The trick works because galaxies, and the wider intergalactic medium, contain a lot of neutral hydrogen
Because they coalesced out of the soup of neutral hydrogen
(and a little helium) that filled the early cosmos, these stars grew large, burned bright and blue and then died quickly, probably surviving around 100 million years, give or take.
The epoch, roughly referring to between 150 million and one billion years after the Big Bang, was when the neutral hydrogen
in the universe became ionized, allowing light to move freely through space and making it visible.
There were no stars or galaxies, and the universe was filled with neutral hydrogen
Separate neutral hydrogen
and put aside in Balmer series chamber.
That's when the light-blocking fog of charged subatomic particles generated in the universe's first few moments finally cooled enough for neutral hydrogen
and helium atoms to form, thus rendering the universe transparent to photons long trapped in limbo.
So, it is not necessarily that other distant galaxies are not there, but that they are hidden from detection behind a wall of neutral hydrogen
fog, which blocks the hydrogen emission signal.
Using the GBT, Pisano was able to detect the glow emitted by neutral hydrogen
gas connecting NGC 6946 with its cosmic neighbors.
Scientists think that the collision of neutral hydrogen
molecules may have helped to drive the Martian atmosphere into space over billions of years.
Among others, the SKA will be able to receive the 21 cm signal emitted by neutral hydrogen
even before recombination, which is of great importance to cosmology.
When molecular hydrogen delivers a single proton to the condensation reactions, it is also delivering a single electron, if a neutral hydrogen
atom subsequently emits.
After outlining a brief history of radio astronomy, Brian Coleman described the physics behind the neutral hydrogen