astronomy, cosmology, particle physics and the universe

David Toback, AESS Seminar 1

Astronomy, Cosmology, Particle

Physics and The Universe

Aerospace Engineering Special Seminar Series (AESS)

September 2014

Prof. David TobackTexas A&M UniversityMitchell Institute for

Fundamental Physics and AstronomySeptember 2014

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

September 2014


Prologue Continued: Dark Matter

September 2014


We live in a remarkable time where scientists have a good understanding of each

We are arrogant enough to think that it is possible to solve major problems in Astronomy, Cosmology and Particle Physics with a single discovery

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

Overview of the Talk

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Will talk about this exciting possibility by answering some questions 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 ThoughtsSeptember 2014

David Toback, AESS Seminar

What is Dark Matter?

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Dark Matter

6

What is some of

the evidenc

e for Dark

matter?

September 2014


How Stars Move in Galaxies

January 2014 7David Toback, AESS Seminar

• 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

September 2014


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)10September

2014David Toback, AESS Seminar

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

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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

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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

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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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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

September 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

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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

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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

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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

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http://cmsdoc.cern.ch/cms/TRIDAS/html/CollisionSide.html


After about 9 billion

years our solar

system and the Earth form

September 2014

http://cmsdoc.cern.ch/cms/TRIDAS/html/CollisionSide.html

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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 agoSeptember

2014David Toback, AESS Seminar

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!September 2014



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…

September 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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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

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Experiment

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Dark Matter Particle

Atom in Detector

Low TemperatureDetector

Ping

I saw it! Eureka!

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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


More Expensive Dark Matter? High Energy Collisions Dark Matter

ParticlesLHC ≈1 ps after the Big Bang

Dark M

atter P

articleDetector

Proton Proton

September 2014D

ark

Mat

ter 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, AESS SeminarSeptember 2014

36

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


How does it do it? Accelerates protons to REALLY high energies, then bashes them together

September 2014

http://people.physics.tamu.edu/toback/Talks/Video/

particle_event_full_ns.avi

Final Thoughts

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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

September 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

• 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!September 2014


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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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astronomy, cosmology, particle physics and the universe

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