The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the Universe will expand forever, even as our view of it shrinks while space expands faster all the time.

Check out the Crash Course Astronomy solar system poster here: http://store.dftba.com/products/crash...

If you want to learn more about the creation and death of the universe, watch Crash Course Big History here:    • Big History  

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Chapters:
Introduction: The Expanding Universe 00:00
The Expansion of Space is Accelerating 2:17
What is Dark Energy? 4:19
Will the Universe Expand Forever? The Geometry of the Universe 5:20
The Cosmic Horizon of the Observable Universe 6:50
Review 10:20
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GEOMETRY OF THE UNIVERSE RESOURCES
Geometry:
http://abyss.uoregon.edu/~js/cosmo/le...
http://starchild.gsfc.nasa.gov/docs/S...

Expanding faster than light:
http://curious.astro.cornell.edu/lega...

General expansion:
https://en.wikipedia.org/wiki/Metric_...

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Follow Phil on Twitter:   / badastronomer  

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PHOTOS/VIDEOS
The Big Bang http://svs.gsfc.nasa.gov/cgi-bin/deta... [credit: NASA]
Collision Scenario for Milky Way and Andromeda Galaxy Encounter http://www.nasa.gov/images/content/65... [credit: NASA; ESA; A. Feild and R. van der Marel, STScI]
Artist's impression of vampire star http://www.spacetelescope.org/videos/... [credit: ESO/M. Kornmesser]
Host Galaxies of Distant Supernovae http://www.nasa.gov/sites/default/fil... [credit: NASA, ESA, and A. Riess (STScl)]
Dark Energy Expands the Universe http://svs.gsfc.nasa.gov/cgi-bin/deta... [credit: NASA]
Expanding Universe http://www.spacetelescope.org/videos/... [credit: ESA/Hubble (M. Kornmesser & L. L. Christensen)]
Hubble Ultra Deep Field 2014 http://hubblesite.org/newscenter/arch... [credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)]