It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of matter like that which makes up you and me is but 5% of the energy budget of the universe. The glittering spectacle of the heavens is a rather thin icing on a very large and dark cake.
REFERENCES
1.
I.
Nicolson
, Dark Side of the Universe
(Johns Hopkins University Press
, Baltimore
, 2007
), Chap. 3.2.
D.
Lincoln
, Understanding the Universe: From Quarks to the Cosmos (Revised)
(World Scientific Press
, Singapore
, 2012
).3.
4.
Ref. 1, Chap. 4.
5.
6.
7.
8.
9.
Ref. 1, p.
75
.10.
11.
Dan
Hooper
, “TASI Lectures on Dark Matter
,” arXiv:0901.4090vl [hep-ph].12.
13.
D.
Lincoln
, The Quantum Frontier: The Large Hadron Collider
(Johns Hopkins University Press
, Baltimore
, 2009
), pp. 35
–43
.© 2013 American Association of Physics Teachers.
2013
American Association of Physics Teachers
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.