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

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

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

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

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

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 http://www.brainpop.com/science/ energy/electromagneticspectrum/

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

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”

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? http://paws.kettering.edu/~drussell/Demos/doppler/carhorn.wav

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