There is no such thing as a substance that does not reflect light. Vantablack from Surrey NanoSystems in the United Kingdom comes the closest. Vantablack absorbs the majority of EM radiation throughout a wide range of wavelengths including infrared, visible, and ultraviolet, but it does not absorb all of it. It's just not possible for any material to completely block out light.
All substances reflect some degree of electromagnetic radiation. Some do so very poorly, while others do so very efficiently. Silver, for example, reflects about 80% of incident light and thus is used as a reflective surface on photography equipment and window glass. Wood is a much better reflector—about 95%—so it is used for outdoor lighting fixtures and sun roofs.
Most materials are good absorbers of certain frequencies of light and bad absorbers of others. For example, copper is a good conductor of heat and electricity and thus is used in hot water pipes and electrical wiring. But because it also absorbs most of the light from the sun, it can cause overheating if it is exposed to direct sunlight for long periods of time. A similar effect would occur with iron, which is both a good conductor and an efficient absorber of light.
Everything has a natural color inherited from its chemical composition. The color of an object depends on its underlying atoms, which are made up of electrons orbiting around nuclei.
Dark surfaces, water, and metal are examples of materials that absorb sunlight strongly. The sun's light energy arrives as a combination of visible light, ultraviolet light, and infrared; certain materials absorb all of these wavelengths well, while others are better adapted to specific kinds of light.
Earth's surface is mostly glass, water, and iron. It has been found that over 70% of the energy from the sun reaches Earth's surface in just 2 bands of the electromagnetic spectrum: the near-infrared and the visible.
Most solar cells used today are made of silicon, which is a white solid that absorbs only a small portion of the near-infrared and visible light from the sun. It was discovered in 1882 by English chemist Sir William Crookes who was studying methods for lighting lamps at night using electricity from the moon. He observed that when he placed a piece of paper under a lamp it began to smoke, indicating that some of the light was being absorbed by the paper.
Silicon is the basis for most modern electronics, including computers and smartphones. It is also the most common element in the earth's crust (after oxygen), so it is not likely to last forever. However, scientists have been working on making solar cells that use other elements instead, such as zinc oxide or cadmium telluride. These cells can be much more efficient than silicon cells at converting sunlight into electricity.
IR radiation is absorbed by glass, Plexiglas, wood, brick, stone, asphalt, and paper. Infrared radiation is absorbed by standard silver-backed mirrors, which reflect visible light wavelengths and allow you to view your reflection. Infrared radiation is also efficiently absorbed by gold, manganese, and copper.
Infrared light is invisible to the human eye, but it can be seen with special equipment. Cameras that use infrared film or digital sensors view objects that are not visible to the naked eye. This video shows some common items that contain infrared technology: night lights, remote controls, keychains, and body heat sensors.
Items that contain metal components such as printed circuit boards (PCBs), transistors, and resistors will not function properly if they are exposed to IR radiation. These objects should always be placed under a black box to protect them from infrared light.
In conclusion, infrared materials are used in night lights, remote controls, keychains, and body heat sensors. Metal components prevent these items from functioning correctly if exposed to infrared light.
In reality, all objects, alive or inanimate, can absorb light. Absorption is always affected by the electromagnetic frequency of the light being transmitted (i.e., the color) as well as the nature of the atoms in the item. For example, black has no electrons so it cannot be absorbed. White has no electrons either but it can be absorbed if there are any electrons in its vicinity that need to be pulled into an orbital with a lower energy level.
The ways in which objects can absorb light are many and varied. A perfect conductor will absorb all light rays that fall on it. A semiconductor allows some light to pass through it but not all of it; this means it absorbs a portion of the light that falls on it. An insulator completely blocks light from passing through it.
Some materials act as both a conductor and a semiconductor at once. These are called dichroic materials. For example, glass is a good conductor but also a good semiconductor. When glass is cut to make windows, lenses, and other optical devices, this property is used advantageously - except when you want to allow all wavelengths of light to pass through.
An object's ability to absorb light is usually described in terms of its transparency to light.
Light cannot pass through opaque materials. Opaque materials, in reality, absorb the light that shines on them. However, some of the light is reflected back. Each item reflects a certain color's light waves. Red, for example, includes wavelengths that make it possible to reflect red light waves only. Blue contains wavelengths that are used to reflect blue light waves only.
When red light hits an object that is made of red-reflecting material, only those red light waves will be transmitted through the object. The rest are absorbed. For similar reasons, when blue light waves strike a piece of blue stuff, only blue light will be transmitted; all other colors are absorbed.
Because transparent materials allow light to pass through them, they also allow refraction. Refraction is the bending of light as it passes from one medium into another (for example, from air into glass).
The amount of refraction depends on how much the light wave is bent. In general, the more the light wave is bent, the farther it travels before reaching the next obstacle. For example, if a light wave enters water at an angle greater than 45 degrees, it will be refracted and spread out over a large area when it reaches the opposite side. On the other hand, if the entry angle is less than 45 degrees, most of the wave will continue along its original path.
Mirrors and polished metals, for example, have smooth, bright surfaces that reflect light brilliantly. Surfaces that are dull and dark, such as dark textiles, do not reflect light well. These types of surfaces may appear shiny to the eye.
Metals that are not polished can also be used as mirrors - including non-polished metal sheets you pick up at a hardware store. However, because they are not smooth, no light is reflected at all times. Instead, only when an object directly in front of the mirror breaks down the surface tension of water or oil, then light is reflected.
So, while glass, ceramic, and some other materials can act like mirrors under certain conditions, for general purposes we consider anything with a solid surface to be reflective.
Mirrors reflect light from one side to the other, while lamps emit light from both sides. Therefore, objects that contain lamps will also contain mirrors (such as yourself!). Because you are made of solid material, you too reflect light.
And just like mirrors, these objects also break down the surface tension of liquid so they, too, can act as lights!