Each year, John Brockman's website, The Edge, asks a question
and gets many answers to it. This year, the question is: What is
your favourite deep, elegant, or beautiful explanation? Some of the
answers are fascinating. Here's mine:
It's hard now to recall just how mysterious life was on the
morning of 28 February 1953 and just how much that had changed by
lunchtime. Look back at all the answers to the question "what is
life?" from before that and you get a taste of just how we, as a
species, floundered. Life consisted of three-dimensional objects of
specificity and complexity (mainly proteins). And it copied itself
with accuracy. How?
How do you set about making a copy of a three-dimensional
object? How to do you grow it and develop it in a predictable way?
This is the one scientific question where absolutely nobody came
close to guessing the answer. Erwin Schrodinger had a stab, but
fell back on quantum mechanics, which was irrelevant. True, he used
the phrase "aperiodic crystal" and if you are generous you can see
that as a prediction of a linear code, but I think that's
stretching generosity.
Indeed, the problem had just got even more baffling thanks to the
realization that DNA played a crucial role-and DNA was monotonously
simple. All the explanations of life before 28 Feb 1953 are
hand-waving waffle and might as well speak of protoplasm and vital
sparks for all the insights they gave.
Then came the double helix and the immediate understanding that,
as Crick wrote to his son a few weeks later, "some sort of
code"-digital, linear two-dimensional, combinatorially infinite and
instantly self-replicating-was all the explanation you needed.
Never has a mystery seemed more baffling in the morning and an
explanation more obvious in the afternoon.
Here's part of Francis Crick's letter, 17 March 1953:
"My dear Michael,
Jim Watson and I have probably made a most important
discovery...Now we believe that the DNA is a code. That is, the
order of the bases (the letters) makes one gene different from
another gene (just as one page pf print is different from another).
You can see how Nature makes copies of the genes. Because if the
two chains unwind into two separate chains, and if each chain makes
another chain come together on it, then because A always goes with
T, and G with C, we shall get two copies where we had one before.
In other words, we think we have found the basic copying mechanism
by which life comes from life...You can understand we are
excited."
