Ductile fracture. The propagation of a ductile crack involves substantial plastic flow and ductile fracture usually gives a characteristic rough fracture surface.Fracture occurs by a process known as microvoid coalescence. First, plastic strain causes small microvoids to form in the material, most often at sites of inclusions.he propagation of a ductile crack involves substantial plastic flow and ductile fracture usually gives a characteristic rough fracture surface.
An illustration of the space-time curvature caused by Earth. Space-time is a mathematical model that joins space and time into a single idea called a continuum. This four-dimensional continuum is known as Minkowski space. Combining these two ideas helped cosmology to understand how the universe works on the big level (e.g. galaxies) and small level (e.g. atoms).
cosmic time - the time covered by the physical formation and development of the universe. time - the continuum of experience in which events pass from the future through the present to the past. sidereal time - measured by the diurnal motion of stars. solstice - either of the two times of the year when the sun is at its greatest distance from the celestial equator. equinox - either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length.