Dark Energy, Cosmology part 2: Crash Course Astronomy #43

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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.

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Expanding faster than light:

General expansion:

Table of Contents
Majority of the Universe is Made of Dark Energy 4:35
Dark Energy Accelerates the Expansion of Space 3:42
We Think The Universe Will Expand Forever 5:20

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The Big Bang http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=10128 [credit: NASA]
Collision Scenario for Milky Way and Andromeda Galaxy Encounter http://www.nasa.gov/images/content/654284main_i1220bw.jpg [credit: NASA; ESA; A. Feild and R. van der Marel, STScI]
Artist’s impression of vampire star http://www.spacetelescope.org/videos/astro_bn/ [credit: ESO/M. Kornmesser]
Host Galaxies of Distant Supernovae http://www.nasa.gov/sites/default/files/images/593872main_hs-2006-52-a-print.jpg [credit: NASA, ESA, and A. Riess (STScl)]
Dark Energy Expands the Universe http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=10135 [credit: NASA]
Expanding Universe http://www.spacetelescope.org/videos/hst15_expanding_universe/ [credit: ESA/Hubble (M. Kornmesser & L. L. Christensen)]
Hubble Ultra Deep Field 2014 http://hubblesite.org/newscenter/archive/releases/2014/27/image/a/ [credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)]


Delores Snyder says:

maybe we haven't found life on other planets because of dark matter and dark energy

Ultrametric says:

What lunacy! No wonder fundamental physics is in such bad shape – this guy doesn't even understand SPECIAL relativity.

Fyx5010 says:

Here's the answer to the universe. Matter wants everything to come together. Basically gravity. Dark matter wants everything to be pushed away, like two electrons close together. Dark matter/energy outnumbers Normal matter/energy 20:1. So "Antigravity" wins against "gravity. That's why space is expanding, yet normal matter isn't. Matter and antimatter are like yin and yang. They don't affect each other physically, but are in the same "universe" together. Eventually I think the universe will soon stop expanding. This is due to dark matters anti force tendency to "push away" and eventually the force that wants to keep stretching space apart will be over a big enough volume that normal matters tendency to create gravity and a gravitational force will equal this anti force.

LUCkiswithme says:

if space is not infinite, that means there's an edge, a border. last episode you said there was nothing outside it, but how? I can grasp nothingness, I can understand that there can literally be nothing (no space, no time, no matter, no nothing), but if there actually is something not – infinite inside nothing? how does that even work?

Kashyap Brahmandam says:

why can't we say that galaxies are moving apart due to relaxing of space after the BigBang…like the gravitational waves moves and contracts space?? please answer my question

Rutuja Deshpande says:

but we r not stationary ..our galaxy is also moving same as others …so we can see that galaxies which r 100 bil. light year away from us…

Tony Bjornson says:

Makes me wonder what the sky looked like during the time of the first life forms on Earth. Could the night sky back then have been way brighter with the details of our own galaxy, maybe even other galaxies?

Alex Fullerton says:

Could somebody please answer my questions?
1. at one point the video he says that the universe may be infinite in size but how does an infinite universe shrink down to a singularity (the big bang)?
2. If the observable universe may only be a fraction of the entire universe, do we know that the entire universe shrunk to a singularity or does this make big bounce theory possible?
3. Are we positive that the universe will keep accelerating making a big bang or a divine creator the only possibilities? If I am missing a plausible theory please state it.
If someone could help me out that would be great. thx

Purely Science says:

before the big bang , there would be no dark energy , that's why there was nothing like anti gravity , so everything came together , but as soon as deti energy came into existence , everything has gone away with a big bang.

Wade Wilson says:

so what happens to light coming from the horizon ? wat happens to their energy?

Per Ringnes says:

what if our universe are pulled towards another universe, and that is why the expansion of the universe are accelerating because it is getting closer and closer to the other universe and the gravity pull is getting stronger and stronger, because we are getting closer and closer?

Abirami Venkatesan says:

if all the galaxies are moving far away does that mean even our milky way too is moving far away from some point ???

Abirami Venkatesan says:

i love astronomy and its damn useful seeing these crash courses thank you sir phil plait

Siddhant Garud says:

did dark energy or dark matter exist before the big bang?

Pure Ironn says:

VEERY , WE , and WILL 😂

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