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Tuesday, 24 November 2009 02:06 |
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Spacetime arrives when supergravity separates into the combined
nuclear forces (strong, weak, electromagnetic) and gravitation.
Matter makes its first appearance during this era as a composite form
called Grand Unified Theory or GUT matter. GUT matter is a
combination of what will become leptons, quarks and  photons. In
other words, it contains all the superpositions of future normal
matter. But, during the GUT era, it is too hot and violent for
matter to survive in the form of leptons and quarks.
Why can't matter remain stable at this point in the Universe's
evolution? This involves the concept of equilibrium, the balance
between particle creation and annihilation.
- while matter is created, its lifetime is very short due to the high temperatures in the early Universe
- as the Universe cools, less massive particles can be produced
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During pair production, energy is converted directly into mass in the
form of a matter and anti-matter particle pair. The simplest
particles are, of course, leptons such as an electron/positron pair.
However, in high energy regimes, such as the early Universe, the
conversion from energy to mass is unstable compared to the more
probable mass to energy conversion (because the created mass must be
so high in mass to match the energy used). In other words, when
temperatures are high, matter is unstable and energy is stable.
Any matter that forms in the early Universe quickly collides with
other matter or energy and is converted back into energy. The matter
is in equilibrium with the surrounding energy and at this time the
Universe is energy or radiation-dominated.
The type of matter that is created is dependent on the energy of its
surroundings. Since the temperatures are so high in the early
Universe, only very massive matter (= high energy) can form. However,
massive particles are also unstable particles. As the Universe
expands and cools, more stable, less massive forms of matter form. |
- 10-6 secs after the Big Bang, ordinary matter comes into existence
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As the Universe expands, matter is able to exist for longer periods
of time without being broken down by energy. Eventually quarks and
leptons are free to combine and form protons, neutrons and atoms, the
ordinary matter of today. |
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