Andrew Connolly: What's the next window into our universe?

84,429 views ・ 2014-09-16

TED


Please double-click on the English subtitles below to play the video.

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So in 1781, an English composer,
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technologist and astronomer called William Herschel
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noticed an object on the sky that
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didn't quite move the way the rest of the stars did.
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And Herschel's recognition that something was different,
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that something wasn't quite right,
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was the discovery of a planet,
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the planet Uranus,
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a name that has entertained
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countless generations of children,
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but a planet that overnight
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doubled the size of our known solar system.
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Just last month, NASA announced the discovery
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of 517 new planets
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in orbit around nearby stars,
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almost doubling overnight the number of planets
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we know about within our galaxy.
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So astronomy is constantly being transformed by this
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capacity to collect data,
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and with data almost doubling every year,
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within the next two decades, me may even
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reach the point for the first time in history
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where we've discovered the majority of the galaxies
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within the universe.
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But as we enter this era of big data,
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what we're beginning to find is there's a difference
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between more data being just better
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and more data being different,
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capable of changing the questions we want to ask,
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and this difference is not about how much data we collect,
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it's whether those data open new windows
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into our universe,
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whether they change the way we view the sky.
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So what is the next window into our universe?
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What is the next chapter for astronomy?
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Well, I'm going to show you some of the tools and the technologies
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that we're going to develop over the next decade,
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and how these technologies,
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together with the smart use of data,
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may once again transform astronomy
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by opening up a window into our universe,
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the window of time.
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Why time? Well, time is about origins,
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and it's about evolution.
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The origins of our solar system,
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how our solar system came into being,
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is it unusual or special in any way?
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About the evolution of our universe.
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Why our universe is continuing to expand,
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and what is this mysterious dark energy
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that drives that expansion?
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But first, I want to show you how technology
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is going to change the way we view the sky.
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So imagine if you were sitting
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in the mountains of northern Chile
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looking out to the west
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towards the Pacific Ocean
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a few hours before sunrise.
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This is the view of the night sky that you would see,
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and it's a beautiful view,
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with the Milky Way just peeking out over the horizon.
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but it's also a static view,
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and in many ways, this is the way we think of our universe:
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eternal and unchanging.
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But the universe is anything but static.
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It constantly changes on timescales of seconds
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to billions of years.
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Galaxies merge, they collide
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at hundreds of thousands of miles per hour.
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Stars are born, they die,
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they explode in these extravagant displays.
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In fact, if we could go back
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to our tranquil skies above Chile,
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and we allow time to move forward
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to see how the sky might change over the next year,
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the pulsations that you see
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are supernovae, the final remnants of a dying star
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exploding, brightening and then fading from view,
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each one of these supernovae
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five billion times the brightness of our sun,
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so we can see them to great distances
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but only for a short amount of time.
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Ten supernova per second explode somewhere
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in our universe.
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If we could hear it,
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it would be popping like a bag of popcorn.
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Now, if we fade out the supernovae,
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it's not just brightness that changes.
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Our sky is in constant motion.
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This swarm of objects you see streaming across the sky
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are asteroids as they orbit our sun,
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and it's these changes and the motion
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and it's the dynamics of the system
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that allow us to build our models for our universe,
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to predict its future and to explain its past.
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But the telescopes we've used over the last decade
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are not designed to capture the data at this scale.
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The Hubble Space Telescope:
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for the last 25 years it's been producing
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some of the most detailed views
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of our distant universe,
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but if you tried to use the Hubble to create an image
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of the sky, it would take 13 million individual images,
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about 120 years to do this just once.
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So this is driving us to new technologies
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and new telescopes,
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telescopes that can go faint
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to look at the distant universe
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but also telescopes that can go wide
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to capture the sky as rapidly as possible,
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telescopes like the Large Synoptic Survey Telescope,
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or the LSST,
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possibly the most boring name ever
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for one of the most fascinating experiments
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in the history of astronomy,
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in fact proof, if you should need it,
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that you should never allow a scientist or an engineer
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to name anything, not even your children. (Laughter)
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We're building the LSST.
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We expect it to start taking data by the end of this decade.
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I'm going to show you how we think
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it's going to transform our views of the universe,
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because one image from the LSST
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is equivalent to 3,000 images
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from the Hubble Space Telescope,
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each image three and a half degrees on the sky,
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seven times the width of the full moon.
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Well, how do you capture an image at this scale?
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Well, you build the largest digital camera in history,
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using the same technology you find in the cameras in your cell phone
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or in the digital cameras you can buy in the High Street,
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but now at a scale that is five and a half feet across,
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about the size of a Volkswagen Beetle,
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where one image is three billion pixels.
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So if you wanted to look at an image
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in its full resolution, just a single LSST image,
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it would take about 1,500 high-definition TV screens.
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And this camera will image the sky,
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taking a new picture every 20 seconds,
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constantly scanning the sky
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so every three nights, we'll get a completely new view
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of the skies above Chile.
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Over the mission lifetime of this telescope,
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it will detect 40 billion stars and galaxies,
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and that will be for the first time
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we'll have detected more objects in our universe
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than people on the Earth.
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Now, we can talk about this
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in terms of terabytes and petabytes
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and billions of objects,
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but a way to get a sense of the amount of data
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that will come off this camera
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is that it's like playing every TED Talk ever recorded
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simultaneously, 24 hours a day,
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seven days a week, for 10 years.
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And to process this data means
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searching through all of those talks
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for every new idea and every new concept,
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looking at each part of the video
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to see how one frame may have changed
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from the next.
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And this is changing the way that we do science,
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changing the way that we do astronomy,
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to a place where software and algorithms
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have to mine through this data,
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where the software is as critical to the science
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as the telescopes and the cameras that we've built.
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Now, thousands of discoveries
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will come from this project,
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but I'm just going to tell you about two
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of the ideas about origins and evolution
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that may be transformed by our access
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to data at this scale.
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In the last five years, NASA has discovered
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over 1,000 planetary systems
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around nearby stars,
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but the systems we're finding
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aren't much like our own solar system,
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and one of the questions we face is
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is it just that we haven't been looking hard enough
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or is there something special or unusual
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about how our solar system formed?
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And if we want to answer that question,
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we have to know and understand
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the history of our solar system in detail,
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and it's the details that are crucial.
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So now, if we look back at the sky,
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at our asteroids that were streaming across the sky,
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these asteroids are like the debris of our solar system.
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The positions of the asteroids
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are like a fingerprint of an earlier time
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when the orbits of Neptune and Jupiter
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were much closer to the sun,
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and as these giant planets migrated through our solar system,
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they were scattering the asteroids in their wake.
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So studying the asteroids
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is like performing forensics,
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performing forensics on our solar system,
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but to do this, we need distance,
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and we get the distance from the motion,
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and we get the motion because of our access to time.
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So what does this tell us?
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Well, if you look at the little yellow asteroids
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flitting across the screen,
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these are the asteroids that are moving fastest,
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because they're closest to us, closest to Earth.
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These are the asteroids we may one day
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send spacecraft to, to mine them for minerals,
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but they're also the asteroids that may one day
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impact the Earth,
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like happened 60 million years ago
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with the extinction of the dinosaurs,
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or just at the beginning of the last century,
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when an asteroid wiped out
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almost 1,000 square miles of Siberian forest,
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or even just last year, as one burnt up over Russia,
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releasing the energy of a small nuclear bomb.
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So studying the forensics of our solar system
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doesn't just tell us about the past,
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it can also predict the future, including our future.
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Now when we get distance,
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we get to see the asteroids in their natural habitat,
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in orbit around the sun.
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So every point in this visualization that you can see
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is a real asteroid.
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Its orbit has been calculated from its motion across the sky.
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The colors reflect the composition of these asteroids,
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dry and stony in the center,
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water-rich and primitive towards the edge,
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water-rich asteroids which may have seeded
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the oceans and the seas that we find on our planet
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when they bombarded the Earth at an earlier time.
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Because the LSST will be able to go faint
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and not just wide,
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we will be able to see these asteroids
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far beyond the inner part of our solar system,
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to asteroids beyond the orbits of Neptune and Mars,
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to comets and asteroids that may exist
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almost a light year from our sun.
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And as we increase the detail of this picture,
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increasing the detail by factors of 10 to 100,
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we will be able to answer questions such as,
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is there evidence for planets outside the orbit of Neptune,
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to find Earth-impacting asteroids
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long before they're a danger,
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and to find out whether, maybe,
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our sun formed on its own or in a cluster of stars,
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and maybe it's this sun's stellar siblings
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that influenced the formation of our solar system,
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and maybe that's one of the reasons why solar systems like ours seem to be so rare.
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Now, distance and changes in our universe —
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distance equates to time,
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as well as changes on the sky.
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Every foot of distance you look away,
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or every foot of distance an object is away,
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you're looking back about a billionth of a second in time,
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and this idea or this notion of looking back in time
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has revolutionized our ideas about the universe,
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not once but multiple times.
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The first time was in 1929,
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when an astronomer called Edwin Hubble
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showed that the universe was expanding,
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leading to the ideas of the Big Bang.
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And the observations were simple:
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just 24 galaxies
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and a hand-drawn picture.
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But just the idea that the more distant a galaxy,
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the faster it was receding,
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was enough to give rise to modern cosmology.
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A second revolution happened 70 years later,
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when two groups of astronomers showed
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that the universe wasn't just expanding,
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it was accelerating,
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a surprise like throwing up a ball into the sky
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and finding out the higher that it gets,
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the faster it moves away.
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And they showed this
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by measuring the brightness of supernovae,
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and how the brightness of the supernovae
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got fainter with distance.
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And these observations were more complex.
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They required new technologies and new telescopes,
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because the supernovae were in galaxies
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that were 2,000 times more distant
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than the ones used by Hubble.
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And it took three years to find just 42 supernovae,
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because a supernova only explodes
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once every hundred years within a galaxy.
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Three years to find 42 supernovae
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by searching through tens of thousands of galaxies.
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And once they'd collected their data,
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this is what they found.
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Now, this may not look impressive,
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but this is what a revolution in physics looks like:
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a line predicting the brightness of a supernova
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11 billion light years away,
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and a handful of points that don't quite fit that line.
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Small changes give rise to big consequences.
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Small changes allow us to make discoveries,
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like the planet found by Herschel.
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Small changes turn our understanding
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of the universe on its head.
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So 42 supernovae, slightly too faint,
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meaning slightly further away,
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requiring that a universe must not just be expanding,
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but this expansion must be accelerating,
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revealing a component of our universe
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which we now call dark energy,
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a component that drives this expansion
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and makes up 68 percent of the energy budget
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of our universe today.
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So what is the next revolution likely to be?
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Well, what is dark energy and why does it exist?
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Each of these lines shows a different model
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for what dark energy might be,
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showing the properties of dark energy.
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They all are consistent with the 42 points,
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but the ideas behind these lines
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are dramatically different.
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Some people think about a dark energy
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that changes with time,
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or whether the properties of the dark energy
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are different depending on where you look on the sky.
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Others make differences and changes
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to the physics at the sub-atomic level.
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Or, they look at large scales
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and change how gravity and general relativity work,
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or they say our universe is just one of many,
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part of this mysterious multiverse,
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but all of these ideas, all of these theories,
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amazing and admittedly some of them a little crazy,
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but all of them consistent with our 42 points.
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So how can we hope to make sense of this
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over the next decade?
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Well, imagine if I gave you a pair of dice,
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and I said you wanted to see whether those dice
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14:54
were loaded or fair.
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14:56
One roll of the dice would tell you very little,
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but the more times you rolled them,
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the more data you collected,
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the more confident you would become,
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not just whether they're loaded or fair,
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but by how much, and in what way.
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15:12
It took three years to find just 42 supernovae
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15:16
because the telescopes that we built
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15:19
could only survey a small part of the sky.
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With the LSST, we get a completely new view
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of the skies above Chile every three nights.
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15:29
In its first night of operation,
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it will find 10 times the number of supernovae
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15:34
used in the discovery of dark energy.
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15:37
This will increase by 1,000
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15:39
within the first four months:
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15:42
1.5 million supernovae by the end of its survey,
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15:46
each supernova a roll of the dice,
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15:50
each supernova testing which theories of dark energy
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15:53
are consistent, and which ones are not.
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15:57
And so, by combining these supernova data
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16:01
with other measures of cosmology,
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16:03
we'll progressively rule out the different ideas
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16:06
and theories of dark energy
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16:08
until hopefully at the end of this survey around 2030,
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16:15
we would expect to hopefully see
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16:18
a theory for our universe,
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16:20
a fundamental theory for the physics of our universe,
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16:23
to gradually emerge.
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16:26
Now, in many ways, the questions that I posed
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16:29
are in reality the simplest of questions.
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We may not know the answers,
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16:35
but we at least know how to ask the questions.
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16:39
But if looking through tens of thousands of galaxies
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16:42
revealed 42 supernovae that turned
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2938
16:45
our understanding of the universe on its head,
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16:48
when we're working with billions of galaxies,
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16:51
how many more times are we going to find
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16:53
42 points that don't quite match what we expect?
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16:59
Like the planet found by Herschel
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17:01
or dark energy
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17:04
or quantum mechanics or general relativity,
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17:08
all ideas that came because the data
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17:10
didn't quite match what we expected.
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17:13
What's so exciting about the next decade of data
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17:17
in astronomy is,
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17:18
we don't even know how many answers
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17:21
are out there waiting,
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17:22
answers about our origins and our evolution.
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17:26
How many answers are out there
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17:27
that we don't even know the questions
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17:31
that we want to ask?
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17:33
Thank you.
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17:35
(Applause)
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