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LIGOThe Laser Interferometer Gravitational-Wave Observatory consists of two detectors in Hanford, Washington, and Livingston, Louisiana, built to observe gravitational waves produced by astronomical phenomena. Like ripples created by objects traveling along water, gravitational waves are ripples produced by objects moving through spacetime. Unlike light, which can be blocked by matter, gravitational waves travel at the speed of light unimpeded, allowing scientists to use LIGO to study otherwise invisible cosmic events, like black holes. Each detector has two 4-kilometer (2.5-mile) tunnels called arms, which form an "L" shape. During each experimental run, a continuous laser beam is split at the point where the arms connect, with each half sent down an arm. The beams reflect off mirrors—one at the end of the arm and one near where they connect—about 300 times before recombining. A passing gravitational wave will cause the recombined beam to produce a specific pattern, which is compared with patterns produced in simulations to determine the characteristics of the cosmic event that created the waves. Requiring extensive flat land, minimal seismic activity, and enough space between them to rule out false positives from the local environment, LIGO detectors were built 3,002 kilometers (1,865 miles) apart. Since going online in 2015 after a series of upgrades, LIGO has detected mergers involving black holes and neutron stars and validated predictions made by Albert Einstein and Stephen Hawking.Explore LIGO

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The construction of LIGO needed to compensate for Earth's curvatureAcross the 4-kilometer (2.5-mile) arms, the height of Earth's surface falls by almost a meter, preventing the lasers traveling within the arms from meeting the mirror at the end of each. Concrete slabs built beneath the arms help keep them level and provide structural support against seismic vibrations. LIGO Lab | Caltech Watch the director's cut of the award-winning documentary about LIGOProduction on the film began in August 2015, shortly before the facilities detected gravitational waves for the first time on September 14. Those interviewed, including future Nobel Laureates Kip Thorne and Barry Barish, provide their accounts of the discovery as events unfold in real time. Advanced LIGO Documentary Project Help scientists at LIGO train AI to resolve glitches in observational dataVolunteers are provided with visual representations of signal abnormalities at various frequencies and tasked with categorizing them based on reference examples. Progressing through the tool unlocks more difficult images and additional features. Categorized images will be used to train machine learning algorithms for automated future classification. Zooniverse LIGO is part of the advanced gravitational wave detector networkLike the Laser Interferometer Gravitational-wave Observatory, Europe's Virgo Gravitational Wave Interferometer and Japan's Kamioka Gravitational Wave Detector reflect laser beams down perpendicular tunnels to detect gravitational waves in the patterns created by the recombined waves. Future observatories are expected to contribute to this network, further improving gravitational wave detections. NASA Since 2017, Virgo has helped LIGO localize astronomical phenomenaThe detector near Pisa, Italy, coordinates its experimental runs with those in Hanford, Washington, and Livingston, Louisiana. Scientists can triangulate the locations of celestial events that generate gravitational waves using signal arrival times, just as earthquake locations can be determined from measurements at three seismic stations. American Physical Society Between 2002 and 2025, upgrades have increased LIGO's detection range tenfoldAfter the construction of Initial LIGO was completed in 1999, no gravitational waves were detected during operations between 2002 and 2010. Instrument redesigns and significant technological improvements brought about Advanced LIGO, which began observations in 2015. Continued upgrades between continuous laser runs have improved detection sensitivity and stability. LIGO Lab LIGO confirmed Stephen Hawking's theorem about black hole surface areasBlack holes are known to grow with increased mass but lose energy during mergers through the emission of gravitational waves. Amid these competing factors, the black hole area theorem—confirmed in 2021 using LIGO data—states that a merged black hole's size cannot be smaller than the combined surface area of its progenitors. Cornell University LIGO boosts its signal sensitivity by manipulating quantum uncertaintyAccording to the uncertainty principle, the amplitude, or height of a wave's peak, and its phase—the point in time when the first peak is observed—are inversely linked. Based on the frequency of the gravitational waves of interest, scientists sacrifice precision in one optical property to reduce noise in another. Caltech LIGO can detect changes in spacetime one ten-thousandth the width of a protonGravity is the weakest of the fundamental forces in nature, meaning the length of objects only changes by minuscule amounts as gravitational waves ripple through space from distant, albeit massive, cosmic events. LIGO's sensitivity can measure an object shifting its position by one seven-hundred-trillionth of the width of a human hair. Massachusetts Institute of Technology The 2017 Nobel Prize in physics was awarded to LIGO's foundersRainer Weiss, Kip Thorne, and Barry Barish won the award for their contributions to the detector a year after the discovery of gravitational waves was announced. Acknowledging the Nobel statutes limited the prize to no more than three people, Thorne stated, "our marvelous discovery is the work of more than a thousand." Caltech LIGO made the first detection of gravitational wavesOn February 11, 2016, scientists at the Laser Interferometer Gravitational-Wave Observatory announced the confirmed detection of ripples in spacetime, which were produced from the collision of two black holes 36 and 29 times the mass of the sun. The detection confirmed that gravitational waves travel at the speed of light, as predicted by Albert Einstein in 1915. Physics World Potential LIGO sites were selected in pairs, approximately 3,000 kilometers apartThe 1,864-mile distance meant gravitational wave signals would be detected no more than 10 milliseconds apart, ruling out many background signals. The sites needed sufficient plots of nearly flat land, proximity to infrastructure (e.g., electricity), and adequate distance from urban areas and geologically active areas to reduce environmental noise. LIGO Lab The NSF funded the design and construction of LIGO by MIT and CaltechThe 1992 Cooperative Agreement between the National Science Foundation and both research institutions came twelve years after funding 1.5-meter (4.9-foot) and 40-meter (131-foot) prototypes. With a 1992 budget of $395M, LIGO was once one of the largest NSF-funded projects in history Caltech Library In LIGO's interferometers, light cancels itself out in the absence of gravitational wavesThe devices are designed so that a laser is split into two beams that later recombine, canceling each other out and producing no signal. Changes in the lengths of the arms due to passing gravitational waves result in an interference pattern whose properties reveal features of the objects that created the waves. SYFY Gravitational waves—ripples in the fabric of spacetime—are detected at LIGO by measuring how two lasers traveling down equally distant, perpendicular tunnels interfere with one another after they reflect back and meet. Veritasium Listen to the pair of colliding black holes detected by LIGOAs ripples in spacetime, gravitational waves do not produce sound, which is the perception of specific vibrations in matter (e.g., vocal cords vibrating air molecules). The "chirp" of gravitational waves comes instead from converting the spacetime ripples into sound waves that the human ear can hear. LIGO Lab Lego's Women of NASA set honors five NASA pioneers: computer scientist Margaret Hamilton, mathematician Katherine Johnson, astronaut Sally Ride, astronaut Mae Jemison, and astronomer Nancy Grace Roman. NPR Light therapy was widely used as a medical treatment for various maladies in the early 1900s before it was replaced by antibiotics. The Nobel Prize Red light therapy—a treatment harnessing a specific form of energy that penetrates the top layers of skin—is marketed for skincare and wellness, but has its roots in NASA plant growth research. Health vs. Hype Tom Liggett, a Bournemouth University student, sent sealed photographic film into space using a helium balloon, producing photographs from cosmic rays—high-energy particles traveling through space at near-light speed. BBC Light takes approximately eight minutes to travel from the sun's surface to Earth, but it takes thousands of years to reach the star's surface from its core—a distance more than 200 times shorter. TED-Ed Watch an artist's impression of two neutron stars merging in a kilonova explosionSuch an event produces enough light to briefly outshine an entire galaxy and to produce characteristic gravitational wave and gamma-ray signals. On August 17, 2017, these signals were captured by the LIGO–Virgo and Fermi/INTEGRAL observatories, respectively, from a kilonova about 130 million light-years away. HubbleWebbESA 'A lion never roars after a kill.'-Coaching legend Dean Smith (1931-2015) Quote Fancy The next generation of gravitational wave detectors may include a triangular designThe Einstein Telescope will use three pairs of underground detectors—each with arms separated by 60 degrees—arranged in an equilateral triangle. The European observatory will work alongside the Cosmic Explorer, a pair of new US detectors, to provide an eightfold increase in sensitivity over LIGO and extend the current detection frequency range. arXiv Bud Light was created to compete in the lower-calorie light beer marketArguably sparked by Miller Lite's successful 1975 launch, Anheuser-Busch rolled out Bud Light in 1982. The brand faced controversy in 2023 after a sponsorship deal with transgender influencer Dylan Mulvaney, sparking a Bud Light boycott. The Atlantic Artificial lighting and modern practices like working late are linked with sleep shiftsAn analysis of five adults participating in a German reality program that tasked them with living in a Stone-Age-like settlement for 2.5 months, provided some insights into how modern conditions may have shifted our circadian rhythms. The participants slept about 90 minutes more under these conditions, and went to bed earlier and rose earlier, raising questions about how circadian rhythms, sleep, and sleep quality are affected by modern lifestyles. Journal of Clinical Sleep Medicine Artificial lightning can improve the yield of shiitake mushroom growersResearchers have found that shockwaves produced from lightning strikes homogenously break internal filaments called hyphae, transitioning the mushrooms from a vegetative growth to a fruiting phase. Repeated minor shocks near mushroom logs mimicked this effect. Physics World Lightning may kill as many as 320 million trees each yearIgnoring the effects of tree loss resulting from lightning-induced wildfires, researchers at the Technical University of Munich developed a quantitative model to estimate the loss of these organisms due to cloud-to-ground strikes, based on global lightning data and forest structure. They expect the estimate to rise due to increased strikes resulting from climate change. Yale e360 Lightning bolts are about as thick as a garden hoseThe conductive filament ranges from about 2.5 to 5.0 centimeters (1 to 2 inches), though its extreme brightness makes it appear much thicker and visible from miles away. Scars on individuals who suffer a direct strike produce Lichtenberg figures with similar maximum thickness. Stuff You Should Know Lightning rods provide a conductive pathway to safely steer massive electric currentsThe device is positioned higher above the ground to "catch" one of the many branching filaments of electrons from clouds before they make contact with other surface structures, which have been induced to have a positive charge by overhead storm clouds. The current is then sent to a conductive grid buried underground. How Stuff Works Watch lightning strike a building at 40,000 frames per secondWhen the built-up layer of negative charge at the bottom of clouds is sufficiently high, a network of charge filaments will emerge. If one of the filaments meets a rising strand of positively charged particles, a highly conductive path forms, and charges across all filaments move to the path, generating lightning AGU Lightning storms are more common in coastal and tropical regionsWater-abundant areas that receive increased solar radiation, such as those near the equator, experience increased rates of evaporation, which produce tall clouds as moisture rises, cools, and condenses. Mountain ranges can also steer air to higher altitudes, creating collisions between atmospheric particles that generate charge imbalances—the precursors to lightning. Ologies with Alie Ward Lightning forms when streams of rising and falling charged particles connectIn cloud-to-ground lightning, a buildup of negative charge at the bottom of clouds repels electrons on Earth's surface, leaving behind positively charged particles. When descending negatively charged air—the stepped leader—meets rising positively charged particles—the upward streamer—brightening runs up the connection, producing intense flashes known as return strokes. NOAA Lightning is the sudden flow of electricity in the atmosphere as two oppositely charged regions seek to become balanced via the movement of electrons. NOAA SciJinks Bright light therapy involves basking in 10,000 lux of light for 30 minutes each morningNothing is better than going outside and soaking up real sunlight. However, this is harder in winter, especially in very cold and cloudy regions. SAD lamps are designed to project 10,000 lux—a unit of illuminance, or how much light actually hits a surface (rather than how much is produced, like watts). This video discusses product options and practical considerations. New York Times Infrared light is most often associated with thermal radiation and cooking foodAlthough extensively used in remote controls for electronics, where LED lights send signals wirelessly, infrared cameras allow for night vision and thermography—imaging of heat patterns in the body to non-invasively reveal blood flow for supplementary diagnostics. Infrared radiation also provides heat in toasters, saunas, and other technologies. Geeks For Geeks Light appears to slow down as it travels through different materialsAs electromagnetic waves interact with particles in a transparent medium, particles vibrate and generate their own electromagnetic waves. The interference of the original and generated waves, which are slightly delayed, results in ensemble light with an effective slower speed but unchanged color. Space.com Light waves can interfere and cancel each other outWhen light waves travel past one another, their peaks and valleys combine, just as overlapping ripples in water can combine to form a larger ripple. When the peak of a light wave meets the valley of another of the same wavelength and brightness, the waves combine to produce no light. Veritasium Light has been modeled as a wave and a stream of particles throughout historyIsaac Newton first identified white light as composed of a spectrum of colors, which he believed consisted of particles of different hues. Various light phenomena, including refraction, led Christiaan Huygens to develop an alternative wave model. Quantum mechanics validated both models through the concept of wave-particle duality. Be Smart When they merge, black holes release multiple solar masses of energyThe energy emanates outward in the form of gravitational waves, which can be detected at observatories like LIGO. After merging, it is impossible to determine the characteristics of the two black holes that merged to create it. NOVA PBS Official Light echoes are expanding shells of reflected starlightJust as sound waves reveal the location of obstacles by reflecting off them, pulses of light emitted by stars illuminate rings of interstellar dust, giving the appearance of ejected material as the light travels outward. NASA Science Chris Lighty represented some of New York's biggest rappers Lighty founded Violator—a record label and management firm—in 1996 and went on to represent Busta Rhymes, A Tribe Called Quest, Nas, 50 Cent and others. In 2012, he was found dead on the patio of his apartment. The death was ruled a suicide, though many close to Lighty believed otherwise. Mogul ‘Guiding Light’ was the longest-running scripted drama in broadcast historyThe show ran for 72 years, starting as a radio program in 1937, and eventually transitioning to television in 1952. Along the way, it launched several Hollywood stars, like Kevin Bacon, James Earl Jones, and Christopher Walken. CBS canceled the show in 2009. NPR Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.Humans have always been fascinated by volcanoes. One of the most stunning phenomena that occurs is volcanic lightning. Understand the science behind it! AccuWeather Fireflies light up to provide mating signals and warnings to predatorsVariations in the illumination patterns and flight paths while emitting light have been observed across firefly species. Some species instead rely on pheromones if they are primarily active during the day or have lost the ability to illuminate. Science Friday Cannes Lions winners, after the awardsRather than focusing on the brands or agencies behind winning campaigns, this list highlights the people who earned Cannes Lions. It’s a fascinating look at what wins awards and what those awards can do for the recipients. Zappi Cannes Lions features over 30 different awardsWhile the classic track is limited to audio and radio, film, outdoor, and print and publishing, Cannes Lions’ many other awards embrace the broad spectrum of the creative fields. Cannes Lions Lighting the menorah is viewed as the most important Hanukkah ritualThis short video guides viewers through the process, from the supplies required to the order in which the candles are lit. It also covers the prayers that are recited nightly and associated blessings for each individual night. Howcast Light pollution is giving oysters insomniaOysters, bivalve mollusks that have light-detecting cells along their skin, can't sleep with all this artificial light. According to a 2022 study, oysters' sleep cycles are disturbed by light dimmer than that provided by the full moon. As with humans, it's possible that these bouts of insomnia could have adverse health effects and contribute to the development of disease over time. Hakai Magazine Lego stop motion reenacts the longest battle in World War IOne of the longest and bloodiest battles of World War I, the Battler of Verdun was a deadly conflict between French and German forces for 10 months in 1916. Some 300,000 lives were lost, but ultimately the French triumphed. This video provides a stop-motion reenactment of the battle in Lego bricks. YouTube

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