Re: "Breaking up is hard to do" ie Shattering the Moon ala "Three


Wayne Throop wrote:

I think the problem is, people think of things floating in space, as
if space were a fluid. And you can have very large chunks of, say,
ice, floating near each other without being smushed together. So
the analogistic reasoning people use to think about objects in space
leads to this as a common error.

I don't know if the thinking involves a fluid. It may just be the idea
that "stuff in space floats instead of falling to earth." The typical
person thinks that astronauts are in zero-g because "there isn't any
gravity in space". They may have heard that gravity gets weaker with
distance, which reinforces their idea that it is gone at some distance.

Gravity is something that the earth has, not something that chunks of
the moon have. If you show them an astronaut on the moon, then they
start thinking of it as a smaller earth that you can stand on and has
gravity. Show them chunks of the moon as seen from earth, and it stops
having gravity. Certainly the pieces don't have any gravity, because
they aren't earthlike at all.

Ask them why the moon orbits the earth, and they may know there is
gravity involved. But they don't notice that this does not fit with
their assumption that the earth's gravity stops long before reaching
the moon.

A typical person's knowledge of science is little separate groups of
"facts", most of which are only true in a limited domain, if at all.
They don't notice that many of their "facts" in one group contradict
"facts" in other groups.

As another example, if you ask the typical person the reason for the
seasons, they will often tell you that it is because the earth is
closer to the sun in summer. If you ask them what season it is in the
southern hemisphere at that time, they know it is winter. But they
have never noticed that their theory of the seasons would make it
summer in both hemispheres at the same time. Apparently somebody did
this with university graduates, and got these answers from most of
them.

.

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