Download The “Big Bang” Theory

The “Big Bang” Theory
The beginning of everything we know
What is the Big Bang?
• The theory says that all matter in the
universe came together due to gravity.
• It became so dense that the pressure
caused it to “explode”.
• This happened approximately 15 billion
years ago.
• All of the matter moved outward and the
universe is still expanding.
What proof do we have?
• Background Radiation
– Scientists detect a background radiation when
they study the universe. The radio signature
is consistent wherever they look.
• Doppler Red Shift (The Doppler Effect)
– The light from stars is analyzed and the
spectrum is shifted toward the longer
wavelengths of light – toward the red
What is the Doppler Effect?
• When energy waves are given off by a
moving object the waves are…
– Stretched when it is moving away
– Compressed when it is moving closer
• The Doppler Effect is used when analyzing
star light, determining the speed of a ball
or motor vehicle, and for weather radar.
A stationary train sends the same sound wave in
every direction and the whistle has the same
sound or pitch no matter where you are standing.
A moving train will have a higher pitch whistle when it is
moving toward you and a lower pitch after it passes you.
Hear the Doppler Effect!
Train
Ambulance
Car
Horn
Truck
Doppler
Song
So what happened after the
“Big Bang”?
• Matter started to “clump” back together
• This was due to gravity
• The galaxies, stars and planets formed
from these clumps of dust and gas
• There are billions of galaxies in the
universe and each galaxy consists of
billions of stars
So What about Earth?
• Our solar system, including the Earth,
formed about 4.6 billion years ago.
• That is about 10 billion years after the “Big
Bang”.
• Hominids (early ancestors of man) have
only been around for about 3.6 million
years and Homo sapiens for only about
200,000 years.
So what’s the deal with Stars?
• Stars are giant balls of mostly gas (usually
hydrogen and helium) that give off huge
amounts of energy through nuclear fusion.
• Nuclear fusion is a process that joins two nuclei
together and gives off a lot of energy in the
process.
• The Sun is our closest star.
• All stars go through a similar evolution or life
cycle which includes…
– Hydrogen (H) to Helium (He) and then Helium (He)
to Carbon (C)
Star Life Cycle
Nebula
Protostar
Star
(Stellar Cloud)
(Cloud Compresses)
Is created when fusion
begins
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Stars like the sun take
about 10 billion years to
convert all Hydrogen to
Helium
Star will expand then cool Red Giant is formed
(Luminosity increase while
temps. decrease)
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Helium in core now reacts
(fusion) to form Carbon
Star contracts. Temps.
too cool for Carbon
fusion.
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Some White Dwarfs do not
just cool and die. Some
may have large explosions
called Novas.
Novas
Explosion may cause star A Super-Nova is a large
to become a million times explosion(s) that destroys
as bright – for a short
a star.
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period of time.
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After explosion of a SuperNova, a dense ball of
neutrons may be formed =
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Neutron Star
When leftovers are too
dense – a Black Hole may
be produced. – So dense,
light cannot escape.
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Stars energy production
stops. White Dwarf is
created.
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The END!!
or is it?
So what about the origins of life?
• There is evidence that the organic material
(amino acids) necessary for life arrived on
Earth in meteorites.
• Organic material is carbon based compounds
and is part of all life as we know it.
• It may have been lightning that made these
compounds become “alive”.
• Water was necessary for life to evolve and this
may have come from comets
• Oxygen in the atmosphere was given off by
early organisms that were very abundant
When did life arrive on Earth?
• Evidence suggests that life arrived on Earth
about 3.6 billion years ago.
• These life forms were the simplest form of life
– simple bacteria.
• There is evidence of multi-cellular life as far
back as 1 billion years.
• As organisms with shells and eventually
bones arrive the fossil record becomes more
detailed because these are more easily
preserved.