Download Dark Matter Dark Energy The History of the Universe More of the

Dark Matter
Dark Energy
The History
of the
Universe
More of the
History of the
Universe
Life on Earth
and Beyond
More life on
Earth and
Beyond
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Does observational evidence suggest there
is more dark matter than visible matter in the
Universe?
YES
What does MACHO stand for?
Massive Astrophysical
Compact Halo Object
What are some examples of MACHOs?
Black holes, brown dwarfs, rogue planets, black
dwarfs, basically anything made of normal
matter that is not emitting light
What does WIMP stand for?
Weakly Interacting Massive Particle
What are some examples of evidence for
dark matter?
Rotation curves of
spiral galaxies,
confinement of hot gas
in clusters, motions of
galaxies in clusters,
gravitational lensing
What percentage of the Universe is made of
WIMPS?
About 22%
MACHOS make up 4% and ordinary matter
makes up 1%
Why did dark matter form structures before
ordinary matter in the early Universe?
Because it is not affected by radiation (light) that
prevented other matter from clumping
Does dark energy makes up most of the
Universe
YES
Evidence for dark energy primarily comes
from
Type Ia supernovae
The effect of dark energy
on the expansion of the
Universe is that the
expansion is _____
Accelerating (getting faster and faster)
What percentage of the Universe is dark
energy?
73% is dark energy
The rest is 26 % dark
matter (4% MACHOS,
22% WIMPS) and 1%
ordinary matter
Do scientists know the
source of dark energy
No! This is an active area of research
Did the Hubble Space
Telescope play a key role
in the discovery of dark
energy?
Yes! It was observations of distant Type Ia
Supernovae with Hubble that helped show
the accelerating expansion of the Universe
What open question about
Type Ia Supernovae might
change some of the
predictions about dark
energy?
Whether all Type Ia Supernovae have the
same cause. This matters because it would
change the assumptions about the
luminosity of the supernovae which are used
to get distances. All Type Ia Supernovae
definitely come from white dwarfs but it is
not known whether all involve accretion from
a nearby star, merging with another white
dwarf, or either/or!
What is the age of the
Universe?
13.8 billion years old
What are the four
fundamental forces?
Gravity, weak, strong, electromagnetism
What forces are united in
the Grand Unified Theory?
Electromagnetism.
strong, and weak
forces
What was the percentage
of elements after the era of
nucleosynthesis?
25% He, 75% H, with trace
amounts of Li, Be, and B
What is the Cosmic
Microwave Background
and what NASA mission
most recently studied it?
The Cosmic Microwave Background is
the light from hot gas in the earliest
moment when light could travel through
the Universe, 380,000 years after the
Big Bang. The NASA Mission was
called WMAP.
Why couldn’t light travel
before the era of atoms?
The light was
scattered by
particles, mostly
free electrons
When did the first stars
form?
About 300 million years
after the Big Bang
Why didn’t heavy elements
like oxygen form in the
early Universe?
Because collisions with
photons and atoms
prevented the formation of
the heavier elements
Light can be converted into
mass by the process of
_____.
Particle/antiparticle
production
Why is the Universe made
of matter, rather than antimatter?
There was a slight excess
of matter over antimatter.
The amount of excess was
very small, less than 1%.
When did cosmic inflation
happen?
Between the GUT
and electroweak
eras, roughly 10-35 s
after the Big Bang
Why does the cosmic
microwave background
show up in microwave
wavelengths
Because it is redshifted by
the expansion of the
Universe
How is dark matter
responsible for structure in
the Universe?
In the early Universe,
radiation smoothed
out clumps of matter,
but dark matter was
not affected and
clumped together
before ordinary
matter. Later, these
dark matter clumps
attracted ordinary
matter, leading to
today’s structure.
The early Universe’s mass
density was predominated
by matter or by light?
Which one?
Light
What are three basic
needs of life?
Liquid (like water but could
be something else),
materials for complex
chemistry (like carbon but
could be something else),
energy (from a star or
geothermal or other
source)
How long did life take to
begin on Earth?
Less than 1 billion years,
as little as 300 million
years!
What is a habitable zone?
The region around a star
where liquid water can
exist?
Which of these is not a basic property
of life?
Organization
Using energy,
Growth
Adaptation
Reproduction
Higher Intelligence
Homeostasis
Responding to stimuli
Higher Intelligence
Is Earth the only place with
liquid water in the Solar
System?
No! Mars shows signs of
liquid water (seasonally
probably), and Enceladus
has water below a frozen
surface.
It is also possible that
Europa, Ganymede, and
Callisto have liquid oceans
below their surface.
What would be the source
of Europa’s warmth to
keep a liquid ocean?
Tidal forces from Jupiter’s
strong gravitational pull.
Why have we found more
Earth-like planets in the
habitable zone around
small cool stars?
Because the habitable
zone is closer to these
stars and our methods of
detecting planets (changes
in luminosity and motion of
the star) make it easier to
detect small planets
around stars like this
compared to small planets
around bigger stars
Would Europa have a
larger planetary habitability
index or Earth Similarity
Index?
Planetary Habitability
Index. This depends on
chemistry, an energy
source, and the ability to
hold a liquid solvent like
water. The Earth Similarity
Index only depends on
physical similarity to Earth.
The meteor ALH84001 is
special because ____
This is a meteor from Mars
(found in Antarctica) that
has rod-shaped structures
that could be nanobacteria.
These are not living
organisms but structures
that suggest the
ingredients for life once
existed on Mars.
Why are extremophiles
important for the study of
life beyond Earth?
Because they show how
life might exist in
conditions very different
from Earth. For example
Antarctic sub-glacial lakes
could show what life (if it
exists) in Europa’s oceans
might be like
Which mission carries a
plaque showing
information about Earth in
case aliens find it?
Pioneer 11
What is SETI and is
anyone encouraged to
help?
The Search for
Extraterrestrial
Intelligence. Everyone is
encouraged to help,
including amateur
astronomers.
How does the Drake
equation answer the Fermi
Paradox?
It provides a way of
measuring the number of
civilizations in the galaxy. If
the equation comes out
with a low number, than
the reason that we haven’t
found/heard from aliens is
that there aren’t any…if the
number is high, the
paradox still exists.
Which values in the Drake
equation do astronomers
have a decent grasp of?
R*: The number of stars
that form in the galaxy (57)
Fp: the fraction of stars
with planets (0.5-1)
Ne: the number of stars
with habitable places is still
not known too well
All the other numbers are
open questions!