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These greedy black holes just swallowed two neutron stars

One of the best things about being an astronomer is being able to discover something new about the universe. In fact, maybe the only thing better is discovering it twice. And that’s exactly what my colleagues and I have done, by making two separate observations, just ten days apart, of an entirely new type of astronomical phenomenon: a neutron star circling a black hole before being gobbled up.

The two observations were made in January 2020, by the Laser Interferometer Gravitational-wave Observatory (LIGO) and the Virgo Observatory, both of which detect gravitational waves from the distant cosmos.

After 18 months of painstaking analysis, our discoveries are published today in The Astrophysics Journal Letters. The new observations open up new avenues to study the life cycle of stars, the nature of space-time, and the behavior of matter at extreme pressures and densities.

The first observation of a neutron star-black hole system was made on January 5 2020. LIGO and Virgo observed gravitational waves — distortions in the very fabric of space-time — produced by the final 30 seconds of the dying orbit of the neutron star and black hole, followed by their inevitable collision. The discovery is named GW200105.

Remarkably, just ten days later, LIGO and Virgo detected gravitational waves from a second collision between a neutron star and a black hole. This event is named GW200115. Both collisions happened around 900 million years ago, long before the first dinosaurs appeared on Earth.

Artist’s impression of a neutron star orbiting and colliding with a black hole – Carl Knox/OzGrav/Swinburne Univ.

Neutron stars and black holes are among the most extreme objects in the universe. They are the fossil relics of massive dead stars. When a star that is more than eight times as massive as the Sun runs out of fuel, it undergoes a spectacular explosion called a supernova. What remains can be a neutron star or a black hole.

Neutron stars are typically between 1.5 and 2 times as massive as the Sun but are so dense that all their mass is packed into an object the size of a city. At this density, atoms can no longer sustain their structure and dissolve into a stream of free quarks and gluons: the building blocks of protons and neutrons.

Black holes are even more extreme. There is no upper limit to how massive a black hole can be, but all black holes have two things in common: a point of no return at their surface called an “event horizon”, from which not even light can escape; and a point at their center called a “singularity”, at which the laws of physics as we understand them, break down.

It is fair to say black holes are an enigma. One of the holy grails of 21st-century physics and astronomy is to find a deeper understanding of the laws of nature by observing these strange and extreme objects.

A new type of star system

Neutron stars orbiting black hole companions have long been thought to exist. LIGO and Virgo had been searching for them for more than a decade, but they have remained elusive until now.

So why are we so confident we’ve now seen not one such system, but two?

When LIGO and Virgo observe gravitational waves, the first question on our minds is “what caused them?” To find that out, we use two things: our observational data, and supercomputer simulations of different types of astronomical events that could plausibly explain those data.

By comparing the simulations to our real observations, we look for those characteristics that best match our data, homing in on the likely ones and ruling out the unlikely ones.

For the first discovery (GW200105), we determined that the most likely source of the gravitational waves was the final few orbits, and eventual collision, between an object around 8.9 times the mass of the Sun, with an object around 1.9 times the mass of the Sun. Given the masses involved, the most plausible explanation is that the heavier object is a black hole, and the lighter one is a neutron star.

Similarly, from the second (GW200115), we determined that its most likely source was the final few orbits and collision of a 5.7-solar-mass black hole with a 1.5-solar-mass neutron star.

There is no definitive smoking gun that the lighter objects are neutron stars, and in principle, they could be very light black holes, although we consider this explanation unlikely. By far the best hypothesis is that our new observations are consistent with the merger of neutron stars and black holes.

Stellar fossil-hunting

Our discoveries have several intriguing implications. Neutron star-black hole systems allow us to piece together the evolutionary history of stars. Gravitational-wave astronomers are like stellar fossil-hunters, using the relics of exploded stars to understand how massive stars form, live, and die.

We have been doing this for several years with LIGO/Virgo’s observations of pairs of black holes and pairs of neutron stars. The newly discovered rarer pairs, containing one of each, are fascinating pieces of the stellar fossil record.

For the first time, we have directly measured the rate at which neutron stars merge with black holes: we think there are likely to be tens or hundreds of thousands of such collisions across the universe per year. With more observations, we will measure the rate more precisely.

What happens to the neutron stars after they’ve been gobbled up? Now we’re really looking at the laws of nature turned up to 11. When neutron stars merge with black holes, they are deformed, imprinting information about their exotic form of matter onto the gravitational waves we observe on Earth.

This can reveal the composition of neutron stars, which in turn tells us about how quarks and gluons behave at extreme pressure and density. It doesn’t tell us what’s going on behind the black hole’s event horizon, although another aspect of our discoveries is that we can look for hints of new physics in black holes in the gravitational-wave signals.

When LIGO and Virgo resume observing in mid-2022 after an upgrade to boost their sensitivity still further, we will see more collisions between neutron stars and black holes. In the coming decade, we expect to amass thousands more gravitational-wave detections.

Over time we hope to piece together the laws of nature that will help us understand the inner workings of the most extreme and impenetrable objects in the universe.

Article by Rory Smith, Lecturer in Astrophysics, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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New superstring theory says black holes may be portals to other universes

We don’t know very much about our universe. We’re fairly certain it exists, but we don’t know how it got here, how long it’s been here, or how big it is. Heck, we don’t even know if our universe is unique.

Ever since Albert Einstein came up with the theory of relativity and other scientists realized that classical physics and quantum mechanics don’t really line up, we’ve been trying to reconcile those worlds.

Many theoretical physicists believe that bridging the gap between obvious reality (classical physics) and the wacky quantum realm could help us finally understand the true nature of our universe.

What’s the big idea?

As far as we know, there’s no such thing as a “god’s eye view”of the universe. We can’t just zoom out in space and time and figure out what’s going on like we’re dealing with a 3D model.

Instead, we have to use math to describe all the features of the universe beyond those we can directly measure with sensors and observations. Basically, scientists take the cosmic events they can observe and measure, and use them as data-points to help inform hypotheses about all the things that could happen beyond our field of observation.

And, when it comes to describing the universe, we need a theoretical framework that can unify classical and quantum physics with an explanation that makes sense of mysterious occurrences in both worlds. That’s where singularities come in.

Why black holes though?

Einstein and his longtime research partner Roger Penrose spent a lot of effort trying to figure out singularities because they’re among the most powerful, exotic objects in existence that we know of. They literally bend light, space, and time. If we can figure out what’s really going on inside a black hole, we’ll be well on our way to determining what’s happening everywhere else in our universe.

The problem: We have absolutely no idea how to physically study a black hole. As far as we know, anything that gets close enough to slip over the event horizon of a singularity is gone forever.

Scientists have long posited that black holes could contain exotic space materials that could have been present at the universe’s genesis event – most commonly thought to be the “Big Bang.”

But, that’s just a guess. As to what’s actually inside of them: we can only theorize.

Any good theories?

M-theory, or string theory, has long been considered a strong candidate for unifying quantum and classical physics. At the risk of grossly oversimplifying, string theory is exactly what it sounds like: instead of being made up of infinite particles, the universe is made up of strings that connect everything to everything else.

And then there’s superstring theory. This adds supersymmetry to the mix which, again grossly oversimplified, accounts for fermions and bosons, particulate objects that are essential to quantum mechanics.

How’s it work?

An international team of researchers recently published a pre-print paper that uses superstring theory to posit a unified explanation of classical and quantum physics that not only explains the origin story for our universe, it also theorizes the existence of innumerable other universes.

And it all relies on black holes.

Per the team’s paper:

We show that an S-Brane which arises in the inside of the black hole horizon when the Weyl curvature reaches the string scale induces a continuous transition between the inside of the black hole and the beginning of a new universe.

This provides a simultaneous resolution of both the black hole and Big Bang singularities.

And there you have it, in one fell swoop we’ve figured out that rather than being destructive vacuums from which nothing can escape, black holes are objects of creation. They’re pregnant with young universes that, one far away day, could mature to contain stars and planets and life just like our own.

For real?

No. Not really. I mean, maybe. The scientists aren’t saying any of this is true. In fact, this pre-print paper isn’t actually saying anything is true: it’s positing mathematical possibilities that could explain why black holes act the way they do.

One the one hand, they could just be sucking everything into them, as Einstein figured, because of regular old gravity-related stuff. That’s pretty much what relativity is; the more massive something is, the more powerful its gravitational pull should be. And black holes are incredibly massive.

But, if they are just acting out extreme classical physics, then we have no way of explaining how they function in the quantum realm. And the problem with that is, we’re pretty sure quantum mechanics drives the machinations of black holes.

So we need a better answer.

And even though superstring theory and the idea that black holes exist to feed energy (or dark energy maybe?) to other universes might seem unbelievable, it does make a modicum of sense.

The bulk of the paper is dedicated to describing the theory in mathematical terms, so the physicists do show their proverbial work. But, because this is a pre-print, it’s still awaiting recognizable peer-review. And we should take everything it says with a grain of salt until then.  

Ultimately, this is a pretty wacky take on the typical theory of everything. But Occam’s Razor tells us the simplest explanation is often the correct one. And when you see a giant tear in the fabric of the universe that appears to be pouring unfathomable amounts of energy somewhere, it makes sense to make the basic assumption it’s a portal.

H/t: Interesting Engineering

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Google has a secret blocklist that hides YouTube hate videos from advertisers — but it’s full of holes

This story is the first of two parts.

If you want to find YouTube videos related to “KKK” to advertise on, Google Ads will block you. But the company failed to block dozens of other hate and White nationalist terms and slogans, an investigation by The Markup has found.

Using a list of 86 hate-related terms we compiled with the help of experts, we discovered that Google uses a blocklist to try to stop advertisers from building YouTube ad campaigns around hate terms. But less than a third of the terms on our list were blocked when we conducted our investigation.

Google Ads suggested millions upon millions of YouTube videos to advertisers purchasing ads related to the terms “White power,” the fascist slogan “blood and soil,” and the far-right call to violence “racial holy war.”

The company even suggested videos for campaigns with terms that it clearly finds problematic, such as “great replacement.” YouTube slaps Wikipedia boxes on videos about the “the great replacement,” noting that it’s “a white nationalist far-right conspiracy theory.”

Some of the hundreds of millions of videos that the company suggested for ad placements related to these hate terms contained overt racism and bigotry, including multiple videos featuring re-posted content from the neo-Nazi podcast The Daily Shoah, whose official channel was suspended by YouTube in 2019 for hate speech. Google’s top video suggestions for these hate terms returned many news videos and some anti-hate content—but also dozens of videos from channels that researchers labeled as espousing hate or White nationalist views.

“The idea that they sell is that they’re guiding advertisers and content creators toward less controversial content,” said Nandini Jammi, who co-founded the advocacy group Sleeping Giants, which uses social media to pressure companies to stop advertising on right-wing media websites and now runs the digital marketing consulting firm Check My Ads.

“But the reality on the ground is that it’s not being implemented that way,” she added. “If you’re using keyword technology and you’re not keeping track of the keywords that the bad guys are using, then you’re not going to find the bad stuff.”

‘Offensive and harmful’

When we approached Google with our findings, the company blocked another 44 of the hate terms on our list.

“We fully acknowledge that the functionality for finding ad placements in Google Ads did not work as intended,” company spokesperson Christopher Lawton wrote in an email; “these terms are offensive and harmful and should not have been searchable. Our teams have addressed the issue and blocked terms that violate our enforcement policies.”

“We take the issue of hate and harassment very seriously,” he added, “and condemn it in the strongest terms possible.”

Even after Lawton made that statement, 14 of the hate terms on our list—about one in six of them—remained available to search for videos for ad placements on Google Ads, including the anti-Black meme “we wuz kangz”; the neo-Nazi appropriated symbol “black sun”; “red ice tv,” a White nationalist media outlet that YouTube banned from its platform in 2019; and the White nationalist slogans “you will not replace us” and “diversity is a code word for anti-white.”

We again emailed Lawton asking why these terms remained available. He did not respond, but Google quietly removed 11 more hate terms, leaving only the White nationalist slogan “you will not replace us,” “American Renaissance” (the name of a publication the Anti-Defamation League describes as White supremacist), and the anti-Semitic meme “open borders for Israel.”

Blocking future investigations

Google also responded by shutting the door to future similar investigations into keyword blocking on Google Ads. The newly blocked terms are indistinguishable in Google’s code from searches for which there are no related videos, such as a string of gibberish. This was not the case when we conducted our investigation.

YouTube has faced repeated criticism for years over its handling of hate content, including boycotts by advertisers who were angry about their ads running next to offensive videos. The company responded by promising reforms, including taking down hate content. Most of the advertisers have returned, and the company reports that advertising on YouTube generates nearly $20 billion in annual revenues for Google.

In addition to overlooking common hate terms, we discovered that almost all the blocks Google had implemented were weak. They did not account for simple workarounds, such as pluralizing a singular word, changing a suffix, or removing spaces between words. “Aryan nation,” “globalist Jews,” “White pride,” “White pill,” and “White genocide” were all blocked from advertisers as two words but together resulted in hundreds of thousands of video recommendations once we removed the spaces between the words.

Credit: The Markup
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Researchers discover huge security holes in Amazon’s ‘skills’ for Alexa

You might want to place a moratorium on using Alexa’s ‘skills’ until Amazon can sort out some gaping privacy holes in its third-party access.

According to a study published today by a team of researchers from North Carolina State University, your personal data – including, potentially, your banking information and contact lists – could be at risk if you’ve installed any third-party skills from the Alexa skills marketplace.

First things first: Skills are Alexa’s versions of apps. They’re useful for everything from controlling third-party hardware gadgets such as smart lights or smart thermostats to logging in to your bank account using voice-command via Alexa.

The only reason the issues raised by the researchers don’t constitute a red-alert situation is that we’re currently unaware of any evidence these security risks have been maliciously exploited. That being said, you might want to uninstall all your third-party Alexa skills until Amazon issues assurance the privacy holes have been plugged.

The problem: Simply put, Amazon doesn’t appear to properly vet third-party skills developers. That means there’s no verification in place to ensure the person or company selling or giving you a skill is who they say they are. Apparently, the system’s set up so that you might think you’re using a skill from your smart thermostat or smart lock manufacturer when in fact you’re being duped by a shady imitator.

It gets worse. The researchers also found that developers can use redundant wake words. In the worst case here, you might be fooled into thinking you’re giving your information to a company you trust because you used an invocation phrase like “Alexa, open the Blah Blah Blah Banking app” when in reality someone’s aped that phrase for nefarious purposes.

Finally, in what could be the most glaring security , according to the researchers Amazon allows third-party skills publishers to change their privacy policies after gaining approval and publishing. Per a university press release:

The researchers demonstrated that developers can change the code on the back end of skills after the skill has been placed in stores. Specifically, the researchers published a skill and then modified the code to request additional information from users after the skill was approved by Amazon.

Quick take: Our advice to anyone who uses an Alexa-enabled device is to go to your Amazon account and ensure you’re not using any third-party skills. At least until Amazon addresses the problems raised by the researchers.

Luckily, it’s really easy to do this.

  • Step one: Log into your Amazon account
  • Step two: Search for “Alexa skills” and click the top result

 

 

  • Step three: click on “Your Skills” and make sure you’re not using any third-party skills.

 

We’ve reached out to Amazon for comment and we’ll update this article as soon as we hear back.

You can read the full paper here.

Edit 1:35 PST 4 February 2021: An Amazon spokesperson gave us the following statement:

The security of our devices and services is a top priority. We conduct security reviews as part of skill certification and have systems in place to continually monitor live skills for potentially malicious behavior. Any offending skills we identify are blocked during certification or quickly deactivated. We are constantly improving these mechanisms to further protect our customers. We appreciate the work of independent researchers who help bring potential issues to our attention.

Published March 4, 2021 — 18:45 UTC



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Supercomputers (and a few humans) create sky map of 25,000 black holes

Astronomers have used a combination of low-frequency telescopes, supercomputers, and algorithms to create a vast sky map of 25,000 supermassive black holes.

The map shows thousands of twinkling dots that look like stars, but are actually enormous black holes, each of which is located in a different, distant galaxy.

The researchers pinpointed the celestial objects by analyzing radio emissions emitted by matter that was ejected when it got close to the black holes.

Credit: LOFAR/LOL Survey