Neurofeedback has been studied since the 1960s, including for disorders like ADHD, PTSD, epilepsy and substance abuse, but the science is still patchy at best.

There is even less research for neurofeedback's use in meditation. While academics -- such as those at the University of Massachusetts Medical School and University of Wisconsin-Madison -- have a decent idea what a meditating brain looks like under EEG or fMRI, it's a leap to associate that with a psychological state. The presence of alpha waves in a monk doesn't mean those waves are causing them to be monk-like. And it doesn't mean one can reverse-engineer that state, essentially shoehorning one brain into the mold of another.

"[To] suggest that neurofeedback can be helpful to people meditating is really grossly overstating the case," said Richard Davidson, the founder of the Center for Healthy Minds at the University of Wisconsin-Madison and a leading neuroscientist in the study of meditation. "The brain is ridiculously complex. Our measures, even though they've come a long way, are absurdly limited and very coarse, and it's nothing short of hubris to think that we have the right measures at this point in time that we should be providing feedback on."

"It's nothing short of hubris to think that we have the right measures at this point in time that we should be providing feedback on."

There are hundreds of meditative states, many of which don't affect alpha waves at all, Davidson said. "I'm a fan of going ahead with the research... but to market it to consumers I think is irresponsible."

Even Siegel, who has completed the program, had his reservations. "People that do it consistently have a positive experience and a transformative experience," he said. "With regard to particular claims around how many years of Zen practice or whatever, I would say no, absolutely not. It's not the same as 40 years."

Still, neurofeedback has become a major site of exploration for meditating technologists -- from Biocybernaut to the at-home device Muse (slogan: "meditation made easy"), which costs $249 for the newest model. Six weeks after we met, Rosenblum emailed: She had "major epiphanies" on her seventh day and was "really just enjoying life as a less reactive person."

More than three months later, she told me, "I'm not sure I would know what 21 to 40 years of meditation is, but I know before I arrived I couldn't even quiet my mind for two to three minutes. ... I am a happier, more content, less triggered person than before, and for that I will be forever grateful."

The thing is, people are biased toward what works for them -- or the thing they think works for them. If it gets them there -- and the app makers, wearable designers and retreat gurus surely know this -- then the question of how may be moot. For instance, a review of placebo surgeries -- i.e., fake surgeries -- showed that patients felt improvements 74 percent of the time. An MIT study from 2008 showed that participants were 24 percent more likely to feel that fake codeine relieved pain when they thought it cost $2.50 rather than 10 cents. Telling people their $10 Cabernet Sauvignon is worth $90 makes them neurologically experience greater pleasure. (Now imagine the subconscious incentive to feel results when you've spent five figures in the Sonoran Desert.) Ultimately, all the credentialed lab coats and replicable lab studies can count for little in our mind's scales compared to our personal n of one.

To see why transformative technology is booming, therefore, requires looking beyond the proven science. It also helps to understand what brought these two apparently incompatible worlds of tech and Buddhism together in the first place.

Video: Broader perspectives

4. States versus traits

Chade-Meng Tan started life at Google as an engineer and employee No. 107 but soon became best known as the company's in-house guru.

In 2007, he launched Search Inside Yourself, a seven-week meditation course that has now expanded into an independent institute that teaches mindfulness to organizations like Ford and American Express.

The initial key to getting wildly overworked Googlers on board, he said, was stuffing the practice into the Trojan horse of productivity and self-interest. He sold it as "the science of emotion."

"They wear stress on their sleeves. They're so proud of being stressed," said Tan of his former co-workers. "We help them become successful, with goodness being the necessary and unavoidable side effect."

Meditation by now is fully ripened in Silicon Valley's culture. Steve Jobs, Jack Dorsey, Sergey Brin -- all have talked about their practices.

On a basic level, working 60-to-80-hour weeks requires some kind of release, and mindfulness is a data-validated, nonintrusive method of lowering your blood pressure. "I think sometimes [through] pop culture representations of Silicon Valley, people forget that they're not just douchebags; they're really hard-working douchebags," said Jay Michaelson, columnist, author of Evolving Dharma: Meditation, Buddhism, and the Next Generation of Enlightenment and meditation teacher.

At the same time, the Bay Area's hippy lineage and culture of innovation mean unconventional solutions don't freak anyone out. "This is a segment of the business world that's interested in disruption," said Michaelson. "They're not afraid of looking weird, because that's how you succeed." It's also a solutionary culture: Every challenge can be fixed, and that extends to the challenges of being human. It's taking a risk on something unproven for an extra advantage.

"Rather than presenting the whole toolbox to the audience, people are just glorifying screwdrivers and hammers."

Tan, a jovial and humble guy, joked that "people want to be successful, and they don't mind world peace." But the world peace part may no longer be an inevitable part of the package. Where stress reduction was once a byproduct of being a compassionate person, today it's the goal in itself. Psychologists like to talk about states versus traits: The former are temporary, the latter lasting. A lot of today's mindfulness tech is sold as inducing desirable states -- but so can DMT or porn.

"It's still some permutation of traditional disciplines that are observation of breath, observation of sensations, observation of emotions and so on. ... It is still deriving from the traditional toolbox, so to speak," said Tenzin Priyadarshi, the director of the Dalai Lama Center for Ethics and Transformative Values at MIT, who is also a monk. "But rather than presenting the whole toolbox to the audience, people are just glorifying screwdrivers and hammers."

The traditional Buddhist would ask if these tools are making you kinder, more engaged in society, said Priyadarshi. The idea of mindfulness was that the attitude would permeate your daily life and become a path to higher virtues. But we're a long way from Buddhism now: Priyadarshi has been asked to train military snipers.

Joi Ito, the director of MIT's Media Lab who teaches a conspicuously low-tech class about mindfulness with Priyadarshi, put it this way: "The more Silicon Valley CEOs that do vipassana, the better Silicon Valley will be. But it has also become like [progressive schooling method] Montessori: When you have a bunch of uptight parents, it isn't Montessori anymore."

Mindfulness was supposed to be about accepting that bliss will always be elusive. Like most religions, Buddhism recognizes that life is inherently hard and everything is transient.

"Some of my big concerns are that these technologies are actually going to inflame people's tendency to try to escape that groundless pit of existential uncertainty by chasing states, by giving them more tools to chase states, and to become addicted to a certain states," said Vincent Horn, the co-founder of the Meditate.io platform and Buddhist Geeks podcast. "To essentially avoid this recognition of the nature of states, which is that they change and they can't be held on to."