Tuesday, April 16All That Matters

Carl Sagan explains the 4th dimension, circa 1980s

by sexymess777

Carl Sagan explains the 4th dimension, circa 1980s

Carl Sagan explains the 4th dimension, circa 1980s from OldSchoolCool




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34 Comments

  • marrymemercedes

    I remember watching this video almost 15 years ago and it started a week long sleepless dive into the topic. It’s always fun to watch it again.

    Reply
  • t3khole

    I’ve never quite understood this explanation.. he mentions at the onset that everything in 2d world is ABOLUTELY flat. If something had 0 height, on these flatland creatures level, they wouldn’t be able to see each other, or their house etc.

    Reply
  • fastornator

    Cool guy but what made him talk like that? It’s not really an accent I recognize. Did he just invent this affectation? I can’t imagine a 10th grade Carl Sagan talking like this.

    Reply
  • Fred-ditor

    One description I really liked was that a cylinder travels through flatland and the flatlanders are startled because what they see is a circle… for a while. Then it’s just.. gone.

    Then a ball passes through flatland and what they see is a small point.. then it gets larger and larger until it reaches the full diameter of the sphere, after which it begins to get smaller and smaller until it disappears completely, never to be seen again.

    And that description makes sense to me because I’m a three dimensional being describing what I think it would look like to a flatlander. But they can’t actually see that. Not exactly.

    Because a two dimensional, perfectly flat creature looking at another flat shape on the same plane wouldn’t see another whole shape unless they were transparent. A green circle, viewed from the same plane, would look like a green line.

    Of course, flatlanders would probably evolve the ability to see in two dimensions even though they were only able to “look”in one dimensional. Maybe a flatlander has two eyes and when their left eye sees a line this big and their right eye sees a line the same exact size, they know it must be a perfect circle, while a square viewed from the side would be the width of its side but from its corner would be the width of its diagonal

    Which is very similar to our two dimensional vision which, with two eyes, allows us to infer the 3 dimensional shapes around us. We can “see” in three dimensions to some extent but we need to move around to fully understand even the 3 dimensional shapes around us.

    Now imagine that a fourth dimensional object like a sphere or cube (a “tesseract”) passes through our 3 dimensional world. What would we see? We’d see a sphere… for a while. Or a cube… for a while.

    Maybe that 4 dimensional sphere starts out small then gets bigger and bigger until it reaches its diameter and then gets smaller and smaller until it disappears.

    And that four dimensional cube… if you want to build one, you can. Take a four meter piece of wire and fold it into four right angles until it touches itself at the other end. You’ll get a square.

    Take four 1×1 meter squares and lay them out, then do the same thing. You’ll get a hollow cube. So add two flaps – in a t-shape – and fold them all at right angles. You’ll get a fully formed cube.

    Now take four 1x1x1 cubes in a t shape, with arms sticking out left and right but also forward and back. And fold all of those arms on right angles towards each other. It’s impossible to actually do this because we can’t imagine where or how those folds would go. But if you could do it, that would be a tesseract. A fourth dimensional cube.

    Fun stuff

    Reply
  • senorpuma

    There is a children’s novel called “The Boy Who Reversed Himself” that explores this same concept, with similar analogies. I remember reading it as a kid in the late eighties – I wonder if the author has seen this video of Sagan.

    Also, i can’t believe Hugo Weaving came up with the Agent Smith voice evidently without having Sagan in mind. It’s uncanny!

    Reply
  • dhagens

    “For heaven’s sake!” says the flatlander. I’m wondering if a concept such as heaven would have formed with a lack of understanding above and below.

    Reply
  • OobleCaboodle

    He’s a great talker but oh my word, what is that accent? It’s wonderfully bonkers!

    I’m a brit of a certain age, so even though I’ve heard a lot *about* Carl Sagan, I’ve never actually heard him before.

    Reply
  • PheIix

    I thought time was the fourth dimension, I’ve heard it referred to as that for space travel?

    It’s not enough to know where you should be back and forth, from side to side, or up and down, you also need to know when.

    But this kind of broke that idea for me?

    Reply
  • ScottishGuy1989

    “A Shakespearen Scholar who lived in Victorian England”

    This suggests he was either had serious longevity in life, or his main study was of the Bard. So how did Shakespeare lead to flatland?

    Reply
  • LAZYandWOKE

    Car Sagan: We walk until we arrive at the place we started at.

    Everyone: Wow, that makes perfect sense!

    (Flat Earthers have left the chat room)

    Reply

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