Birth of the Birth of the UniverseUniverse

Once upon a time, there was nothing, and then…Once upon a time, there was nothing, and then…

AgeAge What Was HappeningWhat Was Happening00☻☻ The “Big Bang”- a cataclysmic event in which The “Big Bang”- a cataclysmic event in which

space, time and matter were effectively born from space, time and matter were effectively born from a point-like source of pure energy. (To date, a point-like source of pure energy. (To date, physics can only explain events after 10physics can only explain events after 10 -43-43 sec!) sec!)

1010-35-35 sec sec The universe was grapefruit-sized; some matter The universe was grapefruit-sized; some matter had appeared, but it was in an “unconventional” had appeared, but it was in an “unconventional” form (quarks, leptons etc); the temperature was form (quarks, leptons etc); the temperature was 10102727 K. K.

no light!no light!

Birth of the Birth of the UniverseUniverse

AgeAge What Was HappeningWhat Was Happening1010-6-6 sec sec The first “conventional” matter had The first “conventional” matter had

appeared (electrons, neutrinos and their appeared (electrons, neutrinos and their anti-particles); the temperature was 10anti-particles); the temperature was 101313 K. K.

2 sec2 sec All matter was in “conventional” form All matter was in “conventional” form (including protons and neutrons); no atoms (including protons and neutrons); no atoms

had yet formed; the temperature was had yet formed; the temperature was 10101010 K. K.

3 min3 min Some atomic nuclei had “fused” (deuterium, Some atomic nuclei had “fused” (deuterium, helium-3 and helium-4); there were still no helium-3 and helium-4); there were still no atoms; the temperature was 10atoms; the temperature was 1099 K. K.

no light!no light!stillstill

Birth of the Birth of the UniverseUniverse

AgeAge What Was HappeningWhat Was Happening101066 yrs yrs Nuclei and electrons had combined to form Nuclei and electrons had combined to form

atoms of hydrogen, deuterium, helium-3 and atoms of hydrogen, deuterium, helium-3 and helium-4; the universe was an expanding helium-4; the universe was an expanding cloud of gas (roughly 92% hydrogen, 8% cloud of gas (roughly 92% hydrogen, 8% helium); the temperature was 3000 K. helium); the temperature was 3000 K.

101077 yrs yrs Due to gravity, “clumps” had begun to form Due to gravity, “clumps” had begun to form within the expanding gas cloud; these would within the expanding gas cloud; these would continue contracting to become the first continue contracting to become the first stars!stars!

no light!no light!stillstill

Stellar EvolutionStellar Evolution

During the first 10 – 100 million years:During the first 10 – 100 million years: A hydrogen/helium gas clump contracts under gravity to form a A hydrogen/helium gas clump contracts under gravity to form a

dense spinning ball (often surrounded by a rotating disc of gas and dense spinning ball (often surrounded by a rotating disc of gas and dust).dust).

Pressure and temperature in the core increase until, at about 10 Pressure and temperature in the core increase until, at about 10 million K, the core ignites and the star begins to “shine”. million K, the core ignites and the star begins to “shine”.

During the next 1 – 10 billion years:During the next 1 – 10 billion years: There follows a long, stable period of hydrogen fusion into helium, There follows a long, stable period of hydrogen fusion into helium,

with inward gravity and outward pressure continuing in perfect with inward gravity and outward pressure continuing in perfect equilibrium.equilibrium.

The larger the star is, the shorter the duration of this period.The larger the star is, the shorter the duration of this period. Our Sun is a small star, roughly halfway through this stage.Our Sun is a small star, roughly halfway through this stage.

Stellar EvolutionStellar Evolution

During the next 10 – 100 million years:During the next 10 – 100 million years: Depletion of hydrogen in the core causes a slight shrinkage.Depletion of hydrogen in the core causes a slight shrinkage. Helium begins fusing into carbon (and carbon into heavier Helium begins fusing into carbon (and carbon into heavier

elements), driving up the core pressure.elements), driving up the core pressure. The star expands into a “red giant”.The star expands into a “red giant”. In the case of our Sun, this expansion will swallow the Earth!In the case of our Sun, this expansion will swallow the Earth!

During the final 1 week – 1 million years:During the final 1 week – 1 million years: When fusion into iron commences in the core, the star begins When fusion into iron commences in the core, the star begins

consuming energy much faster than it can produce it. consuming energy much faster than it can produce it. The core pressure drops steadily and the unstable star begins The core pressure drops steadily and the unstable star begins

to “collapse” under gravity.to “collapse” under gravity. The star is dying, and its final “death state” depends on its size.The star is dying, and its final “death state” depends on its size.

Stellar EvolutionStellar Evolution

Final Death States of a Star:Final Death States of a Star: A small star (like our Sun) shrinks slowly to a tiny, dense “white A small star (like our Sun) shrinks slowly to a tiny, dense “white

dwarf”, eventually cooling to a “black dwarf cinder”.dwarf”, eventually cooling to a “black dwarf cinder”. A large star undergoes a rapid, catastrophic collapse, in which the A large star undergoes a rapid, catastrophic collapse, in which the

core collapses faster than the outer envelope.core collapses faster than the outer envelope. The sudden increase in core pressure produces a “supernova” The sudden increase in core pressure produces a “supernova”

explosion which blows the stellar envelope and most of the core explosion which blows the stellar envelope and most of the core away.away.

The remainder of the original core continues to collapse, ending The remainder of the original core continues to collapse, ending up either as a “neutron star” or a “black hole”.up either as a “neutron star” or a “black hole”.

Since iron is the heaviest element created in the stellar core, the Since iron is the heaviest element created in the stellar core, the fusion of “heavier elements” (e.g. gold, lead, uranium) can only fusion of “heavier elements” (e.g. gold, lead, uranium) can only occur during “supernovae”.occur during “supernovae”.

This is how we know that the Earth is made of “stardust”!This is how we know that the Earth is made of “stardust”!

Birth of the Birth of the Solar SystemSolar System

Our own solar system started to develop about Our own solar system started to develop about 5.0 billion years ago when a cloud of gas and dust, the 5.0 billion years ago when a cloud of gas and dust, the product of earlier first- or second-generation supernova product of earlier first- or second-generation supernova explosions, began to contract due to gravity.explosions, began to contract due to gravity.

As the cloud coalesced, its rotation rate increased (by As the cloud coalesced, its rotation rate increased (by “conservation of angular momentum”) and it flattened “conservation of angular momentum”) and it flattened into a central ball of gas surrounded by a number of into a central ball of gas surrounded by a number of rings of “stellar debris”.rings of “stellar debris”.

Over the next 300 million years, the central ball became Over the next 300 million years, the central ball became the Sun, and the rings evolved into “proto-planets” with the Sun, and the rings evolved into “proto-planets” with “primordial” atmospheres, the third closest of which “primordial” atmospheres, the third closest of which would become planet Earth.would become planet Earth.