Intergalactic Scale Intergalactic Scale
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- Where we left off in the last video, we were just kind of staring,
- amazed at this Earth's view of the Milky Way Galaxy,
- just making sure we understood how enormous and how many stars we were looking at
- and even this, even if each of these dots were stars this is a huge amount of stars
- but a lot of these dots are thousands of stars, are thousands of stars, so, so this
- our minds were already blown but what we're going to see in this video
- in some ways this is kind of just the beginning. And to some I am going to stop doing the particles of
- grain in the football field analogy, because at some point the particles of sand become so vast that our
- mind cannot even grasp it to begin with, but let's just start with our Milky Way
- and we saw in the last video the Milky Way right here - we're sitting here about 25,000 lightyears away from
- the center, it's roughly 100,000 light years in diameter, and then let's put it in perspective
- of its local neighborhood, so let's look at the local group,
- and when we talk about local group we're talking about the local group of galaxies
- of galaxies. so this right here is the Milky Way's local group, that's us right there
- sitting right over here about 25,000 light years from the center of the Milky Way
- you have some of these small, and I use the word "small" in quotation marks because these are also vast
- entities also unimaginable entities but we have these satellite galaxies
- around under the gravitational influence some of them, of the Milky Way, but the nearest large galaxy
- to us is Andromeda right over here, and this distance right over here and now were going to start talking
- in the millions of light years so this distance right here is 2.5 million, 2.5 millon light years just
- as a bit of reference if that's any reference at all 1 light year is roughly the radius of the Oort cloud
- and the Oort cloud was, or another way to think about it, the Oort cloud or one radius of the Oort cloud
- is about 50 or 60 thousand astronomical units and that's the distance from the Sun to the Earth, so you could view
- this as 2.5 million times 60,000 times the distance from the Sun to the Earth so this is an unbelievably
- large distance we're talking about here and that's to get to the next big galaxy over here
- but even these things are huge things with many, i mean just unfathomably many stars, but Andromeda in
- particular you, you know we said that the Milky Way 200-400 billion stars
- Andromeda people believe has on the order of 1 trillion stars, even these just start to become numbers
- its hard to grasp, but were not going to stop here so in this, over here this whole diagram over here
- its about 4 lightyears across if you go point to point if you go from one side to the other side
- this is about... not 4 light years, sorry, this is 4 million light years... 4 million...
- 4 light years is just the distance from us to the Alpha Centauri, so that's nothing,
- that would only take Voyager 1 80,000 years to get to.
- This is 4 million light years, so 4 million times the distance to the nearest star.
- But even this, even this is... I'm starting to stumble on my words, there are no words to describe this,
- even this is small on an intergalactic scale,
- because when you zoom out more, you can see our local group - it's right over here
- and this right over here is the Virgo Supercluster,
- and each dot here is at least one galaxy, but it might be more than one galaxy,
- and the diameter here is 150 million... 150 million light years.
- So what we so in the local group in the last diagram, the distance from the Milky Way to Andromeda,
- which was 2.5 million light years, which would be just this litte dot,
- just like that, that would be the distance between the Milky Way and the Andromeda.
- And now we're looking at the Virgo Supercluster, and that is 150 million light years
- but we're not done yet, we can zoom out even more! We can zoom out even more... and over here,
- so you had the Virgo Supercluster, 150 million light years, in the last diagram,
- this diagram here, I'd like to keep both of them on the screen if I can, this diagram
- right here, 150 million light years across, that would fit right about here, on this diagram.
- So this is all of the superclusters that are near us, and once again, near has to be used very loosely,
- here, this distance is about 150 million light years, a billion light years is 2... 3... 4... 5...
- a billion lightyears is about from here to there, so we start to talk on very massive... I guess we've
- always been talking on a massive scale, but now it's an even more massive scale. We're still not done!
- Because this whole diagram, these dots that you're seeing now, I wanna make it very clear,
- these aren'r stars, these aren' even clusters of stars, or clusters of millions or billions of stars,
- each of these dots are clusters of galaxies, each of those galaxies having
- hundreds of billions to trillions of stars, so we're just at an unbelievably massive scale at this point,
- but we're still not done, this is roughly about a billion light years across,
- right here is actually the best estimate of the visible universe, and in future videos
- we will talk a lot more about what the visible universe means,
- so if you zoom out enough, this entire diagram right here,
- about a billion light years, would fit right over... would fit just like that.
- So we're talking about a super small amount of this part right here...
- and this is just the visible universe, I wanna make it clear, this is not
- the entire universe, and we say the visible universe, 'cause think about what's happening,
- think about a point out here, and we're observing it, let's say, it's 13 billion light years away,
- we're gonna talk more about this in future videos, 13 billion light years,
- and I feel it's almost a sacrilage to be writing on this,
- because this complexity that we're seeing here is just mindboggling,
- but this 13 billion lightyear away object, we're observing... the light's just getting to us....
- the light left at some point, 13 billion lightyears ago, so we're actually observing this object
- close to the beginning of the actual universe, and the reason why it's the visible universe
- is there might have been something a little bit further out, maybe it's light hasn't reached us yet,
- or maybe the universe itself, we'll talk more about this, is expanding so fast
- that the light will never ever reach us, so it's actually a huge question mark,
- on how big the actual universe is, and then some people might say
- well, does it even matter? - because this by itself is a huge, huge distance,
- and I wanna make it clear, you might say, OK, if this light over here
- this is coming from 13 billion light years away, or this is 13 billion light years away,
- then you could say, hey, so everything that we could observe, that we can observe the past of,
- is about 26 billion light years, but even there we have to be careful,
- 'cause remember, the universe is expanding: when this light was emitted,
- and I'll do a whole video on this, because the geometry of it is kind of hard to visualize,
- when this light was emitted, where we are, in the Virgo Supercluster,
- inside of the Milky Way galaxy, where we are was much closer to that point,
- it was on the order of, and I wanna make sure I get this right,
- 36 million light years, so we were super close by, you know, astronomical scales,
- we were super close only 36 million light years to this object when that light was released,
- but that light was coming to us and the whole time the universe expanding, so we were
- also moving away from it, if you just think about it, all the space, everything
- is expanding away from each other, and only 13 billion years later
- did it finally catch up with us. But the whole time it was happening,
- this object has also been moving away from us, so our best estimate of where this object is now
- based on how space is expanding, is on the order of 40 or 45 billon light years away.
- We are just observing where that light was emitted 13 billion years ago. I wanna be very clear,
- what we are observing, this light is coming from something very primitive,
- that object, that area of space where that light was emitted from,
- has now condensed into way more mature astronomical structures,
- if you take it from the other point of view, people sitting in this point of space now
- and now they've moved 46 billion light years out, when they observe our region of space,
- they're not going to see us, they are not gonna see Earth as it is now,
- they're gonna see the region of space where Earth is, at a super primitive stage,
- shortly after the Big Bang - when I use words like 'shortly', I use that also loosely,
- we're talking about hundreds of thousands or even millions of years,
- so I'll talk more about that in a future video, but the whole point of this video is
- you know, it's beyond mind numbing, you know, I would say the last video about the Milky Way
- that alone was mind numbing, but now we are in a reality where
- just the Milky Way becomes something that's almost unbelievably insignificant
- when you think about this picture right here. And the really mind numbing thing is,
- if someone told me that this is the entire universe, this by itself would certainly
- put things in perspective, but it is unknown what's beyond it! There are some estimates
- that this might be only one times 10th on the 23rd of the entire universe
- and it might even turn out that the entire universe is smaller than this
- and that's an interesting thing to think about, but I'll leave you there,
- because I think no matter how you think about it, it's just, I don't know,
- actually before doing this video I stared at some of these photos for like half an hour,
- this is my least productive day, just because it's so awe-inspiring to think about
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