QM & Relativity: Can Photons Moving at Speed of Light Be Stationary?

In summary, according to relativity, any uniform motion can be considered stationary, and this includes photons travelling at the speed of light. However, because time moves differently for photons than for other objects, they cannot be at rest in any reference frame.
  • #1
wittgenstein
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My understanding is that any uniform motion ( according to relativity) can be considered stationary. For example if object A is moving at a constant velocity, it is as legitimate to say that it is stationary as to say that it is in motion. Why cannot a photon, moving at the speed of light and at a constant velocity ,be considered stationary? In that case according to the photon's "viewpoint" the space it traverses is non existent. This seems to me to coincide with QM's idea of non-locality.
One more related question. Why is the speed of light 186,282 mps? Why not 186,283mps? To make my point more dramatic, suppose that photons of light in a vacuum traveled at 45 miles per hour. Would time dilation effects then be noticeable at 20 miles per hour? I would guess not ( I could be wrong, I'm not a physicist, just a curious layman) . Then, my question becomes why do photons move at the exact speed that time ( for them) ceases?
 
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  • #2
wittgenstein said:
My understanding is that any uniform motion ( according to relativity) can be considered stationary.
A postulate of relativity is that all uniformly moving reference frames are equivalent and equally entitled to be considered 'stationary'.
For example if object A is moving at a constant velocity, it is as legitimate to say that it is stationary as to say that it is in motion.
OK.
Why cannot a photon, moving at the speed of light and at a constant velocity ,be considered stationary?
Since another postulate of relativity is that the speed of light is the same in all reference frames, light itself cannot be at rest in any reference frame.
 
  • #3
There's no reason why one can't consider a photon to be stationary.
It might be amusing to do so.
I guess that from that perspective the entire universe would contract to a two dimensional plane and time would freeze.
I've never looked into the physics of Black Holes (one day if I live long enough) but I would have thought the math involved should consider a situation close to this.

As to Light at 45mph, George Gamow wrote a book entitled 'Mr Tompkins in paperback' where he discussed this, and other concepts in detail at a popular level - worth a read if you can find a copy.
 

FAQ: QM & Relativity: Can Photons Moving at Speed of Light Be Stationary?

What is the theory of relativity?

The theory of relativity is a fundamental concept in physics that explains how the laws of physics are the same for all observers in uniform motion and how the speed of light is constant for all observers. It is comprised of two parts: special relativity, which deals with objects moving at constant speeds, and general relativity, which deals with objects in accelerated motion and the force of gravity.

Can photons, which move at the speed of light, be stationary?

No, according to the theory of relativity, objects with mass cannot reach the speed of light, let alone exceed it. Photons, which are particles of light, have no mass and therefore always travel at the speed of light. As a result, they cannot be stationary.

How does quantum mechanics relate to relativity?

Quantum mechanics and relativity are two separate theories that govern the behavior of the smallest particles in the universe and the behavior of large objects, respectively. They both work together to explain the behavior of matter and energy in the universe, but they have different principles and laws that govern them.

Is it possible for an object to travel faster than the speed of light?

According to the theory of relativity, it is not possible for an object with mass to travel faster than the speed of light. As an object approaches the speed of light, its mass increases exponentially, making it impossible to reach the speed of light. This is known as the cosmic speed limit.

How does the theory of relativity impact our understanding of time and space?

The theory of relativity has revolutionized our understanding of time and space. It states that the passage of time is relative to the observer's frame of reference and is affected by factors like speed and gravity. It also shows that space and time are interconnected and can be warped by the presence of massive objects, such as stars and planets. This has led to the development of technologies like GPS, which rely on the precise understanding of time and space to function accurately.

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