Life applies only to physical entities without signaling.
In solar thermal collectors , a selective surface or selective absorber is a means of increasing its operation temperature and / or efficiency .. absorber. Absorption ( electromagnetic radiation ). The selectivity is defined as the ratio of solar radiation-absorption -LRB- alpha -RRB- - to thermal infrared radiation-emission -LRB- epsilon -RRB- .. ratio. ratio. solar radiation. solar radiation. absorption. absorption ( electromagnetic radiation ). thermal infrared. thermal infrared. emission. Emission ( electromagnetic radiation ). Selective surfaces take advantage of the differing wavelengths of incident solar radiation and the emissive radiation from the absorbing surface  :. solar radiation. solar radiation. Solar radiation covers approximately the wavelengths 350 nm to 4000 nm ; UV-A , visible and near infrared -LRB- NIR - or IR-A plus IR-B -RRB- .. UV-A. UV-A. visible. Visible light. near infrared. near infrared. NIR. Near infrared. IR-A. IR-A. IR-B. IR-B. Thermal infrared radiation , from materials with temperatures approximately in the interval -40 to 100 ° C , covers approximately the wavelengths 4000 nm to 40,000 nm = 4 um to 40 um ; The thermal infrared radiation interval being named or covered by  : MIR , LWIR or IR-C .. thermal infrared. thermal infrared. MIR. Mid-infrared. LWIR. LWIR. IR-C. IR-C