Listen to the pair of colliding black holes detected by LIGO

LIGO made the first detection of gravitational waves

On 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.

According to general relativity, gravitational waves are ripples in spacetime

First detected a century after Albert Einstein predicted their existence, gravitational waves transmit information about cosmological events by altering the shape of spacetime. Like ripples in water, these waves travel outward and can be detected on Earth, even for objects that do not emit light, such as black holes.

Gravitational waves are detected at LIGO by measuring shifts in interfering lasers

The instruments at each site send lasers down equally long arms, which should take the same amount of time to travel between suspended mirrors. Passing gravitational waves alter the shape of space—lengthening one arm and shrinking the other—altering how long it takes the lasers to complete their path, which scientists can measure.

In LIGO's interferometers, light cancels itself out in the absence of gravitational waves

The 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.

Try to catch the 'sound' of black holes in gravitational wave detector data

In "Black Hole Hunter," users try to listen for gravitational wave signals from black holes in four sample data files that include substantial background noise. With each level, learn more about black holes while being faced with ever-quieter signals.

Supermassive black holes create pressure waves, detectable as extremely low sounds

Space is largely silent because it lacks a medium for sound waves. Some Mars rovers capture sounds of wind, though the sounds are too low to hear. Through sonification, astronomical data can be translated into hearable sounds for broader engagement.

When they merge, black holes release multiple solar masses of energy

The 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.

LIGO can detect changes in spacetime one ten-thousandth the width of a proton

Gravity 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.

Potential LIGO sites were selected in pairs, approximately 3,000 kilometers apart

The 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.

Watch the director's cut of the award-winning documentary about LIGO

Production 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.

LIGO boosts its signal sensitivity by manipulating quantum uncertainty

According 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.

In 1974, a pair of neutron stars provided the first evidence of gravitational waves

Observations of a pulsar—a rapidly rotating neutron star that emits light—revealed it to be part of a system of two stars that orbited one another in a shrinking orbit, indicating gradual energy loss. Calculations showed that the changing orbit was consistent with gravitational waves predicted to carry energy away from such a system.

Watch an artist's impression of two neutron stars merging in a kilonova explosion

Such 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.

Studying 'sonic' black holes

If a fish screams as it falls down a cascading waterfall accelerating to ridiculous speeds, will his fish friends above hear him scream? This analogy, odd as it is, has become an essential tool in the astrophysicists kit for learning how enigmatic black holes operate. Lab experiments mirroring the so-called sonic black hole have achieved insights for their cosmic counterparts. Read how it works in this brief piece.

Neutron star collisions may be the universe's gold factories

In his last broadcast interview, Stephen Hawking comments on detecting gravitational waves from the collision of neutron stars. The event may serve as a new means of measuring cosmological distances and help identify revisions to general relativity.

Listen to the sounds of pulsars, which emit radio pulses up to hundreds of times a second

Just as figure skaters spin faster by tucking in their arms, these celestial objects acquire high rates of spin from the collapse of the cores of massive stars. The star's rotation spins its magnetic field, generating beams of radio waves from its magnetic poles. If either of these poles faces a detector, the signals can be picked up and converted to audio signals.

Physicists detect the sound of heat in superfluids, theorized since 1938

Referred to as "second sound," the flow of heat in a superfluid resembles a sound wave bouncing back and forth. The heat-mapping techniques used to make the detection may improve the study of neutron stars and superconductors.

Oscillating matter in the early universe left behind patterns detailing cosmic expansion

As gravity tried to bring matter closer together in the early universe, its high temperature produced an outward pressure that caused it to expand. These competing forces caused matter to vibrate and produce the equivalent of sound waves, which spread outward as the universe expanded and cooled, serving as relics of dark energy's history.

One study suggests that dark matter may have originated from a dark Big Bang

A student-faculty team at Colgate University modeled the event as occurring months after the conventional Big Bang and determined the potential gravitational wave signal that would have been left behind. Future gravitational wave detectors are expected to be sensitive enough to observe this signal, if it exists.

Nothing can enter white holes—the opposites of black holes

Although a mathematical possibility according to general relativity, there is no observational evidence for these objects, which would endlessly eject material into the universe via anti-gravity. It is also unclear how they would form or avoid collapsing due to the gravity of the ejected material.

The interaction of quantum fields with black hole curvatures makes Hawking radiation

The classic explanation of Hawking radiation depicts virtual photons emitted from a black hole's event horizon. A more accurate explanation involves null geodesics, Bogoliubov transformations, and scattered quantum field nodes to explain the emission of thermal radiation.

Light echoes are expanding shells of reflected starlight

Just 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.

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.

Creating 'Interstellar's' black hole blended visual effects with real physics models

Theoretical cosmologist Kip Thorne was consulted and collaborated with the film's visual effects team to develop new rendering software, integrate general relativity, and generate ultra-high-resolution visuals. The results were so accurate, they were published in scientific journals.

Glacial ice loss can be determined by listening to escaping bubbles

Glaciers form from the accumulation of layers of snowfall over hundreds to thousands of years, trapping air bubbles that serve as time capsules of atmospheric conditions at the time. When glaciers melt, these bubbles produce a distinctive sound that can be detected by underwater microphones, allowing assessment of melting from a safe distance.

Sound can shatter glass if its frequency matches the material's natural vibrations

The sound made by an object when struck is its resonant frequency, which is the sound made when energy is dissipated. Providing energy at that frequency amplifies the vibrations, rather than allowing them to dissipate, which can deteriorate the object's structural integrity.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

Fireworks make a loud booming sound after exploding due to air expanding faster than the speed of sound.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

Waves off the coast of Nazaré, Portugal, can reach over 100 feet and are caused by the area's deep underwater canyon geography

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Brian Wilson wrote the Beach Boys' 'Don't Worry Baby' for the Ronettes, but the legendary girl group rejected it.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.