There is a big difference between what the wave does and what the particles in the medium do. As the wave travels through the medium, the particles of the medium oscillate in response to the wave. In a uniform medium, the wave travels at constant speed; each particle, however, has a speed that is constantly changing.

An example of a medium is a metal spoon sitting in a cup of hot tea that is too hot to touch. An example of a medium is a newspaper from the combined media form of newspapers, television, magazines, radio and the Internet.

Sound can travel through air, water, or solids, but it can’t travel through a vacuum. It needs the medium to help it travel. Other examples include water waves, seismic waves, and waves traveling through a spring. Electromagnetic waves are waves that can travel through a vacuum (empty space).

Waves come in two kinds, longitudinal and transverse. Transverse waves are like those on water, with the surface going up and down, and longitudinal waves are like of those of sound, consisting of alternating compressions and rarefactions in a medium.

Radio waves, microwaves, visible light, and x rays are all examples of electromagnetic waves that differ from each other in wavelength.

The EM spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The common designations are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.

Violet waves

Electromagnetic waves of different frequency are called by different names since they have different sources and effects on matter. In order of increasing frequency and decreasing wavelength these are: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

P-waves

Surface waves

300,000 km/s.

gases

Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. In fact, sound waves travel over 17 times faster through steel than through air.

Types of Waves Sound waves fall into three categories: longitudinal waves, mechanical waves, and pressure waves.

Sound waves are made up of kinetic energy. It takes more energy to make large molecules vibrate than it does to make smaller molecules vibrate. Thus, sound will travel at a slower rate in the more dense object if they have the same elastic properties.

approximately 300,000 kilometers per second

From the perspective of a photon, there is no such thing as time. It’s emitted, and might exist for hundreds of trillions of years, but for the photon, there’s zero time elapsed between when it’s emitted and when it’s absorbed again. It doesn’t experience distance either.

The particles that make up light, photons, may live for at least 1 quintillion (1 billion multiplied by 1 billion) years, new research suggests. If photons can die, they could give off particles that travel faster than light. Many particles in nature decay over time.

As long as it doesn’t get absorbed by something, then yes, light will continue to travel indefinitely. However, due to the expansion of the universe that light wave will get stretched out along with the space it travels through, becoming lower in frequency and energy.

First, let’s think about why sound does not travel forever. Sound cannot travel through empty space; it is carried by vibrations in a material, or medium (like air, steel, water, wood, etc). So, the sound wave gets smaller and smaller until it disappears.

vacuum

We know light can travel through a vacuum because sunlight has to race through the vacuum of space to reach us on Earth. Sound, however, cannot travel through a vacuum: it always has to have something to travel through (known as a medium), such as air, water, glass, or metal.

While the vast majority of space is a vacuum, and thus completely silent, there still are some areas that sound can be heard. An example of where sound in space occurs is within black holes, but unfortunately, it’s humanly impossible to hear.