Light cone and Cherenkov radiation

[Ross Arden]

Hi All

I read somewhere that at close to C the light emitting from a regular light globe ie diffuse light in all directions, will form a cone.

what is the thinking behind this and does anyone have a link where I can read about it ?

 

[PeterDonis]

I read somewhere

Where? Please give a specific reference.

does anyone have a link where I can read about it ?

Haven't you already read about it somewhere? Can you tell us where?

 

[Ross Arden]

I can't find a reference which is why I ended up here I thought you guys would know. I read it about 5 years ago so the ref is lost

 

[Ross Arden]

I think it is based on the assumption that photons have length, so, if a photon is emitted by an electron and the electron is traveling at ~C and as the photon has length it will take a finite time to be emitted from the electron etc etc

 

[sweet springs]

Light cone is a figure in Minkowski xy-t space, not a cone shape in regular space. See https://en.wikipedia.org/wiki/Light_cone .

 

[Dale]

Hi All

I read somewhere that at close to C the light emitting from a regular light globe ie diffuse light in all directions, will form a cone.

what is the thinking behind this and does anyone have a link where I can read about it ?

I think you are asking about this:

https://en.m.wikipedia.org/wiki/Relativistic_beaming

 

[Ross Arden]

I thought about how a photon would exit an electron, if the electron was traveling at ~C, as opposed to stationary. In the attached picture the top series is a photon existing an electron at C at times t1, t2 , t3 , t4, t4 is far right. The bottom series is how a photon would exit a stationary electron. I asked in a forum if what I thought was right. Someone agreed and pointed to a reference. I read some of it. Looking at my pic is what I thought correct ?

 

[Orodruin]

Looking at my pic is what I thought correct ?

No. First of all, you cannot take a classical viewpoint of electrons interacting with photons. They are quantum particles. Second, replacing the photon with a light signal and the electron with an emitting object, your aberration goes in the wrong direction.

Someone agreed and pointed to a reference. I read some of it.

Again. What reference? You cannot just continue throwing out ”I read somewhere that”. In order to help you we need to know and see what you read to know what your misconceptions are and what the text is actually saying.

 

[Ross Arden]

No. First of all, you cannot take a classical viewpoint of electrons interacting with photons. They are quantum particles. Second, replacing the photon with a light signal and the electron with an emitting object, your aberration goes in the wrong direction.Again. What reference? You cannot just continue throwing out ”I read somewhere that”. In order to help you we need to know and see what you read to know what your misconceptions are and what the text is actually saying.

Like I said I don't know the reference it was years ago

 

[Ross Arden]

yeh I am only interested in an electron and photon

 

[Ross Arden]

No. First of all, you cannot take a classical viewpoint of electrons interacting with photons. They are quantum particles. Second, replacing the photon with a light signal and the electron with an emitting object, your aberration goes in the wrong direction.Again. What reference? You cannot just continue throwing out ”I read somewhere that”. In order to help you we need to know and see what you read to know what your misconceptions are and what the text is actually saying.

thanks for that what would be the the quantum mechanical explanation for what would happen ?

 

[Larry Boemler]

I think you may be talking about Chernokov radiation (not sure of spelling). This is where charged particles traveling through a medium like air will emita a cone of light ahead of the particle. i have always thought that this was the source of Auroras near either pole

 

[sweet springs]

Exact spelling in English is Cherenkov radiation. See https://en.wikipedia.org/wiki/Cherenkov_radiation .
It is similar to sonic shock wave generated by supersonic fighter.

 

[PeterDonis]

I thought you guys would know

As should be evident from the responses you are getting, the information you are giving is not sufficient to know what you are talking about. You have been given some suggestions, but you need to do the work of figuring out which one is the one you want to discuss. (Or, if none of them are, you need to figure out what is.)

Like I said I don't know the reference it was years ago

Then you'll need to go and find one and start a new thread based on it. This thread is closed.