Albert Einstein and the Theory of Relativity Chapter 7 Great Idea: All observers, no matter what their frame of reference, see the same laws of nature

Chapter Outline Frames of Reference Special Relativity General Relativity

Frames of Reference

Descriptions in Different Reference Frames Coin’s path appears different depending on your frame of reference

The Principle of Relativity Baseball vs. Light Einstein’s solution: The laws of nature are not the same in all frames of reference Maxwell’s equation could be wrong Our intuitions about the addition of velocities could be wrong Principle of Relativity Every observer must experience the same natural laws Special relativity General relativity The speed of light, c, is the same in all reference frames

Special Relativity

Time Dilation Time Dilation Moving clock appears to tick more slowly

The Size of Time Dilation Calculation of time dilation tGG=tMM Stationary ground-based observer tGG=d/c Distance traveled by light in 1 tick

Distance and Relativity Length Contraction Moving object appears shorter

So What About the Train and the Flashlight? Addition of velocities Valid at small velocities Not valid near speed of light

Mass and Relativity Third consequence Conclusions: Mass is lowest for stationary objects Conclusions: Nothing moving less than speed of light can be accelerated to or past c Object above c cannot be decelerated Objects at c have zero rest mass

Mass and Energy Einstein All objects contain a rest energy Mass can be converted to energy and vice versa

General Relativity

The Nature of Forces Gravitational forces and acceleration Frame of reference

The Nature of Forces Newton vs. Einstein

Predictions of General Relativity The gravitational bending of light Planetary orbits The gravitational redshift

Who Can Understand Relativity? Everyone!!