Why is it Dark at Night?

Have you ever wondered why you look up and see a dark sky at night?
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Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Music by Nathaniel Schroeder

Thanks to Nima Doroud and Niayesh Afshordi for contributions and to Perimeter Institute for support.
http://www.perimeterinstitute.ca

• Category

  Science & Technology

[n00b4liciou5]

Sometimes, before I fall asleep, I look up at the dark, yet sparkling, sky and wonder: Where the Hell is my ceiling?!

[Stephan de Vries]

Now I finally understand how infrared cameras work!

[damagon123]

Before video: One unanswered question.

After video: 10 unanswered questions.

[Spencer Marfy]

Why is the sky blue?

[carr60ick]

check out the work of walter russell at

w w w d o t walter-russell d o t c o m

[Jude Granada]

so by the time all of the lights in the universe reaches us, is it gonna be bright/ daytime in the entire planet?

[rez tonosaur]

you dont say..???

[baadshepherd]

You could see some of the light from it, but the majority of the light from the Big Bang would have spread in different directions, so no, you couldn't see the Big Bang event.

[Jorden Gillespie]

I got this one

[Kasper Kivimäki]

If we would go in somewhere at the universe, very long away. Then could we see the big bang. Cause isn't some of that light still traveling.

[MrMadr0]

Time for us is a linear perception, but time in reality is another dimension of reality, its our perception which gives us the feeling of a forward moving time.

[TFSWOLF]

There is no such thing as time. There can not be a "temporal edge" time is an illusion, a human perception. Everything in the universe happens at once. Without time. Its a bit hard to immagine as things can not litterally happen all at once. I cant go watch the earth being destroyed while drinking tea with abraham lincoln. Just immagine that there is no such thing as time and things just happen one way or another.