Electromagnetic Spectrum:the range of wavelengths or frequencies over which electromagnetic radiation extends.
Electromagnetic Wave:Electromagnetic waves are waves which can travel through the vacuum of outer space. Mechanical waves, unlike electromagnetic waves, require the presence of a material medium in order to transport their energy from one location to another.
infrared:(of electromagnetic radiation) having a wavelength just greater than that of the red end of the visible light spectrum but less than that of microwaves. Infrared radiation has a wavelength from about 800 nm to 1 mm, and is emitted particularly by heated objects.
light year: a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles).
polarization: In politics, polarization (or polarisation) refers to the divergence of political attitudes to ideological extremes. Polarization can refer to such divergence in public opinion as a whole, or to such divergence within a particular sub-set or group (like party elites).
ultraviolet:(of electromagnetic radiation) having a wavelength shorter than that of the violet end of the visible spectrum but longer than that of X-rays.
speed of light:Since 1983, the metre has been defined in the International System of Units (SI) as the distance light travels in vacuum in 1/299792458 of a second. This definition fixes the speed of light in vacuum at exactly 299792458 m/s.