                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2021 October 3

                   The Holographic Principle and a Teapot
                            Image Credit: Caltech

   Explanation: Sure, you can see the 2D rectangle of colors, but can you
   see deeper? Counting color patches in the featured image, you might
   estimate that the most information that this 2D digital image can hold
   is about 60 (horizontal) x 50(vertical) x 256 (possible colors) =
   768,000 bits. However, the yet-unproven Holographic Principle states
   that, counter-intuitively, the information in a 2D panel can include
   all of the information in a 3D room that can be enclosed by the panel.
   The principle derives from the idea that the Planck length, the length
   scale where quantum mechanics begins to dominate classical gravity, is
   one side of an area that can hold only about one bit of information.
   The limit was first postulated by physicist Gerard 't Hooft in 1993. It
   can arise from generalizations from seemingly distant speculation that
   the information held by a black hole is determined not by its enclosed
   volume but by the surface area of its event horizon. The term
   "holographic" arises from a hologram analogy where three-dimension
   images are created by projecting light through a flat screen. Beware,
   some people staring at the featured image may not think it encodes just
   768,000 bits -- nor even 256^3,000 bit permutations -- rather they
   might claim it encodes a three-dimensional teapot.

                      Tomorrow's picture: galaxy tails
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.


