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Here’s Why Black Holes Are Crullers, Not Donuts

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It’s been over 100 years since the first solution for a black hole was discovered in General Relativity. For generations, scientists argued over whether these objects were physical, existing all throughout our Universe, or whether they were mere mathematical artifacts. In the 1960s, Roger Penrose’s Nobel-winning work demonstrated how black holes could realistically form in our Universe, and shortly thereafter, the first black hole — Cygnus X-1 — was discovered.

Black holes are now known to range from just a few times the mass of our Sun up to many billions of solar masses, with most galaxies housing supermassive black holes at their centers. In 2017, a tremendous observing campaign was coordinated between a large number of radio telescopes around the world in an attempt to directly image a black hole’s event horizon for the first time. That first image was released in 2019, revealing a donut-like shape surrounding the interior void. Now, a new series of papers has improved upon that image, and we can see it’s not a donut, but rather a cruller, with sweeping magnetic “lines” tracing out the hot plasma. Here’s the new science behind this epic image, and why black holes are crullers, not donuts.

In our Universe, black holes aren’t merely clumps of mass that have collapsed under their own gravity to a single point. In space, all forms of matter exert gravitational forces on one another, and whenever objects interact in this way, they attract the “closer” parts of the object by a greater amount than the “farther” parts of it. This type of force — known as a tidal force — isn’t just responsible for tides, but also for causing a torque: a change in the angular momentum of an object. As a result, everything that exists in the Universe rotates, or spins, rather than remaining stationary.

This means that the black holes that we form aren’t stationary and non-rotating, but rather spin about some axis. Indirect measurements had previously indicated that black holes spin relativistically: close to the speed of light. However, the major idea of the Event Horizon Telescope is that, regardless of how this spinning black hole is oriented, there will be light emitted from the surrounding matter that just “grazes” the event horizon, and goes off in a straight line, creating a photon ring for us to observe that encircles the dark center, from where no light can escape. (For reasons related to the curvature of space, the size of this dark center is actually more like ~250% the diameter of the physical event horizon.)

The way we went about imaging this was a tremendous technological achievement. We needed to take an array of radio images (at millimeter-submillimeter wavelengths) from all around the globe at once. This gave us the light-gathering power of all the telescopes that were part of the array, combined, but gave us the resolution of the maximum separation between the various telescopes, which was roughly the diameter of Earth.

In order to see anything, then, we had to look for black holes that were simultaneously very large, with a large angular diameter as seen from our perspective on Earth, and were also active: emitting copious amounts of radiation at radio wavelengths. There are only two that fit the bill:

  1. Sagittarius A*, the four million solar mass black hole at the center of our galaxy, just ~27,000 light-years away.
  2. And the black hole at the center of the massive elliptical galaxy M87, which comes in at 6.5 billion solar masses (some 1500 times the mass of Sagittarius A*), but some 50-60 million light-years distant (about 2000 times as far).

In April of 2019, after two years of analysis, the first images were released: a map of the radio light that traced out the emitted photons from around the black hole in the distant galaxy M87.

Even though this is usually depicted as a single image — where the four images from the four different days are added and averaged together — it’s important to recognize what’s actually happening here. Light from a very distant source is striking our telescopes at many different locations on Earth. In order to make sure we’re adding the data from the same exact times together, we have to sync up the various observatories with atomic clocks, and then account for the light-travel time to each unique point on Earth’s surface. In other words, we need to make sure that the telescopes are properly synchronized: a tremendously difficult task.

The reason we have an image of the black hole at the center of M87 and not one of the black hole in our own galaxy’s center is because of its remarkable size. At 6.5 billion solar masses, its diameter is approximately one light-day, meaning that the features in the photon ring take about ~1 day to change appreciably. At just 0.15% of that black hole’s mass, our black hole’s features change by that same amount every single minute, making the image much more difficult to construct.

However, while the Event Horizon Telescope team is still working on our black hole’s first image, the one at the center of M87 has just gotten a far more detailed image thanks to a special set of measurements that were also taken: polarization measurements.

Whether you view them in a quantum way (as photons) or in a classical way (as waves), the phenomenon of light behaves with intrinsic electromagnetic properties. As an electromagnetic wave, light is made of oscillating, in-phase, mutually perpendicular electric and magnetic fields. Whenever light either, passes through a magnetized plasma or reflects off of a material, it can become partially or completely polarized: where instead of having the electric and magnetic fields oriented randomly, they’re preferentially oriented in a particular direction.

Around pulsars — radio-emitting neutron stars with very strong magnetic fields — light can be almost 100% polarized. We’d never measured the polarization of photons from around a black hole before, but in addition to simply measuring the flux and density of photons, the Event Horizon Telescope also measured the information required to reconstruct the polarization data for the black hole at the center of M87.

Just as we were able to reconstruct images of the black hole’s photon ring that evolved with time, so too could we reconstruct polarization data on that individual, day-by-day basis.

The polarization data is completely complementary to the direct light received, as it gives information that’s independent of the shape and density of the light emitted from around the black hole. Instead, polarization data is useful for teaching us about the matter that surrounds the black hole, including what the strength of the magnetic field is in that region, the number density of free electrons, the temperature of that hot plasma, and how much mass the black hole is consuming over time.

What we learn is fascinating, and perhaps not what many expected.

  • The magnetic field strength in the vicinity of the black hole is between 1 and 30 Gauss, where ~1 Gauss is the strength of Earth’s magnetic field at the surface. Compared to neutron stars, where fields can reach more than 1015 Gauss, this is minuscule, but on much larger scales.
  • There are between ten thousand and ten million free electrons in every cubic centimeter around this black hole.
  • The temperature of the plasma that has accreted around this black hole is enormous: between 10 and 120 billion K, or more than 1000 times the temperature at the center of the Sun.
  • And finally, this black hole is consuming mass at a rate that’s between 100 and 700 Earth masses every single year.

Still, as exciting as this is, the greatest sight of all was the new image of the radiation around the black hole, with the magnetic fields (traced out by the polarization data) included.

The first thing you’ll notice — and you might even worry about it — is that these swirling features appear so much sharper than the original image, which looked more like a blurry ring than anything else. Why would this polarization data, which was taken with the same instruments as the regular light data, have such a high resolution?

The answer is: surprisingly, it doesn’t. The polarization data has the same resolution as the regular data, meaning it can resolve features down to about ~20 micro-arc-seconds. There are 360 degrees in a full circle, 60 arc-minutes in each degree, 60 arc-seconds in each arc-minute, and one million micro-arc-seconds in each arc-second. If you were able to view the Apollo mission manual that was left on the Moon from Earth, 20 micro-arc-seconds would span roughly the “Ap” from the word Apollo.

What the polarization data tells us, however, is how much the light twists and in which direction, which basically traces out the magnetic field around the black hole. Just as we see the light and the polarization data evolving over time, we can put those results together, and determine how the photon ring around the black hole’s event horizon has changed and evolved during the course of our observations.

One of the big surprises is how small the photon polarization is. If you have a magnetized plasma surrounding this black hole — and we’re pretty certain that we do — you’d naively expect that the light would arrive almost completely polarized: with polarization fractions of 80-90% or even more. And yet, what we see is that the polarization fraction is tiny: about ~15-20% at its peak, with the actual value being even smaller in most locations.

Why would this be the case?

Unlike pulsars, where the magnetic field can be coherent on scales comparable to the size of the neutron star (about ~10 kilometers), this black hole is absolutely enormous. At about 1 light-day in diameter (about 0.003 light-years) for the black hole, there’s almost certainly a complicated magnetic structure on smaller scales than that. When light passes through a magnetic field, its polarization direction rotates, and rotates proportionally to the strength of the field. (This is known as Faraday rotation.)

However, if that magnetic field is non-uniform, the rotating polarization should “scramble” the signal, reducing its magnitude significantly. If we want to accurately map out the magnetic field, we’d need to leave Earth: building a similar telescope array that was larger than the diameter of our planet.

Still, none of this should diminish just how remarkable an achievement this is. By combining the effects of the light we directly observed with the polarization data, we can more accurately map out the behavior of the light emitted from this supermassive black hole: quite possibly the most massive supermassive black hole within ~100 million light-years of Earth.

When the data from the black hole at our own galaxy’s center is finally put together properly, we should have an incredibly interesting comparison to make. Right now, there are a slew of open questions, including:

  • will the same parts of the black hole remain “bright” and “dark” over time, or will the accretion flows migrate to all directions in space?
  • how large is the magnetic substructure around the black hole compared to the event horizon, and is it consistent between supermassive and ultra-mega-supermassive black holes?
  • will we observe a larger polarization fraction for smaller mass black holes, and will that teach us anything about Faraday rotation?
  • will there be comparable temperatures, magnetic field strengths, and electron densities between these two black holes, or will they be different?

Perhaps most importantly, will our theoretical calculations, borne out through simulations that incorporate all the relevant physics, match the reconstructed data to the extraordinary degree that they aligned for the black hole at the center of M87?

Just a few years ago, we didn’t even know whether it was a certainty that black holes had an event horizon, as we’d never observed one directly. In 2017, a series of observations were finally taken that could settle the issue. After a wait of two years, the first direct image of a black hole was released, and it showed us that the event horizon was, in fact, real as predicted, and that its properties agreed with Einstein’s predictions.

Now, another two years later, the polarization data has been added into the fold, and we can now reconstruct the magnetic properties of the plasma surrounding the black hole, along with how those features are imprinted onto the emitted photons. We still only have the one black hole that’s been directly imaged, but we can see how the light, the polarization, and the magnetic properties of the plasma surrounding the event horizon all change over time.

From over 50 million light-years away, we’re finally beginning to understand how the most massive, active black holes in the Universe work: powered by over 100 Earth masses per year and driven by the combination of Einstein’s gravity and electromagnetism. With a little bit of luck, we’ll have a second black hole that’s very different to compare it to in only a few months.

Source:- Forbes

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Breathtaking NASA Image Shows a Magical ‘Sea of Dunes’ on Mars

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On Thursday, NASA released a stunning photo of a sea of dunes on Mars.

It also shows wind-sculpted lines surrounding Mars’ frosty northern polar cap.

The section captured in the shot represents an area that is 31 kilometers (19 miles) wide, NASA said. The sea of dunes, however, actually covers an area as large as Texas.

The photo is a false color image, meaning that the colors are representative of temperatures. Blue represents cooler climes, and the shades of yellow mark out “sun-warmed dunes,” the US space agency wrote.

Sea of dark dunes surrounds Mars’ northern polar cap.(NASA/JPL-Caltech/ASU)

The photo is made of a combination of images captured by the Thermal Emission Imaging System instrument on the Mars Odyssey orbiter, NASA wrote.

Captured during the period from December 2002 to November 2004, the breathtaking images have been released to mark the 20th anniversary of Odyssey.

The Mars Odyssey orbiter is a robotic spacecraft circling Mars that uses a thermal imager to detect evidence of water and ice on the planet.

It was launched in 2001, making it the longest-working Mars spacecraft in history.

Source:- ScienceAlert

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Humans actually hunted large animals and ate mostly meat for 2 millions years: study – CTV News

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TORONTO —
Despite a widespread belief that humans owe their evolution to the dietary flexibility in eating both meat and vegetables, researchers in Israel suggest that early humans were actually apex predators who hunted large animals for two million years before they sought vegetables to supplement their diet.

In a study recently published in the American Journal of Physical Anthropology, academics from Tel Aviv University in Israel and the University of Minho in Portugal examined modern biology to determine if stone-age humans were specialized carnivores or generalist omnivores.

“So far, attempts to reconstruct the diet of Stone-Age humans were mostly based on comparisons to 20th century hunter-gatherer societies,” one of the study’s authors, Miki Ben-Dor, a researcher at Tel Aviv University, said in a press release.

“This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals – while today’s hunter gatherers do not have access to such bounty.”

Instead, the researchers looked at approximately 400 previous scientific studies on human anatomy and physiology as well as archeological evidence from the Pleistocene period, or “Ice Age” period, which began about 2.6 million years ago, and lasted until 11,700 years ago.

“We decided to use other methods to reconstruct the diet of Stone-Age humans: to examine the memory preserved in our own bodies, our metabolism, genetics and physical build,” Ben-Dor said.

“Human behaviour changes rapidly, but evolution is slow. The body remembers.”

They discovered 25 lines of evidence from the studied papers on human biology that seem to show that earlier Homo sapiens were apex predators at the top of the food chain.

For example, the academics explained that humans have a high acidity in their stomachs when compared to omnivores or even other predators, which is important for consuming animal products.

“Strong acidity provides protection from harmful bacteria found in meat, and prehistoric humans, hunting large animals whose meat sufficed for days or even weeks, often consumed old meat containing large quantities of bacteria, and thus needed to maintain a high level of acidity,” Ben-Dor said.

Another piece of evidence, according to the study, is the structure of human fat cells.

“In the bodies of omnivores, fat is stored in a relatively small number of large fat cells, while in predators, including humans, it’s the other way around: we have a much larger number of smaller fat cells,” Ben-Dor said.

HUNTING EXPERTS

In addition to the evidence they collected by studying human biology, the researchers said archeological evidence from the Pleistocene period supports their theory.

In one example, the study’s authors examined stable isotopes in the bones of prehistoric humans as well as their hunting practices and concluded these early humans specialized in hunting large and medium-sized animals with high fat content.

“Comparing humans to large social predators of today, all of whom hunt large animals and obtain more than 70% of their energy from animal sources, reinforced the conclusion that humans specialized in hunting large animals and were in fact hypercarnivores,” the academics noted.

Ben-Dor said Stone-Age humans’ expertise in hunting large animals played a major role in the extinction of certain large animals, such as mammoths, mastodons, and giant sloths.

“Most probably, like in current-day predators, hunting itself was a focal human activity throughout most of human evolution. Other archeological evidence – like the fact that specialized tools for obtaining and processing vegetable foods only appeared in the later stages of human evolution – also supports the centrality of large animals in the human diet, throughout most of human history,” he said.

This is not to say, however, that humans during this period didn’t eat any plants. Ben-Dor said they also consumed plants, but they weren’t a major component of their diet until the end of the era when the decline of animal food sources led humans to increase their vegetable intake.

Eventually, the researchers said humans had no choice but to domesticate both plants and animals and become farmers.

Ran Barkai, one of the study’s authors and a professor at Tel Aviv University, said their findings have modern-day implications.

“For many people today, the Paleolithic diet is a critical issue, not only with regard to the past, but also concerning the present and future. It is hard to convince a devout vegetarian that his/her ancestors were not vegetarians, and people tend to confuse personal beliefs with scientific reality,” he said. 

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Marimaca Copper: First Drill Hole Intersects Broad Zone of Sulphide Copper Mineralization at Marimaca – Junior Mining Network

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VANCOUVER, British Columbia, April 07, 2021 (GLOBE NEWSWIRE) — Marimaca Copper Corp. (“Marimaca Copper” or the “Company”) (TSX: MARI) is pleased to announce the assay results of the first drill hole of a five-hole program targeting extensions of sulphide mineralization below the Company’s flagship Marimaca Oxide Deposit (“MOD”). Drilling encountered a broad zone of chalcopyrite and minor chalcocite, indicating potential for economic sulphide mineralization.

Highlights

  • Drill hole MAR-125 intersected 116m (expected approximate true width) at an average grade of 0.51% CuT from 162m, including two higher grade zones of:
    • 20m with an average grade of 0.77% CuT from 162m; and
    • 42m with an average grade of 0.92% CuT from 236m.
  • Intersection represents a significantly broader zone of mineralization than anticipated from earlier, nearby, sulphide drilling intersections
  • First drill hole of an initial five-hole campaign to test for extensions of mineralization at depth
    • First hole designed to extend mineralization closer to sulphide zones identified in historical drilling
    • Remaining four holes designed to test the limits of mineralization with step outs of approximately 300m at depth and between 400m and 700m along strike to the north and south of the first hole
  • Sulphide drilling to be completed shortly, with assay results on remaining holes expected by the end of April 2021
  • In response to escalating COVID situation in Chile, the Company has initiated a break in drilling which is not expected to impact the original target of testing all identified targets by the end of 1H 2021.

Sergio Rivera, VP Exploration of Marimaca Copper, commented:

“The results of the first hole of this initial campaign are extremely pleasing, exceeding both the widths and grades we had projected for this zone based on earlier drilling completed nearby. The broad intercept of chalcopyrite mineralization shows good continuity downhole, with potentially economic grades, especially at the bottom of the intercept.

“The drilling has also provided additional geological information, which we are using to refine our understanding of the controls of mineralization and to inform future drillhole locations, targeting mineralized extensions at depth and along strike.

“The next four holes are significant step outs from the known mineralized zones outside of the Mineral Resource Estimate area and are designed to test the limits of the mineralized body, both at depth and along strike. The second hole will be collared approximately 350m to the east of MAR-125, targeting mineralization up to 300m below the current deepest mineralization. The third, fourth and fifth holes will be located between 400m and 700m to the north and south of MAR-125, aiming to test for extensions along strike.

“This first hole has provided encouragement that there is potential for economically interesting sulphide mineralization at Marimaca, while the next four drill holes are designed to better delineate the tonnage potential of this.”

Discussion of Campaign Objectives and Results

The current five-hole drilling campaign at the Marimaca Copper Project is designed to test for extensions to mineralization below the MOD. Based on the structural controls of the mineralization, the results of previous geophysical campaigns and earlier drilling, which extended beyond the current Mineral Resource Estimate (“MRE”) area, the Company believes there is the potential for extensions of the mineralized body at depth across the full strike length of the MOD. All drill holes will be drilled at an azimuth of 270o and at -60o, roughly perpendicular to the north-south striking, easterly dipping mineralizing structures. Intercepts should, therefore, be relatively close to the true width of the mineralization.

The first drill hole (MAR-125) encountered a broad zone of dominantly chalcopyrite mineralization with some pyrite and minor chalcocite over a down hole width (expected to be equivalent to approximate true width) of 116m with an average grade of 0.51% CuT. This includes two zones of higher-grade mineralization including 20m with an average grade of 0.77% CuT and 42m with an average grade of 0.92% CuT at the end of the mineralized intercept. The hole was collared to test mineralization approximately 100m to the east of the earlier hole ATR-82, which intersected 44m of sulphide copper mineralization with an average grade of 1.05% CuT, and 200m and 300m east of holes ATR-93 and ATR-94 respectively, which both intersected mineralization with true widths of around 40m with average grades above 1.0% CuT. MAR-125 has demonstrated an extension to this higher-grade mineralization and provides further areas to target for follow up drilling.

MAR-125 is located in the center of the current MRE area, proximal to a zone of relatively high-grade sulphide mineralization intercepted in several drill holes over widths of between 30m and 50m. The remaining four drill holes have been located to test the limits of the mineralization by stepping out significantly at depth and along strike beyond the current MRE area. The collar of the second hole, MAS-03, is located approximately 100m to the south and 350m to the east of MAR-125 and is aimed to intersect mineralization approximately 300m below MAR-125. MAS-02 and MAS-04, located approximately 400m and 700m, respectively, south of MAR-125, and are planned as significant step outs along strike, targeting the conductivity high noted in the IP survey completed across the MOD

Figure 2

Sampling and Assay Protocol

True widths cannot be determined with the information available at this time. Marimaca Copper RC holes were sampled on a 2-metre continuous basis, with dry samples riffle split on site and one quarter sent to the Andes Analytical Assay preparation laboratory in Calama and the pulps then sent to the same company laboratory in Santiago for assaying. A second quarter was stored on site for reference. Samples were prepared using the following standard protocol: drying; crushing to better than 85% passing -10#; homogenizing; splitting; pulverizing a 500-700g subsample to 95% passing -150#; and a 125g split of this sent for assaying. All samples were assayed for CuT (total copper), CuS (acid soluble copper) by AAS. A full QA/QC program, involving insertion of appropriate blanks, standards and duplicates was employed with acceptable results. Pulps and sample rejects are stored by Marimaca Copper for future reference.

Qualified Person

The technical information in this news release, including the information that relates to geology, drilling and mineralization was prepared under the supervision of, or has been reviewed by Sergio Rivera, Vice President of Exploration, Marimaca Copper Corp, a geologist with more than 36 years of experience and a member of the Colegio de Geólogos de Chile and of the Institute of Mining Engineers of Chile, and who is the Qualified Person for the purposes of NI 43-101 responsible for the design and execution of the drilling program.

Mr. Rivera confirms that he has visited the Marimaca Project on numerous occasions, is responsible for the information contained in this news release and consents to its publication.

Contact Information
For further information please visit www.marimaca.com or contact:

Tavistock
+44 (0) 207 920 3150
Jos Simson/Emily Moss 
This email address is being protected from spambots. You need JavaScript enabled to view it. 

Forward Looking Statements

This news release includes certain “forward-looking statements” under applicable Canadian securities legislation. These statements relate to future events or the Company’s future performance, business prospects or opportunities. Forward-looking statements include, but are not limited to, the impact of a rebranding of the Company, the future development and exploration potential of the Marimaca Project. Actual future results may differ materially. There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially from those anticipated in such statements. Forward-looking statements reflect the beliefs, opinions and projections on the date the statements are made and are based upon a number of assumptions and estimates that, while considered reasonable by Marimaca Copper, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be materially different from the results, performance or achievements that are or may be expressed or implied by such forward-looking statements and the parties have made assumptions and estimates based on or related to many of these factors. Such factors include, without limitation: risks related to share price and market conditions, the inherent risks involved in the mining, exploration and development of mineral properties, the uncertainties involved in interpreting drilling results and other geological data, fluctuating metal prices, the possibility of project delays or cost overruns or unanticipated excessive operating costs and expenses, uncertainties related to the necessity of financing, the availability of and costs of financing needed in the future as well as those factors disclosed in the Company’s documents filed from time to time with the securities regulators in the Provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador. Accordingly, readers should not place undue reliance on forward-looking statements. Marimaca Copper undertakes no obligation to update publicly or otherwise revise any forward-looking statements contained herein whether as a result of new information or future events or otherwise, except as may be required by law.


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