Brian Cox

So the theory itself, historically speaking, strongly suggests that. And so he changed his mind. And then we saw the universe was expanding. We observed that. And then we've now seen the oldest light in the universe, the cosmic microwave background radiation, which is the afterglow of the Big Bang. So we know that the universe was hot and dense 13.8 billion years ago.

So the theory itself, historically speaking, strongly suggests that. And so he changed his mind. And then we saw the universe was expanding. We observed that. And then we've now seen the oldest light in the universe, the cosmic microwave background radiation, which is the afterglow of the Big Bang. So we know that the universe was hot and dense 13.8 billion years ago.

We have so much evidence for that, not least that we have a photograph of it 380,000 years after the Big Bang. It's called the cosmic microwave background radiation. Let's see that images of that. That's from the satellite called Planck, a European satellite and also satellite called COBE. So we have these images of the afterglow of the Big Bang.

We have so much evidence for that, not least that we have a photograph of it 380,000 years after the Big Bang. It's called the cosmic microwave background radiation. Let's see that images of that. That's from the satellite called Planck, a European satellite and also satellite called COBE. So we have these images of the afterglow of the Big Bang.

We have so much evidence for that, not least that we have a photograph of it 380,000 years after the Big Bang. It's called the cosmic microwave background radiation. Let's see that images of that. That's from the satellite called Planck, a European satellite and also satellite called COBE. So we have these images of the afterglow of the Big Bang.

We also have theories that tell us about the abundance of chemical elements in the universe which match this perfectly. So there's multiple lines of evidence that tell us the universe was hot and dense. But none of that tells us that that was the beginning. I think that would be widely accepted. It's a beginning in Einstein's theory.

We also have theories that tell us about the abundance of chemical elements in the universe which match this perfectly. So there's multiple lines of evidence that tell us the universe was hot and dense. But none of that tells us that that was the beginning. I think that would be widely accepted. It's a beginning in Einstein's theory.

We also have theories that tell us about the abundance of chemical elements in the universe which match this perfectly. So there's multiple lines of evidence that tell us the universe was hot and dense. But none of that tells us that that was the beginning. I think that would be widely accepted. It's a beginning in Einstein's theory.

If you just take general relativity, there's a singularity there at the beginning of time. We don't know what it is, but it's there. But it absolutely is true to say that we think that's not complete as a picture. So there it is. So that is light that was emitted about 380,000 years after the Big Bang.

If you just take general relativity, there's a singularity there at the beginning of time. We don't know what it is, but it's there. But it absolutely is true to say that we think that's not complete as a picture. So there it is. So that is light that was emitted about 380,000 years after the Big Bang.

If you just take general relativity, there's a singularity there at the beginning of time. We don't know what it is, but it's there. But it absolutely is true to say that we think that's not complete as a picture. So there it is. So that is light that was emitted about 380,000 years after the Big Bang.

And the key thing, there's so many things to say about these images, but one thing is those colours. correspond to regions of very slightly different density that we detected now in the gases of the young universe.

And the key thing, there's so many things to say about these images, but one thing is those colours. correspond to regions of very slightly different density that we detected now in the gases of the young universe.

And the key thing, there's so many things to say about these images, but one thing is those colours. correspond to regions of very slightly different density that we detected now in the gases of the young universe.

Yeah, the reds and blues, all those as well. They're both the same. So that greeny one, well, either that one or the one with the greeny blue, that one, that's from the Planck satellite. So those colors correspond to regions of different density.

Yeah, the reds and blues, all those as well. They're both the same. So that greeny one, well, either that one or the one with the greeny blue, that one, that's from the Planck satellite. So those colors correspond to regions of different density.

Yeah, the reds and blues, all those as well. They're both the same. So that greeny one, well, either that one or the one with the greeny blue, that one, that's from the Planck satellite. So those colors correspond to regions of different density.

So in this young universe, 380,000 years after the Big Bang, that's only hydrogen and helium gas, basically, and a bit of lithium, some of the lighter elements, but basically hydrogen and helium. So you've got an almost smooth, almost featureless universe then. But these little density fluctuations are very important because as the universe expanded and cooled, they collapsed to form the galaxies.

So in this young universe, 380,000 years after the Big Bang, that's only hydrogen and helium gas, basically, and a bit of lithium, some of the lighter elements, but basically hydrogen and helium. So you've got an almost smooth, almost featureless universe then. But these little density fluctuations are very important because as the universe expanded and cooled, they collapsed to form the galaxies.

So in this young universe, 380,000 years after the Big Bang, that's only hydrogen and helium gas, basically, and a bit of lithium, some of the lighter elements, but basically hydrogen and helium. So you've got an almost smooth, almost featureless universe then. But these little density fluctuations are very important because as the universe expanded and cooled, they collapsed to form the galaxies.