A type of hydrogen that doesn't interact with light could explain how long neutrons live and reveal the identity of the ...

We all know the ingredients for water. You take two atoms of hydrogen and one of oxygen, moosh them together just so, and voila – you have a molecule of the most important compound to life on Earth.

But the attractions are strong enough to pull the two atoms close enough together so that the electrons feel the attraction from both protons and are shared by both atoms. At the end of the animation, ...

and tritium (an isotope of hydrogen containing one proton and two neutrons), and are in fact preferred. This is because in order to fuse two atoms together, the Coulomb force must be overcome.