Summary
"How do we measure the age of the Universe?" asks Simon Whitehead.
A hundred years ago this wouldn't even have been considered a valid question, because we didn't think the Universe had a beginning at all. Even Einstein thought that space was eternal and unchanging.
This is the tale of how we discovered that the Universe had a beginning, and why calculating its age has been one of the greatest challenges in modern astronomy.
We also uncover the mysterious dark energy that pervades the cosmos and discover why it's been putting a scientific spanner in the works.
Helping to unravel today's question are physicists Andrew Pontzen, Jo Dunkley and Jim Al-Khalili.
Presenters: Hannah Fry, Adam Rutherford Producer: Michelle Martin.
Transcript
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| 0:00.0 | I'm Dr Adam Rutherford. And I'm Dr Hannah Fry. And you are going to send us your everyday |
| 0:10.8 | mysteries. And we are going to investigate them using the power of science. Science. I like it. |
| 0:18.2 | I do like it. I like it a lot, even with that squeaky voice. This is the last episode |
| 0:26.4 | in series nine of the curious cases of me and her. And we thought that we would go out with a |
| 0:31.3 | bang. A big bang, if you will. Hey. Yeah. Is it me? Yes. A big astrophysics, big bang. |
| 0:40.9 | Unlike the double episode at the beginning of this series, which is also that big bang's |
| 0:44.7 | in a very different context. So we got tons of pod extras after the show for the devoted |
| 0:49.5 | curious. But if you've just stumbled across this podcast after seeing a strange photo of two |
| 0:56.1 | people wearing fake moustaches, flash up on your screen. And then I hope that you enjoy the episode |
| 1:01.6 | that we have created for you. A grand cosmic puzzle for today sent into curious cases at BBC.co.uk |
| 1:14.0 | by Simon Whitehead. How do we measure the age of the universe? Right. So that sounds like a really |
| 1:19.3 | easy question. Well, you think so, wouldn't you? But to answer it, we are going to need to go |
| 1:24.4 | on an epic voyage that will take us to the furthest reaches of space and to the very beginning of time. |
| 1:30.9 | All right. Calm down, Obi-Wan. Actually, even if we go back just a hundred years, this wouldn't |
| 1:35.8 | be considered a question because we didn't think that the universe had an age at all. |
| 1:39.8 | In the beginning. Well, there was no beginning. At the beginning of the 20th century, I guess the |
| 1:47.6 | consensus was that the universe was eternal. It was ageless. There was not a perception that there |
| 1:53.9 | was actually a beginning to time. It was only later that we realised that in fact it had a beginning |
| 1:59.2 | at all. This episode is the story of how we discovered that the universe did have a beginning |
| 2:07.5 | and therefore an age. And to find out how it all started, I consulted a man for all ages, |
| 2:13.6 | physicist and broadcaster Jim Alculele. When Einstein kicked all this off in 1915 with a general |
| 2:19.7 | theory of relativity, he was so sure that the universe had been around forever that when he |
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