Transcript The Big Bang

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Stars on the Move
• Every single object in the
universe is on the move.
• A spectroscope enables
scientists to determine whether
a particular galaxy is moving
toward the earth or away from
the earth.
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The Red Shift
• Light travels from stars as light
waves.
• A spectroscope breaks up light into
a spectrum because each color of
light has a different wavelength.
• If a star is rapidly approaching the
earth, the light waves from the star
will appear compressed, or pushed
together.
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• Wavelengths from an
approaching star often
appear shorter than they
really are.
• Shorter wavelengths of light
are characteristic of blue and
violet light.
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• The entire spectrum of an
approaching star appears
to be shifted toward the
blue end of the spectrum.
• This shifting is called the
blue shift.
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• If a star is moving away from the
earth, the light waves will be
slightly expanded.
• The wavelengths of the light will
appear longer than they really
are.
• Longer wavelengths of light are
characteristic of the red end of
the spectrum.
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• The spectrum of a star moving
away from the earth appears to be
shifted toward the red end.
• This is called the red shift.
• The more the spectrum of light is
shifted toward the blue or red end
of the spectrum, the faster the star
is moving toward or away from
the earth.
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• The apparent change in
the wavelengths of light
that occurs when an
object is moving toward
or away from the earth is
called the Doppler effect
• Sound
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• When astronomers first used
the spectroscope to study the
light from stars in distant
galaxies, they discovered that
none of the light from these
distant galaxies showed a blue
shift.
• None of them were moving
toward the earth.
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• Light from every distant galaxy
showed a red shift.
• Every galaxy in the universe
seemed to be moving away
from the earth.
• Based on the examinations of
these red shifts, astronomers
concluded that the universe is
expanding.
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• Galaxies near the edge of the
universe are racing away
from the center of the
universe at tremendous
speeds.
• Galaxies closer to the center
are also moving outward, but
at slower speeds.
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The Big Bang Theory
• Astronomers believe the
expanding universe is the result
of an enormous and powerful
explosion called the big bang.
• The big bang theory may
explain how the universe
formed.
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• The big bang theory
states that the universe
began to expand with the
explosion of concentrated
matter and energy and
has been expanding ever
since.
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• According to the theory, all of
the matter and energy in the
universe was then
concentrated into a single
place.
• The big bang shot the
concentrated matter and
energy in all directions.
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•The fastest moving
matter traveled farthest
away.
•Energy also began
moving away from the
area of the big bang.
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• If the big bang theory is
correct, the energy left from
the big bang will be evenly
spread out throughout the
universe.
• This energy is known as
background radiation.
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• Scientists have discovered
that the background
radiation in the entire
universe is the almost the
same everywhere.
• This constant background
radiation is one observation
that supports the big bang
theory.
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• After the initial big bang, the force
of gravity began to affect the
matter racing outward in every
direction.
• Gravity is a force of attraction
between objects.
• All objects have a gravitational
attraction for other objects.
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• The more massive the object is,
the stronger its gravitational
attraction is.
• This force of gravity began to pull
matter into clumps.
• The clumps formed huge clusters
of matter.
• These clumps became the galaxies
of the universe.
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