Retraction undermines the bold claim by physicists who said their material conducted electricity without resistance at 15 ˚C.
Category: physics – Page 108
No, it’s not hypermodern art. This image, generated by NASA
Established in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is “To discover and expand knowledge for the benefit of humanity.” Its core values are “safety, integrity, teamwork, excellence, and inclusion.” NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.
It’s easy to envisage other universes, governed by slightly different laws of physics, in which no intelligent life, nor indeed any kind of organized complex systems, could arise. Should we therefore be surprised that a universe exists in which we were able to emerge?
That’s a question physicists including me have tried to answer for decades. But it is proving difficult. Although we can confidently trace cosmic history back to one second after the Big Bang, what happened before is harder to gauge. Our accelerators simply can’t produce enough energy to replicate the extreme conditions that prevailed in the first nanosecond.
But we expect that it’s in that first tiny fraction of a second that the key features of our universe were imprinted.
It’s a theoretical concept, but realistic enough that NASA’s Innovative Advanced Concepts program has given Davoyan’s group $175,000 to show that the technology is feasible. “There’s rich physics in there,” says Davoyan, a mechanical and aerospace engineer at UCLA. To create propulsion, he continues, “you either throw the fuel out of the rocket or you throw the fuel at the rocket.” From a physics perspective, they work the same: Both impart momentum to a moving object.
His team’s project could transform long-distance space exploration, dramatically expanding the astronomical neighborhood accessible to us. After all, we’ve only sent a few robotic visitors to scope out Uranus, Neptune, Pluto, and their moons. We know even less about objects lurking farther away. The even smaller handful of NASA craft en route to interstellar space include Pioneer 10 and 11, which blasted off in the early 1970s; Voyager 1 and 2, which were launched in 1977 and continue their mission to this day; and the more recent New Horizons, which took nine years to fly by Pluto in 2015, glimpsing the dwarf planet’s now famous heart-shaped plain. Over its 46-year journey, Voyager 1 has ventured farthest from home, but a pellet-beam-powered craft could overtake it in just five years, Davoyan says.
He takes inspiration from Breakthrough Starshot, a $100 million initiative announced in 2016 by Russian-born philanthropist Yuri Milner and British cosmologist Stephen Hawking to use a 100-gigawatt laser beam to blast a miniature probe toward Alpha Centauri. (The star nearest our solar system, it resides “only” 4 light-years away.) The Starshot team is exploring how they could hurl a 1-gram craft attached to a lightsail into interstellar space, using the laser to accelerate it to 20 percent of the speed of light, which is ludicrously fast and would reduce travel time from millennia to decades. “I’m increasingly optimistic that later this century, humanity’s going to be including nearby stars in our reach,” says Pete Worden, Breakthrough Starshot’s executive director.
The Nobel Prize in Physics 1936
Posted in physics
Was divided equally between Victor Franz Hess ‘for his discovery of cosmic radiation’ and Carl David Anderson ‘for his discovery of the positron’.
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Physics is the business of figuring out the structure of the world. So are our brains. But sometimes physics comes to conclusions that are in direct conflict with concepts fundamental to our minds, such as the realness of space and time. How do we tell who’s correct? Are time and space objective realities or human-invented concepts?
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After successful recommissioning in autumn 2022, the Greifswald nuclear fusion experiment has surpassed an important target. In 2023, an energy turnover of 1 gigajoule was targeted. Now the researchers have even achieved 1.3 gigajoules and a new record for discharge time on Wendelstein 7-X: the hot plasma could be maintained for eight minutes.
During the three-year completion work that ended last summer, Wendelstein 7-X was primarily equipped with water cooling for the wall elements and an upgraded heating system. The latter can now couple twice as much power into the plasma as before. Since then, the nuclear fusion experiment can be operated in new parameter ranges.
He was ranked the number 1 most influential neuroscientist in the world by Semantic Scholar in 2016, and has received numerous awards and accolades for his work. His appointment as chief scientist of Verses not only validates their platform’s framework for advancing AI implementations but also highlights the company’s commitment to expanding the frontier of AI research and development.
Friston is short listed for a Nobel Prize, is one of the most cited scientists in human history with over 260,000 academic citations, and invented all of the mathematics behind the fMRI scan. As one pundit put it, “what Einstein was to physics, Friston is to Intelligence.”
Indeed Friston’s expertise will be invaluable in helping the company execute its vision of deploying a plethora of technologies working toward a smarter world through AI.
Walk through a maze of mirrors, you’ll soon come face to face with yourself. Your nose meets your nose, your fingertips touch at their phantom twins, stopped abruptly by a boundary of glass.
Most of the time, a reflection needs no explanation. The collision of light with the mirror’s surface is almost intuitive, its rays set on a new path through space with the same ease as a ball bouncing off a wall.
For over sixty years, however, physicists have considered a subtly different kind of reflection. One that occurs not through the three dimensions of space, but in time.
The breakthrough experiment could lead to low-energy, wave-based computers and new applications for wireless communications.
Researchers at the Advanced Science Research Center at the CUNY Graduate Center (CUNY ASRC) performed a breakthrough experiment in which they observed time reflections of electromagnetic signals in a tailored metamaterial.
Time reflection versus spatial reflection.
Andrea Alu.