Stephen Hawking’s final paper about black holes is now online

Stephen Hawking passed away earlier this year at the age of 76, but his incredible intellect isn’t yet done contributing to the scientific community. The acclaimed physicist’s final paper is now online for anyone to read and it revisits some mysteries of the physical world that came to define his illustrious career. Titled “Black Hole […]

Stephen Hawking href="https://techcrunch.com/2018/03/13/stephen-hawking-has-died-at-76/"> passed away earlier this year at the age of 76, but his incredible intellect isn’t yet done contributing to the scientific community. The acclaimed physicist’s final paper is now online for anyone to read and it revisits some mysteries of the physical world that came to define his illustrious career.

Titled “Black Hole Entropy and Soft Hair,” the paper was co-authored by Hawking collaborators Sasha Haco, Malcolm Perry and Andrew Strominger. The paper is available free on pre-publication repository ArXiv and includes a touching tribute to Hawking.

“We are deeply saddened to lose our much-loved friend and collaborator Stephen Hawking whose contributions to black hole physics remained vitally stimulating to the very end,” it reads.

The paper serves as a kind of bookend to Hawking’s career, collecting some of his final work on the quantum structure of black holes — a topic that Hawking pursued throughout the last 40 years.

It’s fitting that Hawking’s last paper would be a technical dive into one of the greatest unresolved questions in physics — and one he posed to begin with: Can matter that falls into a black hole truly disappear, even though according to the laws of physics that should be impossible? The paradox is troubling because it pits the laws of quantum mechanics against those of general relativity.

In the paper, Hawking and his colleagues proposed that something called “soft hair” could resolve that tension. The “hair” refers to photons at the event horizon, the edge of a black hole. In the soft hair version of events, the so-called hair on the black hole’s border would actually store information about the matter that had fallen into the black hole. That would mean the information attached to that matter wasn’t deleted from the universe at all, rather that it only appeared to vanish beyond an apparent horizon.

“It’s a step on the way, but it is definitely not the entire answer,” co-author Malcolm Perry told the Guardian. “We have slightly fewer puzzles than we had before, but there are definitely some perplexing issues left.”

SETI neural networks spot dozens of new mysterious signals emanating from distant galaxy

The perennial optimists at the Search for Extraterrestrial Intelligence, or SETI, have joined the rest of the world in deploying AI to help manage huge datasets — and their efforts almost instantly bore fruit. 72 new “fast radio bursts” from a mysteriously noisy galaxy 3 billion miles away were discovered in previously-analyzed data by using a custom machine learning model.

The perennial optimists at the Search for Extraterrestrial Intelligence, or SETI, have joined the rest of the world in deploying AI to help manage huge data sets — and their efforts almost instantly bore fruit. Seventy-two new “fast radio bursts” from a mysteriously noisy galaxy 3 billion miles away were discovered in previously analyzed data by using a custom machine learning model.

To be clear, this isn’t Morse code or encrypted instructions to build a teleporter, à la Contact, or at least not that we know of. But these fast radio bursts, or FRBs, are poorly understood and may very well represent, at the very least, some hitherto unobserved cosmic phenomenon. FRB 121102 is the only stellar object known to give off the signals regularly, and so is the target of continued observation.

The data comes from the Green Bank Telescope in West Virginia (above), which was pointed toward this source of fast and bright (hence the name) bursts for five hours in August of 2017. Believe it or not, that five-hour session yielded 400 terabytes of transmission data.

Initial “standard” algorithms identified 21 FRBs, all happening in one hour’s worth of the observations. But Gerry Zhang, a graduate student at UC Berkeley and part of the Breakthrough Listen project, created a convolutional neural network system that would theoretically scour the data set more effectively. Sure enough, the machine learning model picked out 72 more FRBs in the same period.

A Berkeley GIF visualizing the data of a series of bursts.

That’s quite an improvement, though it’s worth noting that without manual and traditional methods to find an initial set of interesting data, we would have little with which to train such neural networks. They’re complementary tools; one is not necessarily succeeding the other.

The paper on the discoveries, co-authored by Cal postdoc Vishal Gajjar, is due to be published in the Astrophysical Journal. Breakthrough Listen is one of the initiatives funded by billionaires Yuri and Julia Milner, of mail.ru and DST fame. The organization posted its own press release for the work.

The new data suggests that the signals are not being received in any kind of pattern we can determine, at least no pattern longer than 10 milliseconds. That may sound discouraging, but it’s just as important to rule things out as it is to find something new.

“Gerry’s work is exciting not just because it helps us understand the dynamic behavior of FRBs in more detail, but also because of the promise it shows for using machine learning to detect signals missed by classical algorithms,” explained Berkeley’s Andrew Siemion, who leads the SETI research center there and is principal investigator for Breakthrough Listen.

And if we’re being imaginative, there’s no reason some hyper-advanced civilization couldn’t cram a bunch of interesting info into such short bursts, or use a pattern we haven’t yet grokked. We don’t know what we don’t know, after all.

Whatever the case, SETI and Breakthrough will continue to keep their antennas fastened on FRB 121102. Even if they don’t turn out to be alien SOS signals, it’s good solid science. You can keep up with the Berkeley SETI center’s work right here.

With moon mining, space tourism and colonization on the horizon, Star Trek is only years away

“Where we are at the beginning of this century is where Star Trek begins,” says Alan Stern, the NASA researcher who was one of the architects of the New Horizons mission to Pluto.  In an age where science fiction is rapidly becoming a simple fact, Stern says moon mining, extra-terrestrial energy generation and space tourism […]

“Where we are at the beginning of this century is where Star Trek begins,” says Alan Stern, the NASA researcher who was one of the architects of the New Horizons mission to Pluto

In an age where science fiction is rapidly becoming a simple fact, Stern says moon mining, extra-terrestrial energy generation and space tourism are just around the corner. As the colonization of space progresses, Stern says that moon mining will be one of the first applications of our burgeoning commercial space industry.

“Platinum is abundant on the moon and other rare earths that we have to strip mine on Earth,” Stern said on the Next Stage at TechCrunch Disrupt SF. “It’s lying there waiting for us on the moon. It’s a tremendous opportunity to quit mining the Earth and instead take advantage of the tremendous resources that the solar system presents us.”

Mining may be one of the early commercial applications of the new space industry, but it’s certainly not the only one.

“We need to think of the next decade of space as the Roaring ’20s,” says Stern. “Access to space for humans is still rare, but that’s going to change.”

The NASA scientist himself has already bought three tickets on Virgin Galactic to enjoy the marvels of space for the first time.

Indeed, space tourism has been a thing in the space industry for a while — albeit one that was haltingly adopted by the masses. It started in the 1990s when Helen Sharman was flown to the Russian space station. But Stern predicts that next year will launch the industry in earnest.

“Beginning next year we should see companies like Blue Origin and Virgin Galactic start flying sub-orbital flights,” Stern says. “I hope to see sub-orbital tourism flying at least once a day by the early 2020s.”

And with new startups reducing the costs of space travel, the pace of launches for the space industry should increase exponentially, Stern says. “I want to see not a launch a week, not a launch a day, but a launch an hour. We ought to be able to use space to reduce travel times to 45 minutes anywhere in the world.”

Companies like Relativity Space, Vector and others are developing new launch technologies that could compete with the established giants like Virgin Galactic, Blue Origin and the leading space launch company of the moment, SpaceX.