Doppler Effect Discoveries

Expanding Universe

• With this discovery, the Doppler effect was the key ingredient. Leading up to the discovery of an expanding universe, many physicists, including Einstein, believed the universe to be static. As astronomers gazed at the sky, a startling commonality occurred. All of the light from distance galaxies were affected by the Doppler effect the same way. The light of the galaxies were shifted red. The Doppler effect alone stated that these lightwaves must be moving away from Earth because the light was stretched red and did not shrink blue.

Original Discovery in Detail

• The original discovery of the Doppler effect was by Johann Christian Doppler. He was a physicist and developed the interesting mathematical relationship. The Doppler effect states mathematically the frequency shifts of all waves and motion. This experiment was conducted for sound waves but the equations are similar for all forms of waves. Imagine the pitch of a train changing as it passes but to the conductor the train toot always sounds the same.

Movement of Weather

• The Doppler effect is commonly used in the weather business. Doppler radars send radio waves down on the clouds and by measuring the differences in the shifts of the received waves the meteorologist can determine wind speed and direction precisely. This has been revolutionary for on-the-spot weather forecasting.

Marine life

• The Doppler effect works well in the ocean for marine biologists. The waves used are sound waves. Sonar waves are powerful enough to reach the bottom of the ocean. The waves that bounce back produce frequency shifts caused by colliding with objects. If the object is moving, as most life does in the ocean, then the received sound waves will produce a certain frequency shift. A motion of 10 miles per hour leads to a received shift of 0.03 kilohertz.