A Goldilocks exoplanet and marijuana on the brain

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Everything you ever wanted to know about Kepler 186f

The planet Kepler 186f is 500 light years away, might have liquid water, and orbits a red dwarf star. Red dwarfs are cooler, yes, and dimmer, but they also burn for billions of years longer than our Sun–meaning that life has lots more time to possibly maybe happen there than the 3 billion years it took here. Nearly a thousand exoplanets have been discovered so far. This is the  one that most closely resembles Earth.

Hence the wild excitement.

But curb your enthusiasm; there are a lot of ifs and maybes. One tipoff that circumspection is advisable is that Bad Astronomer Phil Plait, who has been known to sometimes jump up and down and yell “Wowee!!!!” isn’t doing that about Kepler 186f.

On the left, us. On the right, a fantasy/science fiction conception of Kepler 186f, which almost certainly doesn't look like this. Although they probably got the relative sizes of the two correct. Credit: NASA Ames/SETI Institute/JPL-CalTech

On the left, us. On the right, a fantasy/science fiction conception of Kepler 186f, which almost certainly doesn’t look like this. Although they probably got the relative sizes of the two correct. Credit: NASA Ames/SETI Institute/JPL-CalTech

Plait notes that astronomers have discovered dozens of planets in the habitable zone around stars, the zone where water, if it exists, could be liquid. Kepler 186f is special because it’s 1.1 times Earth’s size, making “it potentially the most Earth-like planet we’ve yet found.” Italics are his.

The known unknowns about Kepler 186f

The fact is, Plait says, we don’t know a lot about Kepler 186f and probably never will. “The techniques used to find planet masses aren’t up to the task for this planet—the star is too dim to get reliable data. The same is true for any air the planet might have as well. And without that, we don’t really know its surface temperature. . . So we don’t know if this planet is like Earth, or more like Venus (with an incredibly thick, poisonous atmosphere that keeps the surface ridiculously hot), or like Mars (with very little air, making it cold). It could be a barren rock, or a fecund water world, or made entirely of Styrofoam peanuts,” he says.

I am guessing he is kidding about the styrofoam, but the question of atmosphere is pretty major. Kepler 186f is at the far edge of the star’s habitable zone. It gets only a third as much light as Earth, and it is colder. So it would need a thick carbon dioxide atmosphere to maintain water as a liquid, according to Alexandra Witze at Nature.

Other reasons for caution: Kepler 186f could have far less surface gravity than Earth–or far more. At ScienceNow, Yudhijit Bhattacharjee says it could be tidally locked to its  star, just as the Moon’s rotation is synchronized to Earth. In that case, half the planet would be permanently sunny and the other half permanently dark and cold. If there is an atmosphere, this heating pattern might cause permanent mighty winds.

NASA is guessing that it’s a rocky planet like Earth, but its mass and composition are in fact unknown. A member of the NASA team calls the planet, which is 10% bigger than Earth, an Earth cousin rather than an Earth twin, according to Nathan Ingraham at The Verge.

But maybe this planet is better than Earth?

On the other hand, at SciAm’s Observations, Michael Moyer speculates that Kepler 186f may be better configured for life than Earth is. The little we do know about it suggests that it might nicely fulfill the requirements for superhabitability.

Nice trees. Must be autumn on Kepler 186f. The lake is overseen  by red dwarf Kepler 186 and other planets in the system. In case you were wondering, this is not a photo.  Credit: NASA/Danielle Futselaar.

Nice trees. Must be autumn on Kepler 186f. The lake is overseen by red dwarf Kepler 186 and other planets in the system. In case you were wondering, this is not a photo. Credit: NASA/Danielle Futselaar.

A superhabitable planet is “one that has all the life-giving features of Earth, but more so,” Moyer says. It’s somewhat bigger than Earth, and for generating life, size matters. A bigger planet would help shield nascent life from radiation. It could have more volcanoes spewing CO2 to warm things up, generating a thicker atmosphere that would cling to the planet because of greater surface gravity. Also, lots more space for things to grow and ramble. And a long-lived red dwarf sun that would give life loads of time to get up and running. We don’t know about volcanoes and an atmosphere, but Kepler 186f is bigger than Earth and is orbiting a life-giving (maybe) red dwarf.

Department of Wild Speculation

Switching from speculation mode to wild speculation mode, let me acquaint you with Hontas Farmer, blogging at Quantum Gravity. He is investigating signals from the Kepler 186 system via SETI Live, a volunteer search for signals from intelligent life. Farmer says he has detected something that might might might be a very noisy and degraded broadband signal coming from the Kepler 186 system.

Farmer has concluded there is a better than 50-50 chance that the system harbors not just intelligent life, but intelligent life that is at least as technologically advanced as we are. Or was 500 years ago, the red dwarf’s light having taken that long to be collected by the SETI telescope.

For another leap of the imagination, think on this. If we did find out that Kepler 186f was looking lifelike, 500 light years is far, far away. Even traveling at the speed of light, which as you may know we can’t, it would take many human generations to get there. So you will be pleased to learn that a scientist at NASA (of course) is looking to solve that problem. He’s working on a warp drive. Really. It must be true because I read it in Scientific American.

A guest blog post by Mark Alpert, who (also) writes science fiction, says that physicist Harold “Sonny” White is working on “a system that could generate a bubble of warped spacetime around a spacecraft. Instead of increasing the craft’s speed, the warp drive would distort the spacetime along its path, allowing it to sidestep the laws of physics that prohibit faster-than-light travel. Such a spacecraft could cross the vast distances between stars in just a matter of weeks.”


The Enterprise visits Kepler 186f. This is not a photo either.

The Enterprise visits Kepler 186f. This is not a photo either.

Ad astra ad nauseam

I’ve had enough of the atmosphere around Kepler 186f for now, but if you haven’t, there’s more, lots more.

Joseph Stromberg has an explainer on exoplanets at Vox.

The paywalled paper on Kepler 186f is from Science. Here’s the abstract.

Knight Science Journalism Tracker Charlie Petit has posted an exhaustive analysis of the extensive media response to Kepler 186f. With links, of course. Many.

Calling the pot black

I have written here before about the likely enormous impact of the coming cavalcade of cannabis. We have, somewhat heedlessly, launched a massive experiment. There’s been a revolution in public attitudes on marijuana use–not to mention striking policy changes like legalization in Colorado and Washington state, and legal medical marijuana in 21 other states plus the District of Columbia, and the Justice Department’s declaration that it doesn’t plan to enforce the federal law against weed.

It’s inevitable that this massive policy turnaround will encounter pushback. Some of it will come to us wearing a science costume. We got two headline-grabbing examples of that  this week, both involving medical research and both involving the perennially maddening writerly confusion over the difference between correlation and causation.

I yearn for the day when all people who write about science and medicine, not just a select group, recognize the difference and routinely explain that difference to readers. When wearing my cynical hat, I suspect that lots of those who pretend ignorance in fact know the difference perfectly well, but ignore it because otherwise they would lose sexy stories that editors love.

Marijuana on the brain

Let’s start with the study purporting to show brain differences between users and nonusers. A distressing number of media outlets fell for it, despite the fact that this was yet another example of correlation, not cause.

That undeserved attention generated its own pushback from several science-savvy sources. In fact, I was a bit heartened by how much denunciation popped up. There looks to be an expanding cadre of well-informed debunkers out there, and I hope hope hope they’re not all preaching to the choir.

Knight Science Journalism Tracker Paul Raeburn excoriated the positive coverage and also linked to the excoriations of others, notably John Gever’s MedPageToday post. Gever’s hed spoke of “Bungling the Cannabis Story.” Raeburn also quoted Berkeley computational biologist Lior Pachter, who blogs at Bits of DNA. Pachter declared that the study was “quite possibly the worst paper I’ve read all year.”


So much is wrong with this research–an MRI study, always a cause for caution–that it’s hard to understand why the usually classy Journal of Neuroscience, published by the very respectable Society for Neuroscience, gave it a home. Not only that, the SfN press release about the paper encouraged misinterpretation, as both Raeburn and Gever point out.

Gever noted that the release allowed senior author Hans Breiter of Northwestern to mischaracterize the study, saying it challenges “the idea that casual marijuana use isn’t associated with bad consequences.” Gever’s comment: “Um, no, it doesn’t — not without before-and-after MRI scans showing brain structure changes in users that differ from nonusers and documentation of functional impairments associated with those changes.”

Said Raeburn, “Reporters who relied on that release remind me of the student who fails his test because he copies the wrong answers from the kid sitting in front of him. The release might help explain why the coverage was so bad. But it’s no excuse.”

And then there were the study subjects.  As Maya Szalavitz points out at The Daily Beast, both the experimental (users) and control groups (nonusers) of 20 each were selected for being in good health and normal. Users who displayed any kind of impairment were excluded. So the brain differences the pot-smoking subjects were said to display were not associated with any abnormalities, any cognitive or mental problems. And the paper does not and cannot show that the brain differences were caused by pot.

Under the hed “The very political neuroscience of cannabis,” Mark Kleiman tore the paper apart at a group blog, The Reality-Based Community. Kleiman is a drug policy expert at UCLA; the LA Times calls him “pot’s go-to guy.” He says the brain differences finding “might mean
1. That using cannabis at that level causes changes in the brain.
2. That something else correlated with cannabis use – for example, use of other illicit drugs – causes changes in the brain.
3. That something about having that kind of brain makes cannabis use more attractive to people to have it than it is to people who don’t.
4. That the brain differences and the cannabis-use differences between the two groups are the product of some unknown third factor.”

Salavitz says, “Marijuana itself may or may not impair cognition— but discussions of marijuana policy clearly do so, in a way that is detrimental to our political health.” Jacob Sullum concluded similarly, at the libertarian group blog Hit and Run, that the paper “provided powerful evidence that MRI scans cause shoddy science reporting.”

For an example of anti-pot pushback, see Babbage at The Economist, who described the paper enthusiastically and then leapt forward with this claim, which is not only a non sequitur, it is nonsense: “[E]ven modest recreational pot-smoking seems to set the brain on a path to addiction.”

Is marijuana an affair of the heart?

Another paper, this one from French researchers, suggests a relationship between pot smoking and heart problems. It’s open-access, and also from a professional group, the Journal of the American Heart Association.

It was published Wednesday, so there hasn’t been much time for commentary yet. LiveScience has taken it on twice, though. Bahar Gholipour reported on the paper, which describes 2000 cases of complications related to marijuana and says 35, less than 2%, involved heart problems, including 20 heart attacks and 9 deaths.

Gholipour points out that this, too, is an example of correlation, not cause. Also that many of the patients had a family history of heart disease and/or other risk factors such as a previous history of heart problems, high blood pressure, and drinking.

In a HuffPo post, Amanda L. Chan notes that 21 of the 35 smoked tobacco. Also that well over a million Frenchpersons are believed to be regular pot users. Chan quotes several naysayers, including doc Valentin Fuster of Mt. Sinai (the hospital, not the home of the Ten Commandments.) He says the evidence is not clear whether pot is or is not riskier than tobacco smoking. He’s quite wrong.

LiveScience also published distressed commentary on the paper from a cardiologist with a book to sell. Suzanne Steinbaum says flatly “marijuana can be damaging to your heart.” She also is worried about the potential for abuse as legalization expands. “Does this potential for abuse exist with marijuana? Maybe, maybe not. But it’s important that we ask the right questions and present the facts about marijuana.”

Who can disagree with that? For a clear and engaging 5-minute summary of what the data on pot use actually show about health effects, see what Incidental Economist Aaron Carroll has to say in his Healthcare Triage video.

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