The Doppler Effect
Energy
waves or sound waves given off by a moving source will compress as the
object
moves towards the observer, and expand out as they move away from the
observer.
As
the ambulance moves towards observer, sound waves compress; As
ambulance As the ambulance moved away from the observer, the waves
expand.
What does Red Shift and Blue Shift mean?
If the
spectra of an element from a star is “Red-Shifted,” what does that mean?
What
did Edwin Hubble discover?
What
does Hubble’s discovery tell us?
What
does the frequency and wavelength of a color of light coming from a star (or any
object) tell us (what can we calculate?)
What is
the speed of light?
| 
The
21st Century