A 65-year old perplexing question may have finally been answered: Why is the Sun’s atmosphere hotter than its surface?
For over six decades, scientists have been baffled by a cosmic mystery of scorching proportions: Why is the Sun’s atmosphere, known as the corona, hotter than its surface?
Continue reading “ESA and NASA join forces to answer the Sun’s heating riddle” »
After years of dedicated research and over 5 million supercomputer computing hours, a team has created the world’s first high-resolution 3D radiation hydrodynamics simulations for exotic supernovae. This work is reported in The Astrophysical Journal.
Ke-Jung Chen at Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in Taiwan, led an international team and used the powerful supercomputers from the Lawrence Berkeley National Laboratory and the National Astronomical Observatory of Japan to make the breakthrough.
Supernova explosions are the most spectacular endings for massive stars, as they conclude their life cycles in a self-destructive manner, instantaneously releasing brightness equivalent to billions of suns, illuminating the entire universe.
When Isaac Newton inscribed onto parchment his now-famed laws of motion in 1,687, he could have only hoped we’d be discussing them three centuries later.
Writing in Latin, Newton outlined three universal principles describing how the motion of objects is governed in our Universe, which have been translated, transcribed, discussed and debated at length.
But according to a philosopher of language and mathematics, we might have been interpreting Newton’s precise wording of his first law of motion slightly wrong all along.
A wild, compelling idea without a direct, practical test, the Multiverse is highly controversial. But its supporting pillars sure are stable.
Some of the world’s leading physicists believe they have found startling new evidence showing the existence of universes other than our own. See more in Season 3, Episode 2, “Parallel Universes.”
#TheUniverse.
Continue reading “The Universe: New Evidence of Parallel Worlds (S3, E2) | Full Episode” »
The “no-hair theorem” of black holes, which greatly simplifies the way we model them, may not be true if an alternative theory of gravity known as the teleparallel formulation is correct, an unpublished paper argues. This could make the study of black holes considerably more complicated, but it would also allow physicists to understand them in ways many have feared they never will.
According to the “no-hair theorem”, a black hole’s mass, electric charge, and spin can tell us everything there is to know about that hole. Anything else we might measure, such as its magnetic moment, can be derived from these three measures.
Crucially, that means that when matter is swallowed by a black hole’s event horizon, all the information contained within it is lost, once the black hole has emitted any gravitational waves or light associated with its meal. It doesn’t matter what elements went into forming a black hole’s predecessor star, or even if it was made of antimatter rather than matter – under the no-hair theorem, it would appear identical to anyone outside its event horizon. The term “hair” is a metaphor for information streaming out of a black hole beyond the point of no return for incoming objects.
The orbits of 27 stars orbiting closely around the black hole at the center of our Milky Way are so chaotic that researchers cannot predict with confidence where they will be in about 462 years. This finding emerges from simulations by three astronomers based in the Netherlands and the United Kingdom. The researchers have published their findings in two papers in the International Journal of Modern Physics D and in the Monthly Notices of the Royal Astronomical Society.
Simulating 27 stars and their interactions with each other and with the black hole is easier said than done. For centuries, for example, it was impossible to predict the motions of more than two interacting stars, planets, rocks, or other objects. It was only in 2018 that Leiden researchers developed a computer program in which rounding errors no longer play a role in the calculations. With this, they were able to calculate the motions of three imaginary stars. Now the researchers have expanded their program to deal with 27 stars that, by astronomical standards, move close to the black hole at the center of the Milky Way.
The simulations of the 27 massive stars and the black hole resulted in a surprise. Although the stars remain in their orbits around the black hole, the interactions between the stars show that the orbits are chaotic. This means that small perturbations caused by the underlying interactions change the orbits of the stars. These changes grow exponentially and, in the long run, make the star orbits unpredictable.
For a few hours after a star smashes into a supermassive black hole, some of the brightest light in the Universe is produced.
The subsequent flash of radio waves were thought to simmer down within weeks or months of a collision. It turns out we might have been a little impatient to turn our gaze elsewhere.
Continue reading “Black Holes ‘Burp’ Years After Shredding Stars, And We Don’t Know Why” »
As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.
But University of Michigan researchers have discovered that the rate at which these large structures grow is slower than predicted by Einstein’s Theory of General Relativity.
They also showed that as dark energy accelerates the universe’s global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory predicts. Their results are published in Physical Review Letters.
Similarly, allowing the MyoLegs to flail around for a while in a seemingly aimless fashion gave them better performance with locomotion tasks, as the researchers described in another paper presented at the recent Robotics Science and Systems meeting. Vittorio Caggiano, a Meta researcher on the project who has a background in both AI and neuroscience, says that scientists in the fields of neuroscience and biomechanics are learning from the MyoSuite work. “This fundamental knowledge [of how motor control works] is very generalizable to other systems,” he says. “Once they understand the fundamental mechanics, then they can apply those principles to other areas.”
This year, MyoChallenge 2023 (which will also culminate at the NeurIPS meeting in December) requires teams to use the MyoArm to pick up, manipulate, and accurately place common household objects and to use the MyoLegs to either pursue or evade an opponent in a game of tag.
Emo Todorov, an associate professor of computer science and engineering at the University of Washington, has worked on similar biomechanical models as part of the popular Mujoco physics simulator. (Todorov was not involved with the current Meta research but did oversee Kumar’s doctoral work some years back.) He says that MyoSuite’s focus on learning general representations means that control strategies can be useful for “a whole family of tasks.” He notes that their generalized control strategies are analogous to the neuroscience principle of muscle synergies, in which the nervous system activates groups of muscles at once to build up to larger gestures, thus reducing the computational burden of movement. “MyoSuite is able to construct such representations from first principles,” Todorov says.
