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Category: physics – Page 157

Last week, NASA’s Perseverance Rover captured a gorgeous view of Phobos eclipsing the Sun, from the surface of Mars. From the point of view of any Martian microbes lurking out there, the eclipse may have seemed more ominous (yeah ok, there might not be living organisms up there, let alone ones sentient enough to grasp the concept of an eclipse) as the moon is destined by physics to one day slam into the red planet.

Phobos – the closest of Mars’ two moons – is set to get ever closer to the planet, before its final descent, while Deimos will drift ever outwards until it leaves Mars’ orbit.

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Have you ever made a mistake that you wish you could undo? Correcting past mistakes is one of the reasons we find the concept of time travel so fascinating. As often portrayed in science fiction, with a time machine, nothing is permanent anymore – you can always go back and change it. But is time travel really possible in our universe, or is it just science fiction?

Our modern understanding of time and causality comes from general relativity. Theoretical physicist Albert Einstein’s theory combines space and time into a single entity – “spacetime” – and provides a remarkably intricate explanation of how they both work, at a level unmatched by any other established theory.

This theory has existed for more than 100 years, and has been experimentally verified to extremely high precision, so physicists are fairly certain it provides an accurate description of the causal structure of our Universe.

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An international team of astronomers reports the discovery of a rare double neutron star millisecond pulsar. The newfound binary pulsar, designated PSR J1325−6253, consists of two neutron stars orbiting one another every 1.8 days. The finding is detailed in a paper published April 14 on arXiv.org.

The most rapidly rotating pulsars, those with rotation periods below 30 milliseconds, are known as (MSPs). It is assumed that they are formed in when the initially more massive component turns into a neutron star that is then spun-up due to accretion of matter from the secondary star.

Some pulsars consist of two (dubbed double neutron star systems—DNS). They are one of the most important classes of objects used to test and understand numerous astrophysical and fundamental physics phenomena, including in the strong-field regime.

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As the early universe cooled shortly after the Big Bang, bubbles formed in its hot plasma, triggering gravitational waves that could be detectable even today, a new study suggests.

For some time, physicists have speculated that a phase transition took place in the early universe shortly after the Big Bang. Phase transition is a change of form and properties of matter that usually accompanies temperature changes such as the evaporation of water into vapor or the melting of metal. In the young and fast expanding universe, something similar likely took place as the plasma, which was filling the space at that time, cooled down.

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The first detection of gravitational waves in 2016 provided decisive confirmation of Einstein’s general theory of relativity. But another astounding prediction remains unconfirmed: According to general relativity, every gravitational wave should leave an indelible imprint on the structure of space-time. It should permanently strain space, displacing the mirrors of a gravitational wave detector even after the wave has passed.

Since that first detection almost six years ago, physicists have been trying to figure out how to measure this so-called “memory effect.”

“The memory effect is absolutely a strange, strange phenomenon,” said Paul Lasky, an astrophysicist at Monash University in Australia. “It’s really deep stuff.”

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Can we find order in chaos? Physicists have shown, for the first time that chaotic systems can synchronize due to stable structures that emerge from chaotic activity. These structures are known as fractals, shapes with patterns which repeat over and over again in different scales of the shape. As chaotic systems are being coupled, the fractal structures of the different systems will start to assimilate with each other, taking the same form, causing the systems to synchronize.

If the systems are strongly coupled, the structures of the two systems will eventually become identical, causing complete synchronization between the systems. These findings help us understand how synchronization and can emerge from systems that didn’t have these properties to begin with, like chaotic systems and .

One of the biggest challenges today in physics is to understand chaotic systems. Chaos, in physics, has a very specific meaning. Chaotic systems behave like random systems. Although they follow deterministic laws, their dynamics still will change erratically. Because of the well-known “butterfly effect” their future behavior is unpredictable (like the weather system, for example).

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Josh SeehermanI don’t think he’s wrong.

Art ToegemannIt’s adjusting to users sharing a password.

Shubham Ghosh Roy shared a link.

At the interface between chemistry and physics, the process of crystallization is omnipresent in nature and industry. It is the basis for the formation of snowflakes but also of certain active ingredients used in pharmacology. For the phenomenon to occur for a given substance, it must first go through a stage called nucleation, during which the molecules organize themselves and create the optimal conditions for the formation of crystals. While it has been difficult to observe pre-nucleation dynamics, this key process has now been revealed by the work of a research team from the University of Geneva (UNIGE). The scientists have succeeded in visualizing this process spectroscopically in real time and on a micrometric scale, paving the way to the design of safer and more stable active substances. These results can be found in the Proceedings of the National Academy of Sciences (PNAS).

Continue reading “Revolutionary images of the birth of crystals” | >

A new spin on one of the 20th century’s smallest but grandest inventions, the transistor, could help feed the world’s ever-growing appetite for digital memory while slicing up to 5% of the energy from its power-hungry diet.

Following years of innovations from the University of Nebraska–Lincoln’s Christian Binek and University at Buffalos Jonathan Bird and Keke He, the physicists recently teamed up to craft the first magneto-electric transistor.

Along with curbing the energy consumption of any microelectronics that incorporate it, the team’s design could reduce the number of transistors needed to store certain data by as much as 75%, said Nebraska physicist Peter Dowben, leading to smaller devices. It could also lend those microelectronics steel-trap memory that remembers exactly where its users leave off, even after being shut down or abruptly losing power.

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