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Are light and sound forms of matter?
Question Date: 2006-02-15
Answer 1:

This is a tricky question. Matter is defined by some scientists as anything that has mass and takes up space.

Other scientists have defined matter as the substance that constitutes all physical objects and of which the observable Universe is composed. This definition does not distinguish between mass and energy because, according to Einsteins theory of relativity

E = M C2, mass can be converted into energy during chemical and nuclear reactions.

This transformation of mass to energy suggests that matter and energy, such as light, are fundamentally related.

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If we accept the first definition of matter, then light and sound are themselves not forms of matter. However, both light and sound either originate from matter or occur as a result of the interactions and movements of matter.

Matter is predominantly composed of atoms. Light neither has mass nor takes up space, and is composed of photons rather than atoms. Photons are wavelike particles of energy that originate from chemical or nuclear reactions that occur within and between the atoms of matter. Light, also called electromagnetism, electromagnetic energy or electromagnetic radiation, is one of the four fundamental forces or interactions of nature

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These four fundamental interactions also include gravity (the pull that everybody of mass exerts on every other body of mass), and the two types of nuclear forces that hold atoms together and describe the interactions between neutrons,protons, and electrons inside every atom. Light (photons) is emitted from matter as a form of energy release during chemical reactions (such as fires or combustion) and nuclear reactions (such as occurs inside the sun and other stars or during the detonation of atomic bombs). This type of energy release often occurs when chemical bonds (bonds between atoms) are broken or formed or when nuclear bonds (bonds within atoms) are broken or formed. When this energy is released as light, the matter that is reacting loses some of its mass, as Einstein predicted, demonstrating the conversion of matter to energy.

Sound is very different from light. Instead of being energy that is released from matter, sound is caused by the movement or vibration of matter, often in the form of compression (or pressure) waves. The technical definition for sound is an alternation in pressure, particle displacement, or particle velocity propagated in an elastic material. This simply means that sound consists of the changing motion of atoms and molecules through matter.

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Whenever you make a sound, whether in the air, water, or through a solid object, you are usually causing that form of matter to alternately compress and expand. The compressions and expansions of that matter cause pressure changes in the air(or water) around our head, which are then detected by our ears as pressure changes felt upon our eardrum. This is what we hear as sound or noise: pressure changes in the fluid (matter) around our ears, caused by vibrations or movements of the particles in this matter.

Answer 2:

Light and sound are not regarded as forms of matter. Light is another name for electromagnetic radiation.

Light is interesting in that it has a dual nature to it; it behaves both like waves and particles. The "particles" of light are called photons and have no mass. In contrast, matter is made up of particles that do have mass.

Sound is a little different in that it is the propagation of a pressure wave through a medium of particles. Since it is a wave, it is not considered a form of matter. Hope this helps.

Answer 3:

Sound is a percept. Ever hear of the question, "If a tree falls in the middle of the forest, and if no one is around to hear it, does it still make a sound?"

Well, the answer to this question is quite simply NO. There would be no sound if people were not around to hear it. Waves of energy (you can call this matter) trigger the tiny hairs in our ear to send nerve signals to the brain.

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