# Absorbency

Why does absorbed water leave the substance that absorbed it when you give that substance a good squeeze?

For that matter, how does absorbency work at all? Why can a sponge or towel absorb more water than say, a silver ingot? What allows anything to absorb anything else? Is there a scale that measures absorbency?

Harkening back to my first question, will absorbed radiation (or light or heat or whatever) also leave the substance that absorbed it if you give it a good squeeze? Are the laws of absorbency constant from one medium to another?

So many questions…

water is absorbed into little holes in the structure by capillary action. The water is loosely held and can be squeezed out. Radiation absorbed is instantly converted mainly into heat, and so can not be recovered

To carry this a little further. Water and most liquids are only slightly compressible. And since two physical objects can’t occupy the same physical space, when you reduce the size of the voids in a sponge or a towel by squeezing the liquid has to come out.

As a matter of fact, when an object heats up by absorbing radiation such as light or heat or whatever (in a vacuum), that radiation is recovered, only at a different wavelength. The temperature of the object rises by the Stefan-Boltzman equation until the radiation input is in equilibrium with the radiation output.

If it isn’t in a vacuum then the object loses the absorbed input radiation by conduction, convection and radiation so that the total out equals the total in.