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R. Barrett and P. P. Delsanto
familiar fields (strong nuclear interaction, weak interaction, and electromagnetism) decouple from each other. The end result is a type of phase transition
resulting in the creation of the particles (gluons, quarks, etc.) carrying the
above interactions. A phase transition is a common phenomenon in physics,
where an entity can exist in different forms (e.g. as H 2 O can exist as ice, water
and water vapour), and under particular conditions can transform from one
to the other.
After the phase transition, the cosmic expansion continues at a much
slower rate, and we enter a domain where we expect more familiar physics
to prevail. The quarks and gluons begin to form protons and neutrons
(hadrons). As the temperature falls, these hadrons combine to form the nuclei
of atoms, such as deuterium (one proton and one neutron) and helium
(two protons and two neutrons). The nucleus of deuterium is known as
the deuteron, and the nucleus of helium is the α-particle, familiar from
the earliest studies of radioactivity. The proton itself is the nucleus of the
hydrogen atom.
At this stage an opportunity arises to use existing nuclear theory to predict
the relative abundances of these lightest elements, as well as the slightly
heavier ones of lithium and beryllium, in the primordial universe. Although
the issue is not yet completely settled, the calculated relative abundance of
helium (25%) is in good agreement with observation.
The next significant stage in the evolution of the universe is reached when,
after approximately 380,000 years, the temperature drops sufficiently to allow
electrons and atomic nuclei to combine to form neutral atoms. Before this
time, the free electrons interact with any photons to prevent their passage.
Once the electrons have been attached to nuclei to form atoms, their electromagnetic field is largely countered by the oppositely charged nuclei, and
their ability to impede the passage of photons is greatly reduced. The universe
becomes transparent, and visible through large telescopes on present-day
earth, looking back through time and space to this past era.
With the short range nuclear forces contained within nuclei, and the electromagnetic force reduced in potency by the close proximity of oppositely
charged particles, gravity becomes the driving force in the universe. The tiny
inhomogeneities that survived inflation begin to grow under its influence.
Slightly dense regions become denser as they attract more particles into their
neighbourhood, with a resultant increase in temperature and pressure. The
temperature rises in these regions until the nuclear fusion of hydrogen into
helium begins, and the first generation stars are born. These are powered by
the “burning” (nuclear fusion) of hydrogen.
R. Barrett and P. P. Delsanto
familiar fields (strong nuclear interaction, weak interaction, and electromagnetism) decouple from each other. The end result is a type of phase transition
resulting in the creation of the particles (gluons, quarks, etc.) carrying the
above interactions. A phase transition is a common phenomenon in physics,
where an entity can exist in different forms (e.g. as H 2 O can exist as ice, water
and water vapour), and under particular conditions can transform from one
to the other.
After the phase transition, the cosmic expansion continues at a much
slower rate, and we enter a domain where we expect more familiar physics
to prevail. The quarks and gluons begin to form protons and neutrons
(hadrons). As the temperature falls, these hadrons combine to form the nuclei
of atoms, such as deuterium (one proton and one neutron) and helium
(two protons and two neutrons). The nucleus of deuterium is known as
the deuteron, and the nucleus of helium is the α-particle, familiar from
the earliest studies of radioactivity. The proton itself is the nucleus of the
hydrogen atom.
At this stage an opportunity arises to use existing nuclear theory to predict
the relative abundances of these lightest elements, as well as the slightly
heavier ones of lithium and beryllium, in the primordial universe. Although
the issue is not yet completely settled, the calculated relative abundance of
helium (25%) is in good agreement with observation.
The next significant stage in the evolution of the universe is reached when,
after approximately 380,000 years, the temperature drops sufficiently to allow
electrons and atomic nuclei to combine to form neutral atoms. Before this
time, the free electrons interact with any photons to prevent their passage.
Once the electrons have been attached to nuclei to form atoms, their electromagnetic field is largely countered by the oppositely charged nuclei, and
their ability to impede the passage of photons is greatly reduced. The universe
becomes transparent, and visible through large telescopes on present-day
earth, looking back through time and space to this past era.
With the short range nuclear forces contained within nuclei, and the electromagnetic force reduced in potency by the close proximity of oppositely
charged particles, gravity becomes the driving force in the universe. The tiny
inhomogeneities that survived inflation begin to grow under its influence.
Slightly dense regions become denser as they attract more particles into their
neighbourhood, with a resultant increase in temperature and pressure. The
temperature rises in these regions until the nuclear fusion of hydrogen into
helium begins, and the first generation stars are born. These are powered by
the “burning” (nuclear fusion) of hydrogen.