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Garen
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Just wondering, if photon A and B are traveling towards each other head on (at the speed of light) why isn't the velocity of B relative to A exceed the speed of light? And no, it is not homework related.
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Doc Al said:Imagine this scenario, which makes the same point. Spaceship A moves at 0.99c with respect to Earth heading north. Someone on Earth shines a flashlight pointing south, directly at the oncoming spaceship A. What will be the speed of the photons with respect to spaceship A?
To answer this you need to understand the basic postulates of special relativity which has implications for how velocities add.
Garen said:Just wondering, if photon A and B are traveling towards each other head on (at the speed of light) why isn't the velocity of B relative to A exceed the speed of light? And no, it is not homework related.
Doc Al said:Imagine this scenario, which makes the same point. Spaceship A moves at 0.99c with respect to Earth heading north. Someone on Earth shines a flashlight pointing south, directly at the oncoming spaceship A. What will be the speed of the photons with respect to spaceship A?
To answer this you need to understand the basic postulates of special relativity which has implications for how velocities add.
I modified the question to make it answerable.atyy said:Doc Al seems to be answering a slightly different question. For a human experimentalist O measuring two photons going in opposite directions, he will measure both photons going at the same speed, no matter what his velocity relative to another human experimentalist P.
Generally, the speed of B "relative to" A means the speed of B as measured from a frame in which A is at rest. But there's no such inertial frame for a photon--they are never at rest and always move at speed c with respect to any frame. That's the problem. You are essentially denying a basic postulate of SR. Once you've done that, all else is fantasy.The question was about photon B "relative" to photon A. The "standard answer" is that the question is meaningless. To be honest, I don't know why - and actually, if it is meaningless, there shouldn't be a reason. But here is my attempt to "prove" that it is meaningless anyway!
Doc Al said:I modified the question to make it answerable.
The speed of light is a fundamental constant in physics and is equal to approximately 299,792,458 meters per second in a vacuum.
According to Einstein's theory of relativity, the speed of light is the maximum speed at which any object can travel. As an object approaches the speed of light, its mass increases and the amount of energy required to accelerate it further also increases. At the speed of light, an infinite amount of energy would be required, making it impossible to exceed.
No, all scientific experiments and observations have confirmed that the speed of light is the ultimate speed limit in the universe.
According to the theory of relativity, time dilation would occur at speeds approaching the speed of light, so an object would experience time passing at a slower rate. Also, the mass of the object would become infinite, making it impossible to reach the speed of light.
Currently, there is no known way to exceed the speed of light. Some theories, such as wormholes and warp drive, propose ways to travel faster than light, but they are still hypothetical and have not been proven to be possible.