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  • One of the most remarkable aspects of the human brain

  • is its ability to recognize patterns and describe them.

  • Among the hardest patterns we've tried to undestand

  • is the concept of turbulent flow in fluid dynamics.

  • The German physicist Werner Heisenberg said,

  • "When I meet God, I'm going to ask him two questions:

  • why relativity and why turbulence?

  • I really believe he will have an answer for the first."

  • As difficult as turbulence is to understand mathematically,

  • we can use art to depict the way it looks.

  • In June 1889, Vincent van Gogh painted the view just before sunrise

  • from the window of his room at the Saint-Paul-de Mausole asylum

  • in Saint-Rémy-de-Provence,

  • where he'd admitted himself after mutilating his own ear

  • in a psychotic episode.

  • In "The Starry Night," his circular brushstrokes

  • create a night sky filled with swirling clouds and eddies of stars.

  • Van Gogh and other Impressionists represented light in a different way

  • than their predecessors, seeming to capture its motion,

  • for instance, across sun-dappled waters,

  • or here in star light that twinkles and melts

  • through milky waves of blue night sky.

  • The effect is caused my luminance,

  • the intensity of the light in the colors on the canvas.

  • The more primitive part of our visual cortex,

  • which sees light contrast and motion, but not color,

  • will blend two differently colored areas together

  • if they have the same luminance.

  • But our brains primate subdivision

  • will see the contrasting colors without blending.

  • With these two interpretations happening at once,

  • the light in many Impressionist works seems to pulse, flicker and radiate oddly.

  • That's how this and other Impressionist works use quickly executed

  • prominent brushstrokes to capture something strikingly real

  • about how light moves.

  • 60 years later, Russian mathematician Andrey Kolmogorov

  • furthered our mathematical understanding of turbulence

  • when he proposed that energy in a turbulent fluid at length R

  • varies in proportion to the 5/3rds power of R.

  • Experimental measurements show Kolmogorov

  • was remarkably close to the way turbulent flow works,

  • although a complete description of turbulence remains

  • one of the unsolved problems in physics.

  • A turbulent flow is self-similar if there is an energy cascade.

  • In other words, big eddies transfer their energy to smaller eddies,

  • which do likewise at other scales.

  • Examples of this include Jupiter's great red spot,

  • cloud formations and interstellar dust particles.

  • In 2004, using the Hubble Space Telescope,

  • scientists saw the eddies of a distant cloud of dust and gas around a star,

  • and it reminded them of Van Gogh's "Starry Night."

  • This motivated scientists from Mexico, Spain and England

  • to study the luminence in Van Gogh's paintings in detail.

  • They discovered that there is a distinct pattern of turbulent fluid structures

  • close to Kolmogorov's equation hidden in many of Van Gogh's paintings.

  • The researchers digitized the paintings,

  • and measured how brightness varies between any two pixels.

  • From the curves measured for pixel separations,

  • they concluded that paintings from Van Gogh's period of psychotic agitation

  • behave remarkably similar to fluid turbulence.

  • His self-portait with a pipe, from a calmer period in Van Gogh's life,

  • showed no sign of this correspondence.

  • And neither did other artists' work that seemed equally turbulent at first glance,

  • like Munch's 'The Scream."

  • While it's too easy to say Van Gogh's turbulent genius

  • enabled him to depict turbulence,

  • it's also far too difficult to accurately express the rousing beauty of the fact

  • that in a period of intense suffering,

  • Van Gogh was somehow able to perceive and represent

  • one of the most supremely difficult concepts

  • nature has ever brought before mankind,

  • and to unite his unique mind's eye

  • with the deepest mysteries of movement, fluid and light.

One of the most remarkable aspects of the human brain

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【TED-Ed】梵高《星空》背後意想不到的數學--娜塔莉亞-聖克萊爾。 (【TED-Ed】The unexpected math behind Van Gogh's "Starry Night" - Natalya St. Clair)

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    稲葉白兎 posted on 2021/01/14
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