PHYS 183 Lecture Notes - Photon, Big Bang, Edwin Hubble
Document Summary
We use distances of galaxies to measure hubble"s law. Hubble"s law dates back to 1920 this is when astronomers were still look through telescopes, and edwin hubble did much of his work during this time. All of the measurements in hubble"s law are made with cepheid variable stars but calibrated. A particular galaxy originally emits a certain spectrum of light, but the spectrum we observe is shifted by 5% to longer wavelengths, indicating that the galaxy is moving away from us at 5% of the speed of light. Hubble measured the distances from galaxies to cepheid variables as well as its velocity relative to us. He saw that the velocity that a galaxy was moving is dependent on the distance it was to us there is large variability, but a general pattern. Hubble"s law is the line that is drawn through the points on the plot (the general pattern)
