Posted: Jun 17, 2010 1:13 am
by Jakov
Very good essay. :)

I have noticed during my time of studying physics that certain theories actually seem to become part of my common sense and intuition.
For example when students are first introduced to Newton's laws, they are often shown an experiment where you place a buggy on an air rail which greatly reduces the friction. When you give the buggy a little push, and have rubber bands at each end to act as reflectors, the buggy can continue in motion for a very long time. When I first saw it many years ago it destroyed my common sense notion that when you push that buggy it would stop eventually, almost as though rest was the 'natural state' of any body. But now it seem equally common sensual to me that without friction, a body in motion will continue forever.

If you as a scientist have common sense on your side it helps massively. One example would be studying the common states of matter, solids, liquids and gases. Humans have a lot of contact with those and it helped us build good theories with them very early in our scientific enlightenment. However plasma physics is much harder because we never come across plasma and it hasn't been built into our common sense. There's nothing intrinsicly special about plasma, its just another state of matter which happens to almost never exist on earth.
PS. a flame is plasma, can you use your common sense to 'feel' how a flame will behave? Its much harder then trying to guess how water or rocks behave.

It can't be denied that the conclusions of science often go against what people subjectively feel is common sense. Sometimes creationists have offered this as a retort against evolution so I've had to bring up the discoveries of special relativity, the heliocentric solar system, super-fluidity of helium, atomic theory saying that everything we see is mostly empty space and light giving you a recoil when it hits you to show that common sense isn't a good guide to how the universe works.

How can we sometimes bring up science going against common sense but later say science is an extension of common sense. It sounds superficially unconvincing.