What does the D in D-Day stand for ?

On 6 June 1944, 156,000 Allied soldiers headed to the shore in Normandy), as part of Operation “Overlord” the code name for the entire Allied invasion of north-west Europe. Not all of the soldiers landed on the beaches on that day. However that day became famously known as D-Day.

The reason behind this is : When a military operation is being planned, its actual date and time is not always known exactly. The term “D-Day” was therefore used to mean the date on which operations would begin, whenever that was to be. The day before D-Day was known as “D-1”, while the day after D-Day was “D+1”, and so on. This meant that if the projected date of an operation changed, all the dates in the plan did not also need to be changed.

This actually happened in the case of the Normandy landings. D-Day in Normandy was originally intended to be on 5 June 1944, but at the last minute bad weather delayed it until the following day.

Why do whips make a cracking sound when snapped?

Whips can attain a speed of more than 1000 km/h when snapped, breaking the sound barrier. What you are hearing is a mini sonic boom..

Why do we kiss under the mistletoe?

The innocuous mistletoe plant, now used to cop a cheap kiss or two, was once considered to be a sacred plant by the ancient Druids. They believed that it could cure sicknesses and shield its owner from evil forces such as witches or ghosts.

Druids gathered the plant at the northern winter solstice, just days before we now celebrate Christmas. With great solemnity and ritual, they cut the mistletoe with a golden sickle reserved solely for this purpose. The plant was so sacred that the Druids never allowed it to touch the ground. The Druids believed that by placing it over their doorways, they could not only protect the health and safety of all who passed through but also promote romance and fertility. If a boy kissed a girl under the mistletoe and gave her one of the plant’s white berries, the ritual meant they would get married within the year.

Ironically, although mistletoe is now associated with Christmas, the Christians in Celtic regions, ashamed of their pagan antecedents, did everything possible to dissociate themselves from the belief in the power of mistletoe. But the practice took hold. And although a kiss under the mistletoe no longer promises marriage, at least we’ve retained the fun part of the ritual.

Why are portholes round?

When most ships were made out of wood, portholes were usually rectangular. But once steel construction came into vogue, sharp corners morphed into arcs. Wood may not be as hard as steel, but it has one feature that makes it more porthole-friendly: wood absorbs the stresses of the rocking of boats on the sea far better than metal. When steel hulls came into vogue in the late 19th century, sailors discovered quickly that stress fractures were endemic to rectangular portholes, starting at the corners. Round portholes, on the other hand, distribute the stress evenly, and naval architects figured out the spherical solution quickly.

Rectangular portholes are far from extinct, however, cruise liners often sport large rectangular windows on decks. But the more violent the weather a boat encounters, the rougher the seas it navigates, and the farther down in the boat it resides, the more likely the porthole is to be cornerless.

Why do website addresses have to start with WWW?

There is not now, and never has been, any reason why a web address has to begin with ‘www’. The address of the first ever website didn’t have the ‘three-dub’: its address was http://nxoc01.cern.ch. That site existed on the computer of machines and devices of Tim Berners-Lee, the British scientist who invented the Web at the beginning of the 1990s.

Berners-Lee considered calling his world-changing invention the ‘Information Mesh’ (which he decided sounded too much like ‘mess’) or the ‘Mine of Information’ (but the double-meaning of the word ‘mine’, he thought, made it sound like he was claiming to ‘own’ the Web). ‘World Wide Web’ was his best idea. The universal use of the three Ws in Web addresses came about later as a mere convention.