Lifeboat Foundation

A new method for studying the behavior of multiparticle systems relies on a simple “head count” of particles in imaginary boxes.

One way to characterize the interactions in a bacterial colony or a polymer mixture is to trace the path of individual particles through the system, but such tracking can become difficult when the particles are indistinguishable. Researchers have developed a new method that extracts particle dynamics from a simple counting of particles in imaginary boxes of adjustable size [1]. They demonstrated this “countoscope” strategy in experiments with small plastic spheres moving around in a liquid. The measured rate of diffusion was different for different sized boxes, which revealed particle clumping. The countoscope’s ability to identify such collective behavior could one day help researchers understand the mechanisms that cause bacteria and other life forms to group together.

Biologists, chemists, and soft-matter physicists often study many-particle systems in which the particles shuffle around each other in a “random walk.” A useful measure of this behavior is the diffusion constant, which describes how fast an individual particle moves. A measurement of the diffusion constant can tell a biologist whether cells are healthy or sick, or it can tell a chemist how fast a molecule will move through a gel in a chemical-analysis device. The diffusion constant is typically determined by following the path of a single particle in a video recording. This trajectory reconstruction becomes difficult, however, when the particles are numerous and all look the same, says Sophie Marbach from Sorbonne University in France.

stores and retrieves important information, such as domain-specific knowledge and memories. One dimension of human memory is the ability to link various aspects of experience to specific life events.

Past studies have suggested that this memory-related process is supported by phase precession, which is a shift in the timing at which specific neurons are fired. Up until now, however, this hypothesis had not been confirmed experimentally.

Researchers at the University of California, Davis, Harvard Medical School, Toronto Western Hospital and Cedars-Sinai Medical Center recently carried out a study aimed at probing the relationship between phase precession and memory.

Astronomers from the European University Cyprus and the University of Hawaii have investigated a recently discovered obscured hyperluminous quasar known as COS-87259. Results of the study, published October 14 in the Monthly Notices of the Royal Astronomical Society, shed more light on the properties of this quasar.

Fusion energy has the potential to be an effective clean energy source, as its reactions generate incredibly large amounts of energy. Fusion reactors aim to reproduce on Earth what happens in the core of the sun, where very light elements merge and release energy in the process. Engineers can harness this energy to heat water and generate electricity through a steam turbine, but the path to fusion isn’t completely straightforward.

A research team has proposed a wind sensing lidar theory based on up-conversion quantum interference and successfully developed a prototype. Their work is published in ACS Photonics.

A new study has uncovered the universal dynamics far from equilibrium in randomly interacting spin models, thereby complementing the well-established universality in low-energy equilibrium physics. The study, recently published in Nature Physics, was the result of a collaborative effort involving the research group led by Prof. Du Jiangfeng and Prof. Peng Xinhua at the University of Science and Technology of China (USTC), along with the theoretical groups of Prof. Zhai Hui from Tsinghua University and Dr. Zhang Pengfei from Fudan University.

Two supermassive black holes will collide in 10,000 years, warping space and time.

A Cosmic Collision in the Making

In a galaxy 9 billion light-years away, two enormous black holes are locked in a cosmic dance that will eventually end in a massive collision. These supermassive black holes, each hundreds of millions of times the mass of our sun, are currently orbiting one another. In about 10,000 years, they will merge in a violent event, unleashing enough force to distort space and time by creating gravitational waves—ripples in the universe’s fabric.

A plasma jet from galaxy M87 appears to move five times faster than light.

In the world of astronomy, a peculiar and seemingly impossible phenomenon is unfolding in galaxy M87. A beam of plasma, or energy, is shooting out from the galaxy’s core and appears to travel at five times the speed of light, as observed by the Hubble Space Telescope. Though this illusion has been known since 1995, it continues to challenge our understanding of the universe’s laws, particularly the cosmic speed limit that states nothing can move faster than light.

Evidence is found for a distant galaxy growing inside-out within the first 700 million years of the Universe. The galaxy has a dense central core comparable in mass density to local massive ellipticals, and an extended star-forming disc.