We have two eyes and each differ in their optical properties - you can easily tell by placing a hand over each and seeing the difference.

As a result of the fits and starts and do-overs in evolution that got us eyes, our vision system results in a blur projected in each retina and then the visual system calibrates itself to give us a clear picture. In the past, researchers had people where glasses where images were upside down. Eventually, our brains compensated and the images were correct - until people took off the glasses. 

Medical marijuana usage has been proliferating across the United States, primarily due to claims about pain management, but the demographics are baffling. Though women have 60 percent of medical visits for pain, 80 percent of medical marijuana prescriptions for pain have been men. 

Yet in instances where the prescriptions have been real, tolerance develops quickly, which means people are inhaling more and more carcinogens, and there are numerous other side effects. 

The concept of randomness has intrigued great minds for as long as history of great thinkers has been recorded.  From the nature of wind to drunks running into lampposts on their way home, scholars have been intrigued with making random predictable. 

A group of chemists say they have challenged traditional interpretations of randomness by computationally generating random and mechanically rigid arrangements of two-dimensional hard disks, think pennies with no thickness, for the first time.

Researchers say they have clear and detailed evidence of the inequitable delivery of mental health care services for disadvantaged Australians. Introduced in 1975, Australia's national health insurance scheme Medicare (originally Medibank) was envisioned to deliver the most equitable and efficient means of providing health insurance coverage for all Australians.

For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, sometimes take the form of calcite, and at other times form a chemically identical form of the mineral, called aragonite, that is more soluble -- and therefore more vulnerable to ocean acidification?

High up in the high Andes mountains of Argentina, a population has adapted to tolerate the toxic chemical arsenic. 

For thousands of years, in some regions of the Andes, people have been exposed to high levels of it, because arsenic in volcanic bedrock is released into the groundwater.

How could this population adapt to tolerate arsenic, a potent killer of such ill repute that it's often the overused plot-driver of many murder mysteries?