News from the Cosmic Microwave Background

News from the Cosmic Microwave Background

News from the Cosmic Microwave Background

Newest – Planck Satellite data, March 2013Oldest – 13.82 billion years ago.

http://spaceinimages.esa.int/Images/2013/03/Planck_CMB

This is both the newest and the oldest photograph of the universe.

It looks like a random bunch of speckles, but it provides a lot of very precise information about the

universe ; what it is made of, how it evolved and what its future will be like.

Part 1: What is the Cosmic Microwave Background?Part 2: What does the Big Bang sound like?

The galaxies appear to be moving away from us. The farther they are – the faster they are receding.

http://www.astro.cornell.edu/academics/courses/astro2201/hubbles_law.htm

Part 1: What is the CMB?

This suggests that the universe used to beA) smaller B) denser C) brighter D) all three

How can you illustrate your answer using bubble gum, sponges and flashlights?

Blow on your hand using a wide, open mouth.Blow on your hand with a small, pursed mouth.

The universe used to be muchA)hotter B) colder

Explain.

A higher temperature means that the particles in the universe are moving faster and colliding

more.

This suggests that the universe used to be moreA) uniform B) uneven

Explain, by referring to one of these examples.

What is true about the Big Bang theory? A)It is a very successful television showB)It used the evidence for an expanding universe to infer that it used to be very small, dense, hot and uniformC)It successfully predicted a number of other features including the cosmic microwave background.D)all of the above

According to the Big Bang theory the universe used to be a hot soup of electrons,

protons, neutrons and light.

Once the universe had ‘cooled’ to 3000 K, electrons would be able to join with protons

to form hydrogen. This would make the universe transparent to light.

How can you model this in a ‘dance’?

The light that was around when the electrons and protons combined has been travelling for a

long time and during this trip it will have becomeA) redder B) bluer C) stretched D) squished

The original wavelength of the light was 1 m or one millionth of a metre. The universe is now 1,000 times bigger in all directions. The light should now be

A) visible light: 1 mB) microwaves: 1 mmC) microwaves: 1 cmD) radio waves: 1 m

Draw waves with this wavelength – actual size

Microwaves invisible but they can be detected.

The waves cause hot spots. How far apart are they?

What is the wavelength of the radiation?(The waves travel at 3 x 108 m/s. The frequency is 3450

MHz.)

About 1% of the static picked up by radios and analogue televisions is from the early universe.

Physicists predicted that 1-mm microwaves should hitting the Earth from all directions. These microwaves were detected by accident.Who should get the Nobel Prize for the discovery - the theorists or the experimentalists? Why?

This Big Bang predicted that the early universe should be very smooth. The CMB is a picture of the

early universe and it is incredibly smooth

However, there has to be some unevenness to produce the galaxies and clusters that exist.

Satellite observations have increased the resolution and contrast of the CMB.

http://scienceblogs.com/startswithabang/files/2012/07/shape.jpeg

1992 2003 2013

The temperature of the CMB is 2.72548 +/- 0.00002K. How does this compare to the

roughness of the Earth which has mountains and valleys that vary its radius by +/- 0.1% ?

The CMB temperature variation is ________ times smaller than Earth`s roughness.A)10 B) 100 C) 1,000 D) 10,000

The CMB temperature is +/- 0.001% or 100 times smaller. To make this tiny variation visible, only the differences from the average are shown.

The top image shows the difference from average of +/- 0.0035 K.

The left half is A)hotterB)colderC)moving awayD)moving toward us

This is a Doppler shift. We are moving at 371 km/s with respect to the average CMB.

The middle image has the effect of our movement removed. It shows differences of +/- 0.00002 K. The middle band of higher temperature is due to radiation from theA)EarthB)Solar systemC)Milky WayD)Local Cluster

The Milky Way’s glow has been removed from the last map.

A Brief Review:Minute Physics - Picture of the Big Bang

http://www.youtube.com/watch?v=_mZQ-5-KYHw

This is the most recent picture. It is coloured to show the tiny variations in temperature. The red

regions are warmer. They will also be denser.

Part 2: What did the Big Bang sound like?

Sound waves are variations in density. This is a picture of the sound the universe was

making 14 billion years ago.

The frequency of the sound has been multiplied by 1026 so we can hear it.

It has also been modified to show how the sound evolved over the first 76,000 years.

What happens to the pitch and volume during the beginning moments? Why?

http://faculty.washington.edu/jcramer/BigBang/Planck_2013/BBSnd100.wav c) John G. Cramer - 2013

What will happen to the pitch and volume as the universe continues to expand?

A)Both will increaseB)Both will decrease

C)Pitch will increase and volume decreaseD)Pitch will decrease and volume increase

http://faculty.washington.edu/jcramer/BigBang/Planck_2013/BBSnd100.wav c) John G. Cramer - 2013

http://www.youtube.com/watch?v=v4ELxKKT5Rw Videos of a resonating rubber circle.

The universe is not vibrating as a whole. It is vibrating as if it was made of many little drums.

http://www.physics.miami.edu/~nearing/mathmethods/drumhead-animations.html animations

You can calculate the size of the largest ‘drum’. The waves were travelling at 2/3 of the speed of light for the 400,000 years since the Big Bang.

How far (in light-years) could they have travelled? The universe has expanded by 1,000

since then. How big should the ‘drums’ be now?A) 300 B) 300,000 C) 300,000,000

This distance forms the base of a triangle.

The light has been travelling for 14 billion years. This is the altitude of the triangle. What angle should it make when it reaches us?

sin() ~ tan() = (3 x 108)/(14 x 109) = 2 x 10-

2, ~ 1o.

Where are the 1o vibrations?

This is a close-up. Where are the 1o vibrations?

+30 K

+20K

+10K

0 K

- 10 K

- 20 K

- 30K

The 1o spots are the fundamental vibration. Are there other harmonics? If the universe was vibrating like a long spring, what size would

second and third harmonics have?

A)1/2o, 1/3o B)2o, 3o

C)1/2o, 1/4o D)2o, 4o

Where are these higher harmonics?

+30 K

+20K

+10K

0 K

- 10 K

- 20 K

- 30K

The map of the CMB has been analysed to find the harmonics and their strengths. This is shown in the graph below. How many harmonics did they find?

A) 2 B) 3 C) 4 D) 5

http://sci.esa.int/planck/51555-planck-power-spectrum-of-temperature-fluctuations-in-the-cosmic-microwave-background/

Build a similar wave using the PhET simulation. How big should the second harmonic be compared

to the first one? A) 5800/2500 B) (5800/2500)2 C) (5800/2500)1/2

http://phet.colorado.edu/en/simulation/fourier

The waves are a result of gravity pulling matter closer and radiation pressure pushing it apart. The size of the first harmonic can be used to measure the total

amount of mass and energy in the universe.

The amount that was found is much bigger than all of stuff we are familiar with – protons, electrons,

photons, etc.

We don’t know what the other 95% of the universe is made of but we do know that it comes in two types -

dark matter and dark energy.

The size of the harmonics indicates how much of the universe is made of each part. Dark matter

responds to gravity but not the radiation pressure.Compare standing waves for a spring on the floor

and a spring in the air. How does gravity change it?

How does each type of matter affect the graphs? atomic matter dark matter

http://background.uchicago.edu/~whu/intermediate/baryons3.html

http://background.uchicago.edu/~whu/intermediate/driving2.html

The universe ‘rings’ differently if you change the amounts of atoms, dark matter and energy.

WMAP Build a Universe Game http://wmap.gsfc.nasa.gov/resources/camb_tool/index.html

What proportions match our universe?

What else needs adjusting?

The earlier surveys could not detect any peaks after the first three. The Planck data clearly shows a

fourth and fifth peak. These provide the seeds for the formation of galaxies and clusters of galaxies.

Why does the universe become less smooth?

http://cosmicweb.uchicago.edu/filaments.htmlhttp://lambda.gsfc.nasa.gov/product/map/current/pub_papers/nineyear/cosmology/images/large/gh9_f02_L.png

Explore how the density of matter and variation in density affect the evolution of the universe.

http://www.learner.org/courses/physics/interactive/lab_interactives/cosmic.html

http://sci.esa.int/planck/51551-simple-but-challenging-the-universe-according-to-planck/

The data from the Planck satellite provides strong support for the Big Bang, dark matter and dark energy.

However, at large angles there are features that are keeping cosmologists up at night.

For more information about the details of the CMB try;

•Parameters of Cosmology http://wmap.gsfc.nasa.gov/mission/sgoals_parameters.html You will find lots more at this site of the WMAP. •Wayne Hu Ringing in the New Cosmology 2001http://background.uchicago.edu/~whu/intermediate/intermediate.html This is a very detailed explanation of the power spectrum with lots of analogies and animations. Also try his Scientific American article Cosmic Symphony 2004 http://background.uchicago.edu/~whu/SciAm/sym1.html •Physics for the 21st C: Unit 11: Dark Energy 2010 (30 minute video) The first half looks at the supernova evidence that the expansion of the universe is increasing. The second half (15:00- 27:00) looks at CMB evidence for dark energy. While you are there, check out the rest of the course on modern physics designed for high school teachers. http://www.learner.org/courses/physics/unit/unit_vid.html?unit=11 •Planck’s View of the Universe 2013 (3:22 minute video)http://spaceinvideos.esa.int/Videos/2013/10/Planck_s_view_of_the_Universe You will find lots more at this site of the Planck Satellite.