翼善冠yi-shan-guan, A Type Of Hat In Chinese Hanfu For Ancient Emperors And Kings.

Washington State University Physicists create 'negative mass'

Washington State University physicists have created a fluid with negative mass, which is exactly what it sounds like. Push it, and unlike every physical object in the world we know, it doesn’t accelerate in the direction it was pushed. It accelerates backwards.

The phenomenon is rarely created in laboratory conditions and can be used to explore some of the more challenging concepts of the cosmos, said Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington. The research appears today in the journal Physical Review Letters, where it is featured as an “Editor’s Suggestion.”

Hypothetically, matter can have negative mass in the same sense that an electric charge can be either negative or positive. People rarely think in these terms, and our everyday world sees only the positive aspects of Isaac Newton’s Second Law of Motion, in which a force is equal to the mass of an object times its acceleration, or F=ma. In other words, if you push an object, it will accelerate in the direction you’re pushing it. Mass will accelerate in the direction of the force.

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TRAILER: “AFTER WE LEAVE” (2019)

Written and Directed by Aleem Hossain, “After We Leave” is a gritty sci-fi feature film about a man who has a once-in-a-lifetime chance to emigrate off Earth… only if he can find his estranged wife and convince her to come with him.

Winner: Best Feature Film at Sci Fi London Winner: Best Director at Berlin Sci Fi Film Fest

shit man this got me emotional

TRAILER: “TIME MASTERS (LES MAÎTRES DU TEMPS)” (1982)

This animated science fiction feature film was directed by René Laloux and Tibor Hernádi but most notably - designed by the artist Mœbius. It is based on Stefan Wul’s 1958 science fiction novel L'Orphelin de Perdide (The Orphan of Perdide).

It’s about a boy, Piel, who is stranded on the desert planet Perdide, where giant killer hornets live. He awaits rescue by the space pilot Jaffar, the exiled prince Matton, his sister Belle and Jaffar’s old friend Silbad - who are all trying to reach Perdide and save Piel before it is too late.

If you’ve seen this film,  you’ve probably seen the English language dubs by the BBC in 1987 or 1991 called Time Masters.

This is a super rare film that you can find on DVD, but usually used, and pretty expensive.

Unveiling the Center of Our Milky Way Galaxy

We captured an extremely crisp infrared image of the center of our Milky Way galaxy. Spanning more than 600 light-years, this panorama reveals details within the dense swirls of gas and dust in high resolution, opening the door to future research into how massive stars are forming and what’s feeding the supermassive black hole at our galaxy’s core.

Among the features coming into focus are the jutting curves of the Arches Cluster containing the densest concentration of stars in our galaxy, as well as the Quintuplet Cluster with stars a million times brighter than our Sun. Our galaxy’s black hole takes shape with a glimpse of the fiery-looking ring of gas surrounding it.

The new view was made by the world’s largest airborne telescope, the Stratospheric Observatory for Infrared Astronomy, or SOFIA.

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Black holes ruled out as universe's missing dark matter

For one brief shining moment after the 2015 detection of gravitational waves from colliding black holes, astronomers held out hope that the universe’s mysterious dark matter might consist of a plenitude of black holes sprinkled throughout the universe.

University of California, Berkeley, physicists have dashed those hopes.

Based on a statistical analysis of 740 of the brightest supernovas discovered as of 2014, and the fact that none of them appear to be magnified or brightened by hidden black hole “gravitational lenses,” the researchers concluded that primordial black holes can make up no more than about 40 percent of the dark matter in the universe. Primordial black holes could only have been created within the first milliseconds of the Big Bang as regions of the universe with a concentrated mass tens or hundreds of times that of the sun collapsed into objects a hundred kilometers across.

The results suggest that none of the universe’s dark matter consists of heavy black holes, or any similar object, including massive compact halo objects, so-called MACHOs.

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in mesopotamia there were no 'cover letters' or 'curriculum vitaes'. there were just, pots.

Gamma-ray Bursts: Black Hole Birth Announcements

Gamma-ray bursts are the brightest, most violent explosions in the universe, but they can be surprisingly tricky to detect. Our eyes can’t see them because they are tuned to just a limited portion of the types of light that exist, but thanks to technology, we can even see the highest-energy form of light in the cosmos — gamma rays.

So how did we discover gamma-ray bursts? 

Accidentally!

We didn’t actually develop gamma-ray detectors to peer at the universe — we were keeping an eye on our neighbors! During the Cold War, the United States and the former Soviet Union both signed the Nuclear Test Ban Treaty of 1963 that stated neither nation would test nuclear weapons in space. Just one week later, the US launched the first Vela satellite to ensure the treaty wasn’t being violated. What they saw instead were gamma-ray events happening out in the cosmos!

Things Going Bump in the Cosmos

Each of these gamma-ray events, dubbed “gamma-ray bursts” or GRBs, lasted such a short time that information was very difficult to gather. For decades their origins, locations and causes remained a cosmic mystery, but in recent years we’ve been able to figure out a lot about GRBs. They come in two flavors: short-duration (less than two seconds) and long-duration (two seconds or more). Short and long bursts seem to be caused by different cosmic events, but the end result is thought to be the birth of a black hole.

Short GRBs are created by binary neutron star mergers. Neutron stars are the superdense leftover cores of really massive stars that have gone supernova. When two of them crash together (long after they’ve gone supernova) the collision releases a spectacular amount of energy before producing a black hole. Astronomers suspect something similar may occur in a merger between a neutron star and an already-existing black hole.

Long GRBs account for most of the bursts we see and can be created when an extremely massive star goes supernova and launches jets of material at nearly the speed of light (though not every supernova will produce a GRB). They can last just a few seconds or several minutes, though some extremely long GRBs have been known to last for hours!

A Gamma-Ray Burst a Day Sends Waves of Light Our Way!

Our Fermi Gamma-ray Space Telescope detects a GRB nearly every day, but there are actually many more happening — we just can’t see them! In a GRB, the gamma rays are shot out in a narrow beam. We have to be lined up just right in order to detect them, because not all bursts are beamed toward us — when we see one it’s because we’re looking right down the barrel of the gamma-ray gun. Scientists estimate that there are at least 50 times more GRBs happening each day than we detect!

So what’s left after a GRB — just a solitary black hole? Since GRBs usually last only a matter of seconds, it’s very difficult to study them in-depth. Fortunately, each one leaves an afterglow that can last for hours or even years in extreme cases. Afterglows are created when the GRB jets run into material surrounding the star. Because that material slows the jets down, we see lower-energy light, like X-rays and radio waves, that can take a while to fade. Afterglows are so important in helping us understand more about GRBs that our Neil Gehrels Swift Observatory was specifically designed to study them!

Last fall, we had the opportunity to learn even more from a gamma-ray burst than usual! From 130 million light-years away, Fermi witnessed a pair of neutron stars collide, creating a spectacular short GRB. What made this burst extra special was the fact that ground-based gravitational wave detectors LIGO and Virgo caught the same event, linking light and gravitational waves to the same source for the first time ever!

For over 10 years now, Fermi has been exploring the gamma-ray universe. Thanks to Fermi, scientists are learning more about the fundamental physics of the cosmos, from dark matter to the nature of space-time and beyond. Discover more about how we’ll be celebrating Fermi’s achievements all year!

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10 Things Einstein Got Right

One hundred years ago, on May 29, 1919, astronomers observed a total solar eclipse in an ambitious  effort to test Albert Einstein’s general theory of relativity by seeing it in action. Essentially, Einstein thought space and time were intertwined in an infinite “fabric,” like an outstretched blanket. A massive object such as the Sun bends the spacetime blanket with its gravity, such that light no longer travels in a straight line as it passes by the Sun.

This means the apparent positions of background stars seen close to the Sun in the sky – including during a solar eclipse – should seem slightly shifted in the absence of the Sun, because the Sun’s gravity bends light. But until the eclipse experiment, no one was able to test Einstein’s theory of general relativity, as no one could see stars near the Sun in the daytime otherwise.

The world celebrated the results of this eclipse experiment— a victory for Einstein, and the dawning of a new era of our understanding of the universe.

General relativity has many important consequences for what we see in the cosmos and how we make discoveries in deep space today. The same is true for Einstein’s slightly older theory, special relativity, with its widely celebrated equation E=mc². Here are 10 things that result from Einstein’s theories of relativity:

1. Universal Speed Limit

Einstein’s famous equation E=mc² contains “c,” the speed of light in a vacuum. Although light comes in many flavors – from the rainbow of colors humans can see to the radio waves that transmit spacecraft data – Einstein said all light must obey the speed limit of 186,000 miles (300,000 kilometers) per second. So, even if two particles of light carry very different amounts of energy, they will travel at the same speed.

This has been shown experimentally in space. In 2009, our Fermi Gamma-ray Space Telescope detected two photons at virtually the same moment, with one carrying a million times more energy than the other. They both came from a high-energy region near the collision of two neutron stars about 7 billion years ago. A neutron star is the highly dense remnant of a star that has exploded. While other theories posited that space-time itself has a “foamy” texture that might slow down more energetic particles, Fermi’s observations found in favor of Einstein.

2. Strong Lensing

Just like the Sun bends the light from distant stars that pass close to it, a massive object like a galaxy distorts the light from another object that is much farther away. In some cases, this phenomenon can actually help us unveil new galaxies. We say that the closer object acts like a “lens,” acting like a telescope that reveals the more distant object. Entire clusters of galaxies can be lensed and act as lenses, too.

When the lensing object appears close enough to the more distant object in the sky, we actually see multiple images of that faraway object. In 1979, scientists first observed a double image of a quasar, a very bright object at the center of a galaxy that involves a supermassive black hole feeding off a disk of inflowing gas. These apparent copies of the distant object change in brightness if the original object is changing, but not all at once, because of how space itself is bent by the foreground object’s gravity.

Sometimes, when a distant celestial object is precisely aligned with another object, we see light bent into an “Einstein ring” or arc. In this image from our Hubble Space Telescope, the sweeping arc of light represents a distant galaxy that has been lensed, forming a “smiley face” with other galaxies.

3. Weak Lensing

When a massive object acts as a lens for a farther object, but the objects are not specially aligned with respect to our view, only one image of the distant object is projected. This happens much more often. The closer object’s gravity makes the background object look larger and more stretched than it really is. This is called “weak lensing.”

Weak lensing is very important for studying some of the biggest mysteries of the universe: dark matter and dark energy. Dark matter is an invisible material that only interacts with regular matter through gravity, and holds together entire galaxies and groups of galaxies like a cosmic glue. Dark energy behaves like the opposite of gravity, making objects recede from each other. Three upcoming observatories – Our Wide Field Infrared Survey Telescope, WFIRST, mission, the European-led Euclid space mission with NASA participation, and the ground-based Large Synoptic Survey Telescope — will be key players in this effort. By surveying distortions of weakly lensed galaxies across the universe, scientists can characterize the effects of these persistently puzzling phenomena.

Gravitational lensing in general will also enable NASA’s James Webb Space telescope to look for some of the very first stars and galaxies of the universe.

4. Microlensing

So far, we’ve been talking about giant objects acting like magnifying lenses for other giant objects. But stars can also “lens” other stars, including stars that have planets around them. When light from a background star gets “lensed” by a closer star in the foreground, there is an increase in the background star’s brightness. If that foreground star also has a planet orbiting it, then telescopes can detect an extra bump in the background star’s light, caused by the orbiting planet. This technique for finding exoplanets, which are planets around stars other than our own, is called “microlensing.”

Our Spitzer Space Telescope, in collaboration with ground-based observatories, found an “iceball” planet through microlensing. While microlensing has so far found less than 100 confirmed planets,  WFIRST could find more than 1,000 new exoplanets using this technique.

5. Black Holes

The very existence of black holes, extremely dense objects from which no light can escape, is a prediction of general relativity. They represent the most extreme distortions of the fabric of space-time, and are especially famous for how their immense gravity affects light in weird ways that only Einstein’s theory could explain.

In 2019 the Event Horizon Telescope international collaboration, supported by the National Science Foundation and other partners, unveiled the first image of a black hole’s event horizon, the border that defines a black hole’s “point of no return” for nearby material. NASA’s Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), Neil Gehrels Swift Observatory, and Fermi Gamma-ray Space Telescope all looked at the same black hole in a coordinated effort, and researchers are still analyzing the results.

6. Relativistic Jets

This Spitzer image shows the galaxy Messier 87 (M87) in infrared light, which has a supermassive black hole at its center. Around the black hole is a disk of extremely hot gas, as well as two jets of material shooting out in opposite directions. One of the jets, visible on the right of the image, is pointing almost exactly toward Earth. Its enhanced brightness is due to the emission of light from particles traveling toward the observer at near the speed of light, an effect called “relativistic beaming.” By contrast, the other jet is invisible at all wavelengths because it is traveling away from the observer near the speed of light. The details of how such jets work are still mysterious, and scientists will continue studying black holes for more clues. 

7. A Gravitational Vortex

Speaking of black holes, their gravity is so intense that they make infalling material “wobble” around them. Like a spoon stirring honey, where honey is the space around a black hole, the black hole’s distortion of space has a wobbling effect on material orbiting the black hole. Until recently, this was only theoretical. But in 2016, an international team of scientists using European Space Agency’s XMM-Newton and our Nuclear Spectroscopic Telescope Array (NUSTAR) announced they had observed the signature of wobbling matter for the first time. Scientists will continue studying these odd effects of black holes to further probe Einstein’s ideas firsthand.

Incidentally, this wobbling of material around a black hole is similar to how Einstein explained Mercury’s odd orbit. As the closest planet to the Sun, Mercury feels the most gravitational tug from the Sun, and so its orbit’s orientation is slowly rotating around the Sun, creating a wobble.

 8. Gravitational Waves

Ripples through space-time called gravitational waves were hypothesized by Einstein about 100 years ago, but not actually observed until recently. In 2016, an international collaboration of astronomers working with the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors announced a landmark discovery: This enormous experiment detected the subtle signal of gravitational waves that had been traveling for 1.3 billion years after two black holes merged in a cataclysmic event. This opened a brand new door in an area of science called multi-messenger astronomy, in which both gravitational waves and light can be studied.

For example, our telescopes collaborated to measure light from two neutron stars merging after LIGO detected gravitational wave signals from the event, as announced in 2017. Given that gravitational waves from this event were detected mere 1.7 seconds before gamma rays from the merger, after both traveled 140 million light-years, scientists concluded Einstein was right about something else: gravitational waves and light waves travel at the same speed.

9. The Sun Delaying Radio Signals

Planetary exploration spacecraft have also shown Einstein to be right about general relativity. Because spacecraft communicate with Earth using light, in the form of radio waves, they present great opportunities to see whether the gravity of a massive object like the Sun changes light’s path.  

In 1970, our Jet Propulsion Laboratory announced that Mariner VI and VII, which completed flybys of Mars in 1969, had conducted experiments using radio signals — and also agreed with Einstein. Using NASA’s Deep Space Network (DSN), the two Mariners took several hundred radio measurements for this purpose. Researchers measured the time it took for radio signals to travel from the DSN dish in Goldstone, California, to the spacecraft and back. As Einstein would have predicted, there was a delay in the total roundtrip time because of the Sun’s gravity. For Mariner VI, the maximum delay was 204 microseconds, which, while far less than a single second, aligned almost exactly with what Einstein’s theory would anticipate.

In 1979, the Viking landers performed an even more accurate experiment along these lines. Then, in 2003 a group of scientists used NASA’s Cassini Spacecraft to repeat these kinds of radio science experiments with 50 times greater precision than Viking. It’s clear that Einstein’s theory has held up! 

10. Proof from Orbiting Earth

In 2004, we launched a spacecraft called Gravity Probe B specifically designed to watch Einstein’s theory play out in the orbit of Earth. The theory goes that Earth, a rotating body, should be pulling the fabric of space-time around it as it spins, in addition to distorting light with its gravity.

The spacecraft had four gyroscopes and pointed at the star IM Pegasi while orbiting Earth over the poles. In this experiment, if Einstein had been wrong, these gyroscopes would have always pointed in the same direction. But in 2011, scientists announced they had observed tiny changes in the gyroscopes’ directions as a consequence of Earth, because of its gravity, dragging space-time around it.

BONUS: Your GPS! Speaking of time delays, the GPS (global positioning system) on your phone or in your car relies on Einstein’s theories for accuracy. In order to know where you are, you need a receiver – like your phone, a ground station and a network of satellites orbiting Earth to send and receive signals. But according to general relativity, because of Earth’s gravity curving spacetime, satellites experience time moving slightly faster than on Earth. At the same time, special relativity would say time moves slower for objects that move much faster than others.

When scientists worked out the net effect of these forces, they found that the satellites’ clocks would always be a tiny bit ahead of clocks on Earth. While the difference per day is a matter of millionths of a second, that change really adds up. If GPS didn’t have relativity built into its technology, your phone would guide you miles out of your way!

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Neutron Stars Collide

The recent detection of two neutron stars colliding has sent waves through spacetime and the astronomical community.

You may have seen headlines in the news and not really know why this is such a big deal.

Here’s the Sparknotes version:

A while back a thing called “gravitational waves” were observed for the first time. These are fluctuations in the fabric of spacetime that propagate out from their source just like light, i.e. radially/like a pebble dropped in water. General relativity shows us that the acceleration of objects with mass cause this event to occur.

Until fairly recently these have been too difficult to observe and in fact Einstein didn’t think we’d ever be able to. A series of laser interferometers have disproved that assumption. Using high-precision analysis of how the lasers shift as a gravitational wave moves through them scientists can now see the small movements in the universe that are gravitational waves.

Importantly, we now have three such observatories capable of working together. Known as the “LIGO-Virgo” team, two observatories in the U.S. and one in Italy detected these shifting in spacetime. Three is a pretty magical number in coordinating detections like this because you can then triangulate where the signal comes from and…

BINGO! Within hours optical observatories were zeroing in on the predicted source of these spacetime fluctuations. Indeed, they confirmed the presence of a previously unseen glow:

What you’re looking at is the glow of two neutron stars colliding into each other. This explosion has the energy of approximately 260,000,000 suns.

Each of these stars has such a large mass that the waves in spacetime are actually detectable from a distance of 140 million light-years away.

Impressive, right? Although you might agree, this still begs the question of what exactly we’ve learned from this event. Well - a lot. Since this is the first observation we have made with both gravitational wave observatories and more traditional astronomical observatories (i.e. light detecting ones) we’ve been able to put some numbers on the phenomenon. Here are some of the things we’ve learned:

1) Gravitational waves propagate at the speed of light!

2) A huge portion of heavier elements (like gold and uranium!) may have their origins in neutron star collisions! Nuclear synthesis in stars more typical like the sun is restricted to closer to 10% of the star’s mass being able to fuse elements together into new ones. This process is actually quite inefficient (actually, YOU are a more efficient radiator than the sun!) and it becomes more difficult for a star to fuse the heavier elements. Before this event we didn’t have a good way of explaining why we found so much more heavy stuff than stellar nuclear synthesis could account for. Now? Baboom! This neutron star collision resulted in the synthesis of so much gold that it’s about 150 times more massive than the Earth! Cha-Ching!

So if you’re an amateur (or professional, I suppose) astronomer and you want to see this collision, now dubbed GW170817, and you build a little radio telescope (another post!), you’ll be able to detect this collision for the next 5-10 years due to the afterglow.

(Image credit: NASA and ESA)