Event Horizon Telescope ready to image black hole

Scientists believe they are on the verge of obtaining the first ever picture of a black hole.

They have built an Earth-sized “virtual telescope” by linking a large array of radio receivers – from the South Pole, to Hawaii, to the Americas and Europe.

There is optimism that observations to be conducted during 5-14 April could finally deliver the long-sought prize.

In the sights of the so-called “Event Horizon Telescope” will be the monster black hole at the centre of our galaxy.

Although never seen directly, this object, catalogued as Sagittarius A*, has been determined to exist from the way it influences the orbits of nearby stars.

These race around a point in space at many thousands of km per second, suggesting the hole likely has a mass of about four million times that of the Sun.

But as colossal as that sounds, the “edge” of the black hole – the horizon inside which an immense gravity field traps all light – may be no more than 20 million km or so across.

And at a distance of 26,000 light-years from Earth, this makes Sagittarius A* a tiny pinprick on the sky.

The Event Horizon Telescope (EHT) team is nonetheless bullish.

“There’s great excitement,” said project leader Sheperd Doeleman from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

“We’ve been fashioning our virtual telescope for almost two decades now, and in April we’re going to make the observations that we think have the first real chance of bringing a black hole’s event horizon into focus,” he told BBC News.

The EHT’s trick is a technique called very long baseline array interferometry (VLBI).

This combines a network of widely spaced radio antennas to mimic a telescope aperture that can produce the resolution necessary to perceive a pinprick on the sky.

The EHT is aiming initially to get down to 50 microarcseconds. Team-members talk in analogies, describing the sharpness of vision as being the equivalent of seeing something the size of a grapefruit on the surface of the Moon.

They emphasise the still complex years of work ahead, but also trail the prospect of an imminent breakthrough.

The scientists certainly have an expectation of what they ought to see, if successful.

Simulations rooted in Einstein’s equations predict a bright ring of light fringing a dark feature.

The light would be the emission coming from gas and dust accelerated to high speed and torn apart just before disappearing into the hole.

The dark feature would be the shadow the hole casts on this maelstrom.

“Now, it could be that we will see something different,” Doeleman said.

“As I’ve said before, it’s never a good idea to bet against Einstein, but if we did see something that was very different from what we expect we would have to reassess the theory of gravity.

“I don’t expect that is going to happen, but anything could happen and that’s the beauty of it.”

Over the years, more and more radio astronomy facilities have joined the project. A key recent addition is the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.

Its extraordinary state-of-the-art technology has at a stroke increased the EHT’s sensitivity by a factor of 10. Hence, the optimism ahead of April.

Even so, scientists have had to install special equipment at all the radio facilities involved in the observations.

This includes big hard drives to store colossal volumes of data, and atomic clocks to precisely timestamp it all.

Nothing happens on the spot – the hard drives must first be flown to a large computing facility at MIT Haystack Observatory in Westford, just outside Boston, Massachusetts.

“Our hard-drive modules hold the capacity of about 100 standard laptops,” said Haystack’s Vincent Fish.

“We have multiple modules at each telescope and we have numerous telescopes in the array. So, ultimately, we’re talking about 10,000 laptops of data.”

It is in Haystack’s correlator computer that the synthesis will begin.

Some very smart imaging algorithms have had to be developed to make sense of the EHT’s observations, but it will not be a quick result.

It could be the end of the year, perhaps the start of 2018, before the team releases an image in public.

Looking to the future, the scientists are already thinking about how to extend their techniques.

For example, the matter closest to the event horizon and about to disappear into Sagittarius A* should take about 30 minutes to complete an orbit.

Katie Bouman, from MIT’s Computer Science and Artificial Intelligence Laboratory, thinks it might be possible to capture this movement.

“We want to push boundaries and to try to make movies from the data,” she told BBC News.

“Maybe we can actually see some of the gas flowing around the black hole. That’s really the next stage of what we’re trying to accomplish with these imaging algorithms.”

First and foremost, the team needs good weather at the participating observing stations in April.

The strategy is to view the galactic centre at a wavelength of 1.3mm (230GHz). This has the best chance of piercing any obscuring gas and dust in the vicinity of the black hole. But if there is too much water vapour above the array’s receivers, the EHT will struggle even to see through Earth’s atmosphere.

Just getting a resolved view of Sagittarius A* would be a remarkable triumph in itself. But the real objective here is to use the imaging capability to go test aspects of general relativity.

If there are flaws to be found in Einstein’s ideas – and scientists suspect there are more complete explanations of gravity out there waiting to be discovered – then it is in the extreme environment of black holes that limitations should be exposed.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos

China ‘social credit’: Beijing sets up huge system

In most countries, the existence of a credit system isn’t controversial. Past financial information is used to predict whether individuals will pay their mortgages or credit card bill in the future.

But China is taking the whole concept a few steps further. The Chinese government is building an omnipotent “social credit” system that is meant to rate each citizen’s trustworthiness.

By 2020, everyone in China will be enrolled in a vast national database that compiles fiscal and government information, including minor traffic violations, and distils it into a single number ranking each citizen.

That system isn’t in place yet. For now, the government is watching how eight Chinese companies issue their own “social credit” scores under state-approved pilot projects.

One of the most high-profile projects is by Sesame Credit, the financial wing of Alibaba. With 400 million users, Alibaba is the world’s biggest online shopping platform. It’s using its unique database of consumer information to compile individual “social credit” scores.

Users are encouraged to flaunt their good credit scores to friends, and even potential mates. China’s biggest matchmaking service, Baihe, has teamed up with Sesame to promote clients with good credit scores, giving them prominent spots on the company’s website.

“A person’s appearance is very important,” explains Baihe’s vice-president, Zhuan Yirong. “But it’s more important to be able make a living. Your partner’s fortune guarantees a comfortable life.”

More and more of Baihe’s 90 million clients are displaying their credit scores in their dating profiles, doing away with the idea that a credit score is a private matter.

However, Sesame Credit will not divulge exactly how it calculates its credit scores, explaining that it is a “complex algorithm”.

The company refused to give an interview to the BBC, citing concerns that the government would refuse to grant a permanent licence to issue credit scores if it engaged with the foreign media.

Instead, their spokeswoman issued a statement, discounting persistent rumours that the organisation monitors users’ social media activity when assessing their social credit.

Sesame Credit tracks “financial and consumption activities of our users, and materials published on social media platforms do not affect our users’ personal Sesame Credit score,” explained spokeswoman Miranda Shek.

Sesame rates the online financial transactions of those using Alibaba’s payment system, in addition to data it obtains from its partners including the taxi service Didi Kuaidi, rating whether users bothered to settle taxi payments.

Controversially, the company does not hide that it judges the types of products shoppers buy online.

“Someone who plays video games for 10 hours a day, for example, would be considered an idle person, and someone who frequently buys diapers would be considered as probably a parent, who on balance is more likely to have a sense of responsibility,” Li Yingyun, Sesame’s technology director told Caixin, a Chinese magazine, in February.

The Chinese authorities are watching the pilot process very carefully. The government system won’t be exactly the same as the private systems, but government officials are certainly taking cues from the algorithms developed under the private projects.

A lengthy planning document from China’s elite State Council explains that social credit will “forge a public opinion environment that trust-keeping is glorious”, warning that the “new system will reward those who report acts of breach of trust”.

Details on the inner workings of the system are vague, though it is clear that each citizen and Chinese organisation will be rated. A long list of people in certain professions will face particular scrutiny, including teachers, accountants, journalists and medical doctors. The special list even includes veterinarians and tour guides.

A national database will merge a wide variety of information on every citizen, assessing whether taxes and traffic tickets have been paid, whether academic degrees have been rightly earned and even, it seems, whether females have been instructed to take birth control.

Critics say the social credit system is “nightmarish” and “Orwellian”. However, some believe that some kind of credit system is badly needed in China.

“Many people don’t own houses, cars or credit cards in China, so that kind of information isn’t available to measure,” explains Wen Quan, a blogger who writes about technology and finance.

“The central bank has the financial data from 800 million people, but only 320 million have a traditional credit history.”

‘Very convenient’

Credit systems build trust between all citizens, Wen Quan says.

“Without a system, a conman can commit a crime in one place and then do the same thing again in another place. But a credit system puts people’s past history on the record. It’ll build a better and fairer society,” she promises.

In a trendy neighbourhood in downtown Beijing, many were enthusiastic when asked about their Sesame Credit ratings, proudly displaying them on their mobile phones.

“It is very convenient,” one young woman smiled. “We booked a hotel last night using Sesame Credit and we didn’t need to leave a cash deposit.”

Sesame has promoted the consumer benefits of a good credit score, from a prominent dating profile on the Baihe matchmaking site to VIP reservations with hotels and car rental companies. A mobile phone game designed by Sesame Credit encourages users to guess whether they have higher or lower credit scores than their friends, encouraging everyone to openly share their ratings.

But few people seemed to understand that a bad score could hurt them in the future, preventing them from receiving a bank loan or signing a lease.

And, even more concerning, many didn’t know they were being rated by Sesame at all. For now, the pilot credit system is voluntary, though it’s difficult to circumvent. Online shopping is a part of life in modern Chinese cities and Alibaba’s financial payment service is ubiquitous.

“We repeatedly remind our customers that using Sesame Credit is voluntary,” explains the matchmaking site’s vice president, Zhuan Yirong.

“But people really care about trust and honesty. Alibaba’s data can provide certain kind of proof. It’s not 100% accurate, but at least it’s one more filter for people to know each other better.”

Perhaps it is good for all citizens to learn quickly about the concept of a “social credit” score, while it is still partly voluntary. Within five years, the government’s mandatory system will rank everyone within China’s borders.