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David Toback, MSC Bethancourt Lecture
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What does Dark Matter have to do with the Big
Bang Theory?
MSC BethancourtLecture
October 2014
Prof. David TobackTexas A&M UniversityMitchell Institute for
Fundamental Physics and AstronomyOctober 2014
Prologue
October 2014 David Toback, MSC Bethancourt Lecture
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We live in a time of remarkable scientific understanding
Scientists are arrogant/crazy enough to think that it may be possible to solve major problems in Astronomy, Cosmology and Particle Physics with a single discovery that ties all three together
Idea: Dark Matter is a particle that was created right after the Big Bang and has had a major impact on the evolution of the Universe and the stuff in it
Goal of this talk: To show you how all this might just tie together
Overview of the Talk
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Will talk about some of the most exciting questions in all of science one-by-one:
• What IS Dark matter and what is some of the evidence for it?
• What is the Big Bang Theory?• What does Dark Matter have to do
with the Big Bang and the evolution of the Universe?
• What are scientists doing today to discover Dark Matter?
Final ThoughtsOctober 2014 David Toback, MSC Bethancourt Lecture
What is Dark Matter?
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Dark Matter
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What is some of
the evidenc
e for Dark
matter?
October 2014 David Toback, MSC Bethancourt Lecture
How Stars Move in Galaxies
January 2014 6David Toback, MSC Bethancourt Lecture
• Start by considering the case that there IS no Dark Matter in galaxies
• Can use laws of gravity to predict two things: –1) The orbits of planets as they move
around the solar system and –2) Stars as they move around a galaxy
• Prediction: both have very massive centers so we expect the data to look consistent with that
• Data:–For the solar system, the data agree
perfectly–For the stars in the outer part of
galaxies, the prediction doesn’t work at all
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http://people.physics
.tamu.edu/toback/Talks/
Video/Lab4_SS1_vide
o.swf
October 2014 David Toback, MSC Bethancourt Lecture
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)9October 2014 David Toback, MSC Bethancourt
Lecture
Lots of other evidence for dark matter like gravitational lensing, but that’s for another day…
Our Place in the Universe
You are here The 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
What is the Big Bang Theory?
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Not that Big Bang Theory
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A Big Bang Occurred… Then What?The Story of the Universe
since the Beginning
October 2014 David Toback, MSC Bethancourt Lecture
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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
October 2014 David Toback, MSC Bethancourt Lecture
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
October 2014 David Toback, MSC Bethancourt Lecture
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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David Toback, MSC Bethancourt Lecture
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A Brief History of Time• 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
October 2014
• 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
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Artists Conception of the Big Bang
Bang
October 2014 David Toback, MSC Bethancourt Lecture
It all started with a Big Bang
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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
October 2014 David Toback, MSC Bethancourt Lecture
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Later, Quarks Combine to Form Nucleons
Quark
Quark
ProtonNuclear Reaction
Quark
qqq Proton
October 2014 David Toback, MSC Bethancourt Lecture
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A Millionth of a Second after the Big Bang
The quarks have combined to form Protons and Neutrons
October 2014 David Toback, MSC Bethancourt Lecture
Creating Heavier Nuclei
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Proton
DeuteriumNuclear Reaction
Proton + Proton Deuterium
October 2014 David Toback, MSC Bethancourt Lecture
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A couple hundred thousand years later: Atoms
Proton
Electron
HydrogenAtom
ElectroMagnetic Reaction
October 2014 David Toback, MSC Bethancourt Lecture
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Wait a Billion Years
After about half a billion
years, because of
gravity, atoms
combine to form the first
stars and galaxies
Our galaxy, the Milky Way
October 2014 David Toback, MSC Bethancourt Lecture
David Toback, MSC Bethancourt Lecture
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After about 9 billion
years our solar
system and the Earth form
October 2014
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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 agoOctober 2014 David Toback, MSC Bethancourt
Lecture
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!October 2014 David Toback, MSC Bethancourt
Lecture
David Toback, MSC Bethancourt Lecture
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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…
October 2014
Today: Observe 5 times more Dark Matter than Atoms (by
mass) 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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David Toback, MSC Bethancourt Lecture
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
October 2014
Experiment
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Dark Matter Particle
Atom in Detector
Low TemperatureDetector
Ping
I saw it! Eureka!
October 2014 David Toback, MSC Bethancourt Lecture
David Toback, MSC Bethancourt Lecture
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
David Toback, MSC Bethancourt Lecture
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More Expensive Dark Matter? High Energy Collisions Dark Matter
ParticlesLHC ≈1 ps after the Big Bang
Dark M
atter P
articleDetector
Proton Proton
October 2014
Dar
k M
atte
r Pa
rticle
Ok… Its more complicated than this
since Dark Matter Particles don’t easily
interact with detectors…
Nor do we usually produce them directly
David Toback, MSC Bethancourt Lecture
October 2014 35
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
David Toback, MSC Bethancourt Lecture
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How does it do it? Accelerates protons to REALLY high energies, then bashes them together
October 2014http://people.physics.tamu.edu/
toback/Talks/Video/particle_event_full_ns.avi
Final Thoughts
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David Toback, MSC Bethancourt Lecture
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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?– More on General Relativity,
Quantum Mechanics and Particle Physics
– Has a lab (if you want) and can be used as a Tier 2 Science Distribution credit
– There is an option to take is an Honors classOctober 2014
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
• Perhaps we 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!October 2014 David Toback, MSC Bethancourt
Lecture
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AbstractScientists have entered a golden age of discovery.
We are starting to be able to answer some of the most exciting questions ever asked, including questions that touch on the Big Bang, the fundamental building blocks of nature, and the Dark Matter that fills the Universe. In this talk I will talk about Astronomy, Cosmology, Particle Physics and The Universe and the reasons to think that the biggest things in the Universe (like the Universe itself) and the smallest things (like quarks and electrons) are inextricably linked. Indeed, many of us believe there is a new, fundamental particle just around the corner waiting to be discovered that could all these things together
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Prologue
(Apologies for the simplistic definitions)
• Astronomy is the study of things we can see through telescopes… Stuff in Universe (space)
• Cosmology is about trying to understand the origin and evolution of the Universe
• Particle Physics is about trying to understand the smallest things that make up the stuff in the Universe
October 2014 David Toback, MSC Bethancourt Lecture
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