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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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were loaded or fair.

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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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It took three years to find just 42 supernovae

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because the telescopes that we built

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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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In its first night of operation,

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it will find 10 times the number of supernovae

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used in the discovery of dark energy.

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This will increase by 1,000

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within the first four months:

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1.5 million supernovae by the end of its survey,

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each supernova a roll of the dice,

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each supernova testing which theories of dark energy

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are consistent, and which ones are not.

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And so, by combining these supernova data

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with other measures of cosmology,

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we'll progressively rule out the different ideas

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and theories of dark energy

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until hopefully at the end of this survey around 2030,

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we would expect to hopefully see

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a theory for our universe,

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a fundamental theory for the physics of our universe,

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to gradually emerge.

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Now, in many ways, the questions that I posed

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are in reality the simplest of questions.

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We may not know the answers,

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but we at least know how to ask the questions.

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But if looking through tens of thousands of galaxies

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revealed 42 supernovae that turned

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our understanding of the universe on its head,

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when we're working with billions of galaxies,

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how many more times are we going to find

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42 points that don't quite match what we expect?

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Like the planet found by Herschel

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or dark energy

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or quantum mechanics or general relativity,

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all ideas that came because the data

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didn't quite match what we expected.

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What's so exciting about the next decade of data

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in astronomy is,

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we don't even know how many answers

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are out there waiting,

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answers about our origins and our evolution.

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How many answers are out there

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that we don't even know the questions

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that we want to ask?

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Thank you.

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(Applause)