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Month: March 2018

You’re looking at an image of an enormous ring of debris, 237 light years away from Earth, orbiting a long-studied, young star called HR 4796A. While the bright white ring of debris may be the most visually striking part of the image, astronomers are more excited about what’s around it: the much larger, less-concentrated area of dust around it.

Scientists have long known about the dust and ring surrounding the star. The ring alone is 77 astronomical units in radius, almost twice Pluto’s average distance from our our sun. But a team recently took another look with the Hubble Space Telescope, and learned that the structure was in fact much larger and more complex than they previously thought.

“The resulting images unambiguously reveal the debris ring embedded within a much larger, morphologically complex, and biaxially asymmetric exo-ring scattering structure,” the authors wrote in the paper published recently in The Astronomical Journal. In other words, it’s big and weird-shaped. Check it out:

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The European Space Agency created the world’s first thruster which allows satellites to remain in orbit for years longer than they currently do. The secret? The thruster runs on particles of air in the atmosphere.

Others have tried to improve the staying power of satellites before, but most are still limited by the amount of fuel they can carry. The new ion thruster “breathes” the rare air particles in the top of the atmosphere, allowing the satellites to remain without immediate need for refueling.

The thruster was developed by an ESA team and built by SITAEL, a private company in Italy. The air particles bounce away from satellites normally, but the thruster collects them and gives them an electric charge, after which they are ejected to provide thrust that counteracts atmospheric drag.

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In 1935, when both quantum mechanics and Albert Einstein’s general theory of relativity were young, a little-known Soviet physicist named Matvei Bronstein, just 28 himself, made the first detailed study of the problem of reconciling the two in a quantum theory of gravity. This “possible theory of the world as a whole,” as Bronstein called it, would supplant Einstein’s classical description of gravity, which casts it as curves in the space-time continuum, and rewrite it in the same quantum language as the rest of physics.

Bronstein figured out how to describe gravity in terms of quantized particles, now called gravitons, but only when the force of gravity is weak — that is (in general relativity), when the space-time fabric is so weakly curved that it can be approximated as flat. When gravity is strong, “the situation is quite different,” he wrote. “Without a deep revision of classical notions, it seems hardly possible to extend the quantum theory of gravity also to this domain.”

His words were prophetic. Eighty-three years later, physicists are still trying to understand how space-time curvature emerges on macroscopic scales from a more fundamental, presumably quantum picture of gravity; it’s arguably the deepest question in physics. Perhaps, given the chance, the whip-smart Bronstein might have helped to speed things along. Aside from quantum gravity, he contributed to astrophysics and cosmology, semiconductor theory, and quantum electrodynamics, and he also wrote several science books for children, before being caught up in Stalin’s Great Purge and executed in 1938, at the age of 31.

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First, let’s get some basics out of the way…

What is Transaction Malleability?

Here are 2 explanations of transaction malleability: [Coindesk] [TechTalk]

In a nutshell, Transaction Malleability is a weakness in the original Bitcoin implementation that enables a bad actor to change the unique ID of a bitcoin transaction before it is confirmed on the Blockchain. Such a change makes it possible for someone to pretend that a transaction didn’t happen, if all necessary conditions are in place.

As the Coindesk article points out, a successful attack requires certain conditions that make a successful attack difficult or even unlikely. Many analysts referred to it as a bug that should eventually be fixed, rather than an urgent issue.

Was This Flaw Addressed

Transaction malleability was addressed (for Bitcoin) with the introduction of Segregated Witness (SegWit) in August 2017. 1, 2

But Was There a Successful Attack?
Attack? Yes. Successful? It’s doubtful…

In March 2017, five months before SegWit was implemented, a mining pool that administers 2% of worldwide activity launched a malleability attack. No one lost money – and some individuals believe that they did this to emphasize urgency and hasten the adoption of SegWit.

What About Lightning Network?

The Lightning Network is a ‘Level 2’ network overlay, currently being adopted by miners (depending on the service or exchange, it is being incrementally activated in the first months of 2018). To function properly, it requires that transaction malleability be solved. But, in the event that a miner is not SegWit compliant, it can resolve the malleability problem in other ways.

1 SegWit should not be confused with SegWit2x, an upgrade process that was cancelled a few months later in November. 2017

2 In the TechTalk article linked above, the author concludes:

“Transaction Malleability is fixed with Segregated Witness by no longer taking into account signatures when calculating the transaction’s fingerprint. Fixing Transaction Malleability means that the Lightning Network can work smoothly.”

Philip Raymond co-chairs CRYPSA, hosts the New York Bitcoin Event and presents at
Crypto Conferences around the world. Book a presentation or consulting engagement.

IT’S BREAKING ALL THE RULES. Ordinarily, a supernova marks the death of a mammoth star, which then briefly outshines an entire galaxy before fading away. Not so for a baffling supernova that went off in a nearby galaxy in 2014. Instead of being the end of the story, the stellar explosion inexplicably began to brighten and has since dimmed, then brightened up again four more times.

If that weren’t odd enough, it turns out a supernova blew up in the same place in the sky more than 60 years ago. Somehow, a star that apparently died around the time Elvis Presley released his first record endured only to die again—truly a “living dead” star.

Astrophysicists suspect this apparent stellar zombie was a rare, colossal type of star with 50 to 100 times the mass of our Sun. The universe’s first stars were similarly huge, they think, though these distant objects lie beyond the reach of even our most powerful telescopes. The re-exploding star could, therefore, be a cosmic anachronism, offering scientists an unprecedented glimpse into the primeval universe.

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Like every other major tech company, Google has designs on being the first to achieve quantum supremacy — the point where a quantum computer could run particular algorithms faster than a classical computer. Today it’s announced that it believes its latest research, Bristlecone, is going to be the processor to help it achieve that. According to the Google Quantum AI Lab, it could provide “a compelling proof-of-principle for building larger scale quantum computers.”

One of the biggest obstacles to quantum supremacy is error rates and subsequent scalability. Qubits (the quantum version of traditional bits) are very unstable and can be adversely affected by noise, and most of these systems can only hold a state for less than 100 microseconds. Google believes that quantum supremacy can be “comfortably demonstrated” with 49 qubits and a two-qubit error below 0.5 percent. Previous quantum systems by Google have given two-qubit errors of 0.6 percent, which in theory sounds like a miniscule difference, but in the world of quantum computing remains significant.

However, each Bristlecone chip features 72 qubits, which may help mitigate some of this error, but as Google says, quantum computing isn’t just about qubits. “Operating a device such as Bristlecone at low system error requires harmony between a full stack of technology ranging from software and control electronics to the processor itself,” the team writes in a blog post. “Getting this right requires careful systems engineering over several iterations.”

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Researchers from the Beijing-based technology firm trained its text-to-speech synthesis system on more than 800 hours of audio, taken from around 2,400 different speakers.

To work at its best, Deep Voice requires 100 five-second sections of sound but it can trick a voice recognition system 95 per cent of the time with just ten five-second samples.

The technology could duplicate the voices of people who have lost the ability to use their voice, developers say.

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