Big Bang Black Holes No Math ASTR PHYS 109 Dr David Toback Lecture 6 7 Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 1 Prep For Today is now due L6 Reading BBBHNM Unit 2 Pre Lecture Reading Questions Unit 1 Revision if needed Stage 1 Unit 2 Stage 1 End of Chapter Quizzes Chapter 4 We Need Physics Big Bang Black 2 Holes No MathTopic 1 Light and Doppler Shifts Prep For Today is now due L7 Reading BBBHNM Unit 2 Pre Lecture Reading Questions Unit 1 Revision if needed Stage 2 Unit 2 Stage 2 End of Chapter Quizzes Chapter 4 We Need Physics Big Bang Black 3 Holes No MathTopic 1 Light and Doppler Shifts Next Set of Topics Physics We Need Finished our introduction Big and small things in the Universe Evidence and the Scientific Method Next we move on learn some of the physics we need in order to understand why scientists Physics We Need Big Bang have Blackconfidence in the Big 4 Holes No MathTopic 1 Light and Doppler Shifts 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 Physics We Need Big Bang Black 5 need to 1 learn some Light and Doppler Shifts Holes No MathTopic The Topics Some stuff we need learn a little about 1 Light and Doppler Shifts 2 Gravity General Relativity and Dark Matter 3 Atomic Physics and Quantum Mechanics 4 Nuclear Physics and Chemistry 5 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 Physics We Need Big Bang Black 6 just start somewhere and get going Holes No MathTopic 1 Light and Doppler Shifts 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 Physics We Need Big Bang Black 7 Holes No MathTopic 1 Light and Doppler Shifts Light What we know about the universe comes from multiple places One of the most important is from looking at both outer space and inner space Need to know Physics We Need Big Bang Black more about the Topic 1 Light and Doppler Shifts Holes No Math 8 Outline for Light 1 Light is a wave 2 and a particle 3 Light is REALLY fast but does have a finite speed 4 Doppler effect Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 9 Part 1 Light is a Wave The light we see is a wave like waves on an ocean Best described by it s wavelength Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 10 Why do we believe light is a wave Water and Sound are also both waves Does light behave like water or sound Can see water waves hitting a wall and what happens to them when they hit two small openings in aBlack wall Physics We Need Big Bang Holes No MathTopic 1 Light and Doppler Shifts Water waves moving towards a wall You are in the sky lookin g down at the waves as Big Bang Black they Physics We Need Holes No MathTopic 1 Light and Doppler Shifts 12 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 We Need Big Bang Black 13 Physics 202 208 Holes No MathTopic 1 Light and Doppler Shifts 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 Physics We Need Big Bang Black measure Holes No MathTopic 1 Light and Doppler Shifts 14 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 Physics We Need Big Bang Black 15 wavelengths Holes No MathTopic 1 Light and Doppler Shifts Part 2 Light is a particle 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 Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts photons where 16 its White Light Lots of Different Color Photons Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 17 Another view Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 18 The Energy of Particles We can think about Energy in many ways One way is the energy of motion Kinetic Energy in the language of PHYS 201 and 218 For a particle with mass in motion The higher the speed the particle has the more energy it has Physics We Need Big Bang Black 19 Holes No MathTopic 1 Light and Doppler Shifts Clicker Question for Energy Which has more energy Which will do more damage to a tree 1 A A Prius moving at 10mi hr or B An SUV at 10mi hr 2 A An SUV moving at 10mi hr or B An SUV moving with 60mi hr 3 A A Prius moving at 60mi hr or B An SUV moving at 10mi hr C Depends on the masses of the PriusPhysics and We the SUV Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 20 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 Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 21 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 Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 22 Part 3 The Speed of Light Not just a good idea it s the law Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 23 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 Physics We Need Big Bang Black Holes No MathTopic 1 Light and Doppler Shifts 24 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 …