Happy Pi Day and Happy Birthday, Uncle Albert!

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Happy Pi Day and Happy Birthday, Uncle Albert!

Postby steve-fung » Sat Mar 14, 2015 11:47 pm

Astronomy, physics, and mathematics are intimately linked, so wishing everyone Happy Pi Day. The day is also special because it is Albert Einstein’s birthday – Happy Birthday, Uncle Albert!

http://www.nj.com/mercer/index.ssf/2015/03/princeton_celebrates_special_pi_day_with_litany_of.html

This year is particularly special because 3/14/15 at 9:26:53 has the first 10 digits of pi. This year also marks the 100th anniversary of Einstein’s Theory of General Relativity, which is the geometric theory of gravitation.

https://www.astronomyhouston.org/forum/viewtopic.php?f=6&t=534

What did you do today?

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Re: Happy Pi Day and Happy Birthday, Uncle Albert!

Postby steve-fung » Sun Mar 15, 2015 10:26 pm

Aside from his birthday, another link between Einstein and π are his field equations from general relativity:

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which basically state that (gravitational curvature of spacetime) = (8πG/c4) × (energy and momentum), where G is Newton’s gravitational constant, and c is the speed of light. Notice that π shows up because we’re calculating gravitational potential field of mass density, which for a point of mass in space spreads with distance r with intensity inversely related to surface area of a sphere, 4πr2. See Gauss' law and Poisson's equation for gravity.

Here is a YouTube explaining Einstein's field equations – for beginners!
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