Nemesis

But why should comets become more likely to hit us every million years? Here we launch ourselves into deep speculation. It has been suggested that the sun has a sister star, and the two orbit each other with a periodicity of about 26 million years. This hypothetical binary partner, which has never been seen but which has nevertheless been given the dramatic name Nemesis, passes, once per orbital rotation, through the so-called Oort Cloud, the belt of perhaps a trillion comets which orbits the...

 The Unspecialized Will Inherit the Earth

Why is it that our whole economic and political system has tended recently to become so sluggish and inflexible? Why have we become resigned to the idea that nothing substantial can ever be done in less than ten years? Obviously there are many reasons. But I believe the principal reason for this sluggishness is that our whole society has fallen into the same trap as our nuclear industry. Not only in the nuclear industry but in many other industries and public institutions, we have pursued eco...

 Overcoming Inherited Bias to Live In Peace

In our earliest history, so far as we can tell, individuals held an allegiance toward their immediate tribal group, which may have numbered no more than ten or twenty individuals, all of whom were related by consanguinity. As time went on, the need for cooperative behavior – in the hunting of large animals or large herds, in agriculture, and in the development of cities – forced human beings into larger and larger groups. The group that was identified with, the tribal unit, enlarged at ea...

 How Radiometric Dating Works

Briefly, a radioactive isotope is a kind of atom which decays into a different kind of atom: for example. one called uranium-238 turns into one called lead-206. Because we know how long this takes to happen, we can think of the isotope as a radioactive clock. Radioactive clocks are rather like the water clocks and candle clocks that people used in the days before pendulum clocks were invented. A tank of water with a hole in the bottom will drain at a measurable rate. If the tank was filled at...

 More Exciting Than the Supernatural

And yet there's so much in real science that's equally exciting, more mysterious, a greater intellectual challenge - as well as being a lot closer to the truth. Did he know about the molecular building blocks of life sitting out there in the cold, tenuous gas between the stars? Had he heard of the footprints of our ancestors found in 4-million-year-old volcanic ash? What about the raising of the Himalayas when India went crashing into Asia? Or how viruses, built like hypodermic syringes, slip...