Ok, so you can’t really fire a vacuum optimized engine at sea level… and this, really, is where aerospikes come in. The idea behind aerospikes is you allow the ambient air pressure to actually form the walls containing the flow of the exhaust so it’s always in nearly

Loud sounds can harm our ears, especially if the noise appears all of a sudden. It's because the so-called acoustic reflex [https://en.wikipedia.org/wiki/Acoustic_reflex] has not enough time to take effect. A car manufacturer has studied this phenomenon because drivers got ear injuries after car accidents.

In any conventional silicon-based solar cell, there is an absolute limit on overall efficiency, based partly on the fact that each photon of light can only knock loose a single electron, even if that photon carried twice the energy needed to do so. But now, researchers have demonstrated a method

Boston University researchers, Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, a Ph.D. student in the Department of Mechanical Engineering, released a paper in Physical Review B demonstrating it's possible to silence noise using an open, ringlike structure, created to mathematically perfect specifications, for cutting

The Lewis–Mogridge position, named after David Lewis and Martin J. H. Mogridge, was formulated in 1990 and observes that as more roads are built, more traffic consequently fills these roads. Speed gains from some new roads can disappear within months, if not weeks. Sometimes, new roads help to reduce

A few days ago, near my office, there was a promotional event for some random brand of cookies. You could get a box for free, but only if you picked a winning ball in the mouth of a dragon statue. I lost, but a friend shared its cookies. While crunching

In probability theory, the multi-armed bandit problem is a problem in which a fixed limited set of resources must be allocated between competing (alternative) choices in a way that maximizes their expected gain, when each choice's properties are only partially known at the time of allocation, and may become better

Experiments suggest that exotic superconducting materials share a “strange metal” state characterized by a quantum speed limit that somehow acts as a fundamental organizing principle. (...) The hypothesis is that electrons in strange metals might be “dissipating as quickly as they can consistent with the [Heisenberg] uncertainty principle,” Hartnoll explained. The

Present an argument or formula which (even barely) predicts what the next prime number will be (in any given sequence of numbers), and your name will be forever linked to one of the greatest achievements of the human mind, akin to Newton, Einstein and Gödel. (...) Since the death of Riemann

As reported in 1756 by Johann Gottlob Leidenfrost, volatile liquids on hot solids form “gleaming drops resembling quicksilver”, a consequence of their levitation on a vapour cushion. This makes the drops spectacularly mobile, moving away as soon as they are deposited—an observation commonly attributed to gravity or surrounding airflows.

Surprisingly few software engineers and scientists seem to know about it, [even if] it is such a general and powerful tool for combining information in the presence of uncertainty. (...) You can use a Kalman filter in any place where you have uncertain information about some dynamic system, and you can

Recent CERN experiments have once again validated a prediction of the standard model. This is embarrassing for scientists, as they are looking for experimental clues of limits of the standard model. Standard model is known not to explain everything. More about these alternative models below (source Wikipedia [https://en.wikipedia.

Pulling on a knitted scarf can stretch it to twice its length, even though the thread it’s knitted from hardly elongates. Knitting is a timeworn craft, at least a thousand years old, but no satisfactory account of the mechanics of its stretchiness exists. New theoretical work describes how individual

Benham's top, also called Benham's disk, is named after the English newspaper-man, amateur scientist, and toymaker Charles Benham, who in 1895 sold a top painted with the pattern shown. When the disk is spun, arcs of pale color, called Fechner colors or pattern-induced flicker colors (PIFCs), are visible at different

Despite numerous studies and 30-plus genomes under their belts, scientists are still struggling to nail down the defining traits of these tall, long-lived, woody plants. https://www.knowablemagazine.org/article/living-world/2018/what-makes-tree-tree HN discussion https://news.ycombinator.com/item?id=16792726

Trapped in the rigid structure of diamonds formed deep in the Earth's crust, scientists have discovered a form of water ice that was not previously known to occur naturally on our planet. The finding, published Thursday in Science, represents the first detection of naturally occurring ice-VII ever found on Earth.

Here are two thought experiments about thermodynamics that can puzzle uninitiated minds: the Brownian ratchet and Maxwell's daemon. -------------------------------------------------------------------------------- The Brownian ratchet In the philosophy of thermal and statistical physics, the Brownian ratchet or Feynman-Smoluchowski ratchet is a thought experiment about an apparent perpetual motion machine first analysed in 1912

Landauer's principle is a physical principle pertaining to the lower theoretical limit of energy consumption of computation. It holds that "any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information-bearing

The Thing, also known as the Great Seal bug, was one of the first covert listening devices (or "bugs") to use passive techniques to transmit an audio signal. It was concealed inside a gift given by the Soviet Union to W. Averell Harriman, the United States Ambassador to the Soviet

While there are lots of things that artificial intelligence can't do yet—science being one of them—neural networks are proving themselves increasingly adept at a huge variety of pattern recognition tasks. These tasks can range anywhere from recognizing specific faces in photos to identifying specific patterns of particle decays

The contest between gravity and quantum physics takes a new turn. It is the biggest of problems, it is the smallest of problems. At present physicists have two separate rulebooks explaining how nature works. There is general relativity, which beautifully accounts for gravity and all of the things it dominates:

Airplane contrails are real, but we know what they are: water vapor  and small amounts of other combustion products created by jet engines.   The other pollutants may be somewhat harmful, but they are basically the  same thing as produced by any other form of combustion.  So what are  chemtrails?  Wikipedia

High in the trees on the Fiji islands, ants in the species Philidris  nagasau are doing something extraordinary. They've brought in seeds from  several species of a large, lumpy fruit from a plant known as  Squamellaria and carefully planted them in the nooks and crannies of the  tree bark. Once