1 00:00:01,184 --> 00:00:03,981 In the last video I hinted that things were about to get wacky, 2 00:00:03,981 --> 00:00:08,707 and they are! So if we start where we left off in the last video, 3 00:00:08,707 --> 00:00:10,937 we started right over here, looking at the distance 4 00:00:10,937 --> 00:00:13,677 to the nearest star and, just a reminder 5 00:00:15,976 --> 00:00:18,259 in this drawing right here this depiction right here this circle right here 6 00:00:18,274 --> 00:00:22,639 this solar system circle, its not the size of the sun, its not the size 7 00:00:25,634 --> 00:00:28,630 of the orbits of the Earth or Pluto or the Kuiper belt this is close 8 00:00:28,630 --> 00:00:34,203 to the size of the Oort cloud. The actual orbit of earth is 9 00:00:34,203 --> 00:00:37,686 about one, well the diameter of the orbit of earth is about one 10 00:00:37,686 --> 00:00:42,051 fifty thousandth of this so you wouldn't even see it on this. it wouldn't even make 11 00:00:42,051 --> 00:00:47,299 up a pixel on this screen right here, much less the actual size 12 00:00:47,299 --> 00:00:48,467 of the sun or something much smaller. 13 00:00:48,467 --> 00:00:53,383 And just remember that orbit of the earth that was at a huge distance. It takes 14 00:00:53,383 --> 00:00:59,048 8 mins for light to get from the sun to the earth. It's a super long distance. 15 00:00:59,048 --> 00:01:05,133 If you shot a bullet at the sun from earth, it would take you 17 years to get to the sun. 16 00:01:05,133 --> 00:01:09,544 So this huge distance wouldnt even show up on this picture. 17 00:01:09,544 --> 00:01:14,048 Now what we saw in the last video is that if you travel at unimaginably fast speeds, 18 00:01:14,048 --> 00:01:21,711 if you travel at 60,000 km/h, and I picked that speed 'cause that's how fast 19 00:01:21,711 --> 00:01:24,219 Voyager 1 actually is travelling 20 00:01:24,219 --> 00:01:27,702 that's one of the fastest, I think one of the fastest objects we have 21 00:01:27,702 --> 00:01:31,278 out there in space, right here, and is actually kind of leaving the solar system 22 00:01:31,278 --> 00:01:35,271 as we speak. But even if you were able to get that fast, 23 00:01:35,271 --> 00:01:44,049 it would still take 80,000 years, 75 or 80,000 years to travel the 24 00:01:44,049 --> 00:01:48,971 4.2 light years to the Alpha Centauri cluster of stars. To the nearest star, 25 00:01:48,971 --> 00:01:54,219 it would take 80,000 years, 80,000 years. 26 00:01:54,219 --> 00:01:58,677 And that scale of time is already an amount of time I have trouble comprehending 27 00:01:58,677 --> 00:02:04,621 You can imagine all of modern civilization has occured definitely in the last 10,000 yrs 28 00:02:04,621 --> 00:02:08,383 but most of recorded history is in the last 4 or 5000 years. 29 00:02:08,383 --> 00:02:12,609 So this is 80,000 years to travel to the nearest star. 30 00:02:12,609 --> 00:02:13,677 So its a huge distance. 31 00:02:13,677 --> 00:02:16,046 Another way to think about it, is that if the sun 32 00:02:16,046 --> 00:02:22,965 were the size of a basketball and you put that basketball in London, 33 00:02:22,965 --> 00:02:26,866 if you wanted to do it in scale, the next closest star which is actually a smaller 34 00:02:26,866 --> 00:02:33,368 basketball right over here, Proxima Centauri, that smaller basketball you'd have to put 35 00:02:33,368 --> 00:02:39,067 in Kiev, Ukraine. in order to have a similiar scale. 36 00:02:39,067 --> 00:02:41,959 So these are basketballs, sitting in these cities and you would have 37 00:02:41,959 --> 00:02:44,374 to travel about 1200 miles 38 00:02:44,374 --> 00:02:49,390 to place the next basketball. and these basketballs are representing these super huge things 39 00:02:49,390 --> 00:02:52,873 that we saw in the first video, the Sun. If you actually made the earth 40 00:02:52,873 --> 00:02:56,030 relative to these basketballs, these would be little grains of sand 41 00:02:56,030 --> 00:03:00,733 so if there are any little small planets over here they would have to be grains 42 00:03:00,733 --> 00:03:05,272 of sand in Kiev, Ukraine versus the grain of sand in London. 43 00:03:05,272 --> 00:03:10,705 So this is a massive, massive distance. Already, at least in my mind, unimaginable. And when it gets 44 00:03:10,705 --> 00:03:14,606 really whacky is when you start realising that this, even this, is a super 45 00:03:14,606 --> 00:03:19,018 super small distance relative to the galactic scale. 46 00:03:19,018 --> 00:03:23,709 So this whole depiction of kind of our neighborhood of stars this thing over here 47 00:03:23,709 --> 00:03:32,346 is about, give or take, and we're doing rough estimates right here 48 00:03:32,346 --> 00:03:40,381 its about 30 light years. I'll just do LY for short. So thats abt 30 LY 49 00:03:40,381 --> 00:03:45,350 Now and once again you cannot actually, you can take pictures of our galaxy 50 00:03:45,350 --> 00:03:49,018 from our point of view but you actually can't take a picture of the whole galaxy from above it. 51 00:03:49,018 --> 00:03:52,687 So these are going to be artist depictions, but if this is 30 LY 52 00:03:52,687 --> 00:03:58,028 This drawing right here of kind of our local neighborhood of the galxy 53 00:03:58,028 --> 00:04:03,693 this right here is roughly, these are all approximations, this is about 54 00:04:03,693 --> 00:04:13,353 let me do this in a darker color, this about 1 thousand LY 55 00:04:13,353 --> 00:04:17,718 and this is the 1000 LY of our suns neighborhood if you can even call it a neighborhood 56 00:04:17,718 --> 00:04:21,619 even this isn't really a neighborhoood if it takes you 80,000 yrs to get to your nearest neighbor 57 00:04:21,619 --> 00:04:26,031 but this whole drawing over here it would take forever to get anywhere over here 58 00:04:26,031 --> 00:04:32,733 it would be 1/30th of this so it would be about that big 59 00:04:32,733 --> 00:04:36,016 this whole drawing and what's really going to blow your mind is 60 00:04:36,016 --> 00:04:40,288 this would be roughly a little bit more than a pixel on this drawing right here 61 00:04:40,288 --> 00:04:44,282 that spans a 1000 LY but then when you start to really put it into 62 00:04:44,282 --> 00:04:48,879 perspective so new lets zoom out a little bit. So this drawing right here 63 00:04:48,879 --> 00:04:55,381 this 1000 LY is now this 1000 LY over here. so this is our local vicinity of the sun 64 00:04:55,381 --> 00:04:59,375 and once again the word local is used in a very liberal way 65 00:04:59,375 --> 00:05:00,675 at this point 66 00:05:00,675 --> 00:05:03,369 so this right here is a 1000 ly 67 00:05:03,369 --> 00:05:11,681 if your sitting here and your looking at an object that is sitting (let me do this in a darker color) 68 00:05:11,681 --> 00:05:14,700 if we're sitting here on earth and we're looking at an object sitting here 69 00:05:14,700 --> 00:05:20,366 that's 500 LY away we're looking at it as it was 500 years ago 70 00:05:20,366 --> 00:05:25,706 becasue the light that is reaching our eyeballs right now or our telescopes 71 00:05:25,706 --> 00:05:33,044 right now left this guy over here 500 yrs ago. in fact he's not even going to be there anymore 72 00:05:33,044 --> 00:05:37,363 he'll probably have moved around a little bit. So just even on this scale, we're alredy 73 00:05:37,363 --> 00:05:41,357 talking abt these unimaginably huge distances and then when we zoom out 74 00:05:41,357 --> 00:05:47,208 this is kind of like our local part of the galaxy over here. This piece right here 75 00:05:47,208 --> 00:05:51,016 this is called the Orion Spur and people are still trying to work out 76 00:05:51,016 --> 00:05:58,354 exactly what the actual details of the actual shape of the milky way galaxy is 77 00:05:58,354 --> 00:06:03,044 the galaxy that we're in but we're pretty sure we have these spiral arms 78 00:06:03,044 --> 00:06:06,620 and we have these spurs off of them, but its actually very hard to come up with the actual shape 79 00:06:06,620 --> 00:06:10,614 especally because you can't see a lot of the galaxy because it's kinda on the other side, 80 00:06:10,614 --> 00:06:12,378 on the other side of the centre 81 00:06:12,378 --> 00:06:16,883 but really just to get a sense, I mean at least it blows my mind if you really 82 00:06:19,508 --> 00:06:22,133 think about what it saying these unbeleivable distances show up as a lil dot here 83 00:06:22,133 --> 00:06:26,635 this whole drawing shows up as a dot here. now when we zoom out over here 84 00:06:26,635 --> 00:06:28,632 that dot would no longer even show up 85 00:06:28,632 --> 00:06:32,208 it wouldn't even register a pixel on this drawing right over here 86 00:06:32,208 --> 00:06:36,341 and then this drawing this whole thing right over here 87 00:06:36,341 --> 00:06:47,067 this whole pic is this grid is this grid right over here it is this right over here 88 00:06:47,067 --> 00:06:52,967 so hopefully that gives you a sense of how small even our local neighborhood 89 00:06:52,967 --> 00:06:55,939 is relative to THE galaxy as a whole 90 00:06:55,939 --> 00:07:00,629 the galaxy as a whole just to give you a sense has 200, 91 00:07:00,629 --> 00:07:05,273 200-400 billion stars 92 00:07:05,273 --> 00:07:11,357 or maybe i should say solar systems just to give you a sense that you know 93 00:07:11,357 --> 00:07:13,029 when we saw the solar system its not just the sun 94 00:07:13,029 --> 00:07:17,719 its all this neat dynamic stuff in there, planets and asteroids 95 00:07:17,719 --> 00:07:22,549 and solar winds and so there's 200 to 400 billion stars 96 00:07:22,549 --> 00:07:27,425 and for the most part 200 to 400 billion solar systems so its and 97 00:07:27,425 --> 00:07:35,000 unimaginably complex or huge place 98 00:07:35,000 --> 00:07:39,221 and just to make it clear you know even when we zoom into this pic right here 99 00:07:39,221 --> 00:07:44,376 and i think its obvious based on this that these lil white pockets right here 100 00:07:44,376 --> 00:07:48,695 these aren't this isn't one star this isn't two stars these are thousands of stars 101 00:07:48,695 --> 00:07:49,949 here so when you go over here 102 00:07:49,949 --> 00:07:54,546 each little blotch of white that you see that's not a star that's not a thousand stars 103 00:07:54,546 --> 00:07:59,376 we're starting to talk in the millions of stars when you look at certain blotches here and there 104 00:07:59,376 --> 00:08:02,023 i mean it maybe one star that closer to you or it might be a million 105 00:08:02,023 --> 00:08:04,949 stars that are far apart and that are just relatively close 106 00:08:04,949 --> 00:08:08,014 together and eveything has to be used in kind of 107 00:08:08,014 --> 00:08:11,218 loose terms here. And we'll talk more about other galaxies 108 00:08:11,218 --> 00:08:14,051 but even this isn't the upper bound of galaxies 109 00:08:14,051 --> 00:08:17,209 people believe the Andromeda Galaxy has a trillion stars in it 110 00:08:17,209 --> 00:08:19,345 a trillion sources and we're talking about these huge 111 00:08:19,345 --> 00:08:22,549 huge immense distances and so just to give you a sense 112 00:08:22,549 --> 00:08:27,286 of where we fit in the picture this is a rough location of our sun 113 00:08:27,286 --> 00:08:29,376 and remember that lil dot i drew just now 114 00:08:29,376 --> 00:08:32,952 is including millions of stars, millions of solar systems 115 00:08:32,952 --> 00:08:37,039 already unimaginable distances but if you really wanna get the sense 116 00:08:37,039 --> 00:08:41,033 relative to the whole galaxy, this is an artist's depiction 117 00:08:41,033 --> 00:08:44,701 once again we could never obviously get this perspective on the galaxy 118 00:08:44,701 --> 00:08:46,048 it would take forever to travel this far 119 00:08:46,048 --> 00:08:49,624 so that you could see the galaxy from above but this is our best guess 120 00:08:49,624 --> 00:08:53,432 looking at things from our vantage point we actually could never even see 121 00:08:53,432 --> 00:08:56,358 we actually can't even see this whole area over here 122 00:08:56,358 --> 00:09:00,026 'cause it's on the other side of the centre of the galaxy which is super super 123 00:09:00,026 --> 00:09:03,695 dense and super bright and so its very hard to see things on the other side 124 00:09:03,695 --> 00:09:09,036 we think or actually there's a super massive black hole at the centre of the galaxy 125 00:09:09,036 --> 00:09:12,426 and we think that they're at the centre of all or most galaxies 126 00:09:12,426 --> 00:09:15,352 but you know the whole pint of this video or actually this whole series of videos 127 00:09:15,352 --> 00:09:22,133 is just to put you in awe a lil bit of just how huge this is 128 00:09:22,133 --> 00:09:27,008 'cause when you think about the scales it's just, i dunno no, words can reallly describe it 129 00:09:27,008 --> 00:09:39,640 but just to give you sense we're about 25000LY from the centre of 130 00:09:39,640 --> 00:09:44,887 the galaxy so even when we look at things at the centre of the galaxy that's how they 131 00:09:44,887 --> 00:09:47,117 were 25000 yrs ago 132 00:09:47,117 --> 00:09:51,621 it took 25000 yrs for that light to get to us, I mean when that light left the centre 133 00:09:51,621 --> 00:09:55,104 of the galaxy I won't even guess to think what 134 00:09:55,104 --> 00:09:58,680 humanity was like at that point in time 135 00:09:58,680 --> 00:10:02,349 so its these huge distances and the whole galaxy of here 136 00:10:02,349 --> 00:10:06,621 and like solar systems its hard to say the edge of the galaxy 137 00:10:06,621 --> 00:10:10,104 'cause there's always gonna be a few more stars and other things orbiting 138 00:10:10,104 --> 00:10:13,030 around the galaxy as you go further and further out but the main 139 00:10:13,030 --> 00:10:23,340 density the main disc is about 100,000LY 140 00:10:23,340 --> 00:10:28,959 is the diameter roughly of the main part of the galaxy and it's about a 1000 LY thick 141 00:10:28,959 --> 00:10:31,699 so you kind of imagine it as a disc its fairly flat 142 00:10:31,699 --> 00:10:40,733 but its a 1000 LY thick! It's a 1000 LY thick you would have to do this distance 143 00:10:40,733 --> 00:10:45,956 250 times just to go from the top part of the galaxy to the bottom part 144 00:10:45,956 --> 00:10:47,721 much less going across the galxy 145 00:10:47,721 --> 00:10:51,204 so it might sem relatively flat but it's still immensely 146 00:10:51,204 --> 00:10:55,012 immensely thick. and just as another way to visualise it 147 00:10:55,012 --> 00:10:58,355 if this thing right over here that includes the Oort cloud 148 00:10:58,355 --> 00:11:06,622 roughly a LY in diameter it is a grain of sand 149 00:11:06,622 --> 00:11:10,105 a mm in diameter grain of sand 150 00:11:10,105 --> 00:11:14,284 then the universe as a whole is gonna be the diameter of a football field 151 00:11:14,284 --> 00:11:19,764 and those are two tractable things, i can imagine a grain of sand 152 00:11:19,764 --> 00:11:25,337 a mm wide grain of sand in a football field. but remember that's a grain sand 153 00:11:25,337 --> 00:11:34,950 that grain of sand is still 50 or 60, 000 times the diameter of the Earth's orbit 154 00:11:34,950 --> 00:11:39,467 and it would still take a bullet or something travelling as fast as a jet plane 155 00:11:39,467 --> 00:11:46,003 15 hrs to just go half of that or sorry 15 yrs or 17 yrs I forgot 156 00:11:46,003 --> 00:11:51,297 the exact number but you knpw 15, 16 , 17 yrs to even cover half of that distance 157 00:11:51,297 --> 00:11:56,777 30 yrs to cover an entire diamtere, so 30 yrs to cover the entire diameter 158 00:11:56,777 --> 00:12:03,696 of earths orbit tahts one 60,000th of our lil grain of sand in the football field 159 00:12:03,696 --> 00:12:12,381 and just to kind of really i dunno have an appreciation for how amaz- i dunno how mind blowing this 160 00:12:12,381 --> 00:12:15,956 really is , this is a picture of the milky way galaxy, our galaxy 161 00:12:15,956 --> 00:12:20,043 from our vantage point as you can see we're in the galaxy so we're 162 00:12:20,043 --> 00:12:22,087 seeing and this is looking towards the centre and 163 00:12:22,087 --> 00:12:25,755 even this picture you start to appreciate the complexity of what a 100 164 00:12:25,755 --> 00:12:31,003 billion stars are but what i really wanna point out is that even in this pic 165 00:12:31,003 --> 00:12:33,789 when yu're looking at some of these things that are like stars 166 00:12:33,789 --> 00:12:39,037 those arent stars! those are thousands of stars or millions of stars 167 00:12:39,037 --> 00:12:41,777 maybe it could be one star closer up but when we're startin 168 00:12:41,777 --> 00:12:43,449 to approach the centre of the galaxy these are thousands 169 00:12:43,449 --> 00:12:46,793 and thousands and millions of stars or solar systems 170 00:12:46,793 --> 00:12:49,765 that we're actually looking at so its really, it starts to 171 00:12:49,765 --> 99:59:59,999 boggle the mind to imagine what might actually be going on over there.