Daniel Whiteson

What's the practical way to make that observation?

I mean, what's the machine?

How do you look back that far?

Yeah, so in terms of astronomy, you just need to look out into the universe.

Neutrinos are really hard to spot because, as we say, they can pass through the whole Earth without interacting, which means if we're transparent to neutrinos, that they're invisible to us.

but they have a tiny chance of interacting.

So we have neutrino detectors, essentially huge underground vats of liquid that are very, very quiet.

And we wait for a neutrino to pass through and to kick one of those atoms in a particular way so we can tell there was a neutrino there.

And these neutrinos from the very early universe are very hard to spot.

They're lower energy than the neutrinos like made by the sun.

So it's a challenge, but it's an experimental challenge.

We just need to build like

bigger neutrino telescopes, these underground vats of liquid that can see neutrinos.

So they're sensitive to the very rare, the very slow, the very quiet cosmic neutrino background.

And the same thing with gravitational waves.

You know, we have space telescopes that look for these signatures, these ripples.

We have...

you know, detectors that look for gravitational waves.

Um, we have even strung together stars.

We have a galaxy size gravitational wave detector built out of all the pulsars in the galaxy.