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Light travels more slowly in materials, such as water, than it does in a vacuum. No particle can travel faster than the speed of light in a vacuum. Particles that travel faster than the speed of light in a given material emit a cone of light, in the same way that objects exceeding the speed of sound emit a sonic boom. Detectors that use this light to detect subatomic particles are known as Cherenkov detectors.
Industry:Physics
Astronomical measurements indicate that luminous matter, such as our sun, makes up only a small percentage of the total matter in the universe. The missing mass that makes up the remainder is known as dark matter.
Industry:Physics
Support structure in animals, against which the force of muscles acts. Vertebrates have a skeleton of bone or cartilage; arthropods have one made of chitin; while many other invertebrates use a hydrostatic skeleton, which is merely an incompressible fluid-filled region of their body.
Industry:Biology
Cavity in the digestive tract just past the mouth itself. May be muscularized for sucking or swallowing in various animals.
Industry:Biology
The process by which an egg (the female gamete) is released from the ovary. In animals other than mammals, with the exception of monotremes, this results in the laying of an egg outside of the body. When female mammals ovulate, the egg, if fertilized, is retained within the uterus.
Industry:Biology
Collection of organs which have related roles in an organism's functioning. The nervous system, vascular system, and muscle system are all organ systems.
Industry:Biology
Collection of tissues which performs a particular function or set of functions in an animal or plant's body. The heart, brain, and skin are three organs found in most animals. The leaf, stem, and root are three organs found in most plants. Organs are composed of tissues, and may be organized into larger organ systems.
Industry:Biology
A specialized cell that can react to stimuli and transmit impulses. A neuron consists of a body which contains the nucleus; dendrites, which are short branches off the body that receive incoming impulses; and a long axon which carries impulses away from the body and to the next neuron.
Industry:Biology
