Jim Baggott

Evidence for simple, single-celled life can be found in fossils dating back about 3.5 billion years. These are bacteria and archaea, two prokaryote life forms that differ in their genes and cell membranes. We have to wait another billion years or so before we see complex eukaryote cells, of the kind that makes up larger life forms (including us). Why?

This is the ninth in a series of posts on the Oxford University Press TUMBLR site.

There is no agreed theory or ‘standard model’ for the origin of life on Earth. But I personally like the idea that life began in alkaline hydrothermal vents. These are geological features that can be found close to the spreading centres of the Earth’s tectonic plates, such as the Mid-Atlantic Ridge which runs along the floor of the Atlantic Ocean. Such vents are sources of molecular hydrogen, a side-product of a natural geological process called serpentinization. In one possible scenario, the hydrogen reacts with carbon dioxide dissolved in the ocean, catalysed by iron-nickel-sulphur minerals. This is the first step in a sequence which potentially can produce a huge assortment of chemicals, including many of biochemical significance such as amino acids.

This is the eighth in a series of posts on the Oxford University Press TUMBLR site.

The Moon is about 40 to 140 million years younger than the Earth and its geology offers broad hints that it was formed in an impact. This is called the giant impact hypothesis.

Nobody can be sure what actually happened, but computer simulations provide some clues. In one simulation, the newly-formed Earth suffers an impact with another planet (called Theia, a little larger than Mars). Theia is torn apart, its core dragged down through Earth’s interior to merge with the Earth’s core. Much of Theia’s mantle is absorbed into Earth’s mantle, and the side of Theia furthest away from the impact is hurled into space. About half the material ejected by the collision is lost and the rest accretes to form the Moon.

This is the seventh in a series of posts on the Oxford University Press TUMBLR site.

The Sun was formed about 4.6 billion years ago from a giant molecular cloud. There are a number of ways this might have happened. The cloud first fragments into a ribbon of dense cores. The cores may then condense naturally under their own weight. Or a compression shockwave from a nearby supernova might induce one or more cores to collapse.

This is the sixth in a series of posts on the Oxford University Press TUMBLR site.

The destruction of the first Population III stars in spectacular supernovas sprinkles interstellar space with clouds of heavy chemical elements. These clouds are drawn together by gravity, producing a second generation of smaller, longer-lived Population II stars. Many stars visible in the night sky are of this type.

This is the fifth in a series of posts on the Oxford University Press TUMBLR site.

The tiny variations in the composition of the early universe caused by quantum fluctuations are believed to have resulted in the large-scale pattern of galaxies, galaxy clusters and voids that we see in the night sky today. A few hundreds of millions of years after the big bang, small excess concentrations of dark matter were drawn together by their gravity to form ‘halos’, which then merged. Ordinary matter – hydrogen and helium atoms – became concentrated at the centres of these halos, leading eventually to the birth of the first stars.

This is the fourth in a series of posts on the Oxford University Press TUMBLR site.

In this series of 6 short videos, Jim talks about aspects of the scientific story of creation, based on his new book Origins, to be published by Oxford University Press on 8 October.

From the Big Bang to Human Consciousness in 12 Episodes

The Warm, Wet Rock and the Origin of Life

The Inevitable Gaps in the Scientific Story of Creation

What Can We Know About the Dawn of Human Consciousness?

Did the Universe Inevitably Produce Human Life?

Is There Other Intelligent Life Out There?

About 380,000 years after the big bang, the universe cooled enough to allow protons and electrons to combine to form neutral hydrogen atoms. This is called recombination. Photons that had previously bounced around between free protons and electrons suddenly had nowhere to go and were released, flooding the universe with cosmic background radiation.

This is the third in a series of posts on the Oxford University Press TUMBLR site.

It seems so simple. Our world is made up of all kinds of stuff. We call it matter, and it possesses something we call mass. But what is mass? Dip into Isaac Newton’s Principia and you’ll soon discover that we’ve never really got to grips with it. And, of course, Albert Einstein subsequently informed us that mass is, in fact, energy: E = mc².

This is the second in a series of posts on the Oxford University Press TUMBLR site.

According to the most widely accepted ‘big bang’ model for the origin of the universe, just 10^-32 seconds after its birth, the universe underwent a very short but frantic period of exponential growth, called cosmic inflation.

This is the first in a series of TUMBLR posts available on the Oxford University Press website.