Answer to Question 1
This is a tricky question to answer because some radioactive particles decay to
nonradioactive progeny, but others decay into particles that are radioactive themselves. There
will certainly be fewer of the original radioactive particles after some decay, but we cannot
be certain that there will be fewer radioactive particles overall, It is to be hoped that students
grasp this, but gives the teacher the opportunity to reinforce this point.
Answer to Question 2
Simon is an economist. Economics is a human endeavor. The limits that exist to
increase of human population are not human-generated limits but exist independent of
human beings.
technology is based on the fruits of science. It cannot supersede science.
Physical limits, such as insolation, are different from those set by humans. Simon seems to
have ignored this distinction.