Into the Primordial Soup
There is no reason to stop
the extrapolation back in time at three minutes AB. We have a very good
knowledge of the types of interactions expected in a universe of electrons,
neutrons, protons, and photons, and so long as we can understand the relevant
constituents of matter and its behavior at high temperature, we can reasonably
speak of the evolution of the universe.
We know that neutrons and protons are not elementary
particles, but rather, are made of quarks and gluons. At sufficiently high temperature and density the neutrons and
protons themselves should melt. Earlier
than a microsecond (one-millionth of a second) after the bang, the universe
should have been a primordial soup of quarks and gluons.
|
Percent
|
ingredient
|
comment
|
|
56%
|
quarks
|
up, down, strange, charm,
top, bottom
|
|
16%
|
gluons
|
strong nuclear force
carriers
|
|
9%
|
W and Z particles
|
weak nuclear force
carriers
|
|
9%
|
electron-like particles
|
electron, muon, tau
|
|
5%
|
neutrinos
|
electron-type, muon-type,
and tau-type
|
|
2%
|
photons
|
electromagnetic force
carriers
|
|
2%
|
gravitons
|
gravitational force
carriers
|
|
1%
|
Higgs bosons
|
still undiscovered
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The Known Ingredients in the
Primordial Soup (circa four picoseconds AB)
Since our goal is to
simulate the extreme conditions of the early universe, we must find a way to
produce the corresponding temperatures in the laboratory. The most powerful tool for generating high
temperatures is the particle accelerator.
The accelerator is used to examine nature on the smallest scales and to
discover the fundamental forces and particles.
Accelerators are the world's most powerful microscopes. But the most powerful microscope is also a
telescope, because by colliding particles at high energy we can recreate the
environment of the early universe and understand how it evolved into the
present universe.
The world's most powerful
accelerator is Fermi National Accelerator Laboratory (Fermilab) in Batavia,
Illinois. Collisions of protons and
antiprotons at Fermilab can produce temperatures of 3,000,000,000,000,000 K,
which existed in the universe four picoseconds (fotir-millionth-millionth of a
second) after the bang. We can study
the early universe by recreating in terrestrial laboratories a little piece of
the primordial soup. The ingredients of
the primordial soup are the elementary particles produced and studied at
accelerators.
The most abundant
ingredients in the primordial soup were quarks and antiquarks. They are so numerous because there are six
types of quarks and each type of quark comes in three ‘colors.’ The next most
abundant particle species in the primordial soup was gluons, the carriers of
the strong force. Quarks, antiquarks,
and gluons make up 72% of the primordial soup.
The electrons, muons, photons, and all the other elementary particles
were the flavorful croutons in the primordial soup.
Contributed by: Dr. Edward Kolb
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