from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A greater than normal density
Sorry, no etymologies found.
The collapse of an overdensity can be thought of as the evolution of a small matter dominated portion of the universe.
In passing through such a growing overdensity, the photons gain energy as they fall into the associated potential well, and lose energy as they climb out of it (this is general relativity after all, and gravity affects light just as it would affect massive particles).
"It appears to me this is an overdensity issue," Brown said.