Month: June 2020

Enlarge / Artist's concept of a supermassive black hole and its surrounding accretion disk of gas. Embedded within this disk are two smaller black holes, orbiting one another, that eventually collided and may have produced a detectable burst of light. (credit: Caltech/R. Hurt (IPAC))

One of the most defining characteristics of a black hole is that nothing can escape once it passes the event horizon—not even light. So one would expect the same to be true when two black holes collide and merge. But some astronomers have posited that there could be unusual conditions in which such a merger could produce an accompanying explosion of light. By combining gravitational wave data with data collected during a robotic sky survey, one team thinks it has found the first evidence of such a phenomenon, according to a new paper in Physical Review Letters.

LIGO detects gravitational waves via laser interferometry, using high-powered lasers to measure tiny changes in the distance between two objects positioned kilometers apart. (LIGO has detectors in Hanford, Washington, and in Livingston, Louisiana. A third detector in Italy, Advanced VIRGO, came online in 2016.) On September 14, 2015, at 5:51am EST, both detectors picked up signals within milliseconds of each other for the very first time—direct evidence for two black holes spiraling inward toward each other and merging in a massive collision event that sent powerful shockwaves across spacetime.

The collaboration picked up two more black-hole mergers from that first run. The second run, from November 30, 2016, to August 25, 2017, produced seven more binary black-hole mergers (including the four just announced) and a binary neutron-star merger, supported by a simultaneous gamma-ray burst and signals in the rest of the electromagnetic spectrum, dubbed a "kilonova." It was an unprecedented recording of a major celestial event, combining light and sound, and officially marked the dawn of so-called "multi-messenger astronomy."

Enlarge / The Facebook app displayed on the screen of an iPhone. (credit: Fabian Sommer | picture alliance | Getty Images)

A leading Facebook executive has told advertisers the company is suffering from a “trust deficit” as it tries to stop brands joining a boycott over its policies on political content moderation.

The world’s largest social media group joined a conference call with almost 200 advertisers on Tuesday, according to people familiar with the discussion. Senior policy executives then defended Facebook’s decision to allow several controversial posts from US president Donald Trump to remain on its platform.

According to leaked audio of the call obtained by the Financial Times, Neil Potts, Facebook’s head of trust and safety policy, acknowledged that the company suffered from a “trust deficit” but added that it was “here to listen” to its clients’ concerns. The call was convened by the Interactive Advertising Bureau trade body in Canada.

Enlarge (credit: Getty Images | Anadolu Agency)

Comcast is partnering with Mozilla to deploy encrypted DNS lookups on the Firefox browser, the companies announced today. Comcast's version of DNS over HTTPS (DoH) will be turned on by default for Firefox users on Comcast's broadband network, but people will be able to switch to other options like Cloudflare and NextDNS. No availability date was announced.

Comcast is the first ISP to join Firefox's Trusted Recursive Resolver (TRR) program, Mozilla said in today's announcement. Cloudflare and NextDNS were already in Mozilla's program, which requires encrypted-DNS providers to meet privacy and transparency criteria and pledge not to block or filter domains by default "unless specifically required by law in the jurisdiction in which the resolver operates."

"Adding ISPs in the TRR program paves the way for providing customers with the security of trusted DNS resolution, while also offering the benefits of a resolver provided by their ISP such as parental control services and better optimized, localized results," the announcement said. "Mozilla and Comcast will be jointly running tests to inform how Firefox can assign the best available TRR to each user."