Speed and direction of radiation

[ParticleOne]

What force is giving radiation (light, gamma and all other EM) its exact same speed c, wether it originates from an electron or nuclei, and what determines the direction, always directly away from the particle's core?

[timo]

What force is giving radiation (light, gamma and all other EM) its exact same speed c, wether it originates from an electron or nuclei, ...

No force. Light, gamma and all other EM are all photons. Photons have the feature to always have a speed of c (regardless of their momentum) because they are massless. In lack of a better analogy: Grass is always green, whether it naturally grows in a grassland or it´s artificially planted in a city park.

 

... and what determines the direction, always directly away from the particle's core?

I am not sure if I understand that question. Purely classically: If a point A, which shall be fixed in space, emmits some other point B which then moves in a straight line: How can B have any other movement than "directly away from A"?

[ParticleOne]

Hello Atheist,

 

I know it is a controversion issue, but that photon have the feature of always having speed c is not suficient explanation. Wether choosing a particle or wave function, the speed must have a reason. Even if it is massless, pure energy must have a reason to displace itself, and thats my question.

 

Why grass is always green has an explanation, the photosynthesis absorbs only red> and <blue frequencies of light and reflects the green colors, no matter where they live.

 

Regarding the direction of radiation: If a photon is released as a quantum process of electron moving from higher to lower valence band, in theory it could take any direction, i.e. it could "collide" with the nucleus if it was released in that direction. But it is always released perpendicular outwards from the nucleus. Why?

[insane_alien]

particle,

1/ the photon can be thought of as a ripple in the electromagnetic field. these ripples travel at c just like the waves on a pond travel at some speed call it d.

 

2/if we can only detect the photons that are released, then of course we're not going to detect photons that collide with the nucleus. and how do we know that they are all released perpendicular to the nucleus

[BhavinB]

particle' date='

1/ the photon can be thought of as a ripple in the electromagnetic field. these ripples travel at c just like the waves on a pond travel at some speed call it d.

 

2/if we can only detect the photons that are released, then of course we're not going to detect photons that collide with the nucleus. and how do we know that they are all released perpendicular to the nucleus[/quote']

 

Isn't the cross-section of a nucleus-photon interaction extremely small?

[insane_alien]

yeah it is. i'm not exactly an expert on this stuff. i'm just going on the few things i know

[swansont]

The wavelength from an atomic transition is much larger than the size of the nucleus. In the far-field, it's basically a point source, so all directions are perpendicular to it.

 

Photons propagate at c because a vacuum has a particular permeability and permittivity; these values are not zero. Oscillating electric fields and magnetic fields mutually induce each other, propagating at some speed given by those parameters. It's how nature behaves.

[ParticleOne]

I'm a bit confused.

 

Insane_alien:

If I take your example of waves on a pond (it cannot be EM field) then it would mean that as an electron changes its valence band it "drops" some energy into some field which causes waves, but these waves have to be omnidirectional then? (Aether theory, which is not proven OR disproven?) If so, then I have a problem with tests from the National Synchrotron Light Source at Brookhaven National Laboratory, where photons where captured at distinct points.?

 

Swantson:

 

I agree, the wavelength of light is far longer than size of a nucleus, and I agree that in the far-field it will be regarded as a point source, but from a sub-sub nm point of view it must still have a direction from the atom. And it must still be GIVEN a direction?

[swansont]

I'm a bit confused.

 

Insane_alien:

If I take your example of waves on a pond (it cannot be EM field) then it would mean that as an electron changes its valence band it "drops" some energy into some field which causes waves' date=' but these waves have to be omnidirectional then? (Aether theory, which is not proven OR disproven?) If so, then I have a problem with tests from the National Synchrotron Light Source at Brookhaven National Laboratory, where photons where captured at distinct points.?

 

Swantson:

 

I agree, the wavelength of light is far longer than size of a nucleus, and I agree that in the far-field it will be regarded as a point source, but from a sub-sub nm point of view it must still have a direction from the atom. And it must still be GIVEN a direction?[/quote']

 

I'm not sure if you can predict the direction of a given photon from de-excitation, only the radiation pattern, which gives you a probability that depends on things like the type of transition. Synchrotron radiation is a different matter, and it has a direction pattern dependent on the acceleration of the charge.