human body
gregladen | November 28, 2011The other day, Amanda, who is currently teaching AP Biology, noted that among the various sources she had at hand, including a couple of textbooks, the number of cells that make up human body seemed to range from about five trillion to fifty trillion with a scattering of numbers in between. It is not clear why this number matters but I suppose if we want to impress students with the smallness of cells and the complexity of life it is worth pointing out, and if it is worth pointing out it might be worth getting it right. So, how many are there?
I believe the correct answer is in the upper…
edyong | July 20, 2009As you read this, you are glowing - weakly, faintly, but glowing nonetheless. Chemical reactions within your body, besides liberating energy and producing heat, are also emitting small numbers of photons, elementary particles of light. The glow is strongest in the late afternoon, and around the lower part of your face.
Many living creatures, including fireflies, jellyfish, squid, glow-worms and deep-sea fish, are known for producing their own light often through the help of bacterial accomplices. But virtually all living things emit some degree of light, albeit so weakly that it's very hard…