6 Debates at the Frontier of Science

In Scientific American:

Is String Theory Unraveling? ….Some string theorists, taking their cue from Leonard Susskind of Stanford University, argue that these manifold universes of string theory may coexist, evolving from one to another in a way that happens to leave universes like ours as a likely outcome…Skeptics see the landscape as an abandonment of centuries-old scientific practice, in which a successful theory is one that ultimately describes only one universe–the one we see around us

Is Global Warming Raising a Tempest?…[Kerry] Emanuel developed a measure, or metric, of the power released by a storm over its lifetime. As he played with the data he discovered a surprisingly tight match between the surface temperature of the Atlantic Ocean and the intensity of storms that had brewed atop it…What is more, according to his measure, storms in the Atlantic and western North Pacific were 40 to 50 percent more powerful in the last 20 years compared to the previous 20.

How Does A Planet Grow?…One puzzling detail is why Jupiter seems to have a relatively light core of no more than 10 Earth-masses, given that the core accretion model suggests a likely value of 20 to 30 Earth-masses. A decade ago, stimulated by this discrepancy and the discoveries of the first extrasolar planets, astronomer Alan Boss of the Carnegie Institution resurrected an alternative idea.

Should Epidemiologists Swear Off Diet Trials?…The past couple of years have witnessed a string of disappointing results from long-term studies looking for the benefits of certain diets against chronic disease. First, fruits and vegetables showed no sign of protecting against cancer in general. Then high-fiber eaters found themselves as cancer-prone as the rest. To cap it off, a low-fat diet did nothing to ward off heart disease and colorectal cancer.

Does Sprouting New Brain Cells Cure Depression?…In recent years, researchers have discovered tantalizing evidence that antidepressants combat depression by promoting neurogenesis, the growth of new neurons in the brain. The evidence derives from several striking observations…[M]ost depression treatments, from drugs such as Prozac to a type of powerful magnetic stimulation, increase new neuron growth by up to 75 percent in rodents.

Was the Hobbit Just a Sick Modern Human?…Other researchers are not convinced, countering that the Hobbit was more likely a Homo sapiens with a broad pathological condition called microcephaly, in which the brain is abnormally small. Inbreeding could have made such individuals common…