27 Relativity Lectures by James L. Pazun Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley

Goals for Chapter 27 To explain relativity and simultaneity in terms of our experience. To apply relativity specifically to time. To see the relativity of length. To use the Lorentz Transformation to see how travel near v=c changes observables. To explain how relativistic momentum and energy make travel at c impossible with technology as we know it today. To study how relativity interacts with Newtonian mechanics.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley A simple demonstration Einstein may not be known for being competitive with Heifetz on the violin BUT he is known for his thoughts on relativity. We should master some bullet points from his theory as delineated on page 899. Note especially the boldface terms and 3 major points of inertial reference frames.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Physical laws are invariant – Figure 27.1,2 Einstein began by asserting that physical behavior was the same in all reference frames. Two examples are shown, kinematics below and electromagnetic induction at right.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Two ideas that will soon clash – Pages The speed of light is always the same. and Velocities are additive in different reference frames (i.e. a person walking on a moving boat looking at a person walking at the same pace on the riverbank. See conceptual Analysis 27.1

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Simultaneity - Figure 27.4 A lightning flash observed from the front and back of a moving train by a moving observer helps us to begin setting up the enigma.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley The light clock – Figure 27.5 A “light clock” will help us to examine differences in time in this Gadunkin experiment. See Conceptual Analysis 27.2.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Time dilation – Figure 27.7 The figure is used in Example Refer to Equation 27.6 on page 906.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Jetliner time dilation – Figure 27.8 Refer to Example 27.2 You may not notice the effect on your wristwatch

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Space travel and the Twin Paradox Although not accompanied by a figure or a problem until you consult Mastering Physics, this is arguably the most famous example of time dilation. One brother leaves earth and travels a short time near c (perhaps a 5 year mission like Captain Kirk). When he returns home he mistakes his brother for his grandfather. Read page 909.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Length contraction – Figure 27.9 Refer to Equation Notice the same velocity fraction as the time dilation problem. It will be designated by gamma.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley A shrinking spaceship – Figure See Example 27.3 and Quantitative Analysis 27.3.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley The Lorentz Transformation – Figure Refer to the yellow boxed equations on pages 913 and 914 and the Problem-Solving Strategy 27.1.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Relativistic velocities – Figure See the worked Examples 27.4 and 27.5.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Relativistic momentum – Figure Refer to the yellow boxed equation on page 917 and Quantitative Analysis 27.4.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Relativistic momentum II – Figure Refer to worked Example 27.8 on page 918. The Stanford Linear Accelerator can move a proton to.99c where relativistic effects may be clearly seen.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Experimental effects on diffraction – Figure Refer to the yellow boxed equations on pages Notice that energy soars exponentially to infinity at c.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Electronic energies – Figure Refer to Worked example 27.7 and The figure at right belongs to the latter example.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Relativity and Newtonian Mechanics – Figure Without outside references, the astronaut can’t tell what is happening outside the capsule. Curved space allows a real test of relativistic effects on objects we can readily observe.