Blood in the Wall
A couple of years
back, I put a torch behind my daughter’s hand, turned it on, and voila! Her
hand appeared red in color. I told her it was because blood is red in color. Because that’s what I’d been told as a kid.
But that’s not the
reason at all, as I learnt later. The correct
reason is:
“Only one color of light passes completely
through your hand- and that's why it looks red. All of the other colors are
completely absorbed, either by the skin, bones, muscles, blood or other cells
in your body. Most of the red light passes right through all of these cells…”
But wait, things
are even more interesting:
“Most of the red light passes right through
all of these cells except your blood cells- but not even all of your blood
cells. Red light passes through the blood in your arteries, but is absorbed by
the blood in your veins. That's why your veins appear black.”
(The difference
between arteries and veins is the amount of oxygen in them, which affects how
much of the red light they absorb. Cool, right?)
Obviously, this is
way too complicated to explain to a kid, so I never corrected things to her.
Not having corrected the “blood is red” reason led to a very amusing
consequence recently.
While playing with
a red rimmed torch, she placed it right against the wall, turned it on, and not
surprisingly, the reflected light shining through the red rim looked… red. Upon
which, she turned to me and announced:
“Look, this proves there is blood in the
wall!”
As she said it,
she had that wicked look of I-know-the-conclusion-is-wrong-but-show-me-the-flaw-in-my-reasoning.
It was a
spectacular reminder of why reasoning from first principles is so important. As
Shane Parrish explains:
“Reasoning by first principles removes the
impurity of assumptions and conventions.”
Why we rarely do
anything from first principles is because, as Elon Musk said, “That takes a lot
more mental energy”. That all too common mental laziness is also what led
Richard Feynman to lament:
“I don’t know what’s the matter with
people: they don’t learn by understanding; they learn by some other way—by rote
or something. Their knowledge is so fragile!”
Guilty as charged,
Feynman.
I fully agree with Feynman's opinion about people, "Their knowledge is so fragile". Of course, my 'people domain' is not limited to ordinary commoners who are ridden with 'mental laziness' because of which they develop skewed ideas having poor linkage to truth. I am inclined to believe that "on the whole, human knowledge itself is fragile". :-)
ReplyDeleteI don't know what Feynman would say about children's way of reasoning. As far as we are concerned, the way children argue their points either wins our heart or make us light-hearted very often! I suppose we develop the ability to loosen ourselves when it comes to children, and simply appreciate their innocent and spirited ways.