Inferring the Universe From Our Limited Perspective

It may seem rash indeed to draw conclusions valid for the whole universe from what we can see from the small corner to which we are confined. Who knows that the whole visible universe is not like a drop of water at the surface of the earth? Inhabitants of that drop of water, as small relative to it as we are relative to the Milky Way, could not possibly imagine that beside the drop of water there might be a piece of iron or a living tissue, in which the properties of matter are entirely diffe...

 An Origami Metaphor for Fetal Development

The sheets of tissue that fold, invaginate and turn inside out in a developing embryo do indeed grow, and it is that very growth that provides part of the motive force which, in origami, is supplied by the human hand. If you wanted to make an origami model with a sheet of living tissue instead of dead paper, there is at least a sporting chance that, if the sheet were to grow in just the right way, not uniformly but faster in some parts of the sheet than in others, this might automatically cau...

 DNA is not a Blueprint

Textbooks of biology repeat time and again that DNA is a 'blueprint' for building a body. It isn't. A true blueprint of, say, a car or a house embodies a one-toone mapping from paper to finished product. It follows from this that a blueprint is reversible. It is as easy to go from house to blueprint as the other way around, precisely because it is a one-to-one mapping. Actually, it's easier, because you have to build the house, but you only have to take some measurements and then draw the blu...