A Brief History Of Time: Journal Entry 3

Chapter 3 (Pg 37-54) Today I read about the revolutionary discovery about how the universe isn't static and that it’s actually expanding and getting bigger. Two important people in this discovery were Edwin Hubble & Alexander Friedmann. I also read about stars, wavelengths, the idea of other galaxies in the universe, and I learned about the Doppler Effect. The Doppler Effect is the change of the frequency of a wave for someone who is moving relative to the source. I read about whether our universe is finite or infinite based off a model found by Friedmann and two other models. There was a short story about two American physicists discovering a sound coming from outside the atmosphere and they would get a Nobel Prize out of it despite two other physicists who also discovered the sound. I learned that our universe is expanding 5 to 10% ever thousand million years. of the wave. Then we revisited the argument on if the universe had a big bang or not and Stephen Hawking started to talk about how he was trying to get his PH.D despite having ALS. Stephen Hawking talked about how he was trying to prove that there must be a singularity only if the universe was expanding fast enough to avoid collapsing again. He then wrote a paper with Roger Penrose that finally proved that there must have been a big bang to start the beginning of the universe.