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In this fascinating video, Michael Stevens explores the question “What is the speed of darkenss?”, piggybacking on his video, The Speed of Push, and referencing the impressive work of Martin Archer.

Exploring amazing concepts like Shadow Kissing and Shadow Blistering, he triggers many “ah-ha” concepts that we actually see quite frequently.

The video becomes more interesting as he explores such concepts of how shadows are faster than light, and explaining Shadows & Light Spots as well.

The video uses intellectual models (explained in a very understandable way, as usual) of projecting light and shadows onto the moon from earth. He ties these concepts in with things we commonly see everyday, but often take for granted, like our commonly experienced sunsets and earth’s shadow producing atmospheric phenomenon like the Belt of Venus.

Belt of Venus
Warm shades and subtle colors come to the sky in the fading sunlight after shadowrise on this little planet. Of course the little planet is planet Earth, and this nadir-to-zenith, around-the-horizon mosaic maps the view from a small airfield near the town of Intendente Alvear, La Pampa province, Argentina. Just above the western horizon (top) the sky shines with the warm colors of sunset. The slate blue shadow of Earth itself extending through the atmosphere can be seen rising as it hugs the eastern horizon (bottom). Wrapped closely above the narrow projection of Earth’s shadow is the gentle glow of reddened, backscattered sunlight called the antitwilight arch or the Belt of Venus. Credit: NASA
Belt Of Venus
From central Australia, this serene 360 degree panorama follows a clear horizon as twilight began on May 28. At left, a bright western sky is still illuminated by the setting Sun. But sweeping right, toward a view centered on the countryside’s dominating sandstone formation called Uluru or Ayers Rock, the sky takes on progressively darker hues and subtle colors. Behind Uluru is the shadow of planet Earth itself, a dark blue arch rising in the east. Cast through the dense atmosphere and still close to the horizon, Earth’s long shadow is bounded above by a pinkish glow or antitwilight arch. Known as the Belt of Venus, the lovely color of the antitwilight arch is due to backscattering of reddened light from the setting Sun. On that night, a nearly full Moon also rose above Earth’s shadow in the eastern sky. Credit: NASA


Never failing to break things down to the level of physics, Mike touches on Constructive and Destructive Wave Interference, along with their Superposition behavior that leads into The Path Difference; when waves from one source meet up with waves from another source.

Constructive Interference

Constructive Interference

Destructive Interference

Destructive Interferiance

Superposition of Waves

Patch Wave

What does this all have to do with the speed of darkness? We learn that Destructive Wave Interference is yet another way of creating darkness, and all these concepts creatively lead into the intriguing topic of the speed of ignorance.

ignorant comic

As he explains the extremely interesting Dunning–Kruger effect, he subtly brings attention to how our expansion of ignorance is symbolically tied into how in-the-dark we can be and how many shadowy things there are left to illuminate (clever).

There is no question this is definitely worth a watch – I hope you enjoy as much as I did!

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