What does Dark Matter have to do with the Big Bang Theory?

Transcription

1 Lunar Society What does Dark Matter have to do with the Big Bang Theory? Prof. David Toback Texas A&M University Mitchell Institute for Fundamental Physics and Astronomy

2 Prologue We live in a time of remarkable scientific understanding di Scientists are arrogant/crazy enough to think that t 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 2

3 Overview of the Talk 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 Thoughts h 3

4 What is Dark Matter? 4

5 Dark Matter What is some of the evidence for Dark matter? 5

6 How Stars Move in Galaxies 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 fplanets 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 6

7 sics.tamu.edu/to back/talks/video /Lab4_SS1_video.swf 7

8 As the Galaxy Turns /Talks/Video/Lab4_GX1_video_slow.sw slow sw f 8

9 Data well explained by lots of Dark Matter we can t see This is where it gets its name In some sense, the name is a statement of almost all we know about it (it doesn t interact with light, and it has mass) Lots of other evidence for dark matter like gravitational lensing, but that s for another day 9

10 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 bowl Not exactly the same denser in the middle because of the pull of gravity

11 What is the Big Bang Theory? 11

12 Not that Big Bang Theory 12

13 A Big Bang Occurred Then What? The Story of the Universe since the Beginning 13

14 Observe lots of galaxies with the world s best telescope We notice that All the far away ones are moving away from us VERY quickly 14

15 So What? All the stuff in the galaxies appears to have come from a single point in space ~13.7 What happened in the past? billion years ago Run the clock backward in time Name this time The Big Bang A moment of Creation 15

16 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? 16

17 Zero A Brief History of Time 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 October 2014 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 David Toback, MSC Bethancourt Lecture 17

18 Artists Conception of the Big Bang It all started with a Big Bang Bang 18

19 The very early Universe Lots of free particles just hanging around Universe is so hot that quarks can t combine to make protons/neutrons 19

20 Later, Quarks Combine to Form Nucleons Quark qqq Proton Nuclear Reaction Proton Quark Quark 20

21 A Millionth of a Second after the Big Bang The quarks have combined to form Protons and Neutrons 21

22 Creating Heavier Nuclei Proton Proton + Proton Deuterium um Nuclear Reaction Deuterium 22

23 A couple hundred thousand years later: Atoms Proton ElectroMagnetic Reaction Hydrogen Atom Electron 23

24 Wait a Billion Years After about Our galaxy, the Milky Way half a billion years, because of gravity, atoms combine to form the first stars and galaxies 24

25 After about 9 billion years our solar system and the Earth form 25

26 Recent History: Life on Earth Earth is about 4 or 5 billion years old Evidence that t 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 26

27 What does Dark Matter have to do with the Big Bang Theory? 27

28 The Known Particles 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 d the Higgs Boson Maybe Dark Matter is a New Particle! 28

29 What IS the Dark Matter? We don t know 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! Today: Observe 5 times more Dark Matter than Atoms (by October 2014 mass) in the Universe David Toback, MSC Bethancourt Lecture 29

30 What are scientists doing today to discover Dark Matter? Just mention two of the fun experiments being done here at Texas A&M! 30

31 Some Sources of Dark Matter are Cheap You are here Our Sun is Moving through our Galaxy Lots of Dark Matter is hitting the Earth every second 31

32 Experiment Dark Matter Particle Ping I saw it! Eureka! Atom in Detector Low Temperature Detector 32

33 Can we Make and Discover Dark Matter? High energy collisions i 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 2014 David Toback, MSC Bethancourt Lecture 33

34 More Expensive Dark Matter? High Energy Collisions Dark Matter Particles LHC 1 ps after the Big Bang Detector Proton Proton October 2014 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 34

35 Aerial View of the LHC Collides high energy protons Lake Leman Geneva Airport CMS Two huge detectors 27 km in Circumference! One of the largest and the most complex scientific instrument ever conceived & built by humankind p p ATLAS October 2014 David Toback, MSC Bethancourt Lecture 35

36 How does it do it? Accelerates protons to REALLY high energies, then bashes them together ks/video/particle_event_full_ns.avi October 2014 David Toback, MSC Bethancourt Lecture 36

37 Final Thoughtsht 37

38 Interested in learning more? Physics & Astronomy 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 Science Distribution credit There is an option to take is an Honors class 38

39 Conclusions It s an incredibly exciting time to be a scientist! Astronomy, Cosmology and Particle Physics are all coming together Perhaps we understand d 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! 39