“We may regard the present state
of the universe as the effect of its past and the cause of its future. An
intellect which at a certain moment would know all forces that set nature in
motion, and all positions of all items of which nature is composed, if this
intellect were also vast enough to submit these data to analysis, it would
embrace in a single formula the movements of the greatest bodies of the
universe and those of the tiniest atom; for such an intellect nothing would be
uncertain and the future just like the past would be present before its eyes.”
—Pierre Simon Laplace, A Philosophical
Essay on Probabilities
Laplace’s idea
has intrigued and disturbed over the years.
The general thinking is that quantum mechanics rendered Laplace’s
position moot, as you cannot know both the exact position and the exact motion
of a particle. I believe, however, that
Laplace’s position fails even without quantum mechanics. Here’s why.
Laplace’s posits
an all knowing intellect, but then places that intellect outside of, and
utterly passive to, the Universe. There
are two problems with this. First, by
definition, nothing can be outside the Universe. Second, it is completely arbitrary to make
this all-knowing intellect passive to the material world. Why should we not assume that this intellect
is itself like a typical scientist, who would use its knowledge to try to make
the world better? If we assume such an
intellect, then Laplace’s conclusion quickly falls apart.
If the intellect
modifies the world based on its knowledge, then it has to have a pre-knowledge
of how it will change the world and include that in its analysis of the
world. But with this knowledge it can
change its own behavior, and so it would have to include that in its analysis
and so on ad infinitum. Once we assume
the all-knowing agent is in the universe and active, then we have to come to
the conclusion that the future would be uncertain for this all knowing, active
being.**
While all this
is quite theoretical, it actually points to the reality of our world. Scientific knowledge has certainly not made
our world more certain and predictable, quite the opposite. Yes, we can predict lunar and solar eclipses
and the orbits of the planets and satellites to great specificity, but down
here on earth the situation is much different.
People living in
the world prior to the rise of science had a fairly good sense of what the
world of their children’s children’s children would be like – it would be
fairly similar to the world they inhabited.
Most of the time this would be correct.
My parents, who were born early in the 20th Century could
scarcely have imagined in their youth the world that I now live in with its
nuclear weapons, space travel, computers, the Internet, exponential population
increase, etc. Similarly, I have little
sense of the world my children will inhabit if they live to be my age. We imagine that the future will be filled
with new technologies, but our past experience tells us that the technologies
we imagine are not likely to be those that actually appear.
We do not know
how creative minds create, but feedback is obviously important. The feedback that spurs creativity is a
relationship between a dynamic mind and a dynamic world -- mind changes world,
world changes mind in an ever iterative spiral.
Dynamic, interactive relationships cannot be reduced, as to reduce to
one side of the relationship or the other is to get an incomplete picture. If this aspect of the world cannot be
reduced, Laplace’s assumption about the universal validity of reductionism is
insufficient. In the end, Laplace’s
universe is an imaginary one. Its
invention, however, had significant causal effects on our little earth. The view it presented helped initiate the
Romantic Movement in the arts. Now that
is something that I suspect Laplace didn’t predict.
** (By this same
reasoning, a loving god that occasionally changed the course of the world’s
events because of that love could not be omniscient – the occasions and results
of its love ultimately would be mysterious even to it. Indeed, the concept of love without the
accompanying concept of mystery signifies nothing.)
