January 2009 David Toback, Saturday Morning Physics
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Prof. David TobackTexas A&M University
January 2014
Dark Matter and the Big Bang
Theory
Overview
January 2014 David Toback, Saturday Morning Physics
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Two of the most exciting topics in all of science are Dark Matter and the Big Bang
Start with questions: • What IS Dark matter and what is the
evidence for it? • What IS the Big Bang Theory?• What does Dark Matter have to do
with the Big Bang? • What are scientists doing today to
discover Dark Matter? Final Thoughts
Dark Matter
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What is some of
the evidenc
e for Dark
matter?
How stars move in galaxies
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• Start by considering the case that there IS no Dark Matter in galaxies
• Can use laws of gravity to predict the orbits of planets and stars as they move around the solar system and galaxy
• For the solar system, the data agree perfectly, but for the outer part of galaxies it should look like stars in orbit around a massive center
• Problem: This isn’t what the data shows
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http://people.physics
.tamu.edu/toback/Talks/
Video/Lab4_SS1_vide
o.swf
As the Galaxy Turns
http://faculty.physics.tamu.edu/toback/Talks/Video/
Lab4_GX1_video_slow.swf
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Data well explained by lots of “Dark Matter” we can’t
seeThis is where it gets its
nameIn some sense, the name is a statement of almost all
we know about it (it doesn’t interact with light,
and it has mass)January 2014 David Toback, Saturday Morning
Physics8
Our Place in the Universe
You are here In some ways, Dark Matter
surrounds the galaxy like the
water in a fishbowl
surrounds a fish in the middle of
the bowlNot exactly the
same… denser in the middle
because of the pull of gravity
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A Big Bang Occurred… Then What?The Story of the Universe
since the Beginning
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Observe lots of galaxies with the world’s best
telescopeWe notice that All the far
away ones are moving away from us VERY
quickly
So What?
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All the stuff in the galaxies appears to have come from a single point
in space ~13.7 billion years ago
Name this time The Big Bang
A moment of Creation
What happened in the past? Run the clock backward in time
Slightly more complicated than that…
• As best as we understand the Universe began with a Big Bang–A REALLY Big Bang
• Then what?• How did we get from the bang to the Universe we have today?
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March 2011David Toback, Texas A&M University
Davidson Scholars 16
A Brief History of Time• Zero
• One millionth of one second after the Bang
• A few minutes
• A few hundred thousand years
• 100 million to 1 billion years
• 9 billion years
• ~13.7 billion years
• The Big Bang produces lots of particles
• Quarks combine to form protons and neutrons
• Protons and Neutrons combine to form the nucleus of an atom
• Nuclei and electrons combine to form atoms
• Atoms combine to form Stars and Galaxies
• The Earth and our solar system forms
• You listen to me talk
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The very early UniverseLots of free particles just hanging
around…Universe is so hot that quarks can’t
combine to make protons/neutrons
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Later, Quarks Combine to Form Nucleons
Quark
Quark
ProtonNuclear Reaction
Quark
qqq Proton
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A Millionth of a Second after the Big Bang
The quarks have combined to form Protons and Neutrons
Creating Heavier Nuclei
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Proton
DeuteriumNuclear Reaction
Proton + Proton Deuterium
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A couple hundred thousand years later: Atoms
Proton
Electron
HydrogenAtom
ElectroMagnetic Reaction
May 2009 David Toback, Texas A&M University 23
Wait a Billion Years
After about a billion years,
because of gravity atoms
combine to form the first stars
and galaxies
Our galaxy, the Milky Way
May 2009 David Toback, Texas A&M University 24
After about 9 billion
years our solar
system and the Earth form
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Recent History: Life on Earth
• Earth is about 4 or 5 billion years old
• Evidence that microbial tracings existed on Earth about 3.5 billion years ago
• Humanoids, like “Lucy” existed a mere 3 million years ago
• Homo-sapiens at around 100,000 years ago
What does Dark Matter have to do with the Big Bang Theory?
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The Known Particles
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– No known particles have the properties of Dark Matter
– Other reasons to believe there are new fundamental particles to be discovered–For example, we just
discovered the Higgs Boson
– Maybe Dark Matter is a New Particle!
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Hypothesis: The Dark Matter in the Universe is made up of LOTS of
particles that we haven’t discovered yet!
Best Guess: Huge numbers got created in the Early Universe like everything else and are still here
today!
Big Bang!
Then Universe gets bigger
What IS the Dark Matter?We don’t know…
Today: Observe 5 times more Dark Matter than Atoms in
the Universe
What are scientists doing today to discover Dark Matter?
Just mention two of the fun experiments being done here at
Texas A&M!
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Some Sources of Dark Matter are Cheap
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You are hereOur Sun is
Moving through our
Galaxy… Lots of
Dark Matter is hitting the Earth
every second
Experiment
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Dark Matter Particle
Atom in Detector
Detector
Ping
I saw it! Eureka!
Can we Make and Discover Dark Matter?
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• High energy collisions between particles in the Early Universe
• Recreate the conditions like they were RIGHT AFTER the Big Bang
• If we can produce Dark Matter in a collision then we can STUDY it
October 2011David Toback, Texas A&M University
Research Topics Seminar 33
More Expensive Dark Matter? High Energy Collisions Dark Matter
ParticlesLHC ≈1 ps after the Big Bang
Dark M
atter P
article
Dar
k M
atte
r Pa
rticle
Detector
Proton Proton
Ok… Its more complicated than this
since Dark Matter Particles don’t easily
interact with detectors…
Nor do we usually produce them directly
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Aerial View of the LHC
CMS
ATLAS
27 km in Circumference!
One of the largest and the most complex scientific
instrument ever conceived & built by humankind
pp
Collides high energy protons
Two huge detectors
Lake LemanGeneva Airport
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How does it do it? Accelerates protons to REALLY high energies, then bashes them togetherhttp://people.physics.tamu.edu/
toback/Talks/Video/particle_event_full_ns.avi
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Interested in learning more?
• Physics department now offers a course entitled “Big Bang & Black Holes”
(ASTR/PHYS 109)– Covers Stephen Hawking’s
“Brief History of Time”– Origin and Evolution of the
Universe– How do stars form?– What is Dark Matter? Dark
Energy?– What are Black Holes?– General Relativity & Quantum
Mechanics– Particle Physics
– High School Students: • Get your school to get involved
with the Talk Science Program http://faculty.physics.tamu.edu/toback/109/
http://people.physics.tamu.edu/toback/TalkScience/
Conclusions
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• It’s an incredibly exciting time to be a scientist!
• Astronomy, Cosmology and Particle Physics are all coming together!
• Starting to understand the role of Dark Matter in the Universe since the Big Bang!
• If our understanding is correct, a major discovery may be just around the corner!
Wanna join us? We need your
help!