Why is it routine for people to gather in a bar and discuss the antics of padded, helmet-wearing pituitary giants but unusual for them to gather in a bar and discuss the science and engineering of things that affect our lives?

That’s a puzzling question for us science fans, but happily that’s also a trick question, because it is no longer unusual. Science Cafe is returning to town.

Science Cafe Concord, an expansion of the long-running Science Cafe New Hampshire program, launches at 6 p.m. next Tuesday, Jan. 12, in the upstairs room of The Draft Sports Bar, with yours truly as moderator.

As it has done at 41 sessions since 2011, Science Cafe will provide knowledgeable panelists to answer questions about a chosen topic asked by anybody who shows up – including you, if you have any sense. It’s free and open to all, no advance tickets needed.

Concord TV plans to be there to record the session for future viewing, if you absolutely can’t make it – but it will be more fun to be there live.

The kick-off topic will be the science, biochemistry and pharmacology of the opioid crisis.

Our panel includes the state medical examiner; the Concord fire chief, who is a paramedic; and two clinicians. You’d be hard pressed to find a more potent mix of theoretical and practical knowledge on this subject, which is the whole idea.

A number of public discussions have been held about heroin and opioids lately, but Science Cafe will be a bit different. As the name suggests, it is a conversation rather than a lecture, and it focuses on issues from a scientific or engineering point of view, not via public policy. The approach is summarized in our only rule: “No politics, no PowerPoint.”

Next Tuesday’s session will be the place to find out what heroin and other opioids actually are, how they interact with our brains at the molecular and cellular and big-picture level, how treatments work or don’t work, what Narcan does, how autopsies determine the role of opioids in death, not to mention more sweeping queries like, “What is addiction, anyway?”

Plus lots of other questions that haven’t even occurred to me.

Later discussions for Science Cafe concern will cover gasholders, that fascinating technology that was once ubiquitous in New England and is ensnared in Concord’s debate about the future of a gorgeous circular brick building on South Main Street; the explosion in genetic modification caused by a process known as CRISPR, which may be biggest advance in scientific practice in a decade; the present and future of self-driving cars in New Hampshire; and the science of beer, which always draws a crowd (surprise!).

Science Cafe New Hampshire was founded in 2011 by a couple of science fans who wanted a place to help us understand how things work and why they happen the way they do, while indulging in a bit of draft beer and pub food.

“The idea is to get into a comfortable, informal setting that encourages people to ask questions that they might be intimidated to ask in a more formal setting, like a classroom,” said co-founder Sarah Eck of Hopkinton.

Eck is a Lyme native who received her Ph.D. in biochemistry a few years ago and is now an independent research analyst and mother of two small children. (No, I don’t think she gets much sleep.)

Like many people in the sciences, she is often dismayed by public uncertainty about basic science facts: “I’ve run into people who didn’t know that cancer is not contagious.”

Back in 2010, she looked into creating science-in-school programs, and in the process was introduced by folks at the New Hampshire Humanities Council to Dan Marcek of Brookline, a tech-company veteran who had similar concerns about public knowledge, or lack thereof.

Marcek had encountered the science cafe scene in Europe and other parts of the U.S. and thought it could work here.

Eck agreed, and the two created Science Cafe New Hampshire. They brought me in to moderate because somebody has to make the feeble jokes.

We started in Concord in May 2011 and moved down to Nashua in 2013, where crowds of 70 were not unusual, overflowing the bar. Nashua’s Science Cafe will continue even as we expand back to Concord.

Over the years our sessions have discussed everything from climate change, vaccines and brain trauma in veterans, to nanotechnology, 3-D printing and electric cars, to Lyme disease, digital privacy and the science of marijuana, with panelists that have included scientists and engineers galore, plus CEOs, doctors and nurses, lawyers, car salesmen, and just about anybody except politicians.

Our success helped spur similar discussions across the state, first by UNH and Dartmouth College, then at the monthly Science on Top sessions in Manchester hosted by the SEE Science Museum.

All in all, it’s a cornucopia of informed discussion (plus beer – don’t forget the beer). You can keep track of it via sciencecafenh.org website.

(David Brooks can be reached at 369-3313, dbrooks@cmonitor.com, or on Twitter @GraniteGeek.)