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The Origin and History of the Universe
TEK Objective 4: The student knows how Earth-based and
space-based astronomical observations reveal differing
theories about the structure, scale, composition, origin, and
history of the universe.
Student Expectations:
a) evaluate the evidence concerning the Big Bang model such as red shift
and cosmic microwave background radiation and current theories of the
evolution of the universe, including estimates for the age of the universe;
b) explain how the Sun and other stars transform matter into energy through
nuclear fusion; and
c) investigate the process by which a supernova can lead to the formation
of successive generation stars and planets.
• How did our
universe begin?
Homo neanderthalensis
Galileo
• How old is our
universe?
• How did matter
come to exist?
• What is our place
in the universe?
True to the nature of science, a majority of these
answers have only led to more intriguing and
complex questions. Perhaps, science is all about
finding the next question, instead of the answers!
Universe
The universe is commonly defined as the totality of everything that
exists,[including all space, time, matter, energy, planets, stars, galaxies, and
intergalactic space
Galaxy
A galaxy is a massive, gravitationally bound system that consists
of stars and stellar remnants, an interstellar medium of gas, dust,
and dark matter. Our galaxy is the Milky Way, and it is a spiral
galaxy.
Star, or Stellar System
A star system or stellar system is a small number of
100 (M100)
stars which orbit each other, boundMessier
by gravitational
Spiral Galaxy
attraction.
Planetary, or Solar Systems
A solar system consists of one or a number of stars,
surrounded by a number of planets and planetary bodies
held by gravitation.
Universe had no beginning
or end…it was truly infinite
With the Big Bang theory,
universe is “finite”:
• 15 billion years ago, huge explosion
which started the expansion of the
universe.
• all matter, and energy of space was
contained at one point.
• this explosion filled all of space with
the particles of the young universe
rushing away from each other.
Edwin Hubble
Observed the
universe expanding
in every direction
and that a galaxy’s
velocity is
proportional to its
distance from us.
Ex: galaxies that are
twice as far from us,
move twice as fast
1) by looking for the oldest
stars; and
2) by measuring the rate of
expansion of the universe and
extrapolating back to the Big
Bang (Recessional Velocity)
This second way uses what is known as the Hubble constant to
measure of the current expansion rate of the Universe.
This mathematical derivation (calculation) can only be
correct, however, if the universe is not significantly
accelerating or decelerating its expansion rate.
If the rate of expansion is rapidly accelerating, the
universe may be older than 15 billion years.
One way to measure these ages is with the travel time of light.
Light travels incredibly fast – 300,000 kilometers per second.
8.3 minutes
from
the Sun,
We•don’t
see these
objects
as they are right now, but as they were
• 4.3
fromThe
the universe
nearest star,
when
theyears
light left.
actually works as a sort of “time
• 8500 years
from
of the
Way galaxy.
machine,”
in which
wethe
cancenter
see into
theMilky
past simply
by looking far
away.
• Speed of light ( Well known from experiments here on Earth)
• Distance of objects ( Far more difficult)
Some galaxies look much smaller and fainter than others,
showing they may be much further away.
The Andromeda galaxy is 2.3 million light years away. That is, we
are seeing it as it was 2.3 million years ago.
In recent decades, astronomers have detected galaxies located
several billion light years away. If the light has been traveling
Galaxy
is the
oldest
billions of years
toUDFj-39546284
reach us, then
the
universe must be at least
galaxy to ever be found, estimated at
that old.
13.7 billion light years from Earth.
Galaxies are not holding still in space, nor are they moving
randomly. From the time of the Big Bang, the Universe has been
expanding in a uniform manner and direction.
• Towards one another (gravity)
• Away from one another (momentum from the Big Bang)
While objects within the Universe have been expanding, for the
most part, in a uniform manner, the motion apart has not all been
at the same speed; instead it follows a pattern where galaxies that
are further apart are moving more quickly. Speed of galactic
motion is proportional to the separation between them. This,
again, is known as Hubble’s Law.
Astronomers detect a galaxy’s motion by looking at its light
spectrum.
This is the name given to the phenomenon of galaxies
moving farther away from each other.
As light approaches
Earth from different
galaxies, the space
between that distant
galaxy and Earth
increases. This leads
to wavelengths of the
light being stretched.
Why red???
This movement would tend to
make objects (or galaxies) that we
are most distant to appear
“reddish”
Remember…the longer wavelengths of the visible light
spectrum include the reds and oranges. The shorter
wavelengths of the visible light spectrum include the indigos
and violets, so the farther away the stars become, the “more
red” they appear
When a galaxy is carried away by the expansion of space, its light
waves are stretched out, making it appear redder. This red shift
can be used to calculate the galaxy’s velocity.
From the measurements of many galaxies, astronomers can
accurately measure the expansion rate of the universe as a
whole. Hubble's Law
The age of universe can be determined by imaging what the
universe looked like in the past, “rewinding” the expansion. In the
past the galaxies must have been closer together, and in the
distant past they would have been packed together in a tiny point.
If we assume that the expansion rate is constant over time, the
age for the universe as a whole is about 10 billion years.
Astronomers have been working over the last 20 years to determine how the
expansion rate changes with time. We now know that early in the universe the
expansion was slowing down, but now it is speeding up. Using careful
measurements of this change in expansion rate, the age of the universe is now
known quite precisely to be 13.7±0.13 billion years
is thermal radiation filling the observable universe
almost uniformly. It is radiation left over from an early
stage in the development of the universe, and its
discovery is considered proof of the Big Bang model
of the universe.
Scientists use
very small
radio telescope
arrays to listen
to CMBR.
The sun represents a source of light and heat upon
which all living things depend for their survival.
This light and heat radiated by the sun is the result
of fusion energy.
Fusion converts matter to energy. Fusion is the
joining of two small elements to form one larger
one. In the process, energy is lost, in the form of
light and heat.
The main fuels used in nuclear fusion are
deuterium and tritium, both heavy isotopes of
hydrogen.
This energy, once it reaches the Earth, is then utilized by plant life to build tissue, and
repair injury, as well as maintain homeostasis.
Then animals and microscopic consumers eat the plants, delivering the energy to
their bodies. Consumers use this energy for the same purposes as plants.
A supernova is a stellar
explosion that is more energetic
than a nova. It represents the
“death” of a star.
The explosion expels much
or all of a star's material[ at
a great velocity driving a
shock wave into the
surrounding space. This
shock wave sweeps up an
expanding shell of gas and
dust called a supernova
remnant.
It is this remnant, or stellar “dust” which has the potential to
form new stars and even planets.
Pre-Lab Exploration: Light and
Temperature…How are they related?
Question: How can we use the amount of radiant energy
emitted by a star to determine the relative surface temperature
of that star?
For Monday, you are going to investigate the properties of the visible light
spectrum, otherwise known as “ROYGBIV”.
You will be given a tool known as a diffraction grating. It takes visible light we
usually see as white, and breaks it down into the various component
wavelengths of light.
A display of colors and lines called a spectrum is produced.
Using this you will look in the direction of assorted sources of light of your
choice. (Remember, you may use the sun, but do NOT directly look at it!) You
will make observations. You will describe what you see.. You will use markers to
sketch what you see in your lab journals.