Understanding the Universe's Expansion and Fate

More than ninety-five percent of every one hundred galaxies we see are

already out of our reach. The oldest light we see traveled for

thirteen point

eight billion years. But because space stretched, the gas

that sent it

is now forty-five point seven billion light-years away.

And the most distant galaxies are already moving away faster than light.

If the history of the universe were a single day, that light

set out two seconds into the day. And everything made of atoms,

you included, is just four point nine percent of the

universe.

The rest is dark matter and dark energy, and we don't

know what they are. And there are three ways time could end.

If dark energy stays constant, space grows forever until everything

reaches the

same cold temperature. If it fades, space could collapse twenty

billion years from now. And if it grows stronger, a big rip would tear

everything apart. If space grows forever, the last things to go

will be giant black holes. They take ten to the power of ninety-nine

years to

evaporate. A one followed by ninety-nine zeros.

Meanwhile, no human has ever gone farther than four

hundred and six thousand seven

hundred and seventy-one kilometers.

Voyager One is so far away that its radio signal takes nearly

twenty-four hours to reach us. And to reach the nearest star,

it would need

seventy-six thousand six hundred years.

Even at Parker Solar Probe's record speed, the trip would still take

sixty-six hundred years. We can see galaxies forty-six point five

billion light-years away, but we will reach very little before time

ends.