1313: Você consegue ver o caranguejo nesta foto? (Dica: está sob o fuzz.)

CIÊNCIA/BIOLOGIA

O caranguejo usa seu casaco para camuflagem.

Um caranguejo nativo da Austrália Ocidental usa um casaco desgrenhado feito de esponjas bronzeadas. (Crédito da imagem: Cortesia do Museu WA. Fotógrafo: Colin McLay )

Uma espécie de caranguejo que foi recentemente descoberta na Austrália se forma com chapéus e casacos maciços feitos de esponjas vivas, o que faz com que o crustáceo pareça um brinquedo de pelúcia maravilhosamente espremível.

(Não se engane, porém – há um exoesqueleto duro sob toda a fofa desgrenhada!)

Uma família avistou pela primeira vez o caranguejo, o recém-nomeado Lamarckdromia beagle, quando ele apareceu em uma praia perto da cidade da Dinamarca, na Austrália Ocidental. Eles enviaram o espécime para Andrew Hosie, curador das colecções de crustáceos e vermes no Museu da Austrália Ocidental, em Perth, que reconheceu o animal como algum tipo de caranguejo esponja, embora “bastante incomum”.

“A extrema fofura foi a doação para nós”, disse Hosie à Live Science por e-mail. “Os caranguejos esponjas são muitas vezes peludos, mas é mais parecido com feltro ou veludo, em vez de este casaco desgrenhado completo.”

Os membros da família do caranguejo de esponja (Dromiidae) usam suas garras dianteiras afiadas para colectar pedaços de esponja e ascidas – alimentadores de filtro, como esguichos no mar – e usam pernas traseiras especializadas para segurar esses enfeites acima de suas cabeças.

Com o tempo, esses enfeites se acumulam para formar uma espécie de tampão apertado sobre o caranguejo, ajudando o animal a evitar ser visto por peixes predadores, outros caranguejos e polvos que podem comê-lo. As esponjas também são conhecidas por produzir produtos químicos nocivos, o que provavelmente torna o caranguejo um lanche menos tentador para predadores, disse Hosie.

Ao receber o espécime coberto de esponja, Hosie contatou Colin McLay, um biólogo marinho aposentado e ex-professor associado da Universidade de Canterbury, na Nova Zelândia, que estuda caranguejos esponjosos há décadas. McLay confirmou que o caranguejo era uma espécie anteriormente desconhecida.

A equipe então comparou o crustáceo com outros membros do género Lamarckdromia alojados nas colecções do Museu da Austrália Ocidental. Ao fazê-lo, eles descobriram quatro espécimes adicionais de L. beagle que haviam sido colectados em vários locais costeiros entre 1925 e 1983, mas ainda não haviam sido descritos ou sinalizados como a mesma espécie. Juntos, esses espécimes sugerem que o L. beagle pode ser encontrado em águas rasas e subtidais entre Hopetoun e Cape Naturaliste na costa sul da Austrália Ocidental, disse Hosie.

O nome da espécie de caranguejo fofo comemora o HMS Beagle, o navio que em 1836 transportou o naturalista britânico Charles Darwin para Albany, na Austrália, durante sua segunda expedição de pesquisa. “Esta viagem é considerada como tendo feito um impacto profundo em Darwin, levando-o em seu caminho para formular sua teoria da selecção natural”, disse Hosie.

O nome “beagle” também se adequa à recém-descoberta espécie de caranguejo porque a pelagem fofa do animal tem a mesma cor marrom-avermelhada que as marcas no rosto e nos ombros de um beagle, acrescentou.

Os pesquisadores descreveram a nova espécie de caranguejo em 28 de Abril na revista Zootaxa (abre em nova aba).

Originalmente publicado em Live Science.
Por Nicoletta Lanese
29.06.2022

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1268: Este é o melhor momento para identificar um raro alinhamento de cinco planetas. Veja como vê-lo

CIÊNCIA/ASTRONOMIA/ALINHAMENTO PLANETÁRIO

Mercúrio, Vénus, Marte, Júpiter e Saturno estão em exibição de madrugada.

Planetas Vénus, Marte e Júpiter se alinham sobre a Ilha de Portland Dorset, Inglaterra, no Reino Unido. (Crédito da imagem: Oliver Taylor / Alamy )

O pássaro madrugador pega a espectacular observação do céu esta semana, enquanto cinco planetas marcham pelo céu antes do amanhecer.

Este raro alinhamento planetário tem sido visível desde o início de Junho. Mas a visão deve ser particularmente impressionante esta semana, já que Mercúrio está mais brilhante e a lua minguante se junta ao desfile dos planetas.

“Este é o início da manhã, então você tem que definir o alarme para fazê-lo – mas é apenas um momento divertido para ver planetas no céu”, disse Michelle Nichols, directora de observação pública do Adler Planetarium, em Chicago.

Como assistir o alinhamento de cinco planetas

O alinhamento é visível pouco antes do amanhecer no Hemisfério Norte. O melhor momento para procurar é cerca de 45 minutos antes do nascer do sol, hora local, disse Nichols.

Os planetas serão espalhados a partir do horizonte leste-nordeste, arqueando em direcção ao sul. Coincidentemente, eles estarão alinhados em sua ordem do Sol: Mercúrio, Vénus, Marte, Júpiter e Saturno. Esta configuração planetária em particular não ocorre desde 1864, informou o site irmão da Live Science, Space.com.

Saturno é o mais antigo deste quíntuplo a subir e será visível no céu sudeste pouco antes do amanhecer, na constelação de Capricórnio. Júpiter, na constelação de Peixes, será visível como um corpo muito brilhante ao lado; ele aparecerá mais do que duas vezes mais brilhante que Sirius, a estrela mais brilhante no céu, de acordo com Space.com.

Marte é um dos planetas mais fáceis de escolher por causa de sua coloração avermelhada; ele estará acima do horizonte oriental. Vénus, parecendo ainda mais brilhante do que Júpiter, vai subir no horizonte, à esquerda de Marte. Mercúrio será o último a aparecer nos 40 minutos ou mais antes do nascer do sol, espiando no horizonte à esquerda de Vénus.

Em 27 de Junho, a lua crescente fornecerá um sinal útil para Mercúrio, que será logo abaixo e à direita do crescente. Mercúrio também pairará perto de uma estrela de cor laranja chamada Aldebaran, que compõe o olho do touro na constelação de Touro.

Uma dica útil para escolher planetas é procurar uma luz constante, disse Nichols. Estrelas brilham, mas os planetas não.

Somando-se ao drama, a lua estará atravessando essa faixa de planetas ao longo da semana. Na quarta-feira (22 de Junho), a Lua estará à direita de Marte. De 23 a 25 de Junho, ele vai se empoleirar entre Marte e Vénus, tornando-se um crescente mais magro a cada noite. Quebre os binóculos antes do amanhecer de 27 de Junho, de acordo com o Space.com, e você pode pegar a última fatia de 3% da lua sentada à esquerda de um Mercúrio relativamente brilhante.

O que é um alinhamento planetário?

Os planetas visíveis não estão realmente alinhados no espaço, mas todos eles estão em um lado do sol. Da Terra, a falta de percepção de profundidade faz com que os planetas pareçam estar ao lado um do outro.

Mercúrio circunda o sol a cada 88 dias terrestres, Vénus a cada 225 dias, Marte a cada 687 dias, Júpiter a cada 12 anos e Saturno a cada 29 anos, de modo que esses alinhamentos ocorrem num horário irregular. A última vez que os cinco planetas visíveis foram alinhados foi em 2020, precedido em 2016 e 2005.

O alinhamento será visível mesmo na presença de poluição luminosa, mas alguns dos planetas – especialmente Mercúrio – são baixos no horizonte, então procure um ponto de vista com um horizonte claro do sul e leste, como uma costa ou outro ponto plano.

Originalmente publicado em Live Science
Por Guia de viagem de Stephanie Pappas
23.06.2022


 

1043: Why have aliens never visited Earth? Scientists have a disturbing answer

UFOs & Search for Extraterrestrial Life

Advanced civilizations could be doomed to stagnation or death

An artist’s image of an alien starship as viewed from a planet’s surface. (Image credit: Coneyl Jay)

Why has humanity never been visited by aliens (that we know of)? The question has confounded scientists for decades, but two researchers have come up with a possible — and disturbing — explanation: Advanced civilizations could be doomed to either stagnate or die before they get the chance.

The new hypothesis suggests that, as space-faring civilizations grow in scale and technological development, they eventually reach a crisis point where innovation no longer keeps up with the demand for energy. What comes next is collapse. The only alternative path is to reject a model of “unyielding growth” in favor of maintaining equilibrium, but at the cost of a civilization’s ability to expand across the stars, the researchers said.

The argument, published on May 4 in the journal Royal Society Open Science, attempts to find a resolution to the Fermi Paradox. Taking its name from the casual lunchtime musings of Nobel Prize-winning physicist Enrico Fermi, the paradox draws attention to the contradiction between the immense scope and age of the universe — two things that suggest the universe should be teeming with advanced alien life — and the lack of evidence that extraterrestrials exist anywhere in sight. “So where is everybody?” Fermi is thought to have remarked.

The researchers of the new study say they may have the answer.

“Civilizations either collapse from burnout or redirect themselves to prioritizing homeostasis, a state where cosmic expansion is no longer a goal, making them difficult to detect remotely,” astrobiologists Michael Wong, of the Carnegie Institution for Science, and Stuart Bartlett, of the California Institute of Technology, wrote in the study. “Either outcome — homeostatic awakening or civilization collapse — would be consistent with the observed absence of [galactic-wide] civilizations.”

The pair came to their hypothesis by researching studies of the “‘superlinear”‘ growth of cities. These studies suggested that cities increase in size and  energy consumption at an exponential rate as their populations grow, inevitably leading to crisis points — or singularities — that cause rapid crashes in growth, followed by an even more precipitous, potentially civilization-ending, collapse.

“We hypothesize that once a planetary civilization transitions into a state that can be described as one virtually connected global city, it will face an ‘asymptotic burnout,’ an ultimate crisis where the singularity-interval time scale becomes smaller than the time scale of innovation,” they wrote.

These close-to-collapse civilizations would be the easiest for humanity to detect, the researchers suggest, as they would be dissipating large amounts of energy in a “wildly unsustainable” way. “This presents the possibility that a good many of humanity’s initial detections of extraterrestrial life may be of the intelligent, though not yet wise, kind,” the researchers wrote.

To avert their doom, civilizations could undergo a “homeostatic awakening,” redirecting their production away from unbounded growth across the stars to one that prioritizes societal wellbeing, sustainable and equitable development and harmony with their environment, the researchers suggest. While such civilizations may not completely abandon space exploration, they would not expand on scales great enough to make contact with Earth likely.

The researchers point to a few of humanity’s “mini-awakenings” that addressed global crises on Earth, such as the reduction of global nuclear arms stockpiles from 70,000 warheads to below 14,000; the halting of the once-growing hole in Earth’s ozone layer by banning chlorofluorocarbon emissions; and the 1982 international whaling moratorium.

The scientists stress, however, that their suggestion is simply a hypothesis, taken from the observation of laws that seem to govern life on Earth, and is designed to “provoke discussion, introspection and future work.”

Their proposal joins a bountiful crop of other scientific and popular suggestions as to why we’ve never made direct contact with celestial visitors. These include the numerous practical challenges presented by interstellar travel; that aliens may actually be visiting in secret; or that aliens arrived to Earth too soon (or humans too early) in the life of the universe for direct contact.

Another hypothesis, published April 4 in The Astrophysics Journal, suggests that the sheer scale of the universe means it could take as long as 400,000 years for a signal sent by one advanced species to be received by another — a timescale that’s far greater than the brief period humans have been able to scan the skies.

Originally published on Live Science.
By Ben Turner
11.05.2022

 


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1st image of our galaxy’s ‘black hole heart’ unveiled

Astronomy & Astrophysics

The giant black hole is at the center of the Milky Way

The Milky Way and the location of its central black hole as viewed from the Atacama Large Millimeter/submillimeter Array. (Image credit: ESO/José Francisco Salgado (josefrancisco.org), EHT Collaboration)

Astronomers have captured the first ever image of the colossal black hole at the center of our galaxy, providing the first direct evidence of the cosmic giant’s existence.

Located 26,000 light-years away, Sagittarius A* is a gargantuan tear in space-time that is four million times the mass of our sun and 40 million miles (60 million kilometers) across. The image was captured by the Event Horizon Telescope (EHT), a network of eight synchronized radio telescopes placed in various locations around the world.

As not even light is able to escape the powerful gravitational pull of a black hole, it’s impossible to see Sagittarius A* itself except as the silhouette of a ring of fuzzy, warped light. This halo comes from the superheated, glowing matter swirling around the entrance to the cosmic monster’s maw at close to the speed of light. Once the slowly stripped and shredded plasma plunges over the black hole’s precipice, or event horizon, it is lost inside forever.

“Our results are the strongest evidence to date that a black hole resides at the centre of our galaxy,” Ziri Younsi, an astrophysicist at University College London and an EHT collaborator, said in a statement. “This black hole is the glue that holds the galaxy together. It is key to our understanding of how the Milky Way formed and will evolve in the future.”

Scientists have long thought that an enormous supermassive black hole must lurk at the center of our galaxy, its gravity tethering the Milky Way’s dust, gas, stars and planets in a loose orbit about it and causing stars closeby to circle around it rapidly. This new observation, which shows light being bent around the space-time-warping behemoth, puts their suspicions beyond all doubt.

“We were stunned by how well the ring size agreed with predictions from Einstein’s theory of general relativity,” Geoffrey Bower, an EHT collaborator and astronomer at Academia Sinica, Taipei, said in a statement. “These unprecedented observations have greatly improved our understanding of what happens at the very center of our galaxy and offer new insights on how these giant black holes interact with their surroundings.”

Einstein’s theory of general relativity describes how massive objects can warp the fabric of the universe, called space-time. Gravity, Einstein discovered, isn’t produced by an unseen force, but is simply our experience of space-time curving and distorting in the presence of matter and energy. Black holes are points in space where this warping effect becomes so strong that Einstein’s equations break down, causing not just all nearby matter but all nearby light to be sucked inside.

The Event Horizon Telescope has captured the first image of Sgr A*, the supermassive black hole at the center of our galaxy. (Image credit: EHT Collaboration)

To build a black hole, you have to start with a large star — one with a mass roughly five to 10 times that of the sun. As larger stars approach the ends of their lives, they start to fuse heavier and heavier elements, such as silicon or magnesium, inside their burning cores. But once this fusion process begins forming iron, the star is on a path to violent self-destruction. Iron takes in more energy to fuse than it gives out, causing the star to lose its ability to push out against the immense gravitational forces generated by its enormous mass. It collapses in on itself, packing first its core, and later all the matter close to it, into a point of infinitesimal dimensions and infinite density — a singularity. The star becomes a black hole, and beyond a boundary called the event horizon, nothing — not even light — can escape its gravitational pull.

Exactly how black holes may grow to become supermassive in scale is still a mystery to scientists, although observations of the early universe suggest they could balloon to their enormous sizes by snacking on dense clouds of gas and merging with other black holes.

The EHT captured the image, alongside the image of another supermassive black hole at the center of the M87 galaxy, back in 2017. The image of the M87 black hole was released in 2019, Live Science previously reported, but it took two more years of data analysis before the Milky Way one was ready.

Part of the reason behind the delay is the vastly different sizes of the two supermassive black holes, which in turn affects the speeds that their plasma clouds whirl around their centers. The M87 black hole (M87*) is roughly a thousand times bigger than Sagittarius A*, weighing in at a jaw-dropping 6.5 billion times the mass of our sun, and its hot plasma takes days or even weeks to orbit it. The plasma of Sagittarius A*, by contrast, can whip around it in mere minutes.

“This means the brightness and pattern of the gas around Sgr A* was changing rapidly as the EHT Collaboration was observing it — a bit like trying to take a clear picture of a puppy quickly chasing its tail,” Chi-kwan Chan, an EHT collaborator and astrophysicist at the University of Arizona, said in a statement.

The imaging process was made even more challenging by the Earth’s location at the edge of the Milky Way, meaning the researchers had to use a supercomputer to filter out interference from the countless stars, gas and dust clouds strewn between us and Saggitarius A*. The final result is an image which looks very similar to the 2019 snapshot of M87*, even though the two black holes are themselves vastly different in scale. This is something the researchers attribute to the startling and persisting accuracy of Einstein’s general relativity equations.

“We have two completely different types of galaxies and two very different black hole masses, but close to the edge of these black holes they look amazingly similar,” Sera Markoff, an EHT collaborator and astrophysicist at the University of Amsterdam in the Netherlands, said in a statement. “This tells us that general relativity governs these objects up close, and any differences we see further away must be due to differences in the material that surrounds the black holes.”

Detailed analysis of the image has already enabled scientists to make some fascinating observations into our black hole’s nature. First, it’s wonky, sitting at a 30-degree angle to the rest of the galactic disk. It also appears to be dormant, making it unlike other black holes such as M87*, which suck in burning-hot material from nearby gas clouds or stars before slingshotting it back into space at near light speeds.

The scientists will follow up with further analysis of both this image and the one of M87*, alongside capturing new and improved images. More images won’t just enable better comparisons between the black holes, but will also provide improved detail, allowing scientists to see how the same black holes change over time and what goes on around their event horizons. This could not only give us a better understanding of how our universe formed, but also help in the search for hints as to where Einstein’s equations could give way to undiscovered physics.

The researchers published their results in a series of papers in the journal The Astrophysical Journal Letters.

Originally published on Live Science
By Ben Turner
12.05.2022


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Distant ‘galaxy’ isn’t a galaxy at all — but one of the brightest pulsars ever detected

Top Science News

The pulsar is 10 times brighter than any other outside our galaxy.

Artist’s impression of newly discovered extra-galactic pulsar, PSR J0523-7125, within the Large Magellanic Cloud. (Image credit: ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav))

A speck of light that scientists once wrote off as a distant galaxy may actually be the brightest pulsar ever detected outside the Milky Way.

Named PSR J0523−7125 and located about 160,000 light-years from Earth in the Large Magellanic Cloud (a satellite galaxy that orbits the Milky Way), the newly-defined pulsar is twice as wide as any other pulsar in the region, and 10 times brighter than any known pulsar beyond our galaxy. The object is so big and bright, in fact, that researchers originally interpreted it as a faraway galaxy — however, new research published May 2 in the Astrophysical Journal Letters suggests that this is not the case.

Using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope in Western Australia, the study authors looked at space through a special pair of “sunglasses” that block all wavelengths of light except for a specific type of emission associated with pulsars, the highly magnetized husks of stars. When PSR J0523−7125 showed up bright and clear in the results, the team realized they weren’t looking at a galaxy at all, but at the pulsing corpse of a dead star.

“This was an amazing surprise,” lead study author Yuanming Wang, an astrophysicist at Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) said in a statement. “I didn’t expect to find a new pulsar, let alone the brightest. But with the new telescopes we now have access to, like ASKAP and its sunglasses, it really is possible.”

The MeerKAT radio telescope’s field of view without ‘sunglasses’ featuring the new pulsar (Image credit: Yuanming Wang)

Glasses on

Pulsars are highly magnetized, rapidly spinning remnants of exploded stars. As they rotate, streams of radio waves erupt from their poles, pulsing like lighthouse beams as those radio waves flash toward Earth.

The radio waves emitted by pulsars are different from many other cosmic light sources, in that they can be circularly polarized — that is, the light’s electric field can rotate in a circle as it propagates forward. This unique polarization can provide scientists with a big clue in the tricky game of distinguishing pulsars from other distant light sources. In their new study, researchers used a computer program to filter out circularly polarized light sources from an ASKAP survey of pulsar candidates.

The team found that the presumed galaxy PSR J0523−7125 was emitting circularly polarized light, meaning it is almost certainly a pulsar. And because pulsars are incredibly small — typically packing a sun’s worth of mass into a ball no wider than a city — that means the object must be much closer, and much brighter, than scientists previously thought. Indeed, if this pulsar lurks in the nearby Large Magellanic Cloud, as the researchers suspect, then it is the single brightest pulsar ever found outside the Milky Way.

The MeerKAT radio telescope’s field of view without ‘sunglasses’ featuring the new pulsar (Image credit: Yuanming Wang)

That exceptional brightness explains why the object was misidentified as a galaxy after its initial detection, the researchers said. And by filtering out circularly polarized light from future star surveys, researchers may be able to unmask even more unusual pulsars that are hiding in plain sight.

“We should expect to find more pulsars using this technique,” study co-author Tara Murphy, a radio astronomer at the University of Sydney in Australia, said in the statement. “This is the first time we have been able to search for a pulsar’s polarization in a systematic and routine way.”

Originally published on Live Science
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12.05.2022


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988: Black Moon solar eclipse looks otherworldly in stunning images

SCIENCE/UNIVERSE/BLACK MOON/SOLAR ECLYPSE

Space and land views showed the moon taking a bite out of the sun on April 30.

A rare solar eclipse Saturday (April 30) stunned viewers across Antarctica, the southern tip of South America, and the Pacific and Atlantic Oceans.

While much of the event took place in remote areas, live cameras on Earth and satellites in space allowed people around the world to witness the moon blocking as much as 64% of the sun. The eclipse happened during a Black Moon, which is the second new moon in a single month.

Heliophysicist C. Alex Young, the associate director for science in the heliophysics science division at NASA’s Goddard Space Flight Center, broadcast several screenshots of a timeanddate.com livestream, which show a gorgeous, seemingly distorted sun with a bite taken out of it.

The eclipse was broadcast from numerous locations across the viewing area, and as Young said in one of his tweets, there are “bonus sunspots” available to look at after an explosive month from our sun. The sun generated several X-class (very strong) flares as it slowly moves toward its peak of solar activity in 2025.

The eclipse was also visible from space via a satellite named GOES-16 (GOES-R when it launched in 2016). The satellite charts lightning, severe storms and solar activity on behalf of the National Oceanic and Atmospheric Administration (NOAA).

While NOAA’s Twitter feed was not active over the weekend, the satellite broadcasts footage via the GOES Image Viewer website and attentive viewers caught views of the eclipse near real-time from space.

NASA said at least part of the eclipse was visible “in Chile, Argentina, most of Uruguay, western Paraguay, southwestern Bolivia, southeastern Peru, and a small area of southwestern Brazil.” (That’s assuming clear skies.)

Some well-known cities or regions with views of the eclipse included Buenos Aires (Argentina), the Falkland Islands (United Kingdom), Machu Picchu Base (Peru), Montevideo (Uruguay) and Santiago (Chile), according to Unitarium.com. Also, at least one cruise was active in the eclipsing region via EclipseTours.com.

The next solar eclipse, also a partial one, will occur on Oct. 25. It will be visible from Europe, northeast Africa, the Middle East and West Asia, according to NASA. There will be no total solar eclipses this year.

Editor’s Note: If you snap an amazing solar eclipse photo and would like to share it with Live Science readers, send your photo(s), comments, and your name and location to community@livescience.com.

Follow Elizabeth Howell on Twitter @howellspace. 

LiveScience
By Elizabeth Howell
02.05.2022


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The universe could stop expanding ‘remarkably soon’, study suggests

SCIENCE/UNIVERSE

In just 100 million years, the universe could start to shrink, new research suggests.

An artist’s impression of star formation in the early universe, a few hundred million years after the Big Bang. (Image credit: NASA)

After nearly 13.8 billion years of nonstop expansion, the universe could soon grind to a standstill, then slowly start to contract, new research published in the journal Proceedings of the National Academy of Sciences suggests.

In the new paper, three scientists attempt to model the nature of dark energy — a mysterious force that seems to be causing the universe to expand ever faster — based on past observations of cosmic expansion. In the team’s model, dark energy is not a constant force of nature, but an entity called quintessence, which can decay over time.

The researchers found that, even though the expansion of the universe has been accelerating for billions of years, the repellent force of dark energy may be weakening. According to their model, the acceleration of the universe could rapidly end within the next 65 million years — then, within 100 million years, the universe could stop expanding altogether, and instead it could enter an era of slow contraction that ends billions of years from now with the death — or perhaps the rebirth — of time and space.

And this could all happen “remarkably” quickly, said study co-author Paul Steinhardt, Director of the Princeton Center for Theoretical Science at Princeton University in New Jersey.

“Going back in time 65 million years, that’s when the Chicxulub asteroid hit the Earth and eliminated the dinosaurs,” Steinhardt told Live Science. “On a cosmic scale, 65 million years is remarkably short.”

Nothing about this theory is controversial or implausible, Gary Hinshaw, a professor of physics and astronomy at the University of British Columbia who was not involved in the study, told Live Science. However, because the model hinges on past observations of expansion alone — and because the present nature of dark energy in the universe is such a mystery — the predictions in this paper are currently impossible to test. For now, they can only remain theories.

Energy of the void

Since the 1990s, scientists have understood that the expansion of the universe is speeding up; the space between galaxies is widening faster now than it was billions of years ago. Scientists named the mysterious source of this acceleration dark energy — an invisible entity that seems to work contrary to gravity, pushing the universe’s most massive objects farther apart rather than drawing them together.

Though dark energy makes up approximately 70% of the total mass-energy of the universe, its properties remain a total mystery. A popular theory, introduced by Albert Einstein, is that dark energy is a cosmological constant — an unchanging form of energy that’s woven into the fabric of space-time. If that’s the case, and the force exerted by dark energy can never change, then the universe should continue expanding (and accelerating) forever.

However, a competing theory suggests that dark energy doesn’t need to be constant in order to fit with observations of past cosmic expansion. Rather, dark energy may be something called quintessence — a dynamic field that changes over time. (Steinhardt was one of three scientists who introduced the idea in a 1998 paper in the journal Physical Review Letters.)

Unlike the cosmological constant, quintessence can be either repulsive or attractive, depending on the ratio of its kinetic and potential energy at a given time. Over the last 14 billions years, quintessence was repulsive.  For most of that period, though, it contributed insignificantly compared to radiation and matter to the expansion of the universe. That changed about five billion years when quintessence became the dominant component and its gravitational repulsion effect caused the expansion of the universe to speed up.

“The question we’re raising in this paper is, ‘Does this acceleration have to last forever?'” Steinhardt said. “And if not, what are the alternatives, and how soon could things change?”

The death of dark energy

In their study, Steinhardt and his colleagues, Anna Ijjas of New York University and Cosmin Andrei of Princeton, predicted how the properties of quintessence could change over the next several billion years. To do this, the team created a physical model of quintessence, showing its repellent and attractive power over time, to fit with past observations of the universe’s expansion. Once the team’s model could reliably reproduce the universe’s expansion history, they extended their predictions into the future.

“To their surprise, dark energy in their model can decay with time,” Hinshaw said. “Its strength can weaken. And if it does so in a certain way, then eventually the antigravitational property of dark energy goes away and it transitions back into something that’s more like ordinary matter.”

According to the team’s model, the repellent force of dark energy could be in the midst of a rapid decline that potentially began billions of years ago.

In this scenario, the accelerated expansion of the universe is already slowing down today. Soon, perhaps within about 65 million years, that acceleration could stop altogether — then, within as few as 100 million years from now, dark energy could become attractive, causing the entire universe to start contracting. In other words, after nearly 14 billion years of growth, space could start to shrink.

“This would be a very special kind of contraction that we call slow contraction,” Steinhardt said. “Instead of expanding, space contracts very, very slowly.”

Initially, the contraction of the universe would be so slow that any hypothetical humans still alive on Earth wouldn’t even notice a change, Steinhardt said. According to the team’s model, it would take a few billion years of slow contraction for the universe to reach about half the size it is today.

The end of the universe?

From there, one of two things could happen, Steinhardt said. Either the universe contracts until it collapses in on itself in a big “crunch,” ending space-time as we know it — or, the universe contracts just enough to return to a state similar to its original conditions, and another Big Bang — or a big “bounce” — occurs, creating a new universe from the ashes of the old one.

In that second scenario (which Steinhardt and another colleague described in a 2019 paper in the journal Physics Letters B), the universe follows a cyclical pattern of expansion and contraction, crunches and bounces, that constantly collapse and remake it. If that’s true, then our current universe may not be the first or only universe, but just the latest in an infinite series of universes that have expanded and contracted before ours, Steinhardt said. And it all hinges on the changeable nature of dark energy.

How plausible is all this? Hinshaw said the new paper’s interpretation of quintessence is a “perfectly reasonable supposition for what the dark energy is.” Because all of our observations of cosmic expansion come from objects that are millions to billions of light-years away from Earth, current data can only inform scientists about the universe’s past, not its present or future, he added. So, the universe could very well be barreling toward a crunch, and we’d have no way of knowing until long after the contraction phase began.

“I think it really just boils down to how compelling do you find this theory to be and, more importantly, how testable do you find it to be?” Hinshaw added.

Unfortunately, there is no good way to test whether quintessence is real, or whether cosmic expansion has started to slow, Steinhardt admitted. For now, it’s just a matter of fitting the theory with past observations — and the authors do that capably in their new paper. Whether a future of endless growth or rapid decay awaits our universe, only time will tell.

Originally published on Live Science
By Brandon Specktor
02.05.2022


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What has no eyes, walked on stilts and died in ‘Paleo Pompeii’? This ancient weirdo

Curious Creatures

The Canadian stone quarry where it was found is rich in marine fossils

Reconstruction of Tomlinsonus dimitrii. (Image credit: Art by Christian McCall, copyright ROM)

Paleontologists recently announced the discovery of an “exceptionally well preserved” ancient animal near the eastern shore of Lake Simcoe in southern Ontario, Canada, in a stone quarry that is such a hotbed for marine fossils that scientists have dubbed the area “Paleo Pompeii.”

Named Tomlinsonus dimitrii, the species represented by the specimen is part of an extinct group of arthropods known as marrellomorphs that lived approximately 450 million years ago, during the Ordovician period, the research team reported in a new study. Other echinoderm fossils that are abundant in the area typically contain mineralized body parts that are more likely to be preserved over time, but this species is entirely soft-bodied, making the discovery all the more startling.

“We didn’t expect to find a soft-bodied species at this site,” said lead study author Joseph Moysiuk, a doctoral candidate in ecology and evolutionary biology at the University of Toronto and a researcher at Toronto’s Royal Ontario Museum (ROM). “When we think of fossils, we typically think of things like dinosaur bones and shells. However, soft-tissue preservation is very rare, and there are only a few sites around the world where soft-bodied organisms have been found,” Moysiuk told Live Science.

Measuring 2 inches (6 centimeters) — just shy of an index finger’s length and able to fit in the palm of a hand — the specimen features an ornate head shield that contains two curved horns covered in feather-like spines. The animal’s segmented body resembles that of other arthropods, such as insects and spiders, and contains multiple sets of segmented limbs — including one very unusual pair.

“Underneath the head, there is this amazing pair of limbs that are extremely long and have foot-like projections at the terminal ends, which we think it most likely used to stilt its way across the seafloor,” Moysiuk said. “It also appears to be blind, since it doesn’t have any eyes at all.”

Researchers discovered the bizarre arthropod last summer during a formal excavation of an active quarry owned by the Tomlinson Group, an infrastructure service company based in eastern Canada. (Paleontologists named the species Tomlinsonus dimitrii as a nod to the Tomlinson Group for letting them excavate the site.)

Prior to this dig, which was led by George Kampouris, the paper’s co-author and an independent paleontological technician who has been investigating the quarry’s fossil beds since 2014, marrellomorphs were predominately found at older fossil sites, like the Cambrian Burgess Shale in the Canadian Rockies of British Columbia. According to paleontologists, the newly described specimen resembles another species of extinct soft-bodied arthropod called Marrella splendens, found at the Burgess Shale.

The Tomlinsonus dimitrii fossil, and a line drawing of the specimen. (Image credit: Copyright ROM)

Similar to the Burgess Shale, the Lake Simcoe quarry was once submerged in water and was part of a shallow tropical marine sea that covered much of what is now modern-day Canada. Over millions of years, the seafloor became blanketed in sediment caused by storms.

“What we’re seeing is the rapid burial of these organisms that were living on this flat, shallow ocean bottom and were repeatedly smothered by large undersea mudflows coming from storm events,” Moysiuk said. “You can imagine hurricanes hitting this shallow shelf area and burying the whole community of organisms, which is why we nicknamed the site “Paleo Pompeii.” These organisms were entombed exactly where they were living, and what we’re seeing is them frozen in time.”

Moysiuk and his fellow researchers hope that this discovery will help “close the gap” in the fossil record for this group of arthropods, they wrote in the study.

The Tomlinsonus dimitrii specimen is now in ROM’s collection and is currently on display in the Willner Madge Gallery as a part of the museum’s “Dawn of Life” exhibit.

The findings were published March 24 in the Journal of Paleontology.

Originally published on Live Science
By Jennifer Nalewicki
23.04.2022

 


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965: What color were the dinosaurs?

What color were the dinosaurs?

Some were iridescent, and others were camouflaged.

Borealopelta, a nodosaur dinosaur, looked like an armored tank, but it still needed countershading to elude predators during the Cretaceous period. (Image credit: Julius T. Csotonyi/Copyright Royal Tyrrell Museum)

No animals have experienced a more dramatic makeover in the past few decades than the nonavian dinosaurs. Animals we used to think had nothing but drab gray and brown scales are now believed to have flaunted feathers in bright colors and patterns.

So what colors were the dinosaurs, really? And how do we know?

One scientist we have to thank for the answers to both questions is Jakob Vinther, an associate professor in macroevolution at the University of Bristol in the United Kingdom. Ever since the first fossilized dinosaur feathers were reported in 1996, scientists had noticed round microscopic structures within them — structures that many had assumed were fossilized bacteria.

But as a doctoral student studying a completely different animal, Vinther realized that these structures might be something more.

“I was looking at fossilized ink in squid- and octopus-like ancestors,” Vinther told Live Science. “It was remarkably well preserved.

“You can take ink from a squid you bought down at the fishmonger and put it under an electron microscope, and you see perfect little round balls,” Vinther said. “And then when you take fossilized ink, it looks exactly the same: perfect little round balls.”

Those balls are melanosomes — microscopic blobs of melanin, the pigment that colors hair, skin, feathers and eyes across the animal kingdom. These round structures turned out to be the same ones being mistaken for bacteria in dinosaur feathers.

Scientists had largely believed that pigment couldn’t survive the fossilization process, but discoveries by scientists such as Vinther have shown not only that pigment survives but that it can tell us the actual colors of extinct animals. That’s because melanin comes not only in “perfect little round balls” but also in many different shapes, each of which produces a different color.

“If you look at a person with black hair or a bird with black feathers, [those melanosomes] are sausage-shaped,” Vinther said. “Whereas if you’re ginger — if you’re a North American robin with a ginger chest or you’ve got ginger hair like Carrot Top — they’re shaped like little meatballs.

“So basically, you just look for sausages and meatballs, and then you can actually put colors on extinct animals,” Vinther said.

Big, fat melanosomes indicate gray or blue pigment. Melanosomes that are long and skinny, flat or hollow are a sign of iridescence.

“That’s actually generated by ordering melanin in a specific way inside the feather in order to create structures that can interact with light,” Vinther said. The flat or hollow shape of the individual melanosomes helps them fit together in a way that creates the metallic sheen of iridescence.

The small bipedal dinosaur Sinosauropteryx had a raccoon-like face mask and countershading when it hunted prey during the Cretaceous period. (Image credit: Bob Nicholls)

The crow-size Anchiornis had black and white wings and a red crest atop its head when it was alive during the Jurassic period. (Image credit: Carl Buell)

The Labrador-size dinosaur Psittacosaurus was countershaded, with a light underbelly and tail and a more pigmented chest during its lifetime in the Cretaceous period. (Image credit: Bob Nicholls)

Once you know the shape of the melanosomes in a fossil, you can learn all sorts of things about the animal. For example, some dinosaurs with fearsome reputations were incredibly showy.

“Many of the close relatives of Velociraptor — you know, that was chasing the kids around in the kitchen [in “Jurassic Park”]?” Vinther said. “First of all, that was covered in feathers. It was really bird-like, not like this naked thing that we see there. But furthermore, most of the relatives that we looked at that were close to it, they were iridescent. So they would have had a metallic sheen, like hummingbirds or peacocks.”

Other dinosaurs had complex camouflage. The first dinosaur Vinther ever studied was a small, bird-like animal called Anchiornis. Based on the melanosomes, Vinther and his team concluded that it had a gray body, white wing feathers with black splotches at the tips and a red crown like a woodpecker’s.

Another dinosaur called Sinosauropteryx — the first dinosaur to be discovered with feathers — had a striped tail and a bandit mask, sort of like a raccoon. It also had countershading, a kind of natural camouflage in which the parts of an animal that would usually be in shadow have a lighter pigment than the parts that would usually be in sunlight. A classic example of this is the white-tailed deer (Odocoileus virginianus), which has a white belly and a brown backside.

This coloring tells scientists about the creatures’ habitat; if the countershading is sharp and high on the body, as it was in Sinosauropteryx, the animal probably lives out in the open. Countershading that’s more gradual and low on the body suggests a forest environment where the light is more diffuse.

Camouflage also distinguishes predators from prey. The huge armored dinosaur Borealopelta markmitchelli seems like it would have had zero predators, but its countershading suggests otherwise.

“If you look at large animals today, they don’t have any color patterns, like elephants [and] rhinos,” Vinther said. “And that’s because nobody messes with them.”

“So, based on the fact that this animal was covered in armor, really huge, but it was countershaded tells us that ‘Jurassic Park’ would have been scary,” Vinther said. “You’re still vulnerable even if you’re that big and that armored.”

Originally published on Live Science
By
24.04.2022

 


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Cosmic ‘angel wings’ emerge from violent galactic collision in Leo constellation

Top Science News

The image of the galaxy merger was discovered by a citizen science project.

The two merging galaxies in the VV689 system have been nicknamed the ‘angel wing’. (Image credit: ESA/Hubble & NASA, W. Keel. Acknowledgement: J. Schmidt)

An angel gets its wings as two distant galaxies collide in a stunning new image snapped by the Hubble Space Telescope.

The galactic smashup took place in the VV689 system in the constellation Leo. The delicate wings formed as the two gravitationally bound objects collided and merged, deforming each other.

“The galactic interaction has left the VV689 system almost completely symmetrical, giving the impression of a vast set of galactic wings,” officials with the European Space Agency (ESA) said in a statement.

While the two galaxies in the VV689 system are truly colliding, other images can be deceiving.

“Unlike chance alignments of galaxies which only appear to overlap as seen from our vantage point on Earth, the two galaxies in VV689 are in the midst of a collision,” ESA officials said in the statement.

For example, in 2012, Hubble captured an image of what looked like two overlapping galaxies, called NGC 3314, seemingly in the midst of a collision. In that case, however, it was merely a trick of perspective, according to ESA.

A Hubble Space Telescope image showing a pair of overlapping galaxies called NGC 331. (Image credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and W. Keel (University of Alabama))

Many galaxy collisions are inevitable and were set in motion billions of years ago. By monitoring how galaxies move relative to each other, scientists can predict if and when galaxies will collide, according to NASA. For example, astronomers have predicted that in around 5 billion years, the Milky Way will inevitably crash into our neighboring galaxy, Andromeda, Live Science previously reported.

The image of VV689 was discovered by the Galaxy Zoo citizen science project, in which hundreds of thousands of volunteers sift through an enormous trove of data collected by different telescopes, including Hubble, according to ESA.

After wading through images of galaxies, the public voted on a selection of noteworthy examples and submitted them for “detailed follow-up observations with Hubble’s Advanced Camera for Surveys,” according to ESA. Some of the submitted examples included ring-shaped galaxies, galaxy spirals and a selection of galactic mergers, including VV689.

Originally published on Live Science
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22.04.2022

 


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