Water in the Cosmos - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 3

second into the Big Bang, 4 protons and neutrons began to appear.
A single proton is the nucleus of a hydrogen atom—but temperatures
(at ten thousand million degrees) were still too high for an electron to
fall into orbit around a proton to complete the building of that atom.
That only took place a little later—about 300,000 years later. Then,
the universe was about a thousandth of its size today (i.e. already
stupendously big) and much cooler, although still hot—about 3,000
degrees Celsius—by human standards. As far as normal matter
was concerned, that was largely that. There was also quite a lot of
helium—about 25 per cent—for in the furnace of the early Big Bang
two protons had occasionally collided violently and precisely enough
to combine to form a helium nucleus, the protons managing to over-
come their natural mutual repulsion for the short-range 'strong'
nuclear forces to bind them together. Occasionally, a third proton was
added, to make up a lithium nucleus. These three elements, initially,
made up the universe.
So, in those early years of the cosmos there was no possibility of
water, because there was no oxygen. Nor was there any sodium, or
chlorine, or potassium, or magnesium to make that water salty. There
were simply those three primordial elements, swirling in the outrush-
ing clouds of the early universe.
The birth of oxygen and of the other elements of the periodic table
required the births—or more precisely the deaths—of the first stars.
These first stars began to form as the densest parts of the clouds col-
lapsed under their own weight, creating spinning spheres of gas.
These became so tightly compressed at their centres that hydrogen
atoms fused to produce yet more helium atoms, releasing the energy
that makes stars hot and bright.
Helium is not the only product of the fusion process in the heart of
a star. Other elements are made as nuclei continue to combine. This
may be either in 'normal' burning processes in large stars, or as the