London pioneered video surveillance in public, but it’s catching on fast. Many major cities have systems, and more are coming. What do these cameras learn? How do they interact with other sources of data? In this culture of disclosure should we even worry about privacy?

As Earth warms, should we try huge geoengineering projects to cool the climate? Would adding iron to fertilize ocean plants withdraw enough carbon dioxide to slow warming — or backfire?

Happy Thanksgiving! We celebrate eating — and food. Hungry: Is that your “food clock” ringing? Why does a fruitfly need to smell? How does bitter taste to you? And could eating MSG make you fat?

After World War II, the “green revolution” sparked an explosion in farm output in developing countries. With soaring food prices and spreading food riots, what can we learn from the green revolution?

Pilot errors have dropped 40 percent over 20 years, but on-the-ground accidents have increased. Why have pilot errors declined? What work remains to increase airline safety?

California’s fires are a tragedy, but are human actions making them worse? What is the role of global warming and zoning? Can we build safer houses in safer locations?

Most adhesives can’t be reused. But a radical new design, based on the foot of frogs, lizards and insects, shows how engineers can learn from nature to make smarter materials.

It’s a fact of life: Hurricanes and floods happen. So why are people rebuilding in the path of storms and floods? Is there a smarter way to plan development?

Trucks create a lot of turbulence at the rear. Can a simple set of plates reduce this turbulence and save 10 percent on an 18-wheeler’s fuel bill?

The solar clock doesn’t quite line up with the atomic clock. We use leap seconds to make them match. Should we dump the leap second?