Objects that move faster than the speed of sound—Mach 1—create shockwaves called sonic booms by building up and forcing sound waves to combine as they lag behind the object.

The bullwhip was the first human-made object to break the sound barrier, producing a small sonic boom heard as a crack when flicked quickly.

If a source of music traveled past someone at twice the speed of sound, assuming sufficiently sensitive hearing and powerful equipment, they would hear the music backward.

Cosmic rays are thought to be accelerated to near the speed of light by repeatedly bouncing across shockwaves produced by high-energy cosmic events, such as supernovae.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

View a collection of sound animations, which depict how a source of sound waves pushes against particles to carry energy away without matter being displaced.

When struck, objects vibrate at unique rates called resonant frequencies, which makes tapping wood sound different from tapping metal, but providing objects with sound at their resonant frequency can cause them to shatter.

Interacting sound waves can create regions where the pressure from each wave combines, allowing objects to levitate in place against gravity or be manipulated for touch-free construction.

Through sonoluminescence, concentrated sound waves can produce short, high-intensity flashes of light by rapidly collapsing microscopic bubbles to temperatures up to twice that of the sun's surface.

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

Variations in rapidly expanding gas and mechanical elements produce fireworks sounds

Chemical compounds designed to vibrate rapidly when ignited produce whistling, screeching sounds, while crackles and pops are created by small star pellets inside the firework, which explode one after another quickly. Fluttering and chirping sounds are produced by spinning elements that rotate rapidly as the firework ascends.

A sound's pitch will seem to change if the listener or the source moves toward or away from the other because motion changes the time it takes each successive sound wave to reach the listener.

A nuclear reactor's characteristic blue light is produced from superluminal particles

When light travels through water, its effective speed is 25% lower than its speed in a vacuum. Just as sound waves bunch up and produce a sonic boom when objects move faster than the speed of sound, particles moving faster than this reduced speed generate a shock wave of light, visible as a blue hue.

Likened to a car backfiring or a faraway cannon fire, skyquakes have been reported worldwide in Earth's atmosphere without any obvious cause.

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.

If the Earth stopped spinning, 85% of the world's population would experience supersonic winds

The planet's equator moves about 470 meters per second—over 1,000 miles per hour—and air there would continue moving at this speed for several minutes if the ground stopped rotating. These conditions would cause tsunamis, global storms, and fling debris fast enough to destroy nearly all human-made structures.

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.

Sonar, or sound navigation and ranging, uses reflected sound waves to map and detect seafloor features, marine organisms, and other obstacles.

High-frequency sound waves have been used to brew espresso with room-temperature water and about one-fourth the energy of a traditional espresso machine, which relies on hot water and pressure.

The deaths of massive stars and the mergers of neutron stars and black holes can produce gamma-ray bursts—jets of particles moving in opposite directions at near-light speed that comprise the universe's most powerful explosions.

A person's voice sounds different when breathing helium, sulfur hexafluoride, or gases other than air because the speed of sound varies with the properties of the material through which it travels.

Listen to the pair of colliding black holes detected by LIGO

As 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.

Ultrasound machines emit and receive high-frequency sound waves to construct images of the body's interior, with differences in the penetrating power of different frequencies allowing medical professionals to identify different structures.

Known as bullet trains in English, the Shinkansen uses electric motors, aerodynamic design, and infrastructure that prioritizes straightaways to travel at speeds equivalent to commercial planes' takeoff velocity.

Explore a visual and auditory guide to wave properties and waveforms to learn how every sound imaginable can be created by combining multiple vibrations of air.

The three smallest bones in the human body—the malleus, incus, and stapes—amplify the vibrations of sound waves by almost 20 times to help enable hearing.

Why starquakes may explain various phenomena associated with neutron stars

Fast radio bursts—repeated millisecond-long pulses of enormous energy from neutron stars—are emitted with a timing that resembles the earthquakes and aftershocks seen on Earth when geological activity releases energy from within the planet. Although pulsars should gradually spin more slowly as they lose energy from emitting jets of radiation, sudden increases may result from interior matter moving during starquakes.

Tornadoes produce inaudible signals to humans hours before forming

Researchers at the National Oceanic and Atmospheric Administration have found that tornado-producing storms generate specific sounds below the range of human hearing, much like the infrasonic signals produced by earthquakes and avalanches. Although difficult to distinguish from wind noise, scientists hope to build systems that use these signals to improve tornado forecasting.

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.

Orbital spaceflight requires reaching 23 times the speed of sound

After the spacecraft accelerates up to at least 17,500 miles per hour, space tourists can travel in elliptical orbits hundreds of miles above Earth for days or weeks at a time. Suborbital flights instead max out at about 2,200 miles per hour and travel only 50 to 70 miles above Earth's surface for a few minutes.

View the 18 vehicles that broke the land speed record

The battery-powered "La Jamais Contente" was the first car to exceed 100 kilometers (62.1 miles) per hour, achieving the feat in 1899. By 1997, advancements in aerodynamic understanding and engineering led to the Thrust Supersonic Car, a jet-powered vehicle that reached a speed of 1,223.6 kilometers (760.3 miles) per hour.

Wave tanks can be used to create and study the impacts of tsunamis by building tension in an underwater object before allowing it to slip and rapidly displace water.

The four types of seismic waves—vibrations that carry energy generated by geological events, such as earthquakes—are categorized as body or surface waves.

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

Airplanes generate enough lift to fly by accelerating air faster over their moving wings, which makes the pressure above the wings lower than the pressure below.

By igniting flammable gas in a tube filled with holes and playing music into it, the fire will take the shape of the sound waves, enabling the visualization of audio.

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.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

Some earthquakes can produce smaller tremors called boomerang earthquakes, which travel in the opposite direction and ripple back to the original earthquake's source.

According to the equivalence principle, objects in a closed space cannot tell the difference between whether they are accelerating or experiencing a uniform gravitational field.

Crackling, popping, and rustling sounds have been reported during auroras

At the altitudes where auroras take place—between 100 and 300 kilometers (62 to 186 miles)—air is not dense enough to efficiently vibrate and carry sound waves to the ground. However, one theory suggests that the geomagnetic energy behind auroras can trigger electrical discharges near the surface, which may be the cause of reported sounds.

The decibel scale measures sound intensity, with hearing damage occurring after prolonged exposure to sounds above 85 decibels—equivalent to a noisy lawnmower.

The wave nature of matter can produce phenomena like negative time and retrocausality

Within quantum mechanics, matter simultaneously exists as both fixed particles and extended waves, allowing it to emerge across barriers—just as sound travels through walls—before it fully enters the obstacle. The resulting measurements can show that particles spent negative time within a barrier, with the future occurring before the past.

If they could be built, antimatter drives, which run on energy released from the collision of matter and antimatter particles, would be the most efficient engines in existence.

Particles produced in cosmic ray showers that would normally decay long before they reach Earth's surface are observed in ground-based detectors because they experience time more slowly when moving near the speed of light—a phenomenon predicted by special relativity.

Tachyons are theoretical particles that travel through space faster than light

The equations of special relativity require these objects to possess imaginary mass, and they would travel faster the more energy is taken away from them. The existence of tachyons would necessitate an unknown form of matter and lead to paradoxes involving information that can hypothetically travel backward in time.

'Silent' fireworks are not entirely noise-free

By using a reduced amount of flash powder—the ingredient responsible for the loud explosions that fireworks make—"silent" fireworks produce displays between 70 and 90 decibels, rather than the approximately 175 decibels heard in professional displays.

Nuclear-powered missiles replace chemical combustion with energy from nuclear fission

In these systems, energy is added to an airstream, which passes through a nozzle to generate thrust. Because the amount of energy released per unit mass of nuclear fuel is millions of times larger than that of chemical propellants, nuclear missiles can travel faster and farther with less fuel.

Within an anechoic chamber, all surfaces are covered with specialized materials that prevent wave reflection, helping prevent sound from echoing in the space.

Internal-combustion engines convert fuel into motion using controlled explosions

Gasoline engines mix fuel and air, compressing it and igniting it to create thousands of tiny explosions that push pistons up and down. This movement spins the crankshaft, which moves a vehicle's wheels.

Noise-canceling headphones use a microphone to identify external sounds, which are then used to produce an out-of-sync version of those sounds to cancel them in your ears.