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🔗 Video games 🔗 Computing

Habitat is a massively multiplayer online role-playing game (MMORPG) developed by LucasArts. It is the first attempt at a large-scale commercial virtual community that was graphic based. Initially created in 1985 by Randy Farmer and Chip Morningstar, the game was made available as a beta test in 1986 by Quantum Link, an online service for the Commodore 64 computer and the corporate progenitor to AOL. Both Farmer and Morningstar were given a First Penguin Award at the 2001 Game Developers Choice Awards for their innovative work on Habitat. As a graphical MUD it is considered a forerunner of modern MMORPGs unlike other online communities of the time (i.e. MUDs and massively multiplayer onlines with text-based interfaces). Habitat had a GUI and large user base of consumer-oriented users, and those elements in particular have made Habitat a much-cited project and acknowledged benchmark for the design of today's online communities that incorporate accelerated 3D computer graphics and immersive elements into their environments.

🔗 Linguistics 🔗 Energy 🔗 Linguistics/Philosophy of language

Long-time nuclear waste warning messages are intended to deter human intrusion at nuclear waste repositories in the far future, within or above the order of magnitude of 10,000 years. Nuclear semiotics is an interdisciplinary field of research, first done by the Human Interference Task Force since 1981.

A 1996 report from Sandia National Laboratories recommended that any such message should comprise four levels of increasing complexity:

• Level I: Rudimentary Information: "Something man-made is here"
• Level II: Cautionary Information: "Something man-made is here and it is dangerous"
• Level III: Basic Information: Tells what, why, when, where, who, and how
• Level IV: Complex Information: Highly detailed written records, tables, figures, graphs, maps and diagrams

🔗 Soviet Union 🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Environment 🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/Cold War 🔗 Russia/Russian, Soviet, and CIS military history 🔗 Military history/Russian, Soviet and CIS military history 🔗 Russia/history of Russia

The Soviet RDS-202 hydrogen bomb (code name Ivan or Vanya), known by Western nations as Tsar Bomba (Russian: Царь-бо́мба, tr. Tsar'-bómba, IPA: [t͡sarʲ ˈbombə], lit. 'Tsar bomb'), was the most powerful nuclear weapon ever created. Tested on 30 October 1961 as an experimental verification of calculation principles and multi-stage thermonuclear weapon designs, it also remains the most powerful human-made explosive ever detonated.

The bomb was detonated at the Sukhoy Nos ("Dry Nose") cape of Severny Island, Novaya Zemlya, 15 km (9.3 mi) from Mityushikha Bay, north of Matochkin Strait. The detonation was secret but was detected by US Intelligence agencies. The US apparently had an instrumented KC-135R aircraft (Operation SpeedLight) in the area of the test – close enough to have been scorched by the blast.

The bhangmeter results and other data suggested the bomb yielded about 58 megatons of TNT [Mt] (240 PJ), and that was the accepted yield in technical literature until 1991 when Soviet scientists revealed that their instruments indicated a yield of 50 Mt (210 PJ). As they had the instrumental data and access to the test site, their yield figure has been accepted as more accurate. In theory, the bomb would have had a yield in excess of 100 Mt (420 PJ) if it had included a uranium-238 tamper but, because only one bomb was built, that capability has never been demonstrated.

The remaining bomb casings are located at the Russian Atomic Weapon Museum in Sarov and the Museum of Nuclear Weapons, All-Russian Research Institute of Technical Physics, at Snezhinsk.

🔗 Computing 🔗 Computer science 🔗 Computing/Software

Hy (alternately, Hylang) is a programming language, a dialect of the language Lisp designed to interact with the language Python by translating expressions into Python's abstract syntax tree (AST). Hy was introduced at Python Conference (PyCon) 2013 by Paul Tagliamonte.

Similar to Kawa's and Clojure's mapping of s-expressions onto the Java virtual machine (JVM), Hy is meant to operate as a transparent Lisp front end to Python's abstract syntax. Lisp allows operating on code as data (metaprogramming). Thus, Hy can be used to write domain-specific languages. Hy also allows Python libraries, including the standard library, to be imported and accessed alongside Hy code with a compiling step converting the data structure of both into Python's AST.

🔗 England 🔗 Geography 🔗 Transport 🔗 UK geography 🔗 East Anglia 🔗 Hiking trails 🔗 East Anglia/Essex

The Broomway is a public right of way over the foreshore at Maplin Sands off the coast of Essex, England. Most of the route is classed as a Byway Open to All Traffic, with a shorter section of bridleway. When the tide is out, it provides access to Foulness Island, and indeed was the only access to Foulness on foot, and the only access at low tide, until a road bridge was built over Havengore Creek in 1922.

At over 600 years old, recorded as early as 1419, the Broomway runs for 6 miles (9.7 km) along the Maplin Sands, some 440 yards (400 m) from the present shoreline. It was named for the "brooms", bundles of twigs attached to short poles, with which the route was once marked. A number of headways or hards ran from the track to the shore, giving access to local farms. The track is extremely dangerous in misty weather, as the incoming tide floods across the sands at high speed, and the water forms whirlpools because of flows from the River Crouch and River Roach. Under such conditions, the direction of the shore cannot be determined. After the road bridge was opened in 1922, the Broomway ceased to be used, except by the military.

🔗 Technology 🔗 Environment 🔗 Science Fiction 🔗 Astronomy 🔗 Transhumanism 🔗 Futures studies 🔗 Energy

The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy they are able to use. The measure was proposed by Soviet astronomer Nikolai Kardashev in 1964. The scale has three designated categories:

• A Type I civilization, also called a planetary civilization—can use and store all of the energy available on its planet.
• A Type II civilization, also called a stellar civilization—can use and control energy at the scale of its stellar system.
• A Type III civilization, also called a galactic civilization—can control energy at the scale of its entire host galaxy.

🔗 Science

Literature-based discovery is a form of knowledge extraction and automated hypothesis generation that uses papers and other academic publications (the "literature") to find new relationships between existing knowledge (the "discovery"). The technique was pioneered by Don R. Swanson in the 1980s and has since seen widespread use.

Literature-based discovery does not generate new knowledge through laboratory experiments, as is customary for empirical sciences. Instead it seeks to connect existing knowledge from empirical results by bringing to light relationships that are implicated and "neglected". It is marked by empiricism and rationalism in concert or consilience.

🔗 Physics 🔗 Astronomy

The Chandrasekhar limit () is the maximum mass of a stable white dwarf star. The currently accepted value of the Chandrasekhar limit is about 1.4 M_☉ (2.765×10³⁰ kg).

White dwarfs resist gravitational collapse primarily through electron degeneracy pressure (compare main sequence stars, which resist collapse through thermal pressure). The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star's core is insufficient to balance the star's own gravitational self-attraction. Consequently, a white dwarf with a mass greater than the limit is subject to further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or black hole. Those with masses up to the limit remain stable as white dwarfs.

The limit was named after Subrahmanyan Chandrasekhar, an Indian astrophysicist who improved upon the accuracy of the calculation in 1930, at the age of 20, in India by calculating the limit for a polytrope model of a star in hydrostatic equilibrium, and comparing his limit to the earlier limit found by E. C. Stoner for a uniform density star. Importantly, the existence of a limit, based on the conceptual breakthrough of combining relativity with Fermi degeneracy, was indeed first established in separate papers published by Wilhelm Anderson and E. C. Stoner in 1929. The limit was initially ignored by the community of scientists because such a limit would logically require the existence of black holes, which were considered a scientific impossibility at the time. The fact that the roles of Stoner and Anderson are often forgotten in the astronomy community has been noted.

🔗 Computing 🔗 Mathematics 🔗 Computing/Software 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Computing/Computer Security

Homomorphic encryption is a form of encryption that allows computation on ciphertexts, generating an encrypted result which, when decrypted, matches the result of the operations as if they had been performed on the plaintext.

Homomorphic encryption can be used for privacy-preserving outsourced storage and computation. This allows data to be encrypted and out-sourced to commercial cloud environments for processing, all while encrypted. In highly regulated industries, such as health care, homomorphic encryption can be used to enable new services by removing privacy barriers inhibiting data sharing. For example, predictive analytics in health care can be hard to apply due to medical data privacy concerns, but if the predictive analytics service provider can operate on encrypted data instead, these privacy concerns are diminished.

🔗 Economics 🔗 Game theory

A Vickrey–Clarke–Groves (VCG) auction is a type of sealed-bid auction of multiple items. Bidders submit bids that report their valuations for the items, without knowing the bids of the other bidders. The auction system assigns the items in a socially optimal manner: it charges each individual the harm they cause to other bidders. It gives bidders an incentive to bid their true valuations, by ensuring that the optimal strategy for each bidder is to bid their true valuations of the items. It is a generalization of a Vickrey auction for multiple items.

The auction is named after William Vickrey, Edward H. Clarke, and Theodore Groves for their papers that successively generalized the idea.

The VCG auction is a specific use of the more general VCG Mechanism. While the VCG auction tries to make a socially optimal allocation of items, VCG mechanisms allow for the selection of a socially optimal outcome out of a set of possible outcomes. If collusion is likely to occur among bidders, the VCG outperforms the generalized second-price auction for both revenues produced for the seller and allocative efficiency.