Submitted by Michel Darche on
How many satellites orbiting around the Earth are needed to compute exactly one’s position at each instant?
The GPS system uses a set of satellites (at least 24) orbiting around the Earth and emitting signals.
An ideal GPS receiver measures the travel time of three signals from emitted by three satellites to the receiver. From each measure it computes its distance to each satellite.
Submitted by Michel Darche on
Using the anomalies in the propagation of seismic waves detected by analysing seismic data recorded by seismographs around the world, the Danish mathematician Inge Lehmann showed in 1936 that the liquid core of the Earth contains a solid inner core of radius 1,200km. Despite a temperature above 5000° C, the inner core becomes solid because of the pressure, which is more than 3.5 millions stronger at a depth of 5000 km than on the surface.
Submitted by Michel Darche on
Global warming causes the expansion of oceans and the melting of glaciers.
Simulation software like ”Flood map”, based on elevation data coming from satellite radars allows to compute the potential consequences of the rising of the sea level on coastal regions and populations, including large cities like Rio de Janeiro, New York, Tokyo, Shanghai, etc.
Submitted by Michel Darche on
In the 60’s, it was noticed that the geometry of rocky coasts is also fractal: this means that, when zooming on a photo, whatever the zoom, we see new details appearing that have the same character as the large scale details.
Submitted by Margarida Oliveira on
Relationship between mathematics and astronomy goes back in time. An analysis, though superficial, of a few episodes in the history of Mathematics shows how this science is actually fundamental to the progress of the different branches of knowledge.
This project consists of five different “experiences” related to Mathematics of Planet Earth (MPE): Cartography, Dynamical system, Wator, Temperature and Cellular automata.
Submitted by Guillaume Jouvet on
Alpine glaciers have been shrinking for more than one century. This trend is expected to continue if the global warming progresses. This film shows how mathematicians and glaciologists work together to produce realistic estimates of the future evolution of glaciers.
Submitted by Christine Leininger on
One of the main goals of wave propagation numerical modeling is to describe some earthquake phenomena as close as possible. The role of numerical wave propagation simulations is not to predict when and where there will be an earthquake, but to determine the strength and the trajectory of the seismic waves, depending on where the earthquake occur. It is important to know the less exposed areas, in order to plan the locations of new buildings. Similarly, it is crucial for the authorities to know where to house the victims of an earthquake to protect them from aftershocks.
Submitted by Christine Leininger on
Beneath the sea surface, there exists a vast network of ocean currents, which, like gigantic conveyor belts, transport huge water volumes. Although the real map of these currents is extremely complex, a couple of simple physical processes explain most of the large scale features.
Submitted by Uli Gaenshirt on
In 1982, Dan Shechtman discovered a nuclear structure with fivefold rotational symmetry. Today, nuclear structures of this type are called quasicrystals.
In general, growth models for decagonal quasicrystals with tenfold or fivefold rotational symmetry are based on geometric, quasiperiodic tilings which were found by Roger Penrose in 1973.
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