… is a dangerous thing, so the saying goes. There a two ways to interpret that saying: 1.) knowledge is power, so even a little bit can be dangerous; 2.) A little bit of knowledge can be dangerously misleading, as it doesn’t accurately represent the whole scenario.
As an example of interpretation 2, Sean Carroll has taken the opportunity to blast Chris Ormell over at Cosmic Variance. In this case, Ormell knows just enough to reach some ridiculous conclusions about modern physics and astronomy. My personal favourite is:
Instead it was discovered that light does not travel in absolutely straight lines, but bends slightly due to the Earth’s gravitation. It is a minute effect and detectable only with great difficulty, but its consequences are deadly. If this degree of bending occurred in outer space, the light from the nearest star would have completed a circular trajectory on its way from its source to our telescopes.
which is complete bollocks. It could only possibly be true if space is filled with black holes, like this:
The red line shows a particular path of light passing near a rotating black hole – I did a few simulations of this for my masters thesis. But space isn’t full of black holes. Even the stars in our galaxy take up something like 1 part in a trillion trillion trillion of the volume of our galaxy.
Carroll’s response is great, and well worth a read.