Introduction to general relativity in a setting with comparatively strong gravitational fields. This has become possible thanks to precision observations of binary pulsars. In such a star system, two highly compact neutron stars orbit each other. At least one of them is a pulsar – an astronomical object that emits a tight beam of radiowaves. These beams strike the Earth at very regular intervals, similarly to the way that the rotating beam of a lighthouse means that an observer sees the lighthouse blink, and can be observed as a highly regular series of pulses. General relativity predicts specific deviations from the regularity of these
Beam bridge great distances; it only means that a series of beam bridges must be joined together, creating what is known as a continuous span. Beam bridge Beam bridges , also known as stringer bridges, are the simplest structural forms for bridge spans supported by an abutment or pier at each end. No moments are transferred throughout the support, hence their structural type is known as "simply supported". The simplest beam bridge could be a log (see log bridge), a wood plank, or a stone (see clapper bridge) laid across a stream. Bridges designed for modern infrastructure will usually be constructed of