Spacetime Curvature: Gravity and Einstein's Special and General Relativity

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This is the third lecture series of my complete online introductory undergraduate college course. This video series was used at William Paterson University and CUNY Hunter in online classes as well as to supplement in-person course material. This is a remaster of the previously released version with improved (though still not perfect) audio.
0:00:00 - lecture 1: Faraday, Maxwell, and the Aether
0:14:48 - lecture 2: The Speed of Light and the Michelson Morley Experiment
0:33:03 - lecture 3: The Great Relativistic Conundrum
0:50:05 - lecture 4: What is Special Relativity?
1:06:35 - lecture 5: Why Does Time Stretch and Space Contract in Special Relativity?
1:33:51 - lecture 6: Why Does General Relativity's Even Exist?
1:53:01 - lecture 7: What is Spacetime Curvature, and How Do We Know It Exists?
2:23:45 - lecture 8: How Does Gravity Bend Light's Path?
2:42:13 - lecture 9: General Relativity and the Slowing of Time by Gravity
3:05:35 - lecture 10: Faster Than Light Tachyons, Causality and Tacos
In this lecture series, we start with Michael Faraday and James Clerk Maxwell finalizing and culminating the wave theory of light. Faraday gives us our best picture of how light "looks" and Maxwell gives us the four equations that unify electricity, magnetism, and light. Also, we check in on Hershel's discovery of infrared, and other wavelengths of light. Next, we ask what is the speed of light? What do the waves of light travel in? What do we know about how light gets here from there? The answers are even more puzzling. In this one, we learn that the waves of light can still be waves, even if they don't actually "wave" anything. Nature starts to show us just how strange she is. Third, we check in on an oddity. Once upon a time, there was classical physics. It had Galilean Relativity, Newtonian Mechanics, and Maxwell's Laws of Electromagnetism. But, these three things, while wildly successful, did not fit together at all. Let's see why. Next, we chat about the postulates of Special Relativity, and three of its main implications: desynchronization of clocks, time dilation, and length contraction. Then we detail the effects of time dilation, length contraction, and clock desynchronization. We also chat about muon decay which demonstrates this effect. In the next lecture, General Relativity arises out of our need to reconcile the issues of Newtonian Gravity. It has some problems that only rethinking Gravity can solve. After this, we start to see why General Relativity is one of the most successful theories of Physics. It helps us give a mechanism to gravity and allows for testable predictions. We'll chat about the Correspondence Principle, The Equivalence Principle, inertial versus gravitational mass, and the nature of spacetime curvature and how it's measured. We'll chat about various tests of general relativity, and how they showed that it's the best explanation so far for the nature of space, time, and gravity. For the next lecture, we see General Relativity’s many interesting results. In this first of two, I try to show how we can more intuitively understand what the curvature of spacetime means. In this one, we look at the Equivalence Principle and show how it requires that light's path is bent according to a distant observer, but if you're falling along with the light, the path looks straight to you. Next, we chat about how light is redshifted as it rises out of a gravity well, and how time runs slower in a gravity well compared to clocks far away. We also dare to ask "into where does space curve.” Finally, we play around by asking what happens when you go faster than light? Can you go faster than light? (well, no, but let's chat anyway). And how do we know that we can't go faster than light? Why does going faster than light mean traveling into the past?

[@user-pw9bh8vw4t]

You're an excellent teacher. A lot of people might take these findings for granted but you're like a wizard, and somehow I understand what you are saying because you break it down and reiterate it very well. The gravity of these considerations actually blows my mind and is changing my reality.

[@PariahDice]

The man!!! 🎉

[@scottbrower9052]

Faraday is an everyman's hero.

[@michaelgonzalez9058]

Magnet on a wire induction is as a torque

[@stickoutofthemud]

Since the term “luminiferous aether” is now available for recycling, I suggest that we change the definition slightly and use it instead of “dark matter.”
Who’s with me?

[@jamesgornall5731]

The GOAT

[@kennethessenwanger268]

Space is efold expanding so at astronomical distances galaxies can move away from each other at speeds exceeding c.

[@kennethessenwanger268]

Apples and oranges: what is the wavelength in your example?

[@kennethessenwanger268]

Jason:
An alien Xenomorph floating in outer space near Milky Way Galaxy but far from any gravitational curvature in spacetime and holding either your accelerometer or a calibrated one, it would indicate no acceleration (inertial frame). An alien Reptilian near but inside of Xenomorph’s universe-horizon also holding an accelerometer (in outer galactic space) would also indicate zero acceleration. Xenomorph and Reptilian would Relatively be moving away from each other at nearly the speed of light AND with efold acceleration towards the speed of light c and beyond c: my very special theory of relativity :)
Jason:
My AI search shows Special Relativity doesn’t apply in Gravitational field, but my understanding was the Principle of Equivalence addressed that ignoring tidal effects. Is that correct?
Also Friedman Expanding universe excludes Special Relativity (due to homogeneous and isotopic assumptions, approximately 100 Mpc out).
Jason:
Doesn’t that technically make Special Relativity an approximation to reality almost everywhere?

[@tradtke101]

Mmm London Broil Society hnghmmmmm