Spacetime Tells Matter How to Move

Here, in honor of the hundredth anniversary of the General Theory of Relativity, is a very nice visualization:

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7 Responses to “Spacetime Tells Matter How to Move”


  1. 1 1 Sub Specie Æternitatis

    Very nice visualisation.

    I’d only slightly quibble with the headline. Spacetime doesn’t tell matter anything. Locally to the matter, all spacetime is flat. Matter, solely under the influence of gravity, always moves along a straight line in this flat space (or, if you will go slightly quantum, matter moves along all paths that extremize eigentime). What spacetime does is determine how this straight line looks to an outside observer.

  2. 2 2 Ken B

    Very nice. Watching it I was reminded of Lewis Carrol Epstein, credited in the video. He has a nice phrase: the reason why you can’t go faster than light is that you can’t go slower either; everything moves through spacetime at the same speed.
    I highly recommend his Thinking About Physics, and Relativity Visualized.

  3. 3 3 Steve Landsburg

    Ken B: In fact this video led me to order both of Lewis Carroll Epstein’s books, and I now believe that everyone should read them.

  4. 4 4 Neil

    Lewis Carroll Epstein’s book on relativity, Relativity Visualized, is the best I have ever read on the subject.

  5. 5 5 Harold

    I now have something for my Christmnas list.

  6. 6 6 Neil

    Epstein seems to live (if he is still alive) below the radar. I tried to find him once to write and tell him how much I admired his books, but no luck. When he wrote his two books in the 1980s, he taught at the City College of San Francisco, but no more.

  7. 7 7 James Roberts

    I’m surprised that Landsburg didn’t know about Epstein. (I teach economics and I assumed that since Epstein’s book predates Armchair Economist, Landsburg was imitating Epstein.) Both books, in simple terms, explain complex ideas. Sadly, there is no equivalent book for quantum mechanics.

    To better understand the situation of my students, every so often, I pick up Relativity Visualized and read a few pages.

    Btw, there’s a youtube video of Einstein’s special relativity: https://www.youtube.com/watch?v=C2VMO7pcWhg

    Unfortunately, the youtube video presents “time” in two ways (dimensions): there’s the youtube time as the red line moves across the screen (and as most people understand time) and then there’s time according to a graph.

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