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A Fundamental Principle of Aeronautical Engineering Has Been Overturned
Aerodynamic drag is a major "barrier" in high-speed airplanes, automobiles, and bullet trains. This is because a design with less aerodynamic drag allows the aircraft to move at higher speeds with less energy. When an aircraft or car body moves at high speed, a thin layer of air called the "boundary layer" is formed on its surface. This boundary layer has two states: laminar flow, in which air flows in an orderly fashion, and turbulent flow, which involves turbulence. The longer the air stays in the laminar flow state with low friction, the smaller the air resistance becomes, but as the air speed increases, it transitions to turbulent flow. The key to reducing aerodynamic drag is how to delay this transition to turbulence.
For more than 80 years, the principle of "the surface of an object must be smooth" has been the basic premise of aeronautical engineering throughout the world in order to suppress the transition to turbulence and reduce aerodynamic drag. This premise was based on the results of a 1940 study by Ichiro Tani, a Japanese aerodynamicist who quantitatively demonstrated the relationship between "surface roughness" (an indicator of the state of the machined surface) and turbulent transition, arguing that surface roughness, which was unavoidable with the manufacturing technology of the time, prevented laminar flow from being realized. However, in 1989 Tani reinterpreted the experimental data on rough-surface pipes obtained by fluid engineer Johann Nikulase in the 1930s, bringing a new perspective that "roughness may not necessarily only promote turbulent transition and increase fluid resistance." Inheriting this idea, a research group led by Yasuaki Kohama of Tohoku University experimentally demonstrated in the 1990s that fibrous rough surfaces, which have fine fibrous irregularities on their surface, have the effect of delaying transition under certain conditions.
The same Tohoku University research team recently announced a discovery that significantly advances this trend. Aiko Yakino, associate professor at Tohoku University's Institute of Fluid Science, and her research group were the first in the world to demonstrate that aerodynamic drag can be reduced by up to 43.6 percent simply by applying distributed micro-roughness (DMR), a surface roughness so fine and irregular that it cannot be distinguished by the naked eye. This technology is fundamentally different from the "rivulet (shark skin) process," which is known as a typical aerodynamic drag reduction technology. The rivulet process mimics the fine longitudinal grooves in shark skin, and by carving grooves approximately 0.1 mm wide along the direction of airflow, it aligns the vortices that occur near the wall surface of turbulent airflow areas. DMR, on the other hand, delays the switch from laminar to turbulent flow by means of random and minute irregularities. The flow zones it affects and the mechanisms it employs are based on completely different concepts.
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Retrocausal capacity of a quantum channel: Communicating through noisy closed timelike curves
We study the capacity of a quantum channel for retrocausal communication, where messages are transmitted backward in time, from a sender in the future to a receiver in the past, through a noisy postselected closed timelike curve (P-CTC) mathematically represented by the channel. We completely characterize the one-shot retrocausal quantum and classical capacities, and we show that the corresponding asymptotic capacities are equal to the average and sum, respectively, of the channel’s max-information and its regularized Doeblin information. This endows these information measures with a novel operational interpretation. Furthermore, our characterization can be generalized beyond quantum channels to all completely positive maps. This imposes information-theoretic limits on transmitting messages via postselected-teleportation-like mechanisms with arbitrary initial- and final-state boundary conditions, including those considered in various black-hole final-state models.
More from the author: Fundamental limits for thermodynamic control with quantum feedback
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Sloan Great Wall
The Sloan Great Wall (SGW) is a cosmic structure formed by a giant wall of galaxies (a galaxy filament). The wall measures 1.37 billion light-years (1.30×1025 m) in length, located approximately one billion light-years away.
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Synthetic Solipsism
Source: Talk: MIT Media Lab: David Rudnick - Context - #Generative #Media #Business
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The Biotech Industry's Big Vision for the Next Decade
- Compressing morbidity: Healthspan Expansion (Squaring the Life Curve) - Scientists are less focused on the absolute maximum age and more focused on stopping the biological clock. The goal is to make a 90-year-old body function with the cellular energy, bone density, and immune resilience of a 30-year-old. If they achieve that, living to 120 or 150 naturally follows because the organs simply stop wearing out
- Neurological homeostasis: "Metabolic Psychiatry" & Neural Optimization - "Mental illness" is historically defined by behavior and mood, but biotech looks at it as physical, structural malfunctions in the brain. By 2035, the goal is to treat depression, anxiety, and addiction not with talk therapy or blunt-force sedatives, but by using advanced molecular tools to fix brain inflammation, repair broken neural pathways, and perfectly balance neurotransmitters.
- Cognitive and physical optimization: Eradication Over Management (True Disease Cures) - It shifts medicine from healing the sick to enhancing the healthy. Using genetic tweaks and neuro-metabolic drugs, the ultimate goal is to eliminate human baseline defects like brain fog, physical fatigue, and age-related memory loss.
- Optimized nutrient partitioning: Body Composition Engineering - The wild success of drugs like retatrutide proved that obesity is a biological design flaw, not a moral failure. The end goal is a therapeutic baseline where a person's metabolism automatically burns excess fat as heat and perfectly preserves skeletal muscle mass, completely decoupling body composition from strict dieting
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Marshall McLuhan noted that the content of any new medium is always an older medium—like early cinema merely filming theater. Today, AI cinema is trapped in that exact same loop, emulating traditional filmmaking structures before it inevitably discovers its own native form.
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On the ever evolving shape of "Advertising"
If traditional advertising was a creative art studio, modern digital advertising is an algorithmic trading floor. The "heart" of advertising has shifted permanently from Madison Avenue creative agencies to Silicon Valley data pipelines.
In the old world, the heart of advertising was the "Big Idea"—a memorable television commercial, a brilliant billboard, or a catchy jingle. Success was measured by cultural impact and brand awareness.Today, the heart of advertising is the Data Feedback Loop. The core engine of a modern business isn't the ad asset itself; it is the infrastructure that allows an ad platform's machine learning engine to talk directly to a company's product database.
The ultimate, invisible layer of the digital advertising ecosystem is summarized by a well-known industry open secret: The global commercial advertising infrastructure is, by design, the most sophisticated mass-surveillance network ever created.Intelligence agencies like the NSA do not need to build their own bespoke tracking networks from scratch. They can simply intercept, purchase, or legally compel access to the massive pipelines of real-time user data generated by the digital advertising world every single second.
