Originally Posted by

**Ziggurat in #26**
First off, I'm not arguing that photons do not interact. … Secondly, in regards to aligning their propagation direction, we know that this cannot happen because it would violate momentum and/or energy conservation.

The objection that propagation alignment of photons violates momentum and /or energy conservation is indeed serious. The bigger the changing angles, the more convincing the objection.

Let us assume that two photons with each the same energy

*E* are close to one another, and that the angle between their propagation directions is 120°. If they want to move in the same direction, then each photon has to change its direction by 60° into the new intermediate propagation direction.

Because of symmetry, the two photons cannot exchange energy, and propagation speed is always c. Before propagation alignment, combined momentum in the new direction:

2 * E/c^2 * 0.5 c = E/c

The factor 0.5 is the result of cos 60°. After alignment, momentum in this new direction:

2 * E/c^2 * c = 2 E/c

Therefore, combined momentum in the new direction would double during propagation alignment.

This problem can be solved by a simple ad-hoc-hypothesis. During alignment, radiation (in the form of one or more photons) with energy 0.5

*E* is emitted in the direction opposite to the new propagation direction, and each of the original two photons loses 25% of its energy

*E*. Then total momentum in the new direction will be again:

2 * 0.75 E/c – 0.5 E/c = E/c

As seen from two such photons:

The attempt not to drift apart leads by momentum conservation to an attempt to reduce propagation speed. There are only two solutions: either to give up the attempt to align propagation direction, or to gain forward momentum by emitting radiation backwards.

In any case, the momentum-compensation hypothesis for aligning photons implies:

- Overall redshift for the interacting photons
- Release of low-frequency radiation (lost in background)

Cheers, Wolfgang

**Simple statistical behavior can be the result of complex individual behavior**