the nature of photons

[Johanluus]

event1

1. A photon is created when object(1) of mass release energy through radiation..

 

event2

2. The Photon is destroyed when it is absorbed by another object(2) absorption.

 

 

Between event 1 and event 2 this PHOTON must be accellerated from rest ( WRT object1) resulting in redshift and Decellerated to rest ( WRT object2) resulting in blueshift.

 

This is directly atributable to Gravitation of both objects as i understand it.

If the photon does not change its speed i.e always c IN ALL INHERTIAL FRAMES.

 

Would it not make more sense to say that redshift /blueshift. is a result of gravitation , and not the speed of recession of the two objects in question.

 

 

For light , velocities of objects, have no physical meaning if its velocity is constant for ALL objects i.e c .Velocities and time are of no importance between linking two events that are not in contact due to gravitation.

 

Why do we always then relate redshift => hubbles constant => expansion of universe. Are these effects on photons , not predominantly due to Gravitational effects e.g LENSING ETC.

[swansont]

The photon is created traveling at c.

[Johanluus]

The photon is created traveling at c.

even so

 

"Would it not make more sense to say that redshift /blueshift. is a result of gravitation , and not the speed of recession of the two objects in question"

[Spyman]

A lightray going from the Earth to the Moon will be redshifted for an observer in a spaceship orbiting Earth relative an observer on Earths surface due to difference in gravity. And it will be blueshifted for an observer standing on the Moon relative the observer in the spaceship, but relative the observer on Earth it will be redshifted since the gravity well is deeper close to Earth than close to the Moon.

 

In General Relativity there are three cinds of redshifts: Relativistic Doppler caused by a speed difference, Cosmological Redshift caused by expanding space and Gravitational Redshift due to differences in gravitational fields.

 

When measuring redshifts from distant objects it's likely that all three effects are involved and stacked upon each other to some degree.

 

Redshift

In physics (especially the physics of astronomical objects), redshift happens when light seen coming from an object is proportionally shifted to appear more red. Here, the term "redder" refers to what happens when visible light is shifted toward the red end of the visible spectrum. More generally, where an observer detects electromagnetic radiation outside the visible spectrum, "redder" amounts to a technical shorthand for "increase in electromagnetic wavelength" — which also implies lower frequency and photon energy in accord with, respectively, the wave and quantum theories of light.

 

Redshifts are attributable to three different physical effects. The first discovered was the Doppler effect, familiar in the changes in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles; an observed redshift due to the Doppler effect occurs whenever a light source moves away from an observer. Cosmological redshift is seen due to the expansion of the universe, and sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase of their distance from Earth. Finally, gravitational redshifts are a relativistic effect observed in electromagnetic radiation moving out of gravitational fields. Conversely, a decrease in wavelength is called blue shift and is generally seen when a light-emitting object moves toward an observer or when electromagnetic radiation moves into a gravitational field.

http://en.wikipedia.org/wiki/Redshift