Amateur Naturalist Galaxies and Atoms

The Outskirts of Infinity

The universe is about 13.7 billion years old. Or anyway that's the best
estimate for now. Only 150 years ago it was thought to be about 240 million
years. And that was roughly 239,995,000 years older than calculations 200
years before that, in the 1600s.
As recently as 1920, it was thought that the Milky Way galaxy contained
the whole universe, planets, stars, other galaxies and everything else. But in
1929 Edwin Hubble invented a more precise way of measuring star
velocities that eventually revealed there were galaxies outside our galaxy -
way outside it, billions of them billions of light-years away.
And not only our idea of it, but the universe itself is thought to be
expanding.
While the astronomers were enlarging the universe, the physicists were
shrinking it. By the 1920s it was clear that, whatever is happening in your
fingernail, it's smaller than atoms. Protons, neutrons, electrons and dozens
of other particles and particles that make up particles, like quarks and
gluons, are bolting around in the cosmic underworld as we speak.
As you look up, the universe gets larger, and as you look down, it gets
smaller.
The distance to other stars is so enormous it's measured not in miles but by
the time it takes a flash of light to get here. Traveling at 186,000 miles per
second, the light from Alpha Centauri takes about four years to strike your
eye. So Alpha Centauri is four light-years away. Light from the nearest large
galaxy, M31 in the constellation Andromeda, takes 2.5 million years to get
here. And M31 is nearby. Most galaxies are millions and billions of
light-years out, and some, like quasars, are so far away it's not certain what
they are.
At the same time, the distance between an atomic nucleus and an electron
is so tiny its number means almost nothing - one estimate is about 53
trillionths of a meter. Anyway, electrons are not actually little balls revolving
around larger balls made of protons and neutrons - that's just a model to
help us understand how energy behaves. Atomic distances are not the same
as star distances. The space inside atoms is not behaving like the space
between stars. Distances down there are spoken of as "quanta," which are
not distances, really, but more like regions where energy happens.
Still, whatever goes on down there, it's occurring in a tiny, tiny space, and it
makes the distance between an atom in your iris and an atom in your
fingertip seem sort of like the distance between Earth and Alpha Centauri.
Science has expanded our understanding of all this since the 1920s, but
most of it is still beyond us. Ninety-six percent of the matter in the universe
has never been detected, and no one knows how to do it. There's no
agreed-upon idea of where subatomic particles go when they vanish, or even
if there's any there there.
It makes you wonder what will happen to the universe in the next hundred
years. Are quarks and quasars the inner and outer limits? Somehow, I doubt
it.
In fact, I'm not sure what stops galaxies from being atoms, or atoms from
being galaxies. The Milky Way might be an atom in the transparent eyeball
of some indefinably enormous being gazing up toward a further range of
stars and galaxies. And indefinably tiny beings might be living on the
electrons in your fingertip and wondering about the subatomic photons
striking their eyes. And so on down through the quantum galactics and up
through the galactic quanta.
I suppose there are theoretical limits on how small and large space-time as
we know it can be. In one theory, called the Big Rip, the universe expands
to its limit and then tears apart. To me, this sounds a lot like the idea that
our galaxy is the whole universe. Or like a limit on our ability to imagine the
outskirts, or inskirts, of infinity. For now.

© Dana Wilde, Bangor Daily News, 2009