First photons
|
 |
 |
Nearly 14 billion years ago, it was the Big Bang: our universe sprang up revealing space and time, but the photons constantly collided with other particles and the light remained trapped.
Then after a few hundred thousand years (380,000 years), the expansion of the universe and the aggregation of the first atomic nuclei allowed photons to finally circulate freely: light appears.
This initial light took about 14 billion years to reach us in the form of fossil radiation: the cosmic microwave background.
The "snow" visible on an old cathode-ray tube television set when not tuned is due for a tiny part (less than 1%) to this original cosmic radiation, drowned among the parasites of the electronic circuits.
The image of this "snow" on an analog television does not represent a distribution of noise in space, unlike the targeted measurements of this radiation which scan space to obtain a spatial map of this cosmic microwave background.
