Imagine that you enter a room full of a poisonous gas wearing a mask that is not good enough to prevent the gas reaching your lungs and killing you. The mask is not good enough because it would allow the gas to diffuse through the fabric it is made of, eventually reaching your nose and […]
Condensed matter • Materials • Physics • Quantum physics • Theoretical physics
At low temperatures, the resistivity of a metal (the inverse of its conductivity) is nearly constant. As the temperature of a material is lowered and as we approach absolute zero the resistivity should approach a constant value. Many metals, known as normal metals, behave in this way. The behaviour of another class of metals and […]
There are some concepts in physics difficult to grasp. Mainly because we have no direct evidence of them and, in orther to get some understanding, we rely on analogies that are not strictly correct. One of these difficult concepts is the spin of the electron. The analogy for the spin usually goes this way: Imagine […]
One of the greatest inventions of the 20th century, if not the greatest, was the transistor. It revolutionized the electronics industry and changed the way people around the world lived, learned, worked, and played. Its invention marked the beginning of solid state electronics which quickly reduced the size and power requirements of existing electronic tube […]
A quantum dot is a nanometric crystalline structure of semiconductor materials. In a quatum dot electrons are confined in a region of space, thus creating a well defined structure of energy levels that depends very much on the size and shape of the quantum dot. This structure resembles that of atoms, that is why sometimes […]
When we think about the new materials of the future some names may come to mind: pure carbon, in the form of graphene or nanotubes or buckyballs or any other exotic allotrope; or some kind of oxide of these carbon allotropes; or some strange combination of metal oxides, manufactured via processes that remind us of […]
Most leaves are various shades of green. This is due to the chlorophylls. The name chlorophyll comes from the Greek words chloros (green) and phyllon (leaf). There are six types of chlorophylls in plants. The two main chlorophylls are chlorophyll a and chlorophyll b. Chlorophyll a absorbs purple and orange light the most. Chlorophyll b […]
The way a carbon atom binds to other atoms is what make this element so important. Apart from its capacity to bind to a wide range of different atoms, most remarkable is the way it can form long chains of carbon atoms with different kinds of covalent bonds between them . Biologically, for instance, the […]
Technology is all around us. There are a lot of acts that we perform daily that involve much more technology than we can imagine. Take for example removing the lid of a diary product; you would expect that the lid will offer some resistance but not so high as to make it impossible to open […]
There are people that have the feeling that if they get to know what something is made of automatically thay have learned something. This attitude is called reductionism. But take water, for example: how knowing that water is composed of molecules and that each of these molecules is composed of two atoms of hydrogen and […]