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Category: physics

Why your faucet drips: Water jet breakup traced to angstrom-scale thermal capillary waves

Some phenomena in our daily lives are so commonplace that we don’t realize there could be some very interesting physics behind them. Take a dripping faucet: why does the continuous stream of water from a faucet eventually break up into individual droplets? A team of physicists studied this question and reached surprising conclusions.

The breakthrough in understanding how a water jet breaks up into droplets was made by a team consisting of Stefan Kooij, Daniel T. A. Jordan, Cees J. M. van Rijn, and Daniel Bonn from the University of Amsterdam (Van der Waals-Zeeman Institute / Institute of Physics), along with Neil M. Ribe from the Université Paris-Saclay. The study is published in the journal Physical Review Letters.

The case for an antimatter Manhattan project

Chemical rockets have taken us to the moon and back, but traveling to the stars demands something more powerful. Space X’s Starship can lift extraordinary masses to orbit and send payloads throughout the solar system using its chemical rockets, but it cannot fly to nearby stars at 30% of light speed and land. For missions beyond our local region of space, we need something fundamentally more energetic than chemical combustion, and physics offers, or, in other words, antimatter.

When antimatter encounters ordinary matter, they annihilate completely, converting mass directly into energy according to Einstein’s equation E=mc². That c² term is approximately 10¹⁷, an almost incomprehensibly large number. This makes antimatter roughly 1,000 times more energetic than nuclear fission, the most powerful energy source currently in practical use.

As a source of energy, antimatter can potentially enable spacecraft to reach nearby stars at significant fractions of the speed of light. A detailed technical analysis by Casey Handmer, CEO of Terraform Industries, outlines how humanity could develop practical antimatter propulsion within existing spaceflight budgets, requiring breakthroughs in three critical areas; production efficiency, reliable storage systems, and engine designs that can safely harness the most energetic fuel physically possible.

At BYU, Nobel Prize-winning modern Galileo talks about his work that helped prove Einstein right about gravitational waves

The universe occasionally produces a huge surprise that proves physicists wrong, says Kip Thorne, who grew up in Logan, Utah, with Elder Quentin L. Cook and Merlin Olsen.

750 Million at Risk: New Study Warns Extreme Water Scarcity Is Closer Than We Think

Climate simulations reveal that Day Zero Drought conditions are approaching rapidly worldwide, putting vast populations at risk of severe water scarcity. A new study in Nature Communications from researchers at the IBS Center for Climate Physics (ICCP) at Pusan National University in the Republic

Scientists Claim to Detect Dark Matter for the First Time Ever

A team of astronomers say they may have detected dark matter, the invisible substance thought to make up over 85 percent of all matter in the universe, for the first time in history.

The claim is controversial, and the findings, published in a new study in the Journal of Cosmology and Astroparticle Physics, will need to be borne out by further observations. But at least until it gets picked apart by other physicists, it’s one of the most exciting developments in the hunt for this omnipresent specter haunting the cosmos.

“This could be a crucial breakthrough in unraveling the nature of dark matter,” study author Tomonori Totani, an astronomer at the University of Tokyo, told The Guardian.

New universal law predicts how most objects shatter, from dropped bottles to exploding bubbles

When a plate drops or a glass smashes, you’re annoyed by the mess and the cost of replacing them. But for some physicists, the broken pieces are a source of fascination: Why does everything break into such a huge variety of sizes? Now, Emmanuel Villermaux at Aix-Marseille University in France and the University Institute of France has come up with a simple, elegant law for how objects shatter, whether they are brittle solids, liquid drops, or exploding bubbles.

Scientists have long suspected that there was something universal about fragmentation. If you count how many fragments fall into each size range and make a graph of that distribution, it would have the same shape regardless of the object that shattered.

The universe is a puzzle that fits together only one way

Heraclitus famously argued that you can’t step into the same river twice. Here, philosopher JB Manchak argues that the whole universe is like that – and that such a universe has some interesting knock-on consequences. One being that although one can add more structure to a Heraclitus spacetime – by adding a big sign saying “here is the centre of the universe!” What one can’t do, Manchak argues, is reduce symmetries in a Heraclitus spacetime by adding such a sign. To illustrate the point, imagine the universe is a giant puzzle in which each event in space and time is a piece. In a non-Heraclitus universe, some pieces would be able to fit in several places. But in a Heraclitus universe, Manchak argues, there is exactly only one way to put the puzzle pieces of the universe together.

The ancient Greek philosopher Heraclitus is known for his theory of constant flux: “It is not possible to step twice into the same river.” It turns out that one can explore this idea within the context of Einstein’s general relativity. A four-dimensional “Heraclitus spacetime” is a model of the universe in which no two events have the same structure. This means that such models exhibit a radical type of spacetime asymmetry.

In what follows, I will first introduce the notion of Heraclitus spacetime within general relativity. To do this, a few basic definitions will be needed as well as a related discussion of spacetime symmetries. Next, I will highlight a curious result: if a model universe has the Heraclitus property, then its local structure completely fixes its global structure as well. In other words, bits of information encoded at each event allow one to piece together what the universe is like in its entirety (e.g. its shape). Finally, I will sketch a way in which the radical asymmetry present in a Heraclitus spacetime can be used to clarify a number of other topics in the philosophy of spacetime physics.

Physicists generate hybrid spin-sound waves, expanding options for 6G implementation

Acoustic frequency filters, which convert electrical signals into miniaturized sound waves, separate the different frequency bands for mobile communications, Wi-Fi, and GPS in smartphones. Physicists at RPTU have now shown that such miniaturized sound waves can couple strongly with spin waves in yttrium iron garnet. This results in novel hybrid spin-sound waves in the gigahertz frequency range.

The use of such nanoscale hybrid spin-sound waves provides a pathway for agile frequency filters for the upcoming 6G mobile communications generation. The fundamental study by the RPTU researchers has been published in the journal Nature Communications.

Surface acoustic waves (SAWs) are ubiquitous. They unleash destructive power in the form of earthquake waves but are also at the heart of miniaturized frequency filters that are used billions of times for GHz-frequency mobile communication in smartphones.

Exceptional points alter the order of lasing modes

Exceptional points (EPs) are non-Hermitian singularities where two or more eigenstates coalesce, resulting in the eigenspace collapsing in dimensionality. Over the past decade, researchers have uncovered a wealth of exotic phenomena near EPs.

In laser physics, for example, EPs have been linked to pump-induced laser termination, loss-induced lasing, and the design of quasi-parity-time-symmetric laser systems that boost the output power of large-area lasers while preserving single-mode operation.

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