Matthew Sweet must move in very small circles ("Science: the umm, err effect", Real Life, 17 November). My science education consists of a Higher School Certificate taken 50 years ago, and desultory reading since, but I made a better shot at his "black hole" questions than any of the people he talked to. And I'm sure that most of my classmates would have done as well. I would have given more precise answers than those he suggests; for example, blood is not "oxygenated in the arteries". The arteries contain blood which has been oxygenated in the lungs, which is different. And the heat extracted from substances in a refrigerator isn't "expelled through a vent"; it is carried away into the air from a closed loop of finned tubing. If these answers came from textbooks no wonder children are confused.
Nor do I think much of Lewis Wolpert's comment on people's beliefs about the "Big Bang". Most of our beliefs, whether about the existence of Australia or the origin of the universe, rest on authority rather than knowledge, those of scientists and technologists no less than those of laymen. Life is too short for it to be otherwise.