Hold your hand up 12 inches from your face: you're seeing your hand as it was a nanosecond

ago.

Everything you look at is, to one degree or another, in the past.

The farther away in space, the more ancient in time.

You can't see the Sun as it is now, but you can see it as it was about 8 minutes ago.

You can't see Alpha Centauri now, but you can see it 4.4 years ago.

You see the Andromeda Galaxy as it was 2.5 million years in the past.

And so on.

With powerful telescopes, we can see galaxies whose light has been traveling to us for more

than 13 billion years.

We see them shining in a universe that's still young, where gravity has barely begun

to pull matter together into stars and galaxies.

But we can see something even more distant, and more ancient, than the first galaxies.

If we peer out far enough, in between the galaxies, we can see parts of the Universe

that are so far away, it has taken the light from that distance very nearly the entire

age of the cosmos to reach us.

When we look at the most distant parts of the cosmos, in every direction, we see parts

of the Universe that are so far in the past, they're still in the final stages of the

Big Bang.

So far away, so far back, the space is completely filled with a dense, roiling plasma, the fire

of creation.

We are not the center of the Universe.

But we are the center of our own perception as light reaches us from afar; we lie embedded

in nesting-doll layers of cosmic time.

Each concentric sphere is an era.

We can see the structure of matter changing, like geological strata all around us

The most distant layer of time that we can see is the light that has been traveling since

the moment the primordial fire began to cool.

The cosmic microwave background surrounds us at every edge of our vision.

We are embedded in shells of cosmic time, and the final one is fire.

Thanks to Katie Mack, aka astrokatie, for collaborating with me on this twitter-thread-inspired

video poem.

Now, if you've ever wondered how we can know things like how far away distant stars

and galaxies are, Brilliant.org, this video's sponsor, has an interactive course on just

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Again, that's brilliant.org/minutephysics.