Special Relativity For Dummies! Mr. Trotts

Classical Relativity 1,000,000 ms-1 1,000,000 ms-1 How fast is Spaceship A approaching Spaceship B? Both Spaceships see the other approaching at 2,000,000 ms-1. This is Classical Relativity. VT = V1 + V2 Mention the Ether

Einstein’s Special Relativity 0 ms-1 300,000,000 ms-1 Moving with respect to the Ether 1,000,000 ms-1 Both spacemen measure the speed of the approaching ray of light. How fast do they measure the speed of light to be?

Special Relativity Stationary man Man travelling at 1,000,000 ms-1 Wrong! The Speed of Light is the same for all observers Mention the Michelson Morley experiment Albert Michelson & Edward Morley Lead Einstein to propose his Theory of Special Relativity

Time Travel! Time between ‘ticks’ = distance / speed of light Light in the moving clock covers more distance… …but the speed of light is constant… …so the clock ticks slower! Moving clocks run more slowly! Consider a clock that uses a light pulse to tick . . . V

Three effects 3 strange effects of special relativity Lorentz Transformations Relativistic Doppler Effect Headlight Effect We will consider three consequences of a constant speed of light

Lorentz Transformations But what happens if the beam is moving?

Lorentz Transformations Light from the top of the bar has further to travel. It therefore takes longer to reach the eye. So, the bar appears bent. Weird!

Doppler Effect The pitch of the siren: The same applies to light! Rises as the ambulance approaches Falls once the ambulance has passed. The same applies to light! Approaching objects appear blue (Blue-shift) Receding objects appear red (Red-shift) When the ambulance is approaching, the sound waves are bunched up. Likewise, once the ambulance has passed, the waves are spread out.

Headlight effect Beam becomes focused. V Counter intuitive result Beam becomes focused. Same amount of light concentrated in a smaller area Torch appears brighter!

Warp Program used to visualise the three effects Demo . . . Notes for the demo. Demonstrate Doppler shift. Demonstrate Lorentz Transformations – including being able to see the back of objects when they are in front of you! Demonstrate Headlight effect by turning it on/off. Demo . . .

Fun stuff Website: http://www.adamauton.com/warp/ Eiffel Tower Stonehenge Website: http://www.adamauton.com/warp/