Friday

soundsound

The Doppler EffectThe Doppler Effect

Tone GeneratorTone Generator

Frog on a moving lily padFrog on a moving lily pad

the doppler effectthe doppler effect

The Doppler EffectThe Doppler Effect

Video: The Doppler Effect (1:56)Video: The Doppler Effect (1:56)

The Doppler EffectThe Doppler Effect

What does the Doppler effect have What does the Doppler effect have to do with stars?to do with stars?

color & wavelengthcolor & wavelength

wavelength in nanometres

700 650 600 550 500 400

red yelloworange green blue indigo violet

emission spectraemission spectra

hydrogen

helium

white light

neon

red-shift blue shiftred-shift blue shiftlaboratory spectrum of sodium

red shift

blue shift

RED BLUE

red-shift blue-shiftred-shift blue-shift

Explore questions…Explore questions…

http://curious.astro.cornell.edu/cosmology.php

The Big Bang TheoryThe Big Bang Theory

Warmup: Warmup:

Explain the spectrum:Explain the spectrum:

TodayToday

Discussion & Video: “Back to the Discussion & Video: “Back to the Beginning”Beginning”

Doppler ShiftDoppler Shift

blue-shifted object –moving towards blue-shifted object –moving towards

red-shifted object moving away

The Balloon Analogy

The Raisin Bread Analogy

Three important observationsThree important observations

1. The expansion of the Universe.

Hubble: galaxies are receding. 1st evidenceHubble: galaxies are receding. 1st evidence

2. The abundance of light elements (H, He, Li)2. The abundance of light elements (H, He, Li)

B.Bang theory predicts these elements should B.Bang theory predicts these elements should have been fused from protons and neutrons in have been fused from protons and neutrons in the first few minutes after the Big Bang.the first few minutes after the Big Bang.

3. Cosmic Microwave Background (CMB) Radiation3. Cosmic Microwave Background (CMB) Radiation The early universe should have been very hot. The early universe should have been very hot.

The CMB radiation is the remnant heat leftover The CMB radiation is the remnant heat leftover from the Big Bang.from the Big Bang.

Cosmic Microwave Background

Big Bang TimelineBig Bang Timeline

We are here

Common MisconceptionsCommon Misconceptions

The Big Bang was an explosion.The Big Bang was an explosion. The universe began as a point.The universe began as a point. The universe is expanding into The universe is expanding into

“something” and we are at the center of “something” and we are at the center of the expansion.the expansion.

Galaxies are “flying away” in space.Galaxies are “flying away” in space.

Predictions of a Big Bang Predictions of a Big Bang UniverseUniverse

Every point is receding away from every Every point is receding away from every other point. Every point seems to be at other point. Every point seems to be at the center of an expanding universe.the center of an expanding universe.

The farther away something is, the faster The farther away something is, the faster it is receding (unlike an explosion).it is receding (unlike an explosion). Farther away Farther away looks redder (Doppler effect) looks redder (Doppler effect)

Relationship is linear: twice as far Relationship is linear: twice as far receding twice as fast.receding twice as fast.

I: Hubble’s Law

Big Bang websitesBig Bang websites

For 2 students (& others?)For 2 students (& others?) http://www.astro.ucla.edu/~wright/doppler.htmhttp://www.astro.ucla.edu/~wright/doppler.htm http://science.howstuffworks.com/big-bang-theory.htmhttp://science.howstuffworks.com/big-bang-theory.htm ““print” button --  this and next few pagesprint” button --  this and next few pages http://map.gsfc.nasa.gov/universe/bb_concepts.htmlhttp://map.gsfc.nasa.gov/universe/bb_concepts.html http://map.gsfc.nasa.gov/universe/WMAP_Universe.pdfhttp://map.gsfc.nasa.gov/universe/WMAP_Universe.pdf http://cosmology.berkeley.edu/Education/IUP/http://cosmology.berkeley.edu/Education/IUP/

Big_Bang_Primer.htmlBig_Bang_Primer.html http://curious.astro.cornell.edu/cosmology.phphttp://curious.astro.cornell.edu/cosmology.php Have students spend ~30 minutes reading through the questions. Have students spend ~30 minutes reading through the questions.

Write (1) new understandings (2) new questionsWrite (1) new understandings (2) new questions http://www.amtp.cam.ac.uk/user/gr/public/bb_home.htmlhttp://www.amtp.cam.ac.uk/user/gr/public/bb_home.html http://curious.astro.cornell.edu/cosmology.phphttp://curious.astro.cornell.edu/cosmology.php http://www.umich.edu/~gs265/bigbang.htmhttp://www.umich.edu/~gs265/bigbang.htm