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Category: physics – Page 5

Cosmic Strings — Cracks in the Fabric of the Universe

Cosmic strings may be ultra-thin defects in spacetime—relic “cracks” from the early universe. How we’d detect them, what they mean for physics, and how aliens might exploit them.

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Watch my exclusive video Settling Saturn’s Rings: https://nebula.tv/videos/isaacarthur–… SFIA Merchandise: https://isaac-arthur-shop.fourthwall… 🌐 Visit our Website: http://www.isaacarthur.net ❤️ Support us on Patreon: / isaacarthur ⭐ Support us on Subscribestar: https://www.subscribestar.com/isaac-a… 👥 Facebook Group: / 1,583,992,725,237,264 📣 Reddit Community: / isaacarthur 🐦 Follow on Twitter / X: / isaac_a_arthur 💬 SFIA Discord Server: / discord Credits: Cosmic Strings – Cracks in the Fabric of the Universe Written, Produced & Narrated by: Isaac Arthur Select imagery/video supplied by Getty Images Chapters 0:00 Intro — Cracks in the Fabric of the Universe 6:11 From Defects to Cosmic Strings 13:31 Civilizations and Cosmic Strings: Tools, Traps, and Temptations 19:43 Nebula 20:39 Cousins, Confusions, and What a Discovery Would Mean.

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Credits:
Cosmic Strings – Cracks in the Fabric of the Universe.
Written, Produced & Narrated by: Isaac Arthur.
Select imagery/video supplied by Getty Images.

Chapters.
0:00 Intro — Cracks in the Fabric of the Universe.
6:11 From Defects to Cosmic Strings.
13:31 Civilizations and Cosmic Strings: Tools, Traps, and Temptations.
19:43 Nebula.
20:39 Cousins, Confusions, and What a Discovery Would Mean.

Earth’s Core Should Be Impossible. A New State of Matter Explains It

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Is Earth’s core a solid or a liquid? Yes. The mysteries of our own planet’s interior have, in many ways, been harder to crack than those of the rest of the cosmos. We can send probes to the edge of the solar system, and the 42 billion light years to the cosmic horizon are largely transparent—a big enough telescope can see the most distant galaxy. But the 6400km to Earth’s center are both opaque to light and far beyond the reach of any conceivable drill. The best we can do for most of our planetary depths is to listen to the faint rumblings of distant earthquakes and then try to piece together how those seismic waves bounce around the interior.

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Fields as Formal Causes, with David Bentley Hart

In this conversation, Rupert Sheldrake and David Bentley Hart delve into the concept of fields in physics, discussing their nature as non-material formative causes and their historical context in scientific thought. They explore the idea that fields, such as gravitational and electromagnetic, act as top-down causes, aligning with Aristotle’s formal and final causes, and argue for a re-evaluation of these ancient concepts in modern science.

Chapter List:

00:00 — Introduction.
01:14 — Exploring Fields as Causes in Nature.
02:08 — Magnetic Fields and Formative Processes.
04:19 — Gravitational Fields and Formative Effects.
06:10 — Aristotle’s Formal and Final Causes.
07:32 — Challenges in Understanding Fields.
09:09 — Fields as Top-Down Causes.
10:34 — Morphic Fields and Formative Causation.
12:23 — Information Theory vs. Form.
14:15 — Fields and Order in Physics.
17:15 — Semantic and Syntactic Information.
18:18 — Universal Gravitational Field.
19:44 — Strong and Weak Nuclear Fields.
21:18 — History of Field Theory and Ether.
23:14 — Gilbert’s Magnetic Theory.
24:46 — Mind-like Structure in Nature.
25:39 — Combination of Top-Down and Bottom-Up Theories.
27:07 — Mechanistic Models and Their Limitations.
28:52 — Recovering Aristotelian Causality.
31:39 — Conclusion and Reflection on Fields as Modern Souls.

—
Dr Rupert Sheldrake, PhD, is a biologist and author best known for his hypothesis of morphic resonance. At Cambridge University, as a Fellow of Clare College, he was Director of Studies in biochemistry and cell biology. As the Rosenheim Research Fellow of the Royal Society, he carried out research on the development of plants and the ageing of cells, and together with Philip Rubery discovered the mechanism of polar auxin transport. In India, he was Principal Plant Physiologist at the International Crops Research Institute for the Semi-Arid Tropics, where he helped develop new cropping systems now widely used by farmers. He is the author of more than 100 papers in peer-reviewed journals and his research contributions have been widely recognized by the academic community, earning him a notable h-index for numerous citations. On ResearchGate his Research Interest Score puts him among the top 4% of scientists.

https://www.sheldrake.org

Gravity follows Newton and Einstein’s rules, even at cosmic scales

Gravity, as most people understand it, is the familiar force that pulls a falling apple toward Earth. But for astronomers and theoretical physicists, it is also a vexing invisible architect that guides the shape and evolution of the largest cosmic structures across the universe.

For decades, puzzling observations of unusually fast-moving galaxies have forced cosmologists like the University of Pennsylvania’s Patricio A. Gallardo to revisit the fundamentals of physics, exploring, for example, whether the laws of gravity as described by Isaac Newton and Albert Einstein truly apply everywhere.

“Astrophysics has been plagued by a massive discrepancy in the cosmic ledger,” says Gallardo. “When we look at how stars orbit within galaxies or how galaxies move within galaxy clusters, some appear to be traveling way too fast for the amount of visible matter they contain.”

Scientists Make Breakthrough on 40-Year-Old 2D Physics Puzzle

Why do patterns emerge as surfaces grow, whether in crystals, flames, or living systems? Physicists have long turned to the Kardar–Parisi–Zhang (KPZ) equation, proposed in 1986, as a unifying description of these processes. This theory captures how randomness and nonlinear effects shape growth across vastly different systems, from spreading bacterial colonies to data-driven algorithms.

Now, researchers at the University of Würzburg have taken a major step toward confirming just how universal this idea really is. After earlier success in one dimension, they have demonstrated for the first time that KPZ behavior also governs growth in two-dimensional systems, a milestone that had remained experimentally out of reach.

Sean Carroll — Why Fine-tuning Seems Designed

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If all is random and our universe is the only universe, the chance existence of human awareness would seem incredible. Because the laws of physics would have to be so carefully calibrated to enable stars and planets to form and life to emerge, it would seem to require some kind of design. But there are other explanations.

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Sean Carroll is Homewood Professor of Natural Philosophy at Johns Hopkins University and fractal faculty at the Santa Fe Institute. His research focuses on fundamental physics and cosmology.

Droplet impacts reveal surprising physics in shear-thickening fluids

From ketchup to quicksand, non-Newtonian fluids have long fascinated and puzzled scientists. Unlike ordinary fluids, their flow properties change depending on how much force is applied, but the precise mechanics governing this behavior remain poorly understood—particularly under rapid deformation. Now, a team led by Xiang Cheng at the University of Minnesota has used droplet impacts to probe these dynamics in new detail, uncovering behaviors which have eluded physicists so far. Their findings appear in Physical Review Letters.

While ordinary Newtonian fluids maintain a constant viscosity regardless of the forces acting on them, non-Newtonian fluids behave very differently: with viscosities that can increase or decrease in response to stress. One classic example is a “shear-thickening” fluid, which can be made simply by mixing cornstarch into water. At high enough concentrations, these suspensions can jam almost completely solid under sudden impacts, even allowing a person to run across them without sinking.

In their study, Cheng’s team prepared cornstarch-water suspensions ranging from 30% to 43% cornstarch by volume, spanning regimes from mild to dramatic shear thickening. They then dropped millimeter-scale droplets of the fluids onto a metal plate at high speeds, producing particularly extreme shear thickening.

Physicists just witnessed pinpricks of darkness moving faster than the speed of light ‪—‬ without breaking the laws of relativity

For the first time, researchers measured singularities in combined light and sound waves moving faster than the speed of light. The findings have implications in fluid dynamics, optics and many other fields.

From ship wakes to soft tissues: Exploring fluid and solid surface-wave physics

A new study by scientists in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) shows that when a pressure disturbance moves across an ultrasoft elastic material, such as a gel or a biological tissue, it generates a V-shaped wake that’s strikingly similar to the waves that travel behind a boat.

Published in Physical Review Letters, the study offers a unified perspective, combining experiments and theory, on surface motion that spans fluids, solids, and the soft materials that lie between. It opens the door to new approaches to imaging and understanding the behavior of both natural and engineered soft materials.

The research was led by L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics, in SEAS and FAS, and includes first author and former postdoctoral researcher Aditi Chakrabarti; postdoctoral researcher Divya Jaganathan, and SEAS research associate Robert Haussman.

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