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Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
1
Big Bang, Black Holes, No Math
ASTR/PHYS 109Dr. David TobackLectures 8-11
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Prep For Today (is now due) – L11• Reading:
– BBBHNM Unit 2 (Chapters 5-9): Was due already– Recommended Reading:
• See P3 of http://people.physics.tamu.edu/toback/109/Syllabus.pdf• Warm-up Quizzes
– Warm-up Quiz Part 4 (Peerceptiv): Was due already• Pre-Lecture Reading Questions:
– Unit 2 Written Assignment: • Changed from Pass/Revise to just requiring a 5/10 to pass, but it will count as part of your
grade. • Everyone has their first attempt graded. Will continue to work grading revisions
– Unit 2 Quiz: Was due before class• You can start as soon as you Pass Written Assignment Stage (now only 5/10)• Also requires Unit 1 and EOC 3
• End-of-Chapter Quizzes– Chapter 5a&b: Was due already
• Paper 1:– Feel free to use the optional Feedback Assignment in Peerceptiv– Will assign when we finish Chapter 6, and text is due one week later. Submit to Peerceptiv and
TurnItIn, and do Reviews directly after– Extra credit for all students who complete all potions within the 72 hour window (see instructions)
• Honors Section:– “Stage 1 Rough Draft”: Was due before Monday’s class– “Stage 1 Final Draft”: Due before next Monday’s class– Need to hear from you at least once every 7 days 4
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
The Data
50
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Does this work for Stars?
Simulation without Dark Matter
Simulation with lots of Dark Matter particles in
the galaxy
http://bigbang.physics.tamu.edu/Figures/StolenAnimations/galrot_anim.gif
Watch how fast a star rotates around the center of the galaxy…
Data looks like this 51
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Data well explained by lots of “Dark Matter” (Dark matter fills our galaxy kinda like a gas
that fills a balloon with the latex being provided by gravity)
This 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 or atoms very much (if at all), and it
has mass like all other matter
52
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
53
Another Experiment
Maybe there isn’t dark matter and General Relativity is
wrong? Look at the gravitational impacton light that travels through
the Universe, through a galaxy, and towards us
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Einstein Ring’s?
54
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Have observed LOTS of Einstein rings (most just
not this pretty)
Fact: We observe Einstein RingsThe “near” galaxy
The light from the “far” galaxy spread out into a ring
55
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Observe and Measure the Amount of Dark Matter from Einstein Rings
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Measure the amount of lensingTwo hypotheses:1. Small lensing effect if
there is only atomic matter (the amount of light tells us how much atomic matter there is)
2. Large lensing effect if there is atomic matter + Dark Matter
Observation: Large lensing… use this to measure the amount of dark matter
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
57
Winner: General Relativity + Dark Matter
• Many observations indicate that General Relativity correctly describes the motion of light, galaxies and stars in the Universe we live in space and time are related
• Space can curve, stretch, change etc. • Curved space-time will be very important in
later chapters when we talk about the expansion of the Universe
• Strong evidence that dark matter exists and has been an important part of the evolution of our universe since the early moments after the bang
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Lecture on Chapter 6 now complete
58
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
Paper 1
59
• Abbreviated description: What is the evidence for Dark Matter? – More detail on Peerceptiv, you REALLY need to read ALL the instructions and
hints– Explain it to someone who isn’t taking the class (no jargon) using the
REQUIRED format– Do Warmup Quizzes, Part 4
• Each paper is usually 5 paragraphs: – Introduction paragraph that gives the “answer” up front and outlines the
evidence• Lawyer’s opening statement
– Body paragraphs where you “make the case”• Make the case using evidence• 1 paragraph per piece of evidence (often, but not always, three… see
Peerceptiv instructions and EOC quizzes)– Conclusion paragraph that ties it together
• Lawyer’s closing arguments• Not just restating the evidence
• Help:– Example of good paper
http://tobackgroup.physics.tamu.edu/toback/109/WritingAssignments/samplepaper.shtml
Big Bang, Black Holes, No Math
Physics We NeedTopic 2: Gravity
60
Taken from Peerceptiv for Paper 1
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
The Training Wheels are now off
• I’m happy to help, but you are expected to know what to do for all assignments
• If you have done the work diligently, you should be able to concentrate on just the science from here on out
2
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
9
So FarTopics1.Light and Doppler Shifts Done2.Gravity, General Relativity and Dark Matter Done
3.Atomic Physics and Quantum Mechanics Now
4.Nuclear Physics and Chemistry5.Temperature and Thermal Equilibrium
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
Where We Are Going NextIn Chapter 3 we learned a little about how the stuff of the Universe is put together
• Big things are made from LOTS of small things
• Small things: The Fundamental Building Blocks of Nature–What is the “stuff” in atoms? 10
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
The Largest Stuff•Most of the light we see from space comes from stars
•What are stars made of?–Stars are lots of atoms interacting
–The ways they interact creates light we can see
–Can study the distant stars by looking at the light from them
–Can study atoms here on Earth. Are they the same? 11
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
12
How do Atoms work?• ElectroMagnetism (electric charge)
– What holds electrons and protons together
• Quantum Mechanics– The way atoms form and do the funny things they do (which allows us to exist)
– Electrons in orbits– Atoms absorbing and emitting photons (light) Chapter 7
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
13
Chapter 8
Different Types of Atoms• The Strong Force
– Keeps protons and neutrons together in the atomic nucleus
– Different types of nuclei different types of atoms
– Different atoms Different light…•Nuclear Physics and Chemistry
• Studying the Stars using their light– Spectral lines of the atoms – Atomic “fingerprints”– The light we see from the stars
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
Overview of the story• Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature
– What is the “stuff” in atoms• ElectroMagnetism (electric charge)
– What holds electrons and protons together• Quantum Mechanics
– Why atoms form the way they do– Electron in orbits– Atoms absorbing and emitting photons (light)
• The Strong Force– Keeps protons and neutrons together– Different types of nuclei different types of atoms– Different atoms Different light…
• Nuclear Physics and Chemistry Different TYPES of Atoms• Studying the Stars using their light
– Spectral lines of the atoms – Atomic “fingerprints”– The light we see from the stars
ThisLecture
NextLecture
14
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
15
The Fundamental Building BlocksOur best understanding:
The very BIG stuff is made up of LOTS of very small stuff
Need to understand:1. What are the
fundamental building blocks of nature
2. How it’s all held together
3. How they “create” the light we see
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
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The experiment gives results like #2!
Early Evidence for the Atomic Model(before we knew it was electrons orbiting a nucleus)
Shoot atoms at a “target”
Bag stuffed with cotton and a few small rocks
The positive charge in an atom and most of its mass is concentrated in a tiny, very dense center: The Nucleus
Bag stuffed with cotton
Theory:
1?
2?
Experiment (1910’s):
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
17
The Building Blocks of NatureIn the 19-teens and 20’s experiments determined:
• Atoms are made of a nucleus surrounded by electrons– Many types of nuclei
– Only one kind of electron
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
Nuclear PhysicsMany years later (using many of the same methods):
• Nucleus is composed of neutrons and protons
• Number of protons and neutrons in the nucleus determines the atom type–Explains the periodic table 18
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
19
The Fundamental Building Blocks of Atoms
• Electrons• Neutrons• Protons–Neutrons and Protons are really made of quarks•Discovered in the 1970’s •We’ll talk more about this in the next chapter
Talked about this in Chapter 3
More in Chapter 8
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
20
Putting Them Together
Why do the fundamental
building blocks stick together to
form atoms?
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
21
Overview of the story• Big things are made from LOTS of small things • Small things: The Fundamental Building Blocks of Nature
– What is the “stuff” in atoms• ElectroMagnetism (electric charge)
– What holds electrons and protons together• Quantum Mechanics
– Why atoms form the way they do– Electron in orbits– Atoms absorbing and emitting photons (light)
• The Strong Force– Keeping protons and neutrons together– Different kinds of nuclei
• Nuclear Physics and Chemistry different atoms• Spectral lines of the atoms
– Atomic “fingerprints”– The light we see from the stars
ThisLecture
NextLecture
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
22
ElectroMagnetism• You probably already know that protons and electrons have “electric” charges
• Positive charge and negative charge attract each other
• Call this ElectroMagnetism
+
-
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
23
Weirdness…You probably never thought about it this way but in many ways the way things with electric charge attract is very similar to gravity
+
-
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
Gravity vs. ElectroMagnetismElectroMagnetism
• Every charged object in the universe “attracts” every other charged object in the universe
• The bigger the charge, the bigger the attraction
• The further the distance between the objects, the smaller the attraction
Physics 202Physics 207
Gravity• Every object in the universe attracts every other object in the universe
• The bigger the mass, the bigger the attraction
• The further the distance between the objects, the smaller the attraction
Physics 201Physics 206 24
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
25
•Gravity: –All objects attract no matter what – (As far as we know…)
•ElectroMagnetism:
–Ignores neutral particles
What’s different?
Physics We NeedTopic 3: Quantum Mechanics and Atoms
Big Bang, Black Holes, No Math
Prep For Next Time – L11• Reading:
– BBBHNM Unit 2 (Chapters 5-9): Was due already– Recommended Reading:
• See P3 of http://people.physics.tamu.edu/toback/109/Syllabus.pdf• Warm-up Quizzes
– Warm-up Quiz Part 4 (Peerceptiv): Was due already– Warm-up Quiz Part 5 – Feynman Diagrams: Assigned next time (figures being fixed)
• Pre-Lecture Reading Questions:– Unit 2 Written Assignment:
• Changed from Pass/Revise to just requiring a 5/10 to pass, but it will count as part of your grade
• Everyone has their first attempt graded. Will continue to work grading revisions– Unit 2 Quiz: Was due before class
• You can start as soon as you Pass Written Assignment Stage (now only 5/10)• Also requires Unit 1 and EOC 3
• End-of-Chapter Quizzes– If we finished Chapter 7 then End-of-Chapter Quiz 7a & 7b (else, just through Chapter 6)
• Paper 1:– Feel free to use the optional Feedback Assignment in Peerceptiv– Text of Paper 1 is due 1 week from today, submit to Peerceptiv and TurnItIn– Do Reviews directly after submission– Extra credit for all students who complete all potions within the 72 hour window (see instructions)
• Honors Section:– “Stage 1 Rough Draft”: Was due before Monday’s class– “Stage 1 Final Draft”: Due before next Monday’s class– Need to hear from you at least once every 7 days
75