Transcript Origin of Our Universe

Origin of Our Universe
Before the Big Bang?
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As cosmologists begin to understand what happened just after the
Big Bang, many are questioning what led up to the Big Bang (4
possibilities)
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1. No previous era: matter, space, and time began abruptly with
the bang
2. Quantum emergence: ordinary space and time develop out of
a primeval state described by a quantum theory of gravity
3. Multiverse: our universe and others bud off from eternal space
4. Cyclic universe: the big bang is the latest stage in an eternal
cycle of expansion, collapse (Big Crunch), and renewed expansion
Formation of the
Universe
The Big Bang Theory:
The theory that the universe began as a point
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{called the singularity} and has been expanding ever since
1. The universe was originally packed into one dense sphere of
hydrogen about the size of a pearl!
2. The sphere exploded forming a gigantic, hot expanding cloud
3. As the cloud moved, parts condensed and formed billions of
galaxies
Formation of the
Universe
The Big Bang Theory:
The theory that the universe began as a point
(singularity) and has been expanding ever
since
4. The galaxies continue to move outward today
5. Most commonly accepted theory of universe
formation
Formation of the Universe:
previous ideas
The Steady State Theory:
the belief that the universe doesn’t change with
time but more matter is added as it expands
Popular during the 50’s and 60’s
The universe had no beginning and has no end
(no big bang)
Formation of the Universe:
recent developments
The Inflationary Theory:
predicts that there was a sudden expansion when
the universe was very young, more extreme than
predicted by the big bang
Considered to be a “revised” Big Band Theory
universe expanded until about 10-35 seconds
after the big bang when it became so cool
that the forces of nature caused the universe
to inflate tremendously
Evidence for Big Bang/Inflation
1965 Panzias and Wilson discovered background radiation interfering
with radio antennae, causing a hiss in phone lines
That radiation is called cosmic background radiation and
thought to be from the big bang (extreme red-shift into
microwaves, we see a wall of microwave radiation filling the
sky)
Provides a glimpse of the universe at only 380,000 years old
(when atoms formed)
can be detected by common radio and TV antennae (snow)
1980, Nasa discovered that the CMB
Evidence for Big Bang/Inflation
Astronomers also observe “red shifts” throughout
universe
This Red shift, or a Doppler shift toward the
red end of the spectrum, occurs because the
light waves are “stretched,” which shows that
Earth and the source are moving away from
each other.
Formation of galaxies
1. Galaxies begin as a spherical cloud (called a
nebula)in space
2. the cloud collapses under the force of it’s own
gravity, forming galaxies of a variety of shapes
3. Our galaxy, the Milky Way, is a spiral galaxy
consisting of a nucleus surrounded by arms that
rotate in a clockwise fashion
4. Solar systems similar to ours move around in
this galaxy in a regular pattern
Shape of Galaxies
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1. Spiral (like the Milky Way) background pic
… some are Barred
Spirals
Our solar system is here
2. Elliptical
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3. Irregular
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Formation of a Solar system
Within each galaxy are many nebulae (plural of
nebula).
A nebula is a cloud of interstellar dust and gas
from which stars and eventually solar systems
are formed.
A nebula is a cloud of interstellar dust and gas
from which stars and eventually solar systems
are formed.
Nebula can be many colors depending on the
chemical makeup of the gas.
How a Nebula becomes a Solar System The Solar Nebula Hypothesis:
Just as an ice-skater’s spin
speeds up when she pulls her
arms in, so does a cloud of
dust in space. As the cloud
spins faster, enough pressure
is created to produce fusion in
the center of the disk, forming
a star like our sun. Planets
are formed from the rings left
behind as the dust disk
formed.
Formation of OUR solar system:
Our sun was the center of that cloud of dust
and gas.
As the planets formed, the more dense ones
were pulled closest to the sun. They are called
Terrestrial Planets (Mercury, Venus, Earth, and
Mars).
The less dense planets moved toward the
outer portion of the solar system. They are
called Jovian Planets, or Gas Giants. (Jupiter,
Saturn, Uranus, and Neptune)
Pluto is now thought to be a minor planet, most
likely a captured comet who was drawn in by
the gravity of the sun and placed in an orbit
around it (similar to asteroids)
Planetary
Development
Terrestrial planets (like Earth) go through the same 4
stages of development:
1. DIFFERENTIATION - heavier materials move to
the center of the planet, lighter materials move to the
outer portion while it is still molten (liquid)
2. BOMBARDMENT - planets receive surface
features due to cratering from space debris (there
was much more debris in the early universe!)
3. FLOODING - planets were covered with molten
rock or water, filling in lower areas
4. SURFACE EVOLUTION - planets continue to
change their look from impacts, erosion, or plate
tectonics.
Planetary
Development
Gas Giants
Jovian planets (gas
giants) all went through
differentiation, but we are
unsure about
development after that.
We DO know that they
are constantly influenced
by storms that move
through their thick
Formation of
moons and rings
Planets have moons for 2 different reasons:
1. A large object in space hit the planet,
throwing out debris that collected into a
moon (ex: Earth’s moon)
2. Asteroids have been captured by the
planet when the came too close, getting
trapped by the gravitational pull of the
planet (ex: the moons of Mars)
All planets have moons except Mercury and
Venus
Formation of
moons and rings
Some planets also have rings:
Rings are either debris blown
away from the planet but trapped
in it’s gravitational field OR they
are rings of debris from captured
space debris.
Only the Gas Giants have rings