The Earth exists in a dangerous environment. Cosmic bodies, like asteroids and comets, are constantly zooming through space and often crash into our planet. Most of these are too small to pose a threat, but some can be cause for concern.

To date, NASA has tracked only an estimated 40% of the bigger ones. Surprise asteroids have visited Earth in the past and will undoubtedly do so in the future. When they do appear, how prepared will humanity be?

The threat from asteroids and comets

Millions of objects of various sizes orbit the Sun...

Computers are an indispensable part of our daily lives, and the need for ones that can work faster, solve complex problems more efficiently, and leave smaller environmental footprints by minimizing the required energy for computation is increasingly urgent. Recent progress in photonics has shown that it’s possible to achieve more efficient computing through optical devices that use interactions between metamaterials and light waves to apply mathematical operations of interest on the input signals, and even solve complex mathematical problems...

Between 30 and 60 minutes of muscle strengthening activity every week is linked to a 10-20% lower risk of death from all causes, and from cardiovascular disease, diabetes, and cancer, in particular, finds a pooled data analysis of the available evidence, published online in the British Journal of Sports Medicine.

The findings are independent of aerobic exercise. But the analysis points to a J-shaped curve for most outcomes, with no conclusive evidence that more than an hour a week of muscle strengthening activity reduces the risk further still.

Physical activity guidelines recommend regular muscle strengthening activities for adults, primarily because of the known benefits for skeletal muscle health...

For the first time, Northwestern University-led astronomers may have detected an afterglow from a kilonova. A kilonova occurs when two neutron stars—some of the densest objects in the universe—merge to create a blast 1,000 times brighter than a classical nova. In this case, a narrow, off-axis jet of high-energy particles accompanied the merger event, dubbed GW170817. Three-and-a-half years after the merger, the jet faded away, revealing a new source of mysterious X-rays.

As the leading explanation for the new X-ray source, astrophysicists believe expanding debris from the merger generated a shock—similar to the sonic boom f...