This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
if the guy is in a box, you have an unrealistic situation anyway. The smoke is going to disperse in ways totally unrelated to what would happen in reality.
It is not unreasonable to therefore make the assumption that it is evenly dispersed throughout the box. If you want to be conservative, you could make the box half the height of the man, or even assume that the box is the height of the man, but shifted half his height up.
When you start playing these games the assumptions are there to try and get people to jolt out of the box they are currently abiding. Whether it is Fast Food, Salt, Cola, or Smoking, getting people to recognize that Death is at the end of the line for everyone is difficult.
You might get them to realize the error of their thinking by taking them down the path of reason. Don't expect to succeed though. People in these modes are much like those that believe in Astrology, Dowsing, Clairvoyance, etc. In fact, they are the same people. They have discovered that the latter shouldn't be believed in, so they have replaced it with "science".
I have had several non-arguments with my wife lately on these subjects. Non-arguments are those subjects where I realize that I am not gonna change her opinion with an anecdote of a story heard about research. Yesterday's example was McDonalds and Super size me. When someone tried to replicate the Super Size Me results, they discovered that a person could live a perfectly healthy life eating nothing but McDonalds. My wife wasn't buying it. "They might have lost weight, but were they healthy on the inside?" I shut up. She has had it beaten into her head repeatedly that the Food Pyramid is important, that McDonalds is unhealthy, salt is bad for you and fat should be avoided.
"1200 repetitions a day, 7 days a week, 52 weeks a year make 1 truth" -- (paraphrase from A Brave New World).
How to break these truths apart? I don't know, but don't fret about the idealness of the analogy. It should be obvious from the fact that most smokers go through their lives without getting lung cancer that sniffing the equivalent of a cigarette a week isn't going to be bad. If you can get the individual to recognize the idiocy of the paradigm using any means, you are doing a good thing. Don't expect them to like you for it though.
Brad; re you're last e-mail. Do you have a reference (URL) for the statement - "When someone tried to replicate the Super Size Me results, they discovered that a person could live a perfectly healthy life eating nothing but McDonalds."
I'd appreciate it.
I can lead you to the source...
Skeptoid did a podcast about it.
Sadly he doesn't link to any references, but he tell them in the podcast.
There was some kind of junk-food clinical trial in the wake of "super size me". Unsurprisingly, people were found to react differently and unpredictably to being put on a high-fat, high-calorie diet. This means that your genes are at least partly responsible for your shape. Some people just burn the excess energy off, some of them store it up under their skin and in their liver, which is not good for your chances of impressing members of the opposite (or same if that way inclined) sex with your firm, toned body, or for your liver.
We have unrestricted access to highly palatable and highly nutritious food for the first sustained period in human evolution. It is no surprise that people are fatter than ever, and also no surprise that those who are unhealthily fat (myself included) are so because of a combination of genetic (billions of years of evolving to cope with regular shortages) and environmental (lack of food shortage in the last several decades) factors.