A new detector-based method clarifies how gravitational waves should be measured in an evolving universe.
Category: physics
Student astronomer discovers ‘Rosetta Stone’ for mysterious cosmic signals
An international team led by astronomers at the University of Sydney has uncovered the clearest evidence yet for the origin of an unusual class of cosmic signals. In doing so, they have identified a rare stellar system that is providing scientists with a natural laboratory to study extreme physics.
Using CSIRO’s ASKAP radio telescope, the team discovered a small, dense star, called a white dwarf, shredding material from its larger, but less dense, companion star.
As this material spirals in, it produces powerful bursts of radio waves and X-rays in a cycle that repeats every 1.4 hours.
Simplifying complex ideas in sketches
What would you see if you tried to travel alongside a light wave at the speed of light? And suppose you held a mirror in front of you as you zipped along. What would you see in the mirror? This and similar thought experiments were posed by the young Albert Einstein to himself in his teens. It’s come to be known as Einstein’s Mirror and is also the title of a popular book on relativity. It would at first seem that light, reflected off your face, could never reach the mirror to, in turn, reflect back into your eyes to see it. So what would you see? It was only years later that Einstein developed a theory that answered this puzzle. And it required some fundamental adjustments to how we understood the world, which still bend my mind to think about them. These include: You can’t travel at the speed of light. Time is not fixed; it is relative. The speed of light is a universal constant—it is the same, independent of the motion of the source. Einstein wrote: “After ten years of reflection, such a principle resulted from a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c [the velocity of light in a vacuum], I should observe such a beam of light as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing…” — Autobiographical notes, 1949 I’ll try to explain a little as I understand it. Our usual experience is that velocities are additive. Suppose I am on a moving train carriage and I throw a ball from the back of the carriage to the front. For an observer outside the train, that ball moves at the speed of the train plus the speed of the ball relative to me. But light behaves differently. As you approach the speed of light, the energy required to keep accelerating approaches infinity. In effect, you can’t reach the speed of light. So an observer of a flying Einstein wouldn’t see light travelling from him to the mirror at twice the speed of light. What changes is time. For the high-speed Einstein, the light would appear to travel away from him to the mirror and back at its usual immense speed. However, for an observer, what would only seem a moment for the high-speed Einstein might take years for the rest of us—the experience of time changes with velocity. It’s a remarkable turn for a simple and fascinating question. It’s amazing to me that the young Einstein would both pose this question, continue work on it, and then think to question some of the most self-evident facts of our world as we experience it: that time is not fixed, that a speed cannot be reached, and of course, ultimately, that energy is matter. The book Einstein’s Mirror is co-authored by my Dad (respect!). It’s full of photographs, fascinating stories, and the characters that moved physics forward. It includes the people, events and science central to another of Christopher Nolan’s films, Oppenheimer. Perhaps Christopher read it 🤔 Related Ideas to Einstein’s Mirror Also see: Laplace’s Demon Redshift Looking back in time The Doppler Effect Sonic Boom The most beautiful equation — Earlier this year, we attended a showing of Christopher Nolan’s Interstellar at the Royal Albert Hall in London with Hans Zimmer’s soundtrack played by a live orchestra. It was a fantastic way to experience a remarkable film—a film that manages to make black holes, wormholes, and time slippage both understandable (largely) and part of the plot. It strikes me as an astonishing achievement for a mainstream film.
When less is more: Scaling law explains why ultrathin materials get stronger as they get thinner
One of the most fascinating aspects of physics is that nature often behaves in ways that seem completely counterintuitive. A good example comes from ultrathin materials. If I take a sheet of material and make it thinner and thinner, most people would expect it to become weaker. After all, there is less material left to bear a load.
Yet over the last decade, experiments and simulations have repeatedly shown something surprising: when certain materials become extremely thin—only a few nanometers or even a few atomic layers thick—they can become dramatically more resistant under extreme mechanical loading.
This phenomenon has been observed in systems as different as graphene, graphene oxide, and ultrathin polymer films. The effect was clear, but the reason behind it remained unclear. Why should materials with completely different chemistry and structure all exhibit a similar trend?
When motion prevents order in active matter systems
Pack enough string-like objects together, and they will begin to align with one another. But replace the strings with worms or bacteria living in your gut, and this self-organization becomes much more difficult. A team of University of Amsterdam (UvA) researchers has demonstrated that activity can fundamentally alter one of the most important phase transitions in soft matter physics.
Many systems in nature spontaneously organize themselves: Bird flocks align their flight directions, schools of fish move collectively, snakes and worms protect themselves by forming tight entangled clusters, and even molecules can coordinate their orientation to form ordered phases.
For string-like objects, or filaments, a key transition happens when you increase how densely they are packed together. If the density is low, they point in random directions, much like a crowd of people walking aimlessly through a city square. Physicists call this the isotropic phase. As more filaments are added, however, they begin to align with one another. Eventually, most filaments point roughly in the same direction, creating an ordered state known as a nematic phase.
Why birds ignore Newton: New theory could sharpen models of flocks, crowds and cells
Birds in flocks, bacteria and cells: In many collective systems, individual elements respond to only part of their surroundings, seemingly defying Newton’s third law of motion—action equals reaction. These exceptions are known as nonreciprocal interactions. A Dresden physics team working with Roderich Moessner, a founding member of the Würzburg–Dresden Cluster of Excellence ctd.qmat, has now developed a theory that makes it possible to describe these interactions efficiently and simulate them far more precisely.
Cosmic acceleration holds up as new analysis rebuts slowdown claim
Our universe’s expansion is still accelerating despite recent claims suggesting otherwise, an international team of astrophysicists says.
They refuted a study published last year claiming the growth of the universe is slowing and insist there is no flaw in the widely accepted theory that a mysterious force known as dark energy is driving the expanding cosmos.
The researchers, who include two Nobel laureates and represent institutions worldwide, say the debate that followed last November’s revelations was the result of a scientific misunderstanding rather than a cosmic grenade threatening to blow apart everything we know about the universe.
Are We the Bootloader for Superintelligence?
A 90 minute interview about AI and our human future.
Dr. Hugo de Garis is a computer scientist, AI researcher, and former professor known for his early work on evolvable hardware, artificial brains, and the long-term risks of superintelligent machines. He coined and popularized the idea of the “Artilect War,” a future conflict between those who want to build godlike artificial intellects and those who believe such systems pose an existential threat to humanity. In the interview, he describes himself as trained in pure mathematics and theoretical physics, formerly a computer science professor, and now focused on broader questions about AI, cosmology, civilization, and the future of humanity.
The interview with Prof. Hugo de Garis centers on his long-standing warning that humanity may face an “Artilect War,” a civilizational conflict over whether to build godlike artificial intellects vastly superior to humans. De Garis argues that future computation, potentially extending from nanotech to femtotech and beyond, could produce minds trillions of trillions of times more capable than ours. He distinguishes between Cosmists, who want to build such beings to expand intelligence into the universe, and Terrans, who oppose them because superintelligence may eliminate or marginalize humanity. He personally remains torn, admiring the cosmic grandeur of posthuman intelligence while recognizing the existential danger.
The conversation also covers AI timelines, recursive self-improvement, AI alignment, the U.S.-China race, the Fermi paradox, simulation theory, cyborgs, cryonics, AI-generated content, the decline of universities, and the future of work. De Garis is impressed by current AI systems, treating them almost as intellectual companions, but he doubts that humanity can guarantee long-term control over recursively improving machines. The central theme is that the question “Should humanity build artilects?” may become the defining political and moral problem of the twenty-first century.
Website https://profhugodegaris.wordpress.com… is Roman Yampolskiy: https://grokipedia.com/page/roman_yam… Research papers: https://scholar.google.com/citations?… Books: AI: Unexplainable, Unpredictable, Uncontrollable https://www.amazon.com/Unexplainable-?tag=lifeboatfound-20… Considerations on the AI Endgame https://www.amazon.com/Considerations?tag=lifeboatfound-20… Artificial Superintelligence: A Futuristic Approach https://www.amazon.com/Artificial-Sup?tag=lifeboatfound-20… Artificial Intelligence Safety and Security https://www.amazon.com/Artificial-Int?tag=lifeboatfound-20… Social Media X https://twitter.com/romanyam FB / roman.yampolskiy IN
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