big bang black holes no math astr phys 109 dr david toback lecture 6 7 8
Download
Skip this Video
Download Presentation
Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 6, 7 & 8

Loading in 2 Seconds...

play fullscreen
1 / 87

Ch. 5 - PowerPoint PPT Presentation


  • 400 Views
  • Uploaded on

Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 6, 7 & 8 Prep for Today (Is now due) – L6 Reading: BBBHNM 5 Recommended BHOT: Chap. 1-3 SHU: Chap. 1-2, 3 (p55-69) TOE: Chap. 1 eLearning Quizzes: Chapters 2-3 Reading questions

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Ch. 5' - bernad


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
prep for today is now due l6
Prep for Today (Is now due) – L6
  • Reading:
    • BBBHNM 5
    • Recommended
    • BHOT: Chap. 1-3
    • SHU: Chap. 1-2, 3 (p55-69)
    • TOE: Chap. 1
  • eLearning Quizzes:
    • Chapters 2-3
  • Reading questions
    • Two questions from Chapter 5 or the recommended reading
    • Turned in on eLearning BEFORE class
prep for today is now due l7
Prep for Today (Is now due) – L7
  • Reading:
    • BBBHNM 6
    • Recommended
    • BHOT: Chap. 1-6
    • SHU: Chap. 1-2, 3 (p55-69)
    • TOE: Chap. 1
  • eLearning Quizzes:
    • Chapters 2-4
  • Reading questions
    • Two questions from Chapter 6 or the recommended reading
    • Turned in on eLearning BEFORE class
  • Started looking at Paper 1
prep for today is now due l8
Prep for Today (Is now due) – L8
  • Reading:
    • BBBHNM 6
    • Recommended
    • BHOT: Chap. 1-6
    • SHU: Chap. 1-2, 3 (p55-69)
    • TOE: Chap. 1
  • eLearning Quizzes:
    • Chapters 2-4
  • Reading questions
    • Two questions from Chapter 6 or the recommended reading were due Monday
    • Turned in on eLearning
  • Turned in Paper 1
paper 1 is now posted
Paper 1 is now posted
  • What is the evidence for the Earth going around the Sun?
  • Explain it to someone who isn’t taking the class (no jargon)
  • Format:
    • Introduction paragraph
    • 1 paragraph per piece of evidence
    • Conclusion paragraph that ties it together
    • http://faculty.physics.tamu.edu/toback/109/WritingAssignments/samplepaper.shtml
paper notes
Paper Notes
  • ~2 pages, double spaced (~600 words)
  • No citations! Use your own words
  • Text should be professional. You are “trusted guide” not a “buddy” or “comedian”
administrative stuff
Administrative Stuff
  • Posted on CPR
    • Can get there from my website or eLearning
    • Read all the directions carefully
    • http://cpr.tamu.edu/cpr/resources/documents/misc/Student_Handout.pdf
  • You will need to submit a copy of your final paper ALSO to the turnitin.com line on eLearning
  • Due 1 week from today at noon
paper 1 stuff l8
Paper 1 Stuff – L8
  • Your draft was due today at Noon
    • The calibration and review portions are due next Wed at Noon
    • http://faculty.physics.tamu.edu/toback/109/WritingAssignments/CPR_Grading.pdf
  • Paper 2 will be due 1 week after we finish Chapter 8
elearning quizzes
eLearning Quizzes
  • You are expected to be working on the quizzes on eLearning
  • You cannot pass this course without having gotten a perfect score on all of them
  • You make take as many of each quiz as you like to get perfect scores without penalty
  • Due before the class AFTER we finish a chapter
next set of topics physics we need
Next Set of Topics: Physics We Need

Finished our introduction

  • Big and small things in the Universe
  • Scientific Method

Next we move on learn some of the physics we need in order to understand why scientists have confidence in the Big Bang Theory

overview of physics we need
Overview of Physics We Need
  • Cosmology, the big bang and black holes are some of the most interesting things that can be understood
  • However, to UNDERSTAND them better, and the EVIDENCE for them, we need to learn some physics
the topics
The Topics
  • Some stuff we need learn a little about:
    • Light and Doppler Shifts
    • Gravity
    • Atomic Physics and Quantum Mechanics
    • Nuclear Physics and Chemistry
    • Temperature and Thermal Equilibrium
  • We won’t spend too long on each, just enough to get back to the big picture…
  • Since there is no perfect way to present them (they all tie into each other) we’ll just start somewhere and get going…
back to the big picture
Back to the Big Picture

Questions we’re trying to answer:

  • How did the Universe come into being?
  • How did it evolve into what we know today?
  • What is the evidence for all of this?
light
Light

What we know about the universe comes from multiple places

One of the most important is from looking at the heavens

Need to know more about the “light we see”

outline for light
Outline for Light
  • Light is a wave and a particle…
  • Light is REALLY fast, but does have a finite speed
  • Doppler effect
part 1 light is a wave
Part 1: Light is a Wave
  • The light we see is a “wave”, like waves on an ocean
  • Best described by it’s wavelength
why do we believe light is a wave
Why do we believe light is a wave?
  • How do waves behave?
  • Water waves and Sound waves
  • Can “see” water waves hitting a wall and what happens to them when they hit two small openings in a wall

Waves move this way

Big Waves Here

Small Waves Here

why do we believe light is a wave18
Why do we believe light is a wave?

Shine light from a laser at two small holes in a wall and see what comes out on the wall behind it

The waves make patterns on the wall the same way water waves do

(Physics 202 & 208)

the wavelength of light
The Wavelength of Light
  • Shine white light at a prism and it breaks up into its different colors
  • Each color has a different wavelength which we can measure
what if we look more closely
What if we look more closely?
  • What if we look at smaller and smaller “amounts” of light?
  • The light we see is actually LOTS of particles all moving together
  • Call these Photons

Lots of photons where its bright

Very few photons where its dark

photons
Photons

What do we know about photons?

  • Photons are a type of particle
    • Like an electron or proton
  • Higher energy  smaller wavelength
  • Has no mass, but does have energy
    • Aside for those of you who are interested: It has momentum
light is more than the colors we see
Light is more than the colors we see

You may have thought of

Radio Waves and X-rays as different things, but they are just light with different wavelengths

a particle and a wave
A Particle and a Wave
  • Actually it’s really more complicated than that
  • Light is both a wave and a particle… can describe it as either… it has properties of both
part 2 the speed of light
Part 2: The Speed of Light

“Not just a good idea, it’s the law!”

light has a finite speed
Light has a Finite Speed

Light has been measured to have a specific speed

  • 3 x 108 meters per second
  • 186,000 miles per second
  • 1 foot per nanosecond
  • Really FAST
  • The fastest speed allowed
maxwell s theory
Maxwell’s Theory
  • 1865: James Clerk Maxwell and others showed light was a wave and calculated its expected speed
  • Gave the observed speed of light!
    • Confidence that his theories were correct
    • We can now measure the speed of light to incredible precision

Physics 208

2.99792458 x 108 m/s

a light year
A Light Year
  • Some things are so far away that its easier to express their distance in light-years
    • Light travels at 3 x 108 meters/second and there are p x 107 seconds/year  ~1016 m in a light year
  • If a star is a light year away and it must have taken a year for the light to get to us, we are observing the star the way it was a year ago
  • If we look at light from something billions of light years away, we are “observing” things that happened billions of years ago
part 3 the doppler effect
Part 3: The Doppler Effect
  • 1842: Christian Doppler
  • What happens to waves when the “thing” creating the waves is moving towards us?
    • Or we’re moving towards it?

Physics 221

example with sound from a stationary car
Example with Sound From a Stationary Car

The sound we hear is actually a wave

  • Sound waves
now the car is moving
Now the Car is Moving

Things coming at us have their waves “scrunched up”

Things moving away have their waves “stretched”

the doppler effect for cars
The Doppler “Effect” for Cars

Hears a Lower

Pitched Sound

Hears a Higher Pitched Sound

A car blaring its horn and going past you will give the famous “Eeeeeeee-Yowwwwww” sound

what does this have to with light
What Does This Have to with Light?
  • Since both sound and light are waves, the Doppler “Effect” applies equally to both
    • Normally can’t see this effect for light since its wavelength is small and its speed is fast
  • Can in special cases:
    • Things need to be moving really fast, like stars and galaxies
    • Need really good measuring devices like the ones Astronomers have
doppler effect and light
Doppler Effect and Light

Red Shift Sees light with a larger wavelength

Blue Shift Sees light with a smaller

wavelength

Galaxy moves to the right

look at light from galaxies
Look at Light from Galaxies
  • The light from galaxies moving away from us will appear to have longer wavelength light
    • The light is more Red, or shifted to the Red side of the light spectrum
    • “Red Shifted”
  • The light from galaxies moving towards us will appear with shorter wavelength
    • The light is more Blue, or shifted to the Blue side of the light spectrum
    • “Blue Shifted”
three observers
Three Observers

What does an object emitting light look like to different observers when it is

  • Not moving
  • Moving

Doppler Shift

look at some cases
Look at some cases

Next lets look at three cases where an “explosions” occurs and things expand from that point

  • I’m stationary and the exploding things are moving away from me (I’m the center of the Universe)
  • I’m moving along with the exploding things
  • Same as case two, but how it would look to me in my reference frame
two objects moving away from me
Two Objects Moving Away from Me

What it looks like when I’m stationary (or in my reference frame)

two objects moving away from me40
Two Objects Moving Away From Me

What it looks like when I’m moving relative to the objects

same thing my reference frame
Same Thing: My Reference Frame

Why were these three cases important?

Sorry… you’ll have to wait until we look at galaxies sending us light

doppler effect and light summary
Doppler Effect and Light: Summary

Compare the light coming from a car that’s parked and one that’s coming towards you

If a car is coming toward you with its lights on

  • The color of the light changes
  • The speed of the light does not!
putting it all together
Putting It All Together

Since stars can be billions of light years away and are moving quickly we can use the Doppler effect on light to measure the speed and direction of all objects in the night sky

(Can also use it to tell us what Stars are made of, but for that we need to learn about quantum mechanics…)

outline for unit 2 physics we need
Outline for Unit 2: Physics We Need
  • Light and Doppler Shifts Done
  • Gravity Next
  • Atomic Physics and Quantum Mechanics
  • Nuclear Physics and Chemistry
  • Temperature and Thermal Equilibrium
prep for next time l6
Prep for Next Time – L6
  • Reading:
    • BBBHNM 6
      • Recommended: BHOT 4-6
  • Reading questions
    • Two questions from Chapter 6 or the recommended reading
    • Turn in on eLearning BEFORE class
  • eLearning Quiz
    • Chapter 4
  • Start working on Paper 1
prep for next time p7
Prep for Next Time – P7
  • Reading:
    • BBBHNM 6
      • Recommended: BHOT 4-6
  • Reading questions
    • Two questions from Chapter 6 or the recommended reading
    • Turn in on eLearning BEFORE class
  • eLearning Quiz
    • If we finished Chapter 5, quiz due before the next class (else just 4)
  • Start working on Paper 1
prep for next time p8
Prep for Next Time – P8
  • Reading: (Was due Monday)
    • BBBHNM 6
      • Recommended: BHOT 4-6
  • Reading questions
    • Two questions from Chapter 6 or the recommended reading were due Monday
    • No new reading questions
  • eLearning Quiz
    • Chapter 5 quiz due before the next class
  • Calibrations for Paper 1 due Wed at noon
full set of readings so far
Full set of Readings So Far
  • Required:
    • BBBHNM: Chap 1-6
  • Recommended:
    • BHOT: Chap. 1-6
    • SHU: Chap. 1-3
    • TOE: Chap. 1
in class quizzes
In-Class Quizzes
  • Turn in your two questions on the reading
  • During class you will write down two more
    • This is a separate quiz
  • If you didn’t get a grade you wanted on one of the first few reading quizzes see me about trying again
what if we look more closely51
What if we look more closely?
  • What if we look at smaller and smaller “amounts” of light?
  • The light we see is actually LOTS of particles all moving together
  • Call these Photons

LOTS of photons

A few photons

Lots of photons

in class writing assignment
In-Class Writing Assignment

Write down, during the course of lecture,

Two questions you want to know the answer to

reading
Reading

Full reading so far:

  • BBBHNM: Chap 1-6
  • Prelude
  • BHOT: Chap. 1-6, 9 and 11 (117-122)
  • SHU: Chap. 1-3, 6, 7 (up-to-page 153)
  • TOE: Chap. 1
before we start the next topic
Before we start the next topic
  • Don’t forget to take your eLearning quizzes
    • Can’t pass the course without getting 100% on all of them
  • Make sure your name and DATE are on EVERYTHING you turn in
how do we answer these questions
How do we answer these questions?

As previously discussed we have two avenues:

  • Theory
  • Experiment

What do both have to say about Light?

slide57
Quiz
  • What time is lecture on Wednesday?
  • Where are we meeting?
    • Name
    • Today’s date
before we begin
Before we begin
  • As a special treat the class will attend a special Department of Physics colloquium on the LHC this Wednesday (Sept 17th)
  • Class will start at 4PM in the teaching wing of the Engineering/Physics building, room 202 (big class room)
  • Class will be over by 5PM
  • You will be expected to sign in with me or Mike as your in class quiz
light is more than the colors we see59
Light is more than the colors we see

Visible

color

Microwaves

Ultraviolet

X-rays

Infrared

Radio Waves

in class writing assignment60
In-Class Writing Assignment

Write down, during the course of lecture

Two questions you want to know the answer to

webct
WebCT
  • It has come to my attention that people are not finishing the quizzes in WebCT
  • If they don’t get finished we will start requiring people to do them in Recitation to help enforce that they are done
    • You should be done with Quizzes 1-3 now
    • Done with Quizzes 4-6 by the end of next week
a different example
A Different Example

It is as if a traveling salesman were to send a letter home once a week during his travels

  • While he is traveling away from home, each successive letter will have a little farther to go than the one the week before  Letters will arrive a little more than a week apart
  • On the way home each successive letter will have a shortest distance to travel will arrive more frequently than once a week
old beliefs
Old beliefs
  • Light is so fast that people used to believe that it was simply instantaneous
  • You can measure the speed of sound pretty easily
    • Listen to the alumni side at a football game. When they sing, they’re always LATE!
  • Couldn’t answer the question with an experiment until 1600’s
why do we believe it has a finite speed
Why do we believe it has a finite speed?
  • Danish Astronomer Ole Christian Roemer in 1676
  • Moons of Jupiter are helpful again!
  • Look at the eclipses of the moons of Jupiter as it moves towards us and away from us

We can measure this really accurately now, but that’s another story…

eclipses of the jupiter s moon
Eclipses of the Jupiter’s Moon

Now you see it!

Now you don’t!

measure the time between eclipses
Measure the Time Between Eclipses
  • When Jupiter is moving towards us we get shorter times between eclipses
  • When Jupiter is moving away from us we get longer times between eclipses
announcements
Announcements
  • Recitation tomorrow in ENPH 210
  • No office hours today
    • Call/email if you need to meet
  • WebCT Quizzez
slide71
Stars can be billions of light years away!
  • Binary system: SHU p68
  • Had a way of measuring both the direction and speed of travel of every source of light in the night sky
slide74
However, in reality they are separate particles (feynman diagram?) and each photon interacts with an atom individually. Again a diagram?
  • Individual interacting with an atom (Figure here)
doppler effect and light77
Doppler Effect and Light
  • Galaxies moving towards us have shorter wavelength light
    • The light is more Blue, or shifted to the Blue side of the light spectrum
    • “Blue Shifted”
  • Galaxies moving away from us have longer wavelength light
    • The light is more Red, or shifted to the Red side of the light spectrum
    • “Red Shifted”

Replace with P65 from SHU

why do we believe light is a wave81
Why do we believe light is a wave?
  • Shine white light at a prism and it breaks up into its different colors
  • These different colors are waves with different wavelengths
light is a wave
Light is a wave

The light we see is a “wave” and it is best described by it’s wavelength

ad