Your criticism of televised ads for prescription drugs in “This Drug Ad Is Not Right for You” [Science Agenda] is right on. These ads lead patients to push prescriptions on their doctors by saying that they will find another physician if their request is not met, and together with the extraordinary pricing in the drug industry, they are huge burdens on the American public.

I was in active practice for 40 years. I recall vividly the expensive gifts, vacations, sports tickets and rounds of golf offered to physicians. This was drastically reduced a few years ago, but now TV “health education” is on day and night.

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A more reasonable middle ground between reining in increasing prescription drug costs and preserving freedom of speech would be to forbid mentioning specific products that are not easy to purchase legally in “educational” advertising. That would allow drugmakers to send out messages to inform people with particular symptoms that their problems may now be treatable. Then doctors and their patients could confirm that guess with expert diagnosis and sort through the treatment options—including the one that prompted the drugmaker to send the message.

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I am not a big fan of TV or magazine drug ads, but I was very disappointed in the solutions the editors proposed (including a moratorium for new drugs or an outright ban). We are talking about prescription drugs here, so I have to wonder about the role of my doctor. The editors state that a survey shows that 12 percent of ad viewers walked out of a doctor's office with that drug prescribed, but they say nothing about whether it was the right drug for the patient, the right diagnosis or, most important, whether it turned out to be successful.

We need to find a way for doctors to be fully aware of new drugs and how they fare compared with similar treatments. We also need doctors who will prescribe the right medicine for the diagnosis. If we can't do that, then stopping ads will have no effect, because drug company agents will still be their primary source of information on new medicine.

Humble, Tex.


“Born of Chaos,” by Konstantin Batygin, Gregory Laughlin and Alessandro Morbidelli, asserts that our solar system is unusual in its large orbits and small inner planets and that the typical planetary system has one or more super Earths orbiting closely to a star. But given that the era of discovering extrasolar planets is still in its infancy, with methods that more easily detect planets if they are massive and in tight orbits, how can we be certain that the exoplanets discovered so far are typical?

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Parts of the scenario for the formation of the solar system that the authors describe appear to violate the law of conservation of energy. I can see how planets could migrate inward from aerodynamic drag in the early solar system, but where did all the large planets receive the energy to boost them into much higher orbits? And if Jupiter and Saturn were locked in some resonance duet—for one to move out, the other must move in—they could not both move out or in without the law of conservation of energy again being violated.


THE AUTHORS REPLY: Farson is right that analogues to our solar system cannot be discovered yet, given the limitations of our current observational techniques. But observations show that 70 to 80 percent of the stars we look at have planets with characteristics that we don't have here. We do not know yet whether systems like ours represent the remaining 20 percent, 1 percent or 0.01 percent, because we have not discovered any. So while waiting for an observational answer to this question, we use theoretical modeling to understand which processes sculpted the solar system as it is and how generic these processes could be. If our understanding is correct, its history has been marked by specific events, each of which looks improbable. Thus, we are inclined to think that our solar system is rare, although we are not able to quantify how rare it is.

Regarding Cole's questions: The planets do not migrate by gas drag but rather by their gravitational interaction with the planet-forming disk of gas and dust that surrounds a newborn star. Because the disk inside the orbit of a planet rotates faster than the planet around the star, it pushes that planet outward. Meanwhile the outer disk, which rotates slower than the planet, pushes it inward. Thus, the direction of migration of a planet depends on the relative importance of the inner versus outer disks. In the case of a lonely planet, the inner disk is significantly depleted relative to the outer disk because the planet blocks part of the gas flow from the outer to the inner part, so the outer disk wins.

In the case of Jupiter and Saturn, the gas is conveyed efficiently from the outer to the inner disk, and the inner disk is therefore more massive and moves the two planets outward. The migration of Jupiter and Saturn violates no conservation laws because it is balanced against movements of the disk. If Jupiter and Saturn move outward, the disk moves inward, and vice versa.


In “Who's Responsible When a Car Controls the Wheel?” [Advances], Corinne Iozzio discusses automakers' current plans for, and setbacks in, developing driverless cars. As a practicing engineer, I have to say that all those involved in meaningful research relating to developing safer driving technology should be very proud of the results that are being obtained.

I also have to add that, over the years, I have seen a number of promising areas of research discarded because they were released to the public too soon and without sufficient developmental testing. Iozzio states that “later this year Volvo will roll out the U.S.'s first semiautonomous highway driving feature, called Pilot Assist, on the 2017 S90 sedan.” This “rush to market” approach by Volvo is similar to other catastrophes that I have witnessed in the past.

Because computers are capable of virtually instantaneous communication with other computers (relative to human reaction time), then perhaps the idea of autonomous vehicle operation should be restrained until all the similar computers in all the vehicles within a half-mile radius can communicate with one another. This approach could enable cooperation among vehicles without the need for human intervention.

Honeoye Falls, N.Y.


“Show Venus Some Love,” by Alexander Rodin [Forum], stated that Venus “rotates on its axis once every 224 days.” It does so every 243 days.

“Drawing for a Remedy,” by Jessica Wapner [Advances], incorrectly spelled the name of Sheela Shenoi of Yale University.

“Saving Eden,” by Rachel Nuwer, referred to the WWF as the “World Wildlife Fund for Nature.” The full name of the international organization is the World Wide Fund for Nature.