Let’s think about a wave, that we can represent by a wave function ψ(t) where t represents time, that has a time-period is T. An example is the time-dependent electrical potential, shown above (see also post 18.14) that has T = 0.25 ms. The Fourier transform of this one-dimensional function is defined by This is… Continue reading 23.8 Frequency analysis

Before you read this, I suggest you read post 21.8. We usually think that when individual animals can breed, to produce fertile offspring, that they belong to the same species. If they can’t – they belong to different species (see post 23.5). So where do individual species come from? The English biologist Charles Darwin (1809-1882)… Continue reading 23.7 Darwin’s theory of evolution

Before you read this, I suggest you read post 21.8. In my previous posts (21.11, 21.14 and 21.23), it may appear that genes are constant sources of information that never change. This idea explains most of what we know about why individuals have a different genotype and, therefore, a different phenotype to their parents. But… Continue reading 23.6 Mutation