Energy loss of a photon

[kymner]

TL;DR

Quick question about energy loss of a photon due to its own gravitational field.

I've been told that a photon doesn't lose energy as it travels through a vacuum because it doesn't experience time. However, general relativity states that any energy creates a gravitational field that travels away from the energy at the speed of light. Doesn't this imply that a photon once created should immediately create a gravitational wave that very slightly decreases it's energy changing its gravitational field and creating more gravitational waves causing it to very lose all of its energy over astronomically large distances? Since the gravitational field expands out to infinity shouldn't the energy lost be perpetual so that it continues losing energy forever until it ceases to exist? Wouldn't this explain the apparent expansion of the universe without actually requiring expansion?

 

[Nugatory]

I've been told that a photon doesn't lose energy as it travels through a vacuum because it doesn't experience time…. general relativity states that any energy creates a gravitational field that travels away from the energy at the speed of light.

Whoever told you these things, either they’re wrong or you misunderstood them.
(It is true that light doesn’t lose energy as it travels through a vacuum, but that isn’t because it “doesn’t experience time”).

As this thread is based on a mistaken premise, it is closed.