Relativity videos (i.e., Relativity videos):

1. Special relativity videos (AKA Special relativity: videos):
   
   1. minutephysics: Einstein's Proof of E=mc**2 | 2:10: It's too quick for yours truly, but watch and listen as if it were poetry as would say Roger Penrose (1931--). Too long for the classroom. In fact, E=mc**2 means 2 things. For the long explication, click e_mc2.html. The short explication is:
      1. Energy (the quantified conserved capacity for change) and mass (the quantified resistance to acceleration relative to inertial frame AND the cause of gravity) are equal (or more exactly proportional) measures of the same thing which in relativity speak we call mass-energy.
      2. There is such thing as rest mass: the mass-energy just associated with the existence of massive particles: e.g., electrons, protons, and neutrons. Since all forms of energy are interconvertible, rest mass can be converted into any other form of energy. Note 1 megaton of TNT equivalent = 4.184*10**15 J = 1.162*10**9 kWh = 132.6 megawatts for 1 Julian year = (0.04656 kg)*c**2 = (46.56 g)*c**2. So much energy from so little rest mass---fortunately, it's NOT easy to do the transformation quickly---unfortunately, it's NOT easy to do the transformation slowly either. Another way of looking at it is that the energy of nuclear reactions (which is how we mostly transform rest mass) are typically of order 10**6 larger than that of chemical reactions. That factor of a million has mesmerized people every since 1905 when Einstein first presented special relativity. So much energy from so little fuel.
   2. E=mc**2: Einstein explains his famous formula | 0:57: Albert Einstein (1879--1955) explains it all for you. Our master's voice. NOT suitable for the classroom.
   3. minutephysics: Complete Solution To The Twins Paradox | 3:33: Lorentz transformations, time dilation, twins paradox, A little long for the classroom.
   4. Time Dilation - Travel at Speed of Light - Special Relativity | 4:24: Time dilation explained by Carl Sagan (1934--1996). Too long for the classroom.
   5. Simultaneity - Albert Einstein and the Theory of Relativity | 2:03: Simultaneity is reference-frame dependent. Time flows differently in different reference frame. With creepy animated humans in the uncanny valley. NOT OK for the classroom.
   6. Relativity: The Twin Paradox | 9:02: Too long for classroom.
2. General relativity videos (i.e., General relativity videos):
   
   1. The Elegant Universe: Episode 1 - Einstein's Dream | 16:00--56:07 Brian Greene (1963--) explains, elegantly, general relativity. Too long for the classroom.
   2. Gravitational wave videos (i.e., Gravitational wave videos):
      
      1. Gravitational waves: GW20150904: LIGO video 2016feb11 | 2:55: Best GW170817 video ever!!!! LIGO of the gravitational waves: first observation (AKA GW150914) which came from a black hole merger.
         Keywords: black hole, black hole binary, black hole merger, gravitational waves, inspiral, LIGO, merger, ringdown.
         See also SciAm slideshow. Very good for the classroom.
      2. Warped Spacetime and Horizons of GW150914 | 1:13: Mostly redundant with the preceding video. Good for the classroom.
      3. Observing neutron stars collide, 2017oct16 | 4:17: Too long for the classroom.
      4. Classroom Aid - Gravitational Wave Geometry | 3:19: This is good on gravitational waves as changes in spacetime. Too long for the classroom.
      5. Gravitational Waves Explained Using Stick Figures | 3:20: this good on gravitational waves changes in the gravitational field which is the weak gravity limit point of view.
      6. Gravitational waves: general intro | 4:37: Makes some good points, but is NOT the ideal video. For one thing, gravitational waves do lose energy to matter if they the matter isn't free to move.???? Too long for the classroom.
3. See relativity keywords in the insert below (local link / general link: keywords_relativity.html):
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Local file: local link: relativity_videos.html.
File: Relativity file: relativity_videos.html.