Page 72 - The Origin of Life and the Universe - International Conference 2016

The Origin of Life and the Universe

that exist in the universe are hydrogen and helium. There are small
amounts of lithium and beryllium but for all intents and purposes you can
ignore that. All the elements heavier than this, carbon, nitrogen, oxygen,
those are formed in the hearts of stars. So Lawrence Krauss is very much
right, the carbon and nitrogen and oxygen in our bodies, is the dust left
over from stars, so we are made up of stardust. But as scientists have
studied how well stars produced the carbon and the oxygen, they found
huge deficiencies in how much they expected to be produced and how
much was necessary for life to exist. Unless some remarkable coincidences
were true.
In particular, the difficulty of producing carbon is that three helium
nuclei have to come together to make carbon. So carbon has six protons
and six neutrons, each helium has two protons and two neutrons. To get
helium to come together to form carbon you have to have three of them
come together at the same time. And because it's three of them coming
together at the same time that's an incredibly slow reaction. However as
scientists look more closely they recognize two important factors that
allow the formation of carbon. First when two helium atoms come together,
they can actually form a beryllium-8 nucleus. Two of them stick together,
now that beryllium-8 nucleus is not actually stable. So it doesn't stick
around for a long time. But it does stick around for a while. What that
means is that in order for carbon to be made now another helium just has
to come and hit that beryllium nucleus. That's a 2-body reaction that
proceeds much more rapidly. So in order to form carbon this beryllium-8
nucleus speeds up the reaction considerably.
However even with this metastable beryllium-8 nucleus, stars would
not produce enough carbon. Something else was missing. It's when
scientists working on the problem recognized a solution that would
produce carbon rapidly enough. If carbon had a particular energy level
just above its ground state, so if this is its ground state they had energy
level just a little bit higher, then the reaction would proceed much more
rapidly. Now, this energy level was unknown at the time. But scientists
subsequently studied this prediction made by Fred Hoyle and found that
it indeed existed. And so without this stable brilliant eight nucleus and a