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SPEAKER_00 This is Earth.
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SPEAKER_00 You live here on this planet somewhere, and everything that you've ever known is located right here.
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SPEAKER_00 But, just how small exactly is Earth when compared to the scale of the entire universe?
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SPEAKER_00 Let's start by zooming out to where we can see our nearest cosmic neighbor, the Moon.
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SPEAKER_00 You may think that the Moon is very close to Earth since it dominates our night skies, but in reality the Moon isn't this close to our planet, it's actually about this far away.
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SPEAKER_00 384,400 kilometers away from you right now on average.
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SPEAKER_00 You could fit 30 entire Earths in between this distance, and if you somehow were able to drive a car at a constant 100 kilometers per hour speed, it would take you about 160 days to drive the entire distance.
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SPEAKER_00 Despite this incredible distance, however, 12 humans have actually set foot here, representing the furthest away that any individual human has ever been away from the Earth, and one of humanity's greatest achievements.
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SPEAKER_00 This is what the Earth would look like from there if you were standing there with them, and if you wanted to communicate with somebody back at home, it would take a message about two and a half seconds to travel between you and them, since that's how fast the speed of light can travel at.
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SPEAKER_00 This is a photo that was taken on Mars, and that tiny dot that you see there is Earth as seen from the Martian surface.
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SPEAKER_00 On average, Mars is an incredible 225 million kilometers away from Earth, but that distance can be as high as 401 million kilometers.
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SPEAKER_00 That means that whenever humanity finally gets around to landing a human on the planet, that person will be 986 times further away from Earth than the astronauts who landed on the moon were.
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SPEAKER_00 In addition, the time delay for sending a message from Mars back to Earth isn't just two and a half seconds, it's actually more like 20 minutes each direction, which would render instant communication in the event of an emergency impossible.
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SPEAKER_00 When we zoom out even further away, we can find the Voyager 1 space probe, which is the furthest away man-made object from Earth.
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SPEAKER_00 It is currently located 138 AUs from the Earth.
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SPEAKER_00 AU meaning astronomical unit, which is the distance between the Earth and the Sun.
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SPEAKER_00 Which means that Voyager 1 is 138 times further away from us than the Sun is.
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SPEAKER_00 At some point on its long voyage, Voyager 1 turned its camera around and took this photograph.
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SPEAKER_00 It may not look like much at first, but in my opinion, this is the greatest single photograph ever taken in all of human history.
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SPEAKER_00 This tiny, pale blue dot is Earth, and I don't think that anybody has ever said something as amazing about this as Carl Sagan when he said, If you look at it, you see a dot.
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SPEAKER_00 That's here.
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SPEAKER_00 That's us.
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SPEAKER_00 On it, everyone you ever heard of, every human being who ever lived, lived out their lives.
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SPEAKER_00 The aggregate of all our joys and sufferings.
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SPEAKER_00 Thousands of confident religions, ideologies, and economic doctrines.
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SPEAKER_00 Every hunter and every forager.
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SPEAKER_00 Every hero and coward.
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SPEAKER_00 Every creator and destroyer of civilizations.
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SPEAKER_00 Every king and every peasant.
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SPEAKER_00 Every young couple in love.
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SPEAKER_00 Every hopeful child.
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SPEAKER_00 Every mother and every father.
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SPEAKER_00 Every inventor and explorer.
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SPEAKER_00 Every teacher of morals.
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SPEAKER_00 Every corrupt politician.
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SPEAKER_00 Every superstar.
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SPEAKER_00 Every supreme leader.
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SPEAKER_00 Every saint and sinner in the history of our species lived there, on a moat of dust suspended in a sunbeam.
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SPEAKER_00 Voyager 1 is currently traveling at 17 kilometers every single second, but even at that speed, it won't break out of the reach of our solar system for another 30,000 years.
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SPEAKER_00 Once we go beyond the solar system, we arrive in our interstellar neighborhood.
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SPEAKER_00 Here we shift to the light year unit of measurement, which is the distance that light travels in a full Earth year, or about 9.461 trillion kilometers.
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SPEAKER_00 The star Proxima Centauri here is the closest other star to us other than our Sun, but it's still 4.24 light years away from us.
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SPEAKER_00 To put that into perspective, if it was heading in the right direction, it would still take Voyager 1 over 70,000 years to reach it.
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SPEAKER_00 In other words, if you drove your car at 100 kilometers an hour like in our previous example to the moon, it would take over six times longer than the entire age of the universe is just to finally get there, and it wouldn't even exist still when you arrived.
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SPEAKER_00 When we zoom out even further, we can see the entire Milky Way galaxy, inside of which Earth is located right here.
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SPEAKER_00 This yellow dot is the furthest extent of humanity's radio broadcasts throughout history, which means that any possible aliens who live outside of this range are totally unaware of humanity's presence.
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SPEAKER_00 It's complete silence outside of this yellow dot as far as we are currently aware, but the entire galaxy spans over 100,000 light years from end to end.
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SPEAKER_00 There are over 100 billion stars and over 100 billion planets inside of our galaxy.
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SPEAKER_00 But you have never seen the full glory of the galaxy at night, because 99% of the stars that you can see with the **** eye are limited to this small, tiny region right here.
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SPEAKER_00 But even this massive galaxy is nothing compared to the rest of what's out there.
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SPEAKER_00 Zooming out even further and we arrive at the local group of galaxies, a collection of 54 different galaxies that is about 10 million light years across.
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SPEAKER_00 But zooming out even further and we can see the Virgo Supercluster, of which the local group here is just a tiny segment of.
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SPEAKER_00 There are at least 100 other groups of galaxies just like our own local group inside of here, and the distance from one side to the other is a mind-numbing 110 million light-years.
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SPEAKER_00 But even the massive Virgo Supercluster is nothing but a quiet and tiny lobe of the great Laniakea Supercluster, an enormous structure that is home to our galaxy as well as 100,000 other galaxies.
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SPEAKER_00 The distance from one side to the other is 520 million light years, but from even there we can zoom out all the way to the entire observable universe and see that even the titanic Laniakea supercluster is just a tiny and insignificant part of everything.
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SPEAKER_00 This is the observable universe, and it contains everything that we know of.
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SPEAKER_00 It is home to at least two trillion different and individual galaxies, which together contain more stars than there are grains of sand on the entire Earth.
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SPEAKER_00 The distance from Earth to any side of the observable universe is 46.5 billion light years, which means that the entire width is 93 billion light years across.
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SPEAKER_00 What's perhaps even more interesting, however, is what actually lies beyond the observable universe.
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SPEAKER_00 Keep in mind that the observable universe is all that we can currently see, and it's entirely possible that the rest of the universe outside of it is vastly larger and more fantastic than we can possibly ever imagine.
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SPEAKER_00 We simply don't know what else is out there, because the light from these incredibly distant places has not yet had enough time in the universe's history to reach us yet back on Earth.
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SPEAKER_00 and the light from some places may never reach us at all.
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SPEAKER_00 Because some parts of space very far away from Earth are expanding away from us faster than the speed of light, that means that the light from these places will never, in an infinite amount of time, reach Earth.
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SPEAKER_00 Meaning that even if humanity is eternal and exists forever, there will still be an unknown number of places in the universe that we will never know about or ever see.
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SPEAKER_00 So, it is very likely that as unbelievably enormous as it seems, the observable universe is just a tiny slice of what we can currently see of the entire universe.
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SPEAKER_00 According to the theory of cosmic inflation that was proposed by Dr. Alan Guth,
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SPEAKER_00 If it is assumed that cosmic inflation began at 10 to the negative 37th of a second after the Big Bang, and with the assumption that the size of the universe before inflation began was equal to its age times the speed of light, then this would seem to suggest that at the present day, the entire universe is 150 sextillion years old.
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SPEAKER_00 billion times larger than the observable universe.
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SPEAKER_00 That number for reference looks like this, with this many zeros.
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SPEAKER_00 Let this number sink in for just a moment.
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SPEAKER_00 This would be similar to you thinking that the entire observable universe, everything that you could see, was the size of a lightbulb.
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SPEAKER_00 but then realizing that in reality the entire universe is larger than the former planet of Pluto.
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SPEAKER_00 Imagine a lightbulb in the center of Pluto, but we inside the lightbulb were totally unaware that Pluto existed outside of it, and that's a similar situation to this.
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SPEAKER_00 We are all so unbelievably small, but you shouldn't worry, because all that means is that there is so much left out there for us to discover together.