Gravity and Light

[Amr Morsi]

The whole relativity depends upon the speed of light which is totally electromagnetic. And, photons only do move with the speed of light at a certain space-time position. Is this strange somewhat? Or, photons do move with the upper limit of relativity, speed of light and why?

[mathematic]

Photons are the particles of light, radio, x-rays, etc. Your question is confusing.

[csmyth3025]

The whole relativity depends upon the speed of light which is totally electromagnetic. And, photons only do move with the speed of light at a certain space-time position. Is this strange somewhat? Or, photons do move with the upper limit of relativity, speed of light and why?

One of the basic assumptions of special relativity is that the speed of light in a vacuum will always be the same no matter what the relative motion of the observer and the emitting source may be. This has been confirmed by many experiments.

 

Is this what you're asking about?

 

Chris

[Amr Morsi]

The question is: Why do photons move with the maximum possible velocity permitted in nature? Because it is their nature. Then, there may be a relation between Relativity and Electromagnetism. This is what Einstein were trying to do, if I am not wrong.

[csmyth3025]

The question is: Why do photons move with the maximum possible velocity permitted in nature? Because it is their nature. Then, there may be a relation between Relativity and Electromagnetism. This is what Einstein were trying to do, if I am not wrong.

The relationship between special relativity and electromagnetism is that an observer will always see light traveling at ~300,000 km/s in a vacuum regardless of his own motion or the motion of the emitting source.

 

Is this the relationship to which you're referring?

 

Chris

[IM Egdall]

Why does light always travel at the same speed (about 670 million miles an hour) in a vacuum?

 

Per Maxwell, light is an an electromagnetic wave. And an electromagnetic wave contains a constantly changing electric field and perpendicular constantly changing magnetic field. Each field generates the other. The key word is changing. An electromagnetic wave must move (change) to exist. There is no such thing as an electromagnetic wave at rest.

 

So Einstein thought about this and wondered what would happen if you traveled at the same speed as the electromagnetic wave (the speed of light). If you did, wouldn't the wave appear to be standing still with respect to you? If so, then according to Maxwell, there would now be no electromagnetic wave. How can this be?

 

Einstein concluded you can never catch up to an electromagnetic wave, no matter what speed you travel at. The electromagnetic wave always travels at the same speed (the speed of light) with respect to you. This is (roughly) Einstein's light postulate, which has since been verified in a number of experiments.

 

Relativity also says that any particle with mass cannot reach the speed of light. And all massless particles, such as photons (carriers of electromagnetism), gluons, and the yet to be discovered gravitons always travel at the speed of light.

[md65536]

The question is: Why do photons move with the maximum possible velocity permitted in nature? Because it is their nature. Then, there may be a relation between Relativity and Electromagnetism. This is what Einstein were trying to do, if I am not wrong.

I believe that anything can be considered to be moving at c. It is more of a standard speed than a maximum speed.

c is essentially a constant linking distance and time.

I'm pretty sure this view requires some misinterpretations of accepted science! Hopefully someone can correct me.

 

The details are:

- All energy, unobstructed, travels at c.

- Energy and mass are equivalent. One might consider mass to be "made of" energy, however I remember reading comments that suggest this is misleading?

- Therefore all particles or energy that can be considered to be moving < c according to some frame of reference (including their rest frame), must oscillate or change directions. If the energy moved in a single direction, it would move at c.

- If energy is moving at c, but oscillates or changes direction, then after a time t its total displacement will be less than the total distance traveled by the energy. So if you consider a moving particle, the energy that makes up that particle is moving at c, but the particle itself can move at speeds < c. As an analogy, if a sailing ship moves from point A to B in a time of t, its (average) velocity is ||B-A||/t, but if it is tacking in the wind its speed through the water can be much greater.

 

 

So, if you are considering a mass moving in a straight line, its velocity is its displacement over a given time, while the speed of its constituent energy is the total distance that energy oscillates over the same time (which will always be c).

 

With this view, the maximum speed occurs when displacement and distance are the same, ie. movement in a straight line.

In which case, light etc. travels at c in a vacuum because it travels in a strictly straight line in a vacuum.

[Amr Morsi]

Any fundamental particle does have mass and electric charge, except for neutrinos which are proven to have neither (or approximately neither, so not to be debated now). And, so electric and gravitational currents are exactly restricted to each others. Then, very easily, even if the two forces are not the same, then they can obey certain one law, simply as the electroweak force.