When scientists consider mysteries they want to solve, they can come up with lists that knock your socks off. The journal Science, for example, has picked 125 such items in honor of its 125th anniversary. These include such mind bogglers as the biological basis of consciousness, what the universe is really made of, and what can replace cheap oil.
Daunting as these quests may be, the overarching challenge for 21st-century science lies elsewhere. The traditional approach to understanding - using basic physical laws to explain the world - isn't working so well. Scientists are beginning to realize they have to account for environmental conditions, historical development, and even human thought to understand how the world we see emerges from underlying law.
This challenge is laid out in an essay by mathematician George Ellis at the University of Cape Town in South Africa. In Physics Today, he notes that the bottom-up approach to understanding "is based on the concept of an isolated system." Scientists experiment on systems isolated from external influences, hoping to identify the essential causes that underlie physical reality. "The problem is that no real physical or biological system is truly isolated, physically or historically," he explains. This approach thus "tends to ignore the kinds of interactions that can trigger the emergence of order, patterns, or properties that do not preexist in the underlying physical substratum."
Quantum mechanics can't predict a bluebird. Einstein's general relativity can't by itself explain the structure of the universe.
Scientists must understand how circumstances channel the operation of physical law. The action of the physics and chemistry of biological organisms, for example, is guided by the need for organisms to adapt to environments. Without that guidance, physics and chemistry alone would not produce that bluebird.
On Earth, human thought has emerged as another guiding factor. This is not mind-over-matter mysticism. It's simply recognition that the essential factor in producing the phenomenon of, say, an airplane is the idea of "airplane" itself. The physics and chemistry that underlie the airplane structure and the aerodynamics that make it fly are channeled by this abstract concept to produce the reality we call air transport.
The impact of human concepts are pervasive on Earth. But "causal models of the real world remain incomplete unless they account for the various effects of intention, purposes, and goals," says Dr. Ellis.
None of the 125 items in Science's list of challenging scientific questions will be answered without taking account of how the complexities they involve emerge from basic laws. (See www.sciencemag.org/sciext/125th.)
Scientists' answers to these questions are likely to be rough approximations of reality. The "pure truth" that researchers once sought remains elusive. Even Newton's laws contain convenient fiction, writes Nobel winner Frank Wilczek in Physics Today. Newton's concept of acceleration has no meaning in quantum physics, he points out. The answers to the 21st-century scientific questions, though useful, will also contain such fictions.