Scientists move closer to understanding the dual fates of embryonic stem cells — to divide or develop

Reverting adult cells to an embryonic state without creating embryos is a tricky business (p. 16)

A century ago, mathematician Hermann Minkowski famously merged space with time, establishing a new foundation for physics; today physicists are rethinking how the two should fit together

Successful heart transplant experiment in infants draws attention to debate on defining death of organ donors.

A panel of scientists involved in the anthrax investigations released new details.

Free radicals similar to those in cigarette smoke may form when car exhaust cools off, and may persist indefinitely in the air.

Some magpies recognize themselves in mirrors, indicating that a basic form of self-recognition evolved in one family of birds.

Species vulnerable to enslavement may evolve ways to fight their captors.

A reward chemical in the brain helps keep sleep-deprived people awake. (p. 11)

A new study suggests that a surprising number of universes, even those with laws of physics different from those in our universe, can still support stars.

Possible comet may be distant visitor from the innermost region of the Oort Cloud, the proposed comet reservoir of the outermost solar system.

Faint yet distinct ground motions recorded by a large network of seismic instruments in Japan in early 2006 are the strongest, most direct evidence that Earth’s inner core is solid. (p. 14)

Herds of grazing and resting deer and cattle tend to align themselves with the Earth’s magnetic field, a hint that the large mammals can somehow sense the invisible field.

The chemical bisphenol A may raise the risk of heart attacks and type 2 diabetes by suppressing a protective hormone. (p. 15)