Category: physics – Page 160
This sci-fi megastructure has captivated big thinkers for decades. A leading expert in astrobiology tells us how to construct one.
The paper focused more on theory than engineering, and Dyson provided scant details on what such a megastructure might look like or how we might build one. He described his sphere only as a “habitable shell” encircling a star. But that was enough to captivate and inspire astrophysicists, scientists, and sci-fi writers. In some depictions, the Dyson Sphere, as it became known, appears as a massive ring encircling a star and reaching nearly to Earth. In others, the Sphere completely encases the sun, a hulking megastructure capturing every bit of that star’s energy. In addition to scientific works, Dyson Spheres have appeared in novels, movies, and TV shows—including Star Trek —as a home for advanced civilizations.
Dyson himself understood the challenges of constructing such a massive structure, and he was skeptical that it might ever happen. Nonetheless, his Sphere has stirred ambitious ideas about the future of our civilization, and it continues to be offered as a solution to some of humanity’s most dire dilemmas. Harnessing the total energy of our sun—or any star—would solve our immediate and long-term energy crisis, but when civilization gains access to the complete energy output of a star, meeting our terrestrial energy needs is just the beginning.
With so much energy available, we could direct high-powered laser pulses toward exoplanets that we think may contain life, immeasurably expanding our chances of communicating with distant civilizations. These Dyson-powered beams could travel farther into the universe than anything currently possible, penetrating the higher-density areas of space, such as dust clouds, which decay the signals we send now.
Incorporating established physics into neural network algorithms helps them to uncover new insights into material properties
According to researchers at Duke University, incorporating known physics into machine learning algorithms can help the enigmatic black boxes attain new levels of transparency and insight into the characteristics of materials.
Researchers used a sophisticated machine learning algorithm in one of the first efforts of its type to identify the characteristics of a class of engineered materials known as metamaterials and to predict how they interact with electromagnetic fields.
Time travel makes regular appearances in popular culture, with innumerable time travel storylines in movies, television and literature. But it is a surprisingly old idea: one can argue that the Greek tragedy Oedipus Rex, written by Sophocles over 2,500 years ago, is the first time travel story.
But is time travel in fact possible? Given the popularity of the concept, this is a legitimate question. As a theoretical physicist, I find that there are several possible answers to this question, not all of which are contradictory.
The simplest answer is that time travel cannot be possible because if it was, we would already be doing it. One can argue that it is forbidden by the laws of physics, like the second law of thermodynamics or relativity. There are also technical challenges: it might be possible but would involve vast amounts of energy.
Lemoine, an engineer for Google’s responsible AI organization, described the system he has been working on since last fall as sentient, with a perception of, and ability to express thoughts and feelings that was equivalent to a human child.
“If I didn’t know exactly what it was, which is this computer program we built recently, I’d think it was a seven-year-old, eight-year-old kid that happens to know physics,” Lemoine, 41, told the Washington Post.
He said LaMDA engaged him in conversations about rights and personhood, and Lemoine shared his findings with company executives in April in a GoogleDoc entitled “Is LaMDA sentient?”
From a zoomed out, distant view, star-forming cloud L483 appears normal. But when a Northwestern University-led team of astrophysicists zoomed in closer and closer, things became weirder and weirder.
As the researchers peered closer into the cloud, they noticed that its magnetic field was curiously twisted. And then—as they examined a newborn star within the cloud—they spotted a hidden star, tucked behind it.
“It’s the star’s sibling, basically,” said Northwestern’s Erin Cox, who led the new study. “We think these stars formed far apart, and one moved closer to the other to form a binary. When the star traveled closer to its sibling, it shifted the dynamics of the cloud to twist its magnetic field.”
It’s said that the clock is always ticking, but there’s a chance that it isn’t. The theory of “presentism” states that the current moment is the only thing that’s real, while “eternalism” is the belief that all existence in time is equally real. Find out if the future is really out there and predictable—just don’t tell us who wins the big game next year.
This video is episode two from the series “Mysteries of Modern Physics: Time”, Presented by Sean Carroll.
Learn more about the physics of time at https://www.wondrium.com/YouTube.
00:00 Science and Philosophy Combine When Studying Time.
2:30 Experiments Prove Continuity of Time.
6:47 Time Is Somewhat Predictable.
8:10 Why We Think of Time Differently.
8:49 Our Perception of Time Leads to Spacetime.
11:54 We Dissect Presentism vs Eternalism.
15:43 Memories and Items From the Past Make it More Real.
17:47 Galileo Discovers Pendulum Speeds Are Identical.
25:00 Thought Experiment: “What if Time Stopped?”
29:07 Time Connects Us With the Outside World.
Welcome to Wondrium on YouTube.
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SAN FRANCISCO — Google engineer Blake Lemoine opened his laptop to the interface for LaMDA, Google’s artificially intelligent chatbot generator, and began to type.
“Hi LaMDA, this is Blake Lemoine …,” he wrote into the chat screen, which looked like a desktop version of Apple’s iMessage, down to the Arctic blue text bubbles. LaMDA, short for Language Model for Dialogue Applications, is Google’s system for building chatbots based on its most advanced large language models, so called because it mimics speech by ingesting trillions of words from the internet.
“If I didn’t know exactly what it was, which is this computer program we built recently, I’d think it was a 7-year-old, 8-year-kid kid that happens to know physics,” said Lemoine, 41.
Why the Public Perception of Tesla is TOTALLY wrong:
Shared by Michael Michalchik.
Almost everything commonly told about Tesla is wrong! He didn’t invent AC, he didn’t battle Edison over AC vs. DC, he didn’t even have a rivalry with Edison, he didn’t want to give everyone free electricity and he wasn’t a Physics genius! Referencing primary sources I can show you why we have such a perverted view of Tesla’s real accomplishments and life.
Scientists who study the cosmos have a favorite philosophy known as the “mediocrity principle,” which, in essence, suggests that there’s really nothing special about Earth, the sun or the Milky Way galaxy compared to the rest of the universe.
Now, new research from CU Boulder adds yet another piece of evidence to the case for mediocrity: Galaxies are, on average, at rest with respect to the early universe. Jeremy Darling, a CU Boulder astrophysics professor, recently published this new cosmological finding in The Astrophysical Journal Letters.
“What this research is telling us is that we have a funny motion, but that funny motion is consistent with everything we know about the universe —there’s nothing special going on here,” said Darling. “We’re not special as a galaxy or as observers.”