as you probably think you are. Every human body,
including yours, is actually a complex ecosystem made up of about ten
trillion human cells (you) and also more than one hundred trillion
microbes (not you). Weird as it seems, if you could conduct a census
of the space your body occupies, you would find that what you think
of as all you is actually mostly other lifeforms such as tiny arthropods,
bacteria, viruses, and fungi. You are a minority in your own skin. But
you are not only outnumbered, you are also tiny-very tiny.
How small are we? Most humans today weigh less than two hundred pounds and are less than six feet tall. Compare that to our planet's
mass, which is estimated at an intimidating 6,000,000,000,000,000,
000,000,000 kilograms. The Milky Way galaxy, our immediate neigh borhood, is one hundred twenty thousand light years wide. (A light
year is the distance it takes light to travel in one year, or about
5,879,000,000,000 miles.) Our galaxy contains more than a hundred
billion stars. Our universe probably contains more than one hundred
billion galaxies. It's anyone's guess as to how many planets there are.
So much is going on out there without us that it can seem as if we
are invisible, even nonexistent. There are beautiful clouds of dust and
gas called nebulae that are much larger than our entire solar system.
Stars are born. Stars die. Sometimes an entire galaxy smashes into
another galaxy. And this is just in the "observable universe." Some
cosmologists think there may even be many more universes besides
ours. Feeling tiny?
Size and numbers are not the only potential sources of human
insecurity. By the measure of time we don't add up to much either. The
universe is so old (fifteen billion years, give or take a few billion) that
we might think of ourselves as mayflies, enjoying nothing more than
a brief afternoon in the sun. A long life for an individual human today
is about eighty years. That's a fairly small slice of time on a planet that
is four and a half billion years old. It has been at least seven thousand
years since we made the transition from the Stone Age to civilization.
So many lives have come and gone in that period. Imagine all the dramatic events of those seven thousand years that we missed. Imagine
all the interesting and beautiful people who died before our time.
Wouldn't it be nice if something or somebody, maybe a god, could
make us feel important, relevant, and large? Maybe the god could even
allow us to live forever. It sounds appealing. For some, the desire to
feel important is sufficient motivation for them to seek out the comforting arms of a god, even if that god has never been shown to exist.
But hope and desire should not be confused with certain knowledge
about something. Many believers in many different societies say that
believing in a god or gods makes them feel significant in a vast and
intimidating universe. But this benefit from believing is not necessarily evidence for the existence of gods. It can easily be the believing
alone, not a real god, that provides the reassurance.
Many belief systems make a big deal about this issue of the significance of the individual. Religious leaders are well aware that people
often feel overwhelmed and lost in the herd of humanity so they are
quick to offer a solution. Many Christian preachers, for example, talk
about the "Book of Life" in which a god has written down the names
of believers. Christians have told me that their god knew my name,
even before I was born. Obviously this is a story that could make me
feel special. But although having your name in a god's "Book of Life"
may sound great, someone first should provide an explanation as to
how we can know that such a book exists. Where is it? If it's up in a
place called heaven that we cannot see, then how does anyone down
here know about it? If the only source of information about this magical book is found in ancient writings by