dynamicallystatic

Matt Waren, Science Mag:

Scientists have gone to great lengths to make the blackest possible surfaces. But it turns out that nature is pretty good at creating light-absorbing structures, too. WIRED reports that certain male birds of paradise have “superblack” feathers that absorb as much as 99.95% of light. The profoundly black appearance is produced by the microscopic structure of the feathers. Whereas other birds’ feathers have lots of tiny filaments that lie flat and are neatly organized, on the birds of paradise these filaments are tightly packed and bend upward, with deep cavities between them. As light enters the feather, it bounces around these cavities and gradually gets absorbed. Writing in Nature Communications, the scientists speculate that superblack feathers make neighboring, colorful patches on the bird appear even brighter to impress females during courtship.

Great Internet Mersenne Prime Search (GIMPS) on phys.org:

The Great Internet Mersenne Prime Search (GIMPS) has discovered the largest known prime number, 2^77,232,917-1, having 23,249,425 digits.

[…]

The new prime number, also known as M77232917, is calculated by multiplying together 77,232,917 twos, and then subtracting one. It is nearly one million digits larger than the previous record prime number, in a special class of extremely rare prime numbers known as Mersenne primes. It is only the 50th known Mersenne prime ever discovered, each increasingly difficult to find. Mersenne primes were named for the French monk Marin Mersenne, who studied these numbers more than 350 years ago. GIMPS, founded in 1996, has discovered the last 16 Mersenne primes. Volunteers download a free program to search for these primes, with a cash award offered to anyone lucky enough to find a new prime. Prof. Chris Caldwell maintains an authoritative web site on the largest known primes, and has an excellent history of Mersenne primes.

The primality proof took six days of non-stop computing on a PC with an Intel i5-6600 CPU. To prove there were no errors in the prime discovery process, the new prime was independently verified using four different programs on four different hardware configurations.

• Aaron Blosser verified it using Prime95 on an Intel Xeon server in 37 hours.

• David Stanfill verified it using gpuOwL on an AMD RX Vega 64 GPU in 34 hours.
• Andreas Höglund verified the prime using CUDALucas running on NVidia Titan Black GPU in 73 hours.
• Ernst Mayer also verified it using his own program Mlucas on 32-core Xeon server in 82 hours. Andreas Höglund also confirmed using Mlucas running on an Amazon AWS instance in 65 hours.