Making the world around us
Take part in an explosive journey through the story of how the universe was created, looking at the 'biggest bangs' in the universe and how they form the building blocks for everything that we see around us.
In this six week series, discover what is inside a star, why they get so hot and what happens when they reach the end of their life. We will look at the life and death of a star and unravel the mysteries of atoms, supernovae and nuclear fusion in our search for the universe's 'biggest bangs'.
Atoms are microscopic particles that make up the world around us, and they are about a hundred thousand times smaller than a human hair. All atoms are made up of three building blocks; protons, neutrons and electrons.
These three particles each have a different role in the atom.
The protons and neutrons are found in the nucleus. Protons have a positive charge and repel each other, and the number of protons defines what element the atom is. Neutrons have no charge and they bind to the protons in the nucleus, in order to reduce the electromagnetic repulsion between the protons; they stabilise the nucleus, allowing multiple protons to exist within the same nucleus. Without this stabilising factor, hydrogen would be the only element able to exist. Electrons have a negative charge and the interaction of the electrons defines an atom’s chemical reactivity and other properties. An un-ionised atom will have the same number of electrons as protons.
While electrons are fundamental particles, protons and neutrons can be broken down even further into quarks: a Proton contains two up quarks and one down quark, and a neutron contains one up quark and two down quarks.
The Periodic Table of the elements arranges all the discovered elements according to their proton number. It is called the Periodic Table because of the order and patterns that are exhibited by the elements. For example, the first period contains the highly reactive alkali metals, and the last period the largely inert noble gases.
The shape of the Periodic Table is determined by the arrangement of electrons around the nucleus. Electrons do not orbit around the nucleus, as planets do. Instead they are arranged into shells and sub-shells. Each row of the Periodic Table represents an electron shell and each block a sub-shell.
The exact layout is determined by the quantum mechanical nature of electrons. Each successive shell (or row) is made up of an additional sub-shell, and each sub-shell may contain four further electrons: the s sub-shell may hold two; the p sub-shell six; the d sub-shell ten; and the f sub-shell fourteen.
All of the elements in the Periodic Table are formed in stars, in many different processes. The smallest elements are made in small stars, but to make the biggest elements we need bigger stars, higher temperatures and the 'biggest bangs' that the Universe can offer.
In the next episode, we'll take a look at Nuclear Fusion.
"My principle research interests focus on gamma-ray bursts and supenovae. As the brightest explosions in the Universe by far, gamma-ray bursts can be seen across most of the visible Universe, and make powerful cosmological probes. My research into GRBs has two broad avenues. The first is to understand the progenitor systems for these extraordinary explosions, the second is to subsequently deploy them as probes of the Universe across cosmic time. GRBs are now mainly found by the Swift satellite, while my followup programme utilises the Hubble Space Telescope, Chandra X-ray Observatory and Spitzer Space Telescope, as well as numerous large ground based facilities (e.g. VLT, Gemini, WHT).
More recently I have become interested in other extreme transients events, including the tidal disruption of stars by supermassive black holes, and new kinds of extremely bright supernovae."