黑体辐射Black-body radiation

斯特藩-玻尔兹曼定律：总辐射功率与绝对温度四次方成正比，M = σT⁴；维恩位移定律：辐射峰值波长与温度成反比，λ_max·T = 2.898 × 10⁻³ m·K。太阳表面约 5800 K，峰值在约 500 nm 的可见光区；人体约 310 K，峰值约 9.4 μm 的红外区；宇宙微波背景辐射约 2.725 K，是近乎完美的黑体谱。

The Stefan–Boltzmann law says total radiated power scales with the fourth power of absolute temperature, M = σT⁴; Wien's displacement law says the peak wavelength is inversely proportional to temperature, λ_max·T = 2.898 × 10⁻³ m·K. The Sun's surface, about 5800 K, peaks near 500 nm in the visible; the human body, about 310 K, near 9.4 μm in the infrared; and the cosmic microwave background, at 2.725 K, is an almost perfect black-body spectrum.

按经典统计力学得到的瑞利-金斯公式在长波区与实验相符，但预言短波区辐射能量趋于无穷大，被称为“紫外灾难”。1900 年 12 月 14 日，德国物理学家马克斯·普朗克假设振子的能量只能是 hν 的整数倍，导出了与实验完全吻合的普朗克辐射定律。这一天被视为量子理论的诞生日。普朗克获 1918 年诺贝尔物理学奖。

The Rayleigh–Jeans formula from classical statistical mechanics fitted the long-wavelength data but predicted infinite energy at short wavelengths, the 'ultraviolet catastrophe'. On 14 December 1900 the German physicist Max Planck assumed that oscillator energies come only in whole multiples of hν and derived a radiation law that matched experiment exactly; that day is regarded as the birth of quantum theory. Planck received the 1918 Nobel Prize in Physics.

黑体辐射原理用于红外测温仪、热成像相机、天体表面温度测定、白炽灯和色温标定（如 6500 K 白点）。地球表面向外的红外辐射被温室气体吸收，是温室效应的物理基础。

Black-body physics underlies infrared thermometers, thermal cameras, measuring the surface temperatures of stars, incandescent lamps and colour-temperature standards such as the 6500 K white point. Absorption of the Earth's outgoing infrared radiation by greenhouse gases is the physical basis of the greenhouse effect.