocity can change that constant. This was proved when measureing the speed of light from a double star orbiting around a black hole.{Look at figure below}

<<------

Star A Black Hole Star B

--------->>

In this example the two stars are orbiting the hole counter-clockwise, {I am unsure of the exact date or reference to this experiment, but I am looking for it as we speak. This was also loosely mentioned in the reading} On earth we simply measured the speed of light coming off these two orbiting stars. The speed was constant coming from either star. In the theory proposed in chapter 7, he is saying that the star on the right, B, should have a slower C then star A. And in most physics, that would be true. But as we see in this expierment, it would not work. Therefore, it was a good theory but would be void. {Any continueing comments or arguements? Please post.}

7. I heard something about light not being able to escape the power or whatever of a black hole... If light is a constant, this can't happen, right? Or will it just turn towards the black hole and go 300,000km/s that way? Also, things do seem to slow light down..., like glass, water, diamonds, etc... I may be thinking about something else, (seeing that you people are talking about adding speed by another object), but this should be no different, right?

BTW: What would happen if you were in a rush to get back home..., in reverse? Would light be able to keep its constant speed then? Maybe this is where the shift stuff comes in, like red-shift, and purple-shift (or blue-shift?)... It goes the same speed, but the density (frequency) is different... Maybe the frequency of the light answers these things...

Oh well... Just more to think about...

-Tim_axe

8. Tim: Light itself is not a constant. The speed of light is not a constant. The speed of light in a vacuum *IS* a constant. In Einstein's equations, c is the speed of light in a vacuum, not the speed of light period. There are some liquids where light travels faster through it than it would in an oxygen/nitrogen gas environment.

We've proven that we can stop light in condensed, cooled sodium gas, and that doesn't require gravity at all.

This supports the idea that light is made up of photons -- weightless particles that emit lots of energy along various spectrums.

9. chsh: Ok...

Let's look at this at a much slower speed..., sound... They are similar, waves..., and I'm guessing that they act the same way in certain situations... I'm only looking at one here...

You are the person sitting at the bus stop... We will be dealing with sound, so there is air. Some person has his boom-car set to play a low sound frequency, let's say 60hz... He races past you... While he is approaching you, it may sound like 70hz... After he passes you, it sounds like 50hz... Yet the speed of sound has not changed... Only the frequency does...

So, instead of white light (which contains all of the visible frequencies), let's talk about a green light or something... If they are coming at you super fast, the light may look purple, or blue... After they pass you, it would look red... Light still travels at the same speed, the frequency just shifted because of the object emitting it...

I may be stressing the wrong part, but it is kinda like the boat... The wave may be going 2m/s, but there are more waves closer together... That's correct, right?

Another chance for you to see me confusing myself explaining stuff BTW: Maybe I should read the article to see what we are debating here

-Tim_axe

10. Tim_axe: That's called the Doppler effect and yes, it's very common; can be observed with a passing ambulance/police car/firetruck.
This is used to measure how far some stars or galaxies are - they measure the redness of the light and count the diffenrence to non-red light (or something..). The light turns a bit red, because the universe stretches between the star and our observing place and therefore stretches the light -> makes it red.

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