 My name is Emma Chapman, and I'm a Royal Society Dorothy Hodgkin Fellow and Astrophysicist. As a teenager, I was fascinated with all things ancient and I wanted to be an Egyptologist. Then I came across a book explaining special relativity, saying that time travel wasn't impossible, and that the faster you move through space, the slower you age. I was instantly captivated and thought I have to study this. Fast forward to today, and I study the early universe. So let's start at the very beginning. About 13.8 billion years ago, our universe started with a big bang. This is not an explosion, as we know it, but the emergence and expansion of space-time itself. After a few seconds of exponential expansion, the universe began to cool and the matter within it began to spread out into a smooth cloud of gas. Let's pause and give ourselves a sense of proportion. Carl Sagan came up with the idea of thinking of the universe's timeline across one year. With the big bang starting the year, and us cheering New Year's Eve one year later. Using this scale, the universe slowed and cooled for the first few days of January. The first stars formed on the 5th of January, and the first galaxies formed on the 9th. But the thin disk of the Milky Way galaxy didn't form until May. Our solar system and Earth formed in September. Dinosaurs evolved on the 25th of December, and were already extinct by the 30th. The first known cave paintings date from 90 seconds to midnight on New Year's Eve, and the pyramids were built only 12 seconds ago. There is one period in this whole history that we know incredibly little about, almost nothing, the Dark Ages. These lasted from about 380,000 years after the big bang, to about 180 million years after the big bang. The only elements present were hydrogen and helium, and it was a time of incredible darkness and cold. But behind the scenes there was a different kind of matter at work, dark matter. Dark matter spread through the universe, making a web, which drew in the hydrogen gas such that the gas traced this web almost perfectly. And then finally the hydrogen gas itself collapsed under its own gravity in the densest patches, and the first stars blazed into existence. My work explores the creation, lives and deaths of the first stars. We call these population 3 stars, and they were the fundamental cosmic factories that fused the hydrogen and helium into heavier elements such as the carbon that we're made of. These stars cannot physically form in our modern polluted universe, and so they're likely to be an extinct species. These first stars were very different from any stars that we see around us today. First, they were hot. Our sun is 5,000 to 8,000 Kelvin, whereas these were around 100,000 Kelvin on the surface. They were massive as well. Our simulations indicate they were generally 10 to 100 times more massive than our sun. They died in an instant. A population 3 proto-stars life was on the scale of 100 or so million years, a blink of an eye compared to our sun's 10 billion year lifetime. To relate this to our cosmic year, the first stars would die only three days after formation, compared to our sun, which would live a whole eight months. When these first stars died in supernovae, the explosion threw heavy elements out into the surrounding gas, which in turn cooled and reformed into fundamentally different population 2 stars. To study this period, we must look back in time. We're only able to do this because we have telescopes that can look really far away. The thing with light is that it takes time to travel. So, for example, the sunlight that's hitting us right now left the sun a whole eight minutes ago. And if, for example, there were an alien species on our nearest neighbour galaxy, Andromeda, and they were pointing a telescope at us today, they wouldn't be seeing us, they'd be seeing the earliest ancestors of the human race. The further we look back in space-time, the more the light we observe has been stretched by the expansion of the universe. Visible light telescopes and infrared telescopes have limits on how far they can see back. So to look at the very earliest events in the universe, we need to look at the longest wavelengths, the radio. But stars aren't normally that loud in the radio frequencies, so how can we hope to observe some of the farthest and faintest light in our universe? Well, we look instead to the effect those stars have on the environment. The first stars burned bubbles in the surrounding hydrogen gas, and the size and shape of these bubbles can tell us a lot about these stars. In 1957, the Lovell Telescope was built at JoJo Bank. At the time, it was the largest steerable radio dish in the world, and it still holds the title for third place even now, and that's because there's an engineering limit to how big you can build these dishes before they simply collapse. A really useful aspect of radio telescopes is that you can distribute them into arrays, with bigger arrays offering better resolution and sensitivity. I've been involved for over a decade now in a big project called the Square Kilometre Array. This will be the largest radio telescope array to ever have been built by many magnitudes, with over 100,000 antennas in its initial configuration. The arrays are now being built in the quietest radio areas on Earth, the Western Australian Outback and the South African Desert, and here at JoJo Bank we have the headquarters. These radio telescopes are going to be so sensitive that they'll be able to pick up an airport radar from an extraterrestrial race ten light years away. That's a big step up from current radio telescopes, which would only be able to pick up that signal if the aliens resided on Mars. Construction has already begun, and when data begins streaming we're going to be facing one of the single largest computational challenges that humanity has ever faced. We're streaming the universe over a billion years. This project represents huge effort and investment from teams all over the world. I can't wait to start exploring that data and unearthing the lives of those most ancient stars.