RW
RationalWiki (RW) is an online wiki launched on May 22, 2007, operated as a collaborative platform by the nonprofit RationalMedia Foundation, aimed at promoting critical thinking through the analysis and refutation of pseudoscience, documentation of fringe theories and crank magnetism, and scrutiny of authoritarianism, fundamentalism, and media distortions.[1] Unlike traditional encyclopedias, it forgoes neutrality, adopting a "snarky point of view" (SPOV) that blends factual debunking with irreverent humor, advocacy for scientific consensus, and a self-acknowledged center-left ideological tilt.[1] Originating as a direct rebuttal to Conservapedia—a conservative fork of Wikipedia perceived by its founders as ideologically compromised—RW has amassed thousands of articles on topics ranging from alternative medicine to political extremism, positioning itself as a skeptic's resource amid broader cultural debates over rationality and evidence.[2] While effective in highlighting logical fallacies and empirical shortcomings in pseudoscientific claims, RationalWiki's editorial approach has sparked controversies over perceived partisanship, with critics arguing it disproportionately targets right-leaning figures, movements, and ideas while downplaying similar issues on the left, reflecting a progressive bias that undermines claims of pure rationalism.[3][4] External assessments rate it as left-center biased due to loaded language against conservatives but generally high in factual accuracy on verifiable topics, though its snark and opinionated tone limit reliability for neutral overviews.[3] Notable incidents include defamation lawsuits, such as Matthews v. RationalWiki Foundation (2014), where contributors' characterizations of individuals led to legal challenges over accuracy and malice.[5] These defining traits—combative skepticism fused with ideological advocacy—distinguish RW from more dispassionate references, appealing to audiences seeking pointed critiques but cautioning users to cross-verify amid its selective focus.[6]Geography
Rwanda
The Republic of Rwanda is a sovereign state in East Africa, designated by the ISO 3166-1 alpha-2 code RW for international use.[7] Landlocked and bordered by Uganda to the north, Tanzania to the east, Burundi to the south, and the Democratic Republic of the Congo to the west, it occupies 26,338 square kilometers in the African Great Lakes region.[8] Its capital and largest city is Kigali, situated centrally at an elevation of approximately 1,567 meters above sea level.[9] Rwanda's population reached an estimated 13.95 million in 2023, reflecting a 2.22% annual growth rate amid one of Africa's highest densities at 566 people per square kilometer.[10][11] This density stems from limited arable land and rapid demographic expansion, with over 80% of the terrain consisting of hills and mountains that constrain urban and agricultural expansion. The economy has emphasized services, tourism, and agriculture post-independence, though challenges persist from geographic isolation and reliance on subsistence farming. The 1994 genocide against the Tutsi marked a defining crisis, triggered by acute ethnic tensions between the Hutu majority and Tutsi minority, fueled by Hutu extremist propaganda and political power struggles rather than originating solely from colonial-era divisions.[12] From April 7 to July 19, approximately 800,000 people—primarily Tutsi and moderate Hutu—were killed in massacres orchestrated by Hutu militias, representing about 70% of the Tutsi population.[13] Following the Rwandan Patriotic Front's victory in July 1994, which ended the genocide and installed a Tutsi-led government, Rwanda's GDP contracted by over 40% that year but rebounded with average annual growth exceeding 7% from 1995 onward, driven by institutional reforms, foreign aid, and investments in infrastructure and human capital.[14] This recovery has positioned Rwanda as a regional model for stability and development, though it has faced criticism for centralized governance limiting political pluralism.[15]International codes and domains
.rw top-level domain
The .rw top-level domain (ccTLD) is the country code assigned to Rwanda by the Internet Assigned Numbers Authority (IANA), with registration dated October 21, 1996.[16] It operates under the oversight of the Rwanda Internet Community and Technology Alliance (RICTA) Ltd, which serves as the sponsoring organization and registry operator, handling administrative and technical functions including WHOIS services at whois.ricta.org.rw.[16] RICTA assumed management following a 2012 redelegation from prior entities like the Rwanda Information Technology Authority, aiming to enhance local internet governance and stability.[17] Domain registration under .rw typically requires a connection to Rwanda, such as for local organizations, businesses, or government bodies, to prioritize national digital development over unrestricted global access.[18] Second-level domains (e.g., example.rw) and subdomains (e.g., .gov.rw for government, .co.rw for commercial) are available, with .gov.rw registrations mandating approval via the Rwanda Information Society Authority (RISA) and submission to the Office of the President.[19] Registrants must provide organizational details, contact information, and proof of Rwandan presence, with minimum terms of one year and restrictions against hyphens or numbers in names shorter than three characters.[20][21] Usage of .rw remains limited, with registrations estimated in the low thousands, far below major ccTLDs like .uk or .de, due to Rwanda's evolving internet penetration and infrastructure focus on local entities rather than international speculation.[22] As of 2025, it accounts for approximately 0.0% of global websites, primarily serving Rwandan government, academic, and commercial sites to bolster national online presence.[23] Traction increased post-2011 alongside broadband expansions, but growth lags behind regional peers.[22]Language codes
"RW" is the ISO 639-1 alpha-2 code assigned to Kinyarwanda, a Bantu language belonging to the Niger-Congo family.[24][25] This standardization, maintained by the International Organization for Standardization (ISO), ensures consistent identification of Kinyarwanda in linguistic databases, software localization, and international documentation.[26] The corresponding ISO 639-2 and ISO 639-3 codes are "kin," facilitating broader interoperability across bibliographic and computational systems.[24] Kinyarwanda is spoken natively by approximately 15 million people, primarily in Rwanda where it serves as the lingua franca for over 99% of the population, as well as by communities in neighboring Uganda and the Democratic Republic of the Congo.[27][28] It functions as one of Rwanda's four official languages, alongside English, French, and Swahili, with its universal use in the country underscoring its role in national identity and daily communication.[29] The language's tonal and agglutinative structure, characteristic of Bantu languages, influences its coded representation in applications requiring phonetic or orthographic processing.[27] These ISO codes distinguish Kinyarwanda from similarly abbreviated identifiers, such as the ISO 3166-1 alpha-2 country code "RW" for Rwanda, preventing ambiguity in global data exchange protocols like Unicode locale specifications (e.g., "rw-RW").[30] Adoption of "rw" promotes precision in fields like translation services, machine learning language models, and library cataloging, where accurate tagging supports multilingual resource management.[27]Computing and storage
Read–write
In computing, read–write (RW) access denotes the dual capability of a storage medium, memory device, or file system to retrieve data (read) from its physical or logical structure—such as by sensing magnetic domains or electronic charges—and to modify or store new data (write) by altering those structures, enabling dynamic data operations fundamental to general-purpose computing.[31] This contrasts with read-only (RO) access, which allows data retrieval but prohibits modification to preserve integrity, as seen in media like punched cards or early ROM chips where write operations are mechanically or electronically impossible.[32] RW functionality relies on reversible physical mechanisms, such as magnetic hysteresis in tapes or flash cell charge trapping in SSDs, ensuring causal persistence of changes until overwritten or erased.[33] The concept originated in the early 1950s with magnetic tape drives, which used read–write heads to encode and decode binary data on oxide-coated reels, marking a shift from static punch-card storage to mutable media for batch processing in mainframes like the UNIVAC I (1951).[34] By 1956, IBM's RAMAC introduced the first commercial RW disk storage with 50 platters holding 5 million characters, establishing random-access RW as standard for hard disk drives (HDDs), later extended to solid-state drives (SSDs) via NAND flash and dynamic RAM for volatile RW memory.[35] These technologies underpin modern systems, where RW access supports iterative algorithms and user modifications without hardware reconfiguration. In operating systems like Unix, RW permissions are specified symbolically (e.g., 'rw-' via the chmod command grants owner read and write access but no execution) or octally (e.g., 6 for rw), controlling user, group, and other access to prevent unauthorized alterations while enabling collaborative editing.[36] [37] RW errors, such as uncorrectable sector writes in HDDs, signal hardware degradation like bad sectors or head failures, often detected via checksum mismatches during write verification and resolvable by tools like chkdsk that remap defective areas.[38] [39]Optical media formats
CD-RW (Compact Disc-ReWritable) represents the principal optical storage format enabling repeated data writing and erasure on compact discs, leveraging phase-change materials to store information. Ricoh commercialized the first CD-RW drives in 1997, building on the established CD standard for 650-700 MB capacity per disc, with the rewritable layer allowing up to 1,000 cycles before significant degradation sets in.[40][41][42] The recording mechanism relies on a thin alloy layer, often Ag-In-Sb-Te, that toggles between highly reflective crystalline and low-reflectivity amorphous phases under precise laser control. A high-intensity laser pulse melts targeted areas into an amorphous state for data "pits," which scatters readout light; a medium-intensity pulse then recrystallizes the material for "lands" during erasure, restoring reflectivity. Read operations use a low-power laser to detect phase-induced reflection differences, akin to standard CDs, though CD-RW's 14-28% reflectivity demands MultiRead-compatible drives to avoid read failures in legacy CD-ROM hardware; write processes inherently operate at slower speeds due to required thermal dwell times.[43][44][45] Despite initial utility for iterative data tasks like software testing, CD-RW usage waned post-2000s as USB flash storage proliferated, providing superior durability, random access speeds exceeding 100 MB/s versus CD-RW's sequential limits, and plummeting costs below $0.01 per GB by 2010. Phase-change layers exhibit bit-error accumulation from thermal fatigue and oxidation, with empirical tests showing readability loss after 10-20 years even unused, far inferior to flash's electron-trap stability; cloud and SSD alternatives further eroded demand by eliminating physical media handling.[46][47][48]Science, mathematics, and astronomy
Robertson–Walker metric
The Robertson–Walker metric provides a mathematical description of spacetime in general relativity for a universe that is homogeneous and isotropic on large scales, assuming the cosmological principle of uniformity in space and observer independence. This metric takes the formds^2 = -c^2 dt^2 + a(t)^2 \left[ \frac{dr^2}{1 - k r^2} + r^2 (d\theta^2 + \sin^2 \theta \, d\phi^2) \right],
where t is cosmic time, (r, \theta, \phi) are comoving spatial coordinates, a(t) is the dimensionless scale factor evolving with time, c is the speed of light (often set to 1 in natural units), and k is the curvature parameter normalized to k = -1 (open hyperbolic geometry), k = 0 (flat Euclidean), or k = +1 (closed spherical).[49] The metric arises from first-principles geometric constraints: isotropy fixes the angular part to the standard 2-sphere metric d\Omega^2, while homogeneity requires the radial part to satisfy the embedding conditions of constant spatial curvature, yielding the specific dr^2 / (1 - k r^2) term without additional assumptions.[50] Howard Percy Robertson derived the kinematic form in 1935, emphasizing the metric's structure from dynamical spacetime symmetries, while Arthur Geoffrey Walker independently obtained it in 1937 as part of classifying conformally static spacetimes.[51] This built on Alexander Friedmann's 1922 solutions to Einstein's equations for expanding dust-filled universes but generalized to arbitrary perfect-fluid stress-energy tensors while ensuring spatial homogeneity.[51] Substituting the metric into Einstein's field equations G_{\mu\nu} + \Lambda g_{\mu\nu} = (8\pi G / c^4) T_{\mu\nu}, with a perfect fluid T_{\mu\nu} (diagonal energy density \rho and pressure p, isotropic in comoving frame), yields the Friedmann equations:
\left( \frac{\dot{a}}{a} \right)^2 = \frac{8\pi G}{3} \rho - \frac{k c^2}{a^2} + \frac{\Lambda c^2}{3},
\frac{\ddot{a}}{a} = -\frac{4\pi G}{3} \left( \rho + \frac{3p}{c^2} \right) + \frac{\Lambda c^2}{3},
where H(t) = \dot{a}/a is the Hubble parameter, governing expansion rate. These encode causal dynamics: matter/radiation dominance (p = 0 or p = \rho c^2 / 3) drives deceleration via gravitational attraction, while positive \Lambda (cosmological constant) accelerates, as inferred from supernova distance moduli showing H_0 \approx 70 km/s/Mpc and q_0 < 0.[52] Empirical validation stems from observations aligning with the metric's predictions of uniform expansion: Edwin Hubble's 1929 law v = H_0 d for galaxy redshifts up to z \approx 0.1, extrapolated to higher z via luminosity distances, matches the scale-factor evolution for k \approx 0.[52] Cosmic microwave background (CMB) anisotropies, measured by COBE (1992, \Delta T / T \sim 10^{-5}) and Planck (2018, power spectrum to \ell \sim 2500), confirm near-perfect isotropy (< 10^{-5} deviation), supporting homogeneity over scales \gtrsim 10^3 Mpc, though local voids introduce small-scale deviations.[52][53] In the \LambdaCDM extension, dark energy (\Lambda or quintessence) comprises \sim 68\% of energy density to fit acceleration data, but relies on indirect inference from integrated Sachs-Wolfe effect and baryon acoustic oscillations rather than direct detection, prompting critiques of overparameterization amid tensions like the $4-5\sigma Hubble discrepancy (local Cepheid H_0 = 73.0 \pm 1.0 km/s/Mpc vs. CMB $67.4 \pm 0.5) and S_8 clustering amplitude mismatch, which question curvature flatness or dark component stability without modified gravity alternatives.[54][55] The metric's core, however, remains robust for causal realism in Big Bang nucleosynthesis (predicting ^4He mass fraction $0.247 \pm 0.003, observed $0.244 \pm 0.002) and structure formation via linear perturbation growth \delta \propto a in matter era.[52]