COPERNICAN PRINCIPLE
Robert Scherrer
Professor
John Rapaport paced back and forth at the front of his Astronomy 111 class,
waving a sheaf of papers in the air.
“Class,” he said, “your performance on the midterm exam was
abysmal. Let me correct a few of your
misconceptions: Venus is not a
star. The Sun is a star. And Pluto is not, repeat not ‘Mickey’s dog.’”
John
dropped the exams on the lectern and surveyed the faces of his yawning
students. Mike McNamara snored in the
last row, his enormous forearms folded on the desk, his crew-cut head resting
on his arms. Mike had been the football
team's star linebacker until that unfortunate incident involving the Chevy
dealer.
“Mike,
wake up!”
Mike's
head shot up. “Yes, Professor Rapaport?”
“Mike,
today we’re going to discuss the Copernican Principle.” John picked up a green marker and wrote
“COPERNICAN PRINCIPLE” on the whiteboard. “What is the Copernican Principle?”
Mike stared, his eyes wide and his mouth gaping – a moose
caught in the headlights. “Uh, I don't
remember.”
“Did
anyone do the assigned reading?” asked John.
“Paul, please tell me that you did the reading.”
Paul
Kresge put down his newspaper, revealing a face covered with metal studs –
pierced ears, pierced nose, pierced lips. Did the man set off airport metal
detectors? But at least Paul thought for
himself – he was the only one in class who ever challenged anything John said.
“No,”
said Paul. “I thought this week's
reading was boring. I read Chapter 17
instead.”
“Not
too smart, Paul,” said John. “Okay, class, I'll just tell you what the
Copernican Principle says. Copernicus
showed that the earth is not the center of the universe. The Copernican
Principle says that we don't occupy any
special place in the universe.” John
sketched a green spiral on the whiteboard and marked an X near the edge. “For example, the sun is not located at the
center of the Galaxy. It occupies an
unremarkable location about two-thirds of the way out from the center.”
“Wait
a minute,” said Paul. “Last week you told
us that our galaxy is larger than average.
Doesn't the Copernican Principle mean we should live in an average-sized
galaxy?”
John
smiled. “Now you're thinking, Paul. The Copernican Principle says that the earth
should orbit an average star. We're just as likely to orbit one star as any
other –”
“–
and the bigger galaxies have more stars,” interrupted Paul, “so we're more
likely to find ourselves living in a big galaxy.”
“Exactly!” said John. “Can anyone think of another
application of the Copernican principle?”
An
awkward silence filled the room, broken only by the faint ticking of the wall
clock above the whiteboard. Paul raised
his hand. “I've got one for you,” he
said. “I just read about this guy in
England who claims that any advanced civilization will make computer
simulations that are just like real life.
So if every civilization made a million of these simulations, then the
Copernican Principle says that we're more likely to be living inside a computer
than in the real world.”
“Well,
Paul, you shouldn't push these arguments too far.”
“And
what's wrong with my argument?” asked Paul.
“Well,
it's just that. . .” John scratched his
head. “Let me think about it – I'll tell
you tomorrow.”
Walt
Gustafson slurped a strand of egg noodles in the Chinese dive on High Street
where he always met John for lunch on Wednesdays. “That’s the problem with theoretical types
like you,” said Walt, pointing a chopstick at John. “An engineer like me is
never going to start believing this kind of nonsense.”
“But
how can you prove it?” asked John.
Walt
tried to pry open a plastic pouch of hot Chinese mustard with his fingers, gave
up, and slit it with a knife. “Well, for
one thing,” said Walt, “if we lived in a computer simulation, these mustard
pouches would be a lot easier to open.”
“Be
serious,” said John. “I think the kid's
argument is basically right – the Copernican Principle says we’re more likely
to be living in a computer simulation than not.”
Walt
shrugged. “Theories should follow
reality, not the other way around.” He
cracked open his fortune cookie and pulled out the slip of paper from
inside. “Hey, look at this,” he
said. “It says, ‘The system will be
shutting down in five minutes. Please
save your work.’”
“What!”
said John. He lunged across the table
and tried to grab the fortune, but Walt pulled it away from his grasp.
“Sheesh,”
said Walt. “I’m just kidding.” He popped the fortune cookie into his
mouth. “You’re really wound up about
this.”
“Well,
what if they did shut us down?”
“Let
me put your mind at ease,” said Walt. He
slapped the table, rattling the dishes and knocking over a plastic cup. “There, does that sound like a computer
simulation to you? Ouch, it hurt,
too. That's reality.”
“Or
it could just be a very convincing simulation of reality,” said John.
“Oh, it's going to be hard to convince you, isn't it? I'll tell you what – suppose I can come up with an argument from the Copernican Principle that's so completely absurd that it shows that the whole idea is preposterous. Will you give up and stop worrying then?”
“Oh, it's going to be hard to convince you, isn't it? I'll tell you what – suppose I can come up with an argument from the Copernican Principle that's so completely absurd that it shows that the whole idea is preposterous. Will you give up and stop worrying then?”
“Like
what?” asked John.
Walt
leaned back in his chair. “Try this
one,” he said. “Any advanced
civilization is going to produce an enormous number of works of fiction. So the Copernican Principle says that we're
actually more likely to be fictional characters than real people. Now you have to admit that that’s ridiculous.”
John
was silent for a moment and then chuckled.
“That’s a good one, Walt.”
Walt
laughed. “And the funniest thing is that
when the story ended, we would just disappear – poof! Now stop worrying and please pass the – ”
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