Cosmology Lecture 1

What people said

Strong rec Keith Knauber · 2020-06 · Physics Stack Exchange · on “Can anyone recommend video lectures on all subjects of physics for a masters student?”

One of my favorite lecture series is Leonard Susskind Stanford cosmology series [this video] . Then when you need a comedic break from that, check out Stanford’s Robert Sapolsky series [LINK]

Recommends Keith Knauber · 2020-03 · Physics Stack Exchange · on “Expansion of space or contracting of matter?”

The answers proposed by others here are correct and they give you intuitive reasons why they are correct. I’ve thought about similar questions before. Another way of asking it, if I were to try and guess what you are proposing, would be: “Could dark energy expansion be explained by proposing that the Planck distance is not actually a constant?” A good resource for thinking about this would be Leonard Susskind’s YouTube Stanford lectures on cosmology. At some point he derives Planck constants from scratch, and gives good explanations for why these things are constants and why they don’t vary. [this video] Lots of equations, but always explained well.

Cites user288251 · 2021-02 · Physics Stack Exchange · on “Did the Big Bang cause an outward push of gravity?”

The big bang is not "inverse gravity." It is gravity as GR explains gravity (it's not a force, it's curved spacetime, etc). Your intuitive picture of GR is not exactly right. To really understand GR you must look at the actual equations and not popular analogies. The possibility of the big bang was in Einstein's field equations from the beginning. He introduced the cosmological constant to avoid such a thing. When Hubble found that the universe was expanding, the cosmological constant was taken to be 0. Now, we know the expansion is accelerating and the cosmological constant is not exactly 0. Susskind. Lectures on Cosmology. [this video] Tegmark. Lectures on Cosmology. [LINK] Because general rela

Cites Ruye · 2024-01 · Physics Stack Exchange · on “Movement of galaxies vs expansion of space”

I can readily accept the theory that the universe is expanding as a mathematical model to explain the fact that all galaxies are moving away from each other, but I have difficulty understanding intuitively how the space itself can physically expand. How can one tell the difference between these two scenarios: the space (carrying all galaxies in it) is expanding; all galaxies happen to be indeed moving away from each other within the space as a fixed framework. The consequence of either of the two scenarios seems to be the same to an observer on Earth, who sees all galaxies are moving away from the Earth (redshift observed by Hubble). Based on this observation, how can one tell it is due to s