How do you mean nerves aren't connected?
The force that keeps them together is the Sun's gravity. This is the connection.
Not concepts, but names. Misnames happen, even in science. For example, a light year is not a unit of time measurement, but of distance measurement. However, it is conventionally kept.
As for contesting things: there was a time when geocentric model of the world was a commonly recognized concept. Yet some people dared to contest it. And now another view on how the universe is built is recognized. Several times the structure of the atom was reconsidered. So science is about contesting things.
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