What technologies and questions about technology are just too hot to handle?

According to researchers presenting at “Forbidden Research,” a conference held last week at the MIT Media Lab, in Cambridge, Massachusetts, the list includes child sex robots, genetic gene drives, and a simple but controversial way to save Earth from rising temperatures.

We added a couple of our own to create the following list of forbidden technologies. Each question is morally or legally fraught and sets up a clash of ethics between individual technologists in search of solutions and institutions that see possible harm.

MIT Media Lab biologist Kevin Esvelt calls for full disclosure by scientists seeking to develop advanced genetic technology.

Can we engineer the climate?

Solar engineering could be the most important technology of the 21st century. The idea is to offset rising temperatures by releasing sulfur dioxide high in the atmosphere, which will reflect some sunlight away from Earth. David Keith, a professor at Harvard, says it would be cheap and easy to do and “for sure” could turn temperatures back to their preindustrial levels. Questions remain, though: would it damage the ozone layer? To find out, some small-scale atmospheric tests will be needed. But no such tests are under way, because people worry about what it would mean to try to fix global warming by injecting even more pollutants into the atmosphere. “We have collectively decided we prefer ignorance. We need a serious, open, no-nonsense international research program, and we don’t have one. That is political cowardice,” says Keith.

More: “A Cheap and Easy Plan to Stop Global Warming”

Should we give pedophiles child sex robots?

A few researchers—a very few—think child-size sex robots or virtual reality could help them to study pedophiles, learning what arouses them or maybe even giving them a safe outlet. But pedophiles are a group of people about which little is known and who are hard to study. In the U.S. researchers are required to report them to police. “I want to know [if] we can use robots therapeutically to help,” says robot ethicist Kate Darling, of the MIT Media Lab. “We have no idea if we can, and we can’t research it because of the huge social stigma.” She says high-quality sex robots are arriving “faster than society can have this conversation.”

More: “How Virtual Reality Can Help Treat Sex Offenders"

What is the public health cost of guns?

Are guns a public health menace? Obviously they are. But don’t ask the Centers for Disease Control and Prevention, home of America’s star squad of epidemiologists, what the true cost of gun violence is. In 1996 Congress forbade the agency from any research that could possibly lead to legal controls on firearms.

More: “Why the CDC Still Isn’t Researching Gun Violence Despite the Ban Being Lifted Two Years Ago”

What health-care technology is worth the money?

Health-care spending in the U.S. is high and drug prices are soaring. But good luck finding out how cost-effective any given medical technology really is. As part of Obamacare, the White House created a new federal research institute that last year lavished $491 million studying which medical treatments work best. But thanks to lobbying by industry and doctors’ groups, the bonanza came with a proviso: no research, none at all, can be done on what any of it costs.

More: “We Need a Moore’s Law for Medicine”

Should access to scientific knowledge be totally free?

Should everyone, everywhere on Earth, have access to the fruits of publicly funded scientific research? That’s the idea behind SciHub, a pirate site in Russia that has accumulated nearly 55 million papers, many lifted from behind publishers’ paywalls. Alexandra Elbakyan, the Kazakhstan student who created the site, says she can’t travel to the U.S. or Europe for fear of arrest. But the site has also proved impossible to shut down. “The only thing now is to make it legal,” she says.

More: “The Frustrated Science Student behind Sci-Hub”

Can we genetically modify an entire species?

A “gene drive” is a radical new way of using the gene-editing technology CRISPR to spread genetic traits through wild populations of animals. Think mosquitoes that can’t transmit malaria, or invasive species that self-destruct. But this time, it’s scientists who are objecting to the technique. The technology, some say, can’t even be tested safely in the lab, at least not without elaborate controls and complete, transparent public disclosure. They fear a lab accident that spreads among animals in the wild could harm the public’s trust in science forever. “Some things are forbidden and arguably shouldn’t be, but other things perhaps we need some more barriers,” says Kevin Esvelt, a synthetic biologist with the Media Lab.

More: “Meet the Moralist Policing Gene Drives, a Technology That Messes with Evolution”

Is my phone sending radio signals right now?

Do your computer and smart phone do what you tell them? Or are they stuffed with cookies, code, and alerts doing someone else’s bidding? Even when set on airplane mode, recent iPhone models still emit radio signals, according to Edward Snowden, the whistleblower who drew attention to surveillance of Americans’ mobile phones by the National Security Agency. He says that could put journalists reporting from conflict zones at risk. So with engineer Andrew Huang he is working on a new device for journalists that will attach to their iPhones and tell them if they are transmitting radio signals or not. What’s forbidden by law and by practice in this case, says Snowden, is communication technology that’s truly secure for the user and protected from the state.

More: “Snowden Designs a Device to Warn if Your iPhone’s Radios Are Snitching