Special Relativity: Lenght contraction and a photon.

In summary, the conversation discusses the size of a photon and whether it can be measured. It is concluded that since a photon travels at the maximum velocity, it cannot have a size due to length contraction. Additionally, the concept of relativity is brought up and it is explained that it does not apply to photons or any particle with a light-like spacetime interval. It is also mentioned that photons and electrons are considered point particles with no size. However, there is a disagreement on whether photons can be considered point particles due to their lack of a well-defined position.
  • #1
Ianchez
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Reading an old thread (wich is now closed or i would post the question there) there was a discussion about the size of a photon, and if it was an adequate question at all.

The discussion on the other thread couldn't agree on a response. Yet there was some postulates that could work with this idea I am bringing to you now:

In special relativity, one of the effects for a stationary viewer is length contraction, higher the speed, higher the contraction in the direction of the movement.
So, can we assume since a photon travels at maximun velocity, it has maximun contraction?
Maybe that could explain why we can't messure a size in a photon, and its duality? yet we can in an electron?

What would this means? a photon's size would be relative to origin and destination?

Am I talking nonsense? why?
 
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  • #2
An electron is a charged particle. While the electron itself is considered a point, its field extends over a distance. A photon is also a point particle, but has no charge.
 
  • #3
These types of questions are all misunderstandings of what relativity says. Relativity is about transformations between inertial frames. You can't attach an inertial frame to a photon since it moves at the speed of light so such musings are meaningless.

Thanks
Bill
 
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  • #4
Remember length contraction and time dilation do not apply to photons or any particle with a light-like spacetime interval because there does not exist a rest frame for the particle by which to relatively measure time. Boosts to light-like vectors do not rotate them in spacetime.

Photons and electrons do not have sizes as the above poster said, they are point particles.
 
  • #5
You can repeat it as often as you like, but photons are not point particles in any classical sense. They don't even have a well-defined position! I guess, it's really time that I write an Insight article on it!
 
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Related to Special Relativity: Lenght contraction and a photon.

What is Special Relativity?

Special Relativity is a theory proposed by Albert Einstein in 1905 that describes how objects move in space and time, particularly at high speeds. It has two main principles: the constancy of the speed of light and the relativity of space and time.

What is length contraction in Special Relativity?

Length contraction is the phenomenon where an object appears shorter when it is moving at high speeds. According to Special Relativity, as an object moves closer to the speed of light, its length in the direction of motion appears to decrease to an outside observer.

How does length contraction affect a photon?

According to Special Relativity, a photon always travels at the speed of light, regardless of the observer's frame of reference. This means that a photon does not experience length contraction, as its length remains constant at all speeds.

Can length contraction be observed in everyday life?

No, length contraction is only noticeable at speeds close to the speed of light, which is much faster than any object can travel in our everyday lives. The effects of length contraction are only observable in extreme situations, such as in particle accelerators.

How does length contraction relate to the concept of time dilation?

Length contraction and time dilation are two sides of the same coin in Special Relativity. As an object's length contracts, time appears to slow down for that object. This is known as time dilation and is also a consequence of the constancy of the speed of light.

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