1. Evidence for the Big Bang?
1920’s – Edwin Hubble
At time of Big Bang, matter was SO dense & hot (billion degrees) that the universe acted like a GIANT nuclear reactor
Hydrogen (H) atoms fused (nuclear fusion) to make light elements (helium (He), lithium (Li) creating billions of stars (in millions of galaxies)
Discovered Andromeda Galaxy: galaxies exist outside our Milky Way
Galaxies are moving apart & away from other galaxies

2. Monday 12/8/2014 Homework: TODAY’S AGENDA:
Notes: Evidence for the Big Bang
EM Spectrum and Visible Light
Homework:
Wavestown Worksheet due Tuesday 12/9/2014 for 20 Points

3. Evidence for the Big Bang Theory
Light & Electromagnetic Radiation
Doppler Effect (Doppler Shift)

4. Evidence for the Big Bang?
The Electromagnetic Spectrum
1665: Isaac Newton observed sunlight (white light) passing through a glass prism produced a rainbow of colors = visible light spectrum

5. The Electromagnetic Spectrum
WAVELENGTH: Distance from the top of one wave to the top of the next wave
Each form of radiation has a different wavelength
What does a radiation’s wavelength tell us?
How powerful (how much energy) the radiation is
What kind of radiation it is

6. Evidence for the Big Bang?
The Electromagnetic Spectrum
Visible Iight travels in the form of electromagnetic (EM) waves
ROYGBIV (red, orange, yellow, green, blue, indigo, violet) & white
Visible light is SMALL portion of electromagnetic (EM) spectrum
Radio waves
Microwaves
Infrared
Ultraviolet rays
X-rays
Gamma rays
Brain Pop: EM Spectrum
energy/electromagneticspectrum/

7. The Electromagnetic Spectrum
Visible light:
Red light = looooooooooooooongest,
Violet light = shortest
On the entire EM Spectrum,
Radio waves: longest wavelength
Visible light: middle
Gamma rays: shortest wavelength

8. Evidence for the Big Bang?
The Doppler Effect
Occurs with starlight (visible light & other forms of EM radiation) in galaxies too!!!
Scientists have observed galaxies moving away & apart from each other at high speeds (Rubberband Lab?)
Light moving toward observer wavelengths of light appear shorter = “Blue Shift”
Light moving away from observerwavelengths of light appear longer = “Red Shift”

9. The Doppler Effect…sound waves
In order to understand the Doppler Effect better, think about standing next to a train track.
What does the train’s horn sound like when it is approaching toward you quickly?
What does the train’s horn sound like when it is moving away from you quickly?

10. Evidence for the Big Bang?
The Doppler Effect
Shift in wavelengths of energy (radiation or sound) moving toward or away from an observer = “Doppler Effect (Doppler Shift)”
The spectra of most galaxies is moving toward the Red end = moving away from us (our galaxy)
Degree of Red Shift = speed at which galaxies are traveling