Perfectly Balanced Universe

Another reminder from Neil DeGrasse Tyson's Astrophysics for People in a Hurry:

  "Since both mass and energy cause space-time to warp, or curve, omega tells us the shape of the cosmos. If omega is less than one, the actual mass-energy falls below the critical value, and the universe expands forever in every direction for all of time, taking on the shape of a saddle, in which initially parallel lines diverge. If omega equals one, the universe expands forever, but only barely so. In that case the shape is flat, preserving all the geometric rules we learned in high school about parallel lines. If omega exceeds one, parallel lines converge, and the universe curves back on itself, ultimately recollapsing into the fireball whence it came."

What a perfectly balanced universe in which we live!

Graphics: Wikipedia, Northern Arizona University

Our Unique Vantage Point

Earlier this year I listened to Neil DeGrasse Tyson's Astrophysics for People in a Hurry and I've been slowly re-reading the ebook. One of many fascinating observations Tyson makes regarding our unique position in the universe is as follows:

"Earth’s Moon is about 1/400th the diameter of the Sun, but it is also 1/400th as far from us, making the Sun and the Moon the same size on the sky—a coincidence not shared by any other planet–moon combination in the solar system, allowing for uniquely photogenic total solar eclipses. Earth has also tidally locked the Moon, leaving it with identical periods of rotation on its axis and revolution around Earth. Wherever and whenever this happens, the locked moon shows only one face to its host planet." --Astrophysics for People in a Hurry"

What an amazing universe in which we live!