Dark Energy, Cosmology part 2: Crash Course Astronomy #43
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- čas přidán 18. 06. 2024
- 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: 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:
abyss.uoregon.edu/~js/cosmo/le...
starchild.gsfc.nasa.gov/docs/S...
Expanding faster than light:
curious.astro.cornell.edu/lega...
General expansion:
en.wikipedia.org/wiki/Metric_...
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PBS Digital Studios: / pbsdigitalstudios
Follow Phil on Twitter: / badastronomer
Want to find Crash Course elsewhere on the internet?
Facebook - / youtubecrashcourse
Twitter - / thecrashcourse
Tumblr - / thecrashcourse
Support CrashCourse on Patreon: / crashcourse
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PHOTOS/VIDEOS
The Big Bang svs.gsfc.nasa.gov/cgi-bin/deta... [credit: NASA]
Collision Scenario for Milky Way and Andromeda Galaxy Encounter www.nasa.gov/images/content/65... [credit: NASA; ESA; A. Feild and R. van der Marel, STScI]
Artist's impression of vampire star www.spacetelescope.org/videos/... [credit: ESO/M. Kornmesser]
Host Galaxies of Distant Supernovae www.nasa.gov/sites/default/fil... [credit: NASA, ESA, and A. Riess (STScl)]
Dark Energy Expands the Universe svs.gsfc.nasa.gov/cgi-bin/deta... [credit: NASA]
Expanding Universe www.spacetelescope.org/videos/... [credit: ESA/Hubble (M. Kornmesser & L. L. Christensen)]
Hubble Ultra Deep Field 2014 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)]
I never expected astronomy to be this heartbreaking and terrifying...
+Shimin Shamim He didn't even get to the possibility of heat death...
+Shimin Shamim BUT WAIT THERE IS MORE!
+Jon thats just cold...
+DTRIGGS He said that the galaxy would stay intact; I think molecules are safe too. He said distant galaxies are get accelerated away, --not that they're getting accelerated away at an increasing rate.-- EDIT: I take this back, I miswrote here. See later msgs.
In any case, every star in the galaxy will be dead by then.
+Jon Or the possibility of the Big Rip
The scariest thing to me is that if there is alien life, they might live in a galaxy so distant that with every second that passes, they get closer to leaving our observable universe. Forever.
And this may have already happened, many, many times...
Our existent is nothing but a blink in term of the cosmos timeline. There might be an ancient civilization that lived and died looooooong ago even before the earth was form or maybe they weren't even came to existent trillion years from now. We never know. However, if there currently exist a live form that can travel trillion of light years and come to us. Their existent will be like gods to us. We can't even comprehend how advance they are. Fun fact, our DNA and the Apes DNA only 1% different from each other, yet look at how much we can achieve. Now imagine another life form live billion if not trillion of light years away.
This is one of the most terrifying videos I have ever watched.
+John Smith Our lives are just a couple decades long so no need to worry about something that might happen a couple 1,000,000,000,000 (trillions) years into the future, so don't worry be happy
+John Smith only if you live WAAAAAY over a Billion years BUT we anly live 70-80 years on average
+Leon Latin 7-8 decades ..being a Decade is 10 years
it reminds me of "the nothing" in the never ending story coming closer all the time
+John Smith True. being a young 13 year old, you think that you have a LOT of life ahead of you and scars you that there might not be beautiful things to look at eventually.
Especially when he said that every day it expands faster every day.
We better hurry, we only have a few trillion years left. I wonder if that gives me enough time to grab a coffee first.
+Caleb Limb Better make it a drip. No time for fancy lattes.
-Nicole
+CrashCourse YOUR WASTING TIME
+Mustafa M Unlike you, who won't even bother with grammar :))
+CrashCourse I wonder... Is it possible to exploit dark energy?
OzixiThrill Dark energy is just the category we use to describe all of the energy that we don't know where it's from or exactly what it is. We just know it exists because it is needed to satisfy inflation and our models of the universe. Just as dark matter is the mysterious matter that is extremely difficult to observe and is possibly more than one type of new particle/substance, we just know it's there because it's needed to account for all of the gravitation we observe an the scale of galaxies.
So no, I don't think we can exploit it.
It's one of my favorite little oddities about cosmology. The rate at which the expansion is changing is known as the deceleration parameter, because of course everyone expected the expansion to be decelerating. But the deceleration parameter is negative.
+Matthew Prorok 'So what's the parameter?'
'You won't beleive it.'
'What? It's less than we expected?'
'Worse.'
'It's orders of magnitude less?'
'Worse.'
'Good grief man1 you don't mean to tell me the expansion ISN'T decelerating? That the parameter's exactly zero?!'
'Well...'
+Gareth Dean man your comment makes learning even more fun
I really thought I hatted astronomy. I took a class in 8th grade and I thought it was just boring calculations that were tedious to make. I thought the Universe was generally boring and the Earth incredibly amazing, but these videos have changed my mind completely.
What kind of awful, awful teacher or curriculum could make astronomy boring? Holy mackerel, you need to be a special kind of awful to do that
+Vectored Thrust My old chemistry teacher loved science, once. But years and years of teaching a class that didn't want to be there and tried to get away with the minimum amount of work wore her down. By the time I passed through her class she had stopped trying. I was the only student in my final year and learned through correspondence schools. She let me drop a brick into boiling acid just because I had an interest.
I have always liked astronomy since I was in 1st grade and now I'm 34 years old.. Too old to be on youtube?
*****
I think Phil's older, and he created this video. Get thee a profile picture!
+Gareth Dean yeah lol phil is 51. I'll get a profile pic soon
NOTHING can go faster than light.
But space itself is literally NOTHING. So the 1st statement holds true.
"We live in a special time, the only time, where we can observationally verify that we live in a special time."
"if you want more information, we have links in the doobly doo"
-Phil Plait
"That would be a cosmic joke," the skeptic told the bartender.
"What?" the bartender inquired.
"If dark energy is nothing more than mind."
"How's that?"
"You can't see or measure it, but there's no doubt it moves matter around."
The bartender smiled as she responded, "It's also what fills many of my customers' heads."
"What's that?" the skeptic asked.
"A lot of empty space."
This was very moving.
+VeganMusic I really hope that pun was intentional.
You are a god among men for that comment. I shall pray to you before bed tonight.
+VeganMusic exponentially moving?
+VeganMusic Haha!
I have to watch this 5 times to literally confirm what i've just heard
This video was actually kinda scary you can imagine what it will be like to be all alone in the observable universe and that thought gives me the chills
My mouth fell open when he started talking about moving faster than the speed of light O_0
Well like he said it's not really moving faster than the speed of light. Space is.
I just want to say this has been the best Astronomy video series I have ever seen online. You have a great way of teaching and explaining things Phil.
"We can't see it, we can't measure it, there's literally no evidence that it's there but the math says it has to be so you better believe it."
That was our relation with black holes since 1784 for a couple centuries.
Although my english isn't very well because I'm french, it's very interesting, kipe going like that.
You have a new French fan.
Surprised this episode isn't just 10 seconds long:
"Dark Energy: We have NO clue, people. None. Thanks for watching!"
Man, I love these Crash Course astronomy videos so much. Extremely well written, factual and simply breathtaking. My jaw literally dropped this morning when I saw this Dark Energy video pop up in my subscriptions. A big thank you for sharing such knowledge of epic proportions.
I look forward to this every weekkk
me 2
Ok
3 weeks to wait for the next one :(
+Headrock and until then the observable universe has gotten even smaller again... :(
+Headrock Merry Christmas
+Han Smith u2 m8
+Han Smith That ruins my Christmas eve tho...
6:54 who watches youtube standing up?? o_O
+Leo H (proceeds to sit down)
+Leo H
People who are butthurt, maybe?
realrunner2000 so you better sit down after 7 min
+Leo H i was laying down, so i actually had to rise and sit
khhnator lol still i thought it was funny...
This channel brings a whole new meaning to I don't know what I don't know. that being said. Thank you for continuously blowing my mind.
Hands down my favorite episode yet! Simply astonishing.
Best CZcams channel, represents the only part of my day when I can say for sure "I learnt something" keep it up
I love this channel
cool episode guys. You did a great job explaining some things I was struggling to understand. thanks.
Some of this stuff i'm hearing for the first time. Awesome video Phil!
I have to sleep to school but oh look another crash course....... Irony
*for school
Why does dark energy have to be such a jerk?
+Brandon Hall Because f*ck you thats why haha
+Brandon Hall if dark energy doesn't exist, the universe would shrink back to the singularity. so what is the jerk in that case?
+praspurgh
It's believed that Dark Energy will cause the Universe to expand indefinitely, leading to heat death.
+Brandon Hall the universe does not care with us and will always defy what made sense to us growing up.
+praspurgh How about we learn how to capture just enough dark energy so that it keeps it in balance .... oh wait .... we'd have to do it for the entire universe wouldn't we .... :(
The series has come to that part of astronomy where things are fascinating, terrifying and unbelievably spectacular.
One of my guest lectures at university was on one of the teams that discovered the expansion of the universe.
Truly a small world we live on.
this explain the end of time in Doctor who. those writers are freaking awesome.
Hey CrashCourse, Can you please make a new series about physics for 2016? You guys make really great videos.
+amir shantia We sure can! See you in March :)
-Nicole
+CrashCourse is that a date? ;)
+CrashCourse with calculus**
Thank you Phil for the knowledge you provide us for free!
If it is possible you can make some future videos that have some equations and some material that is heavier in science since the course is getting more advanced.I think it is possible to mix it up and have a little more science and make it fun at the same time.
Thanks
This is sooooo AWESOME, can't put words to it. Please keep them coming.
4:29 "we can't see it so it's invisible" LOL you don't have to dumb it down that much
Yeah he does. have you seen the state of the American government? everything is either Fake News or considered Fake News by some one. Today's world NEEDS to have everything dumbed down. =(
Do crash course physics!!!!!!!!!!!!!
Why you got a test coming up? Besides, he kinda is.
Hey Phil love the vids, keep up the great work!
Awesome videos! I study physics at university level and these videos are way more interesting than most of my courses. Good job, keep it up. The animations are really helpful to understand it better.
could particles that pop in and out of existence in an instant "create" the space they pop into, creating the expansion in the process? and the more space there is, the bigger the space were "new space" can be created in between?
+Sebastian Schneider A non-zero vacuum energy is one of the theories for what dark energy could be. We're not short on ideas, it's that we've had very little luck ruling them out so far.
we could try to get a mathematical grasp on it in terms of probability of existence for a particle. if it is between 0 and 0,5 on the probability-scale of existence, it would be there, having a mass, without existing in our "reality" we can only observe stuff between 0,5 and 1 (certainty) but the moment it enters reality (0,5 on that scale) it needs to create space since it can't exist in the same space another particle does. that would exclude it from existence, lowering the value of certainty.
+Sebastian Schneider Even if it does create space, somewhere another particle that pops out of existence (for Conservation of Energy purposes) would thus need to destroy space. At least, that is my thought on the matter and is by no means an expert opinion on the subject.
That was actually a question I was hoping they would answer. If space is being created by Dark Energy's continued expansion, then is the density of Dark Energy going down to compensate the increase in space or does it remain the same? If so, why?
its conservation of energy, not space. if you build a patio (space) to put a rockingchair (particle) and later decide to take it back inside (out of existence), you don't neccesarily have to demolish the patio. you would have to take another rocking chair inside so you still have something to sit on next to the chimney, but the amount of chairs stay the same.
thing is, the bigger the universe gets, the more space there is where there probably once was a rocking chair, but you build a new patio everytime you want to put one outside since you don't know if there stil is one. maybe you've already parked something else there, a bench, a grill, your grandson. so basically, as long as you can theoretically put another rocking chair outside, you'll always have to build another patio. the amount of rocking chairs is limited however and if you want to put one were there already is one, you'd have to move the other one away after building a new patio to get it out of the house (into existence) first.
and now i feel old... ^^
+Sebastian Schneider This may be the case, or something like it. Dark energy seems to be a property of space itself, not changing. This could be a field which causes space to expand simply by existing. It may or may not be related to the 'inflaton) (No misspelling!) field that gave the Big Bang a kick.
Dark energy means we are still in the dark ages of knowledge. A lot missing.
These are awesome bunch of videos over internet other than anything. Thanks for Mr.Phil Plait and Crash Course Astronomy team :)
And i would love to watch if you guys do video on 'THE WORM HOLE'
What a lovely episode!! Got me really amazed.
Holy fuck. Stop the universe, I wanna get off now.
I'm a time traveler from far in the future. This isn't a joke. Man, you guys have a lot to learn! No spoilers though.
+culwin NO SPOILERS. Much appreciated. Don't want to ruin the end!
(Spoilers: this series is gonna have some spoilers about the end.)
-Nicole
+CrashCourse Is Will John Green be on a video for one more time?
+culwin I've only one question, will Trump be the president?
M Bayrak
Depends which Trump you mean
Amazing. Thank you for making these videos.
I love your courses Phil. Keep them up.
If the universe is expanding, this assumes there must be an "edge of the universe" that is leading the expansion, and if the universe is expanding slower than the speed of light, what happens when light reaches the edge of the universe?
Nishva Patel
it just goes into more space.
There does not have to be an edge of the universe for the universe to expand
It's not really a bubble getting larger, it's more like the space between everything inside the bubble increases. It's also a bit hard to define the edge of ininity and whatever would happen there. It's probably best to assume that outside our universe is nothing, and nothing can exist in nothingness.
Well it's not expanding the slower than the speed of light. It's expanding more and more the further out you look. Once you can't look any farther the universe is pretty much expanding faster than the speed of light so anything beyond that limit will never reach us.
Here's a silly thought:
Let's assume the universe has the shape of a 3d-toroid (as has been proposed), let's furthermore assume that gravity bends space towards the "inside".
If there were two extremely massive objects on directly opposing sides, so massive, that the bent space overlaps in the "middle" of the toroid... What would happen? Could that even happen?
+d3rrial How could the space overlap? If the universe is a doughnut, what's outside of it? I think space is outside it, nothing but endless space. So if space is being bent by the gravity of the universe, it could be dragged luke a blanket. But no matter how much this blanket space gets curled up, it will still have an infinite amount untugged. I conclude that if these objects make space overlap at the center of the universe, "space" how we refer to it is not emptyness and possibly dark matter/energy is space.
+d3rrial There's technically no inside to a topological toroid. You're thinking of a donut. Think instead of the video game _Asteroids,_ where one side of the screen is equivalent to its opposite.
+TheLivingGlitch You have quite a bit to learn about geometry. Space can be curved without being embedded in a flat higher dimensional manifold.
FirstRisingSouI Yeah. Donut sounds so unscientific tho. :P
+TheLivingGlitch there is no space outside of the universe because the universe is per definition everything...
Thanks! You just proved to be the source I needed to finally know what to write about for my physics paper. :)
Please never stop these videos. They're too awesome
make me sad to know that one day there would be no need for an astronomer or the people in the relative fields :(
If it makes you feel better l, by the time that the observable universe becomes a problem, all traces of human existence will already be wiped from the universe anyway.
+sujit suram nah the sun would be long gone before that. what would be really sad is if we find life on another galaxy only to watch our alien friends fade from our vision
+sujit suram That's like, trillions of years away. Might as well be never. And by then, life will probably be made up of immortal AI, who will preserve and remember the knowledge gained before then.
+sujit suram Depends on what is discovered in between that time if it matters or not ;)
By that time, all the puzzles pieces in astronomy will be in its proper place, and the role of astronomers will be complete.. Unless new pieces will be found, then we need a bigger puzzle frame
Today we learned that Phil can't be bothered doing his part in helping Americans convert to the metric system. So here am I doing it for him:
At 1:08 = 31 miles/second
At 4:38 = 0.393 cubic inches
Your welcome, Phil! All of those Americans funding your work appreciate it.
+JoeyRodz74 Or you can do us all a favor, and learn the metric system... It just makes sense!! Unlike the imperial system!
+Rudy_Eila the imperial system is very similar but us americans use the United States Customary System ;)
+JoeyRodz74 Or, you know, those Americans can dust off that thing between their ears called a brain, and learn the metric system, which is the universal scientific system of measure. It's really not hard to learn.
1 millimetre = 1/1000th of a metre = 1/10th of a centimetre
1 centimetre = 1/100th of a metre
1 kilometre = 1000m
How is that difficult? It's far easier than:
12 inches = 1 foot
5280 foot = 1 mile
not really universal (cuz we dont know what else is out there), but yes, much more widely used than customary so i totally agree.
+ValleysOfRain Exactly, math with such stupid units is so boring, with the Metric system you're just adding or removing zeros from what you want to convert...
He mentions "Standard Candles" with no explanation, but their discovery by an unsung heroine by the name of Henrietta Swan Leavitt and how they are used, probably deserves an episode of its own.
I agree, a truly brilliant astronomer who paved the way for modern astronomy, would've gotten a Nobel Prize for sure.
nice i thought this was gonna be the last episode .. we have more to watch and learn
Maybe we're at the first stages of the big bang still.. i mean when you through a rock it will accelerates from zero to the maximum velocity upwards before slowing down. Maybe the universe is expanding and its expansion is accelerating because we haven't reached the maximum velocity yet. That will completely rule out the existence of imaginary force that mysteriously increases the expansion rate. Another point, there is an initial period in the big bang called the inflation period in which the matter - not the space between matter - but the actual physical matter moved faster than the speed of light for brief instants. This was calculated using the CMB in which its noticed that the singularity should have been more further away in time but its actually 13.772 so as the universe is today the big bang should have happened much further in time. This implies that at some point at the beginning of the big bang the matter moved faster than the speed of light. Some scientists still appose the big bang because this inflation periord doesn't go very well with Einstein equations.
duuude...this explanation with the speed of the expansion its just....wow^^. I really love astronomy, its so cool!
I love this course. Thank you!
I almost cried...Amazing, thank you, Phil.
Thank you! Excellent stuff!
Love the way you explaining with ease so I can understand more. A lot of scientists explain with hard-rare nouns and we just like 'what..what???'.Thank you for let me understand
This aswered my question about light from the time that the Universe was young. Thanks. Nice video.
great video!! thank you for the Andromeda - Milky Way explanation!
Brilliant as usual, Phil!
Good stuff. You learn me more better.
love it. every single episode.
amazing video!!
So I knew from Crash Course: Big History that one day, due to the universe's expansion, our own galaxy would make up the entire observable universe. This video helped explain why, and it's amazing! Thank you for teaching all of this. I look forward to every Thursday afternoon because I know a new episode is coming out. I'll be so sad when it's over!
Great video!
Beautiful. Mindblow.
Phil Plait, both you and astronomy never cease to amaze me
This is so intriguing!
MIND. BLOWN. love it, keep entertaining me please.
i love astronomy and its damn useful seeing these crash courses thank you sir phil plait
Great job Crash Course, you've tramatized us all into thinking our 120,000,000th grandchildren won't see the night sky.
The animations are splendid !
Guh, this is always freaky to think about, but still really cool. It`s like that Star Trek TNG episode where Crusher was in the collapsing universe bubble.
i'm learning so much!
Mind Blown . . . Thank you
I like this channel. It's educational, interesting, and entertaining all at the same time.
THIS IS SO FREAKING AMAZING! 😱
You brilliantly explain things, sir.
Thanks for sharing.
there are days that I watch a bunch of crashcourse videos at once to keep up with what I haven't watched and end up with a headache lol
An ever expanding Universe, great info!
This episode blow my mind indeed!
Crashcourse channel is pretty cool, good host editing and exllent information
You are by far my favorite astrophysics presenter. What do you think about Sakar of Oxford Standard Universe model (non accelerating)?
Mind bent.
Thank You
Need more videos like this 😀
still the best crash course. fascinating and disturbing. gj phil
Thanks Phil!
so well explained
Merry Christmas PPL!
Watching in June 2020 and literally nothing's changed yet... Will be studying Astronomy for my undergrad once the pandemic gets over.
my mind is all over the wall right now, because this is mind-blowing.
Yay new episode!
Still one of the coolest videos in the series
I like your escalator analogy.