A Brief Timeline
• < 10-43 sec, >1032
K or 1019 GeV--- “This is where smoke comes out of
the computer, but physics is still going strong.” (John
Archibald Wheeler) Presumably at t = 0 a spacetime boson
popped into existence in nothingness. If the boson has E
= 0 it can persist indefinitely.
• < 10-36 sec, >1016
GeV--- Possibly
all four fundamental forces have close to the same strength.
• 10-33 to 10-32
sec, 1028 dropping to 1022 K--- The
universe undergoes a phase
transition which results in expansion of space by a
factor of around 1026. The extremely rapid cooling
may “freeze out” the strong force. As this
“inflation field” collapses into very massive bosons, the
bosons in turn decay, through a long chain, ultimately to
particle-antiparticle pairs.
• >10-12 sec, near 1012
K--- An excess of quarks, as well as dark matter particles,
has been slowly forming as a result of particle-antiparticle
annihilations which are nonsymmetric (CP-violating) and
leave behind an excess of particles, about 1 in 109.
Photons are therefore dominant. The Higgs field is active in
providing mass to both fermions and bosons.
• 10-11 sec, 1012
K--- The end of electroweak unification also marks the end of
the era of creation of excess dark matter, leptons and quarks
via various possible CP-violating processes.
• 10-6 sec, >1010
K--- The quark-gluon plasma condenses into protons and
neutrons. The strengths of the four fundamental forces
have their present values. Hadronic antimatter has now
vanished completely.
• 1 sec, 1 MeV (1010 K)---
Neutrinos decouple from baryonic matter. Leptons and
anti-leptons, along with dark matter, still dominate
the mass of the universe, with most particles still being
photons, and still in thermal equilibrium with all other
particles. The part of the universe we can observe
has a radius of about 10 light years at 1 second age.
• 1 to 10 sec, >109
K--- Leptons and anti-leptons are still in thermal
equilibrium with photons. Pair creation and annihilation
closely balance out.
• 10 to 103 sec--- the
First Era of Nucleosynthesis! Protons and neutrons
can fuse to form helium, lithium and isotopes of hydrogen
without being knocked back apart by photons. Essentially
all the helium in the universe (24% of all atoms) was
formed during this era, since the amount of matter that
has ever been inside a star is negligible. At 1000
sec the radius of the part of space which is today the
observable universe was about 300 light years.
• 3 minutes to 240,000 years, 105
K to 4000 K. Matter and Dark Matter dominate over
radiation density and Dark Energy density. At about
3 minutes, photon kinetic energy drops low enough that
leptons can survive without being annihilated by
anti-leptons, and a sea of leptons and antileptons no
longer dominate the mass of the universe (apart from dark
matter).
• 380,000 years, 3000 K--- The
universe cools to a gas, as electrons combine with protons
and other nuclei. At last photons go out of thermal
equilibrium with matter. This is the moment that the
so-called Cosmic Microwave Background is created, and also
the “last scattering surface,” which has yielded a
goldmine of information about the composition of the
entire universe at this time. The part of the
universe currently observable to us had a radius of about
42 million light years during this era.
• 380,000 years to 550 million
years--- The Dark Ages, when photon absorption was extreme
due to the universe consisting of cool hydrogen and helium
gas, with few stars to ionize it again. Reionization
was not complete until about 900 million years on.
During the Dark Ages, dark
matter played the key role, by providing extreme
density variations which through gravity formed structures
of ordinary matter... the earliest stars
("Population III)" and galaxies. Today the diameter
of our part of the universe is around 93
billion light years. It was pointed out by Loeb
a few years ago that when the universe was in the age
range from 10 to 17 million years, the temperature of
space itself was between 100 and 0o Centigrade,
so that liquid water could have existed on even starless
rocky planets! Did life first form in this Dark Age, only
to die out as space cooled?
• Today--- The universe has
transitioned from matter-dominated to
dark-energy-dominated.
Wikipedia Version of Similar Timeline
The James
Webb Space Telescope is a gigantic orbital telescope
specifically designed to probe the Dark Ages,
operating in the very far infrared. It is now fully
operational. Here is
what is currently the confirmed earliest known, observed
galaxy. However, in 2022 an earlier
galaxy may have been seen. Some patience is
required in interpreting the early Webb results because
initial distance assignments are estimates, and accurate
distance measurements will require spectroscopic studies.
SIMULATIONS OF STRUCTURE FORMATION
DARK MATTER
