Top 10 physics facts

Oxygen comes in through pores in the shell. Directly under the shell, there is a small pocket of air. The microscopic pores on the egg surface allow the CO2 to escape and fresh air to get in, so a developing bird can breathe.

In summer. The tower stands 320 meters (1,050 ft) tall, about the same height as an 81-storey building. Because of thermal expansion, the height varies by 15 cm (5.9 in) due to temperature.

Presidency of Israel. In 1952, Prime Minister David Ben-Gurion offered Einstein the position of President of Israel to Albert Einstein, after the death of Israel's first president, Chaim Weizmann. Einstein, then aged 73, refused: "I lack both the natural aptitude and the experience to deal properly with people". He died three years later.

Jupiter moons. Jupiter's moons, especially Io (spot on the left), are powerful sources of auroras on Jupiter. These arise from electric currents along field lines, generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon.

To better see in the dark. The sharpest image is produced by round pupils, and if cats weren’t nocturnal, they probably would have round pupils like us. But the vertical pupil, in combination with horizontal eyelids, gives the cat greater and more accurate control in different types of lighting. A cat may adjust the amount of light by moving eyelids only.

Neutron star. A neutron star is a stellar remnant of a supernova. Neutron stars are very small, but extremely dense - with a radius of only about 12–13 km (7 mi), they can have a mass of about two Suns.

68°C (154.4°F). The boiling point of water depends on the pressure. On top of Mount Everest, the pressure is about 260 mbar (26.39 kPa) and the boiling point of water is 69 °C. (156.2 °F). In contrast, water can still remain liquid near deep hydrothermal vents, even if the temperature is very high.

Heavy water has greater density. Heavy water contains deuterium instead of common hydrogen-1. In its pure form it has a density about 11% greater than water, but otherwise, it is physically and chemically similar. It is not radioactive. Because of greater density and stronger hydrogen-oxygen bonds, its behaviour is slightly different in some biochemical reactions. It may be toxic, but only when a large fraction of water (> 50%) in higher organisms is replaced by heavy water.

Large Hadron Collider . The Large Hadron Collider(LHC) is the world's largest & most powerful particle collider, most complex experimental facility ever built & largest single machine in the world. It lies in a tunnel 27 kilometres (17 mi) in circumference, as deep as 175 metres (574 ft) beneath the France-Switzerland border near Geneva, Switzerland.

Quasar. The four bright objects surrounding it are actually multiple images of a single quasar that lies far beyond the galaxy. The lens was named the Einstein Cross in honor of Albert Einstein, whose relativity theory predicted the phenomena decades before the first gravitational lens was observed in 1979.