I noticed, and perhaps many others have too, that the application of hand sanitizer (mainly ethanol), leaves one's hands feeling rather chilly after application. 

What is responsible for this phenomena? Is it the high heat of vaporization of hand sanitizer? However, explanation doesn't hold water; water has a standard heat of vaporization of 40.65 kJ/mol while ethanol has a heat of vaporization of 38.56 kJ/mol. 

Could it be the low boiling point of ethanol? Hand sanitizer disappears (vaporizes) within seconds upon rubbing the hands together. Water, however, does not.

Additionally, how does one square a high heat of vaporization with a low boiling point? If it takes a lot of energy to vaporize something, then how can that something have a low boiling point? 


Question: What is the Goal of "Hot Network Questions"?
Answer: Well, I can tell you what I hoped for when I was a regular user on a tiny site: network-wide exposure. When Biblical Hermeneutics showed up in the hot question list, I vividly recall day-dreaming that everyone who had an interest in the Bible on the network would see our little site and have a burning desire to ask and answer hermeneutics questions.  It was a good feeling to know that Jack's question and the answers it had already accumulated would get some exposure. It felt like our little community had earned a collective gold star.

Now I'll admit it was a bigger deal in my mind than it was in reality.  As of this writing, the question has fewer than 600 views. It's not anywhere to be found on the first page of BH's Greatest Hits. Likely we didn't get even one new user out of the deal. And we certainly didn't have any crowd control problems. But you know what? I'm still proud of our little community and that question. There aren't a lot of achievements a site can earn from the time pro tem moderators are appointed until graduation, but having a "hot question" is one of them.

Back then, it wasn't as easy to find network-wide hot questions. Now that they are listed in the sidebar, it's not uncommon for me to wander over to a site I'd forgotten even existed.  (Hello, Code Golf!) Ideally, I will find a question that isn't just entertaining to read, but also sparks my interest in writing something. There are some brilliant, eloquent, and thoughtful people on our sites, so I think some cross-pollination can strengthen the whole network.

The other day, I was looking into the RPG site and trying to figure out how it got a healthy bump in visitors since the beginning of the year. As I dug, it became clear that one factor has been direct traffic from other sites on the network. Digging a bit more, I turned up a series of "hot questions" such as Is 3d6 the same as 1d18? Since you don't have to be an expert in a particular RPG system to read, appreciate, or even answer this question, it attracted considerable attention (11,377 views so far). Site traffic also spiked noticeably the week the question was asked.

It was not without pain: two answers were deleted and the voting seems disproportionate. Arguably the question is not even on topic, yet it's tied for 26th on the all-time best questions list. While the answers tend to be good, none of them demonstrate any particular RPG expertise. But the question also got two solid first answers (one from Eric Lippert and the other from someone who has provided an equally upvoted answer). All-in-all, the HQ list looks like a net positive on that site. 

Speaking of rolling the dice, hot questions are a sort of gamble. They take advantage of the blockbuster business model. Every day there are dozens of new hot questions. Some of them blow up and others fizzle. Most sites consider it a great success to convert just one reader in a hundred (or even a thousand) into an occasional contributor. The hot question formula improves the odds by taking into account indicators of interest and quality signalled by regular users of the site. In other words, if lots of people on a site read, answer, and vote on posts, we can feel pretty confident that showing the question around will attract similar people.