What are the true 7 Wonders of the World?

What is the magic of number 7?why most of the things are 7 in the world?as wonders,stars,rainbow colours etc.?

• as they are most of the things are 7 in the world is it there any scientifical or historical meaning behind it?

• Answer:

  The magic of seven Signifies creation, the sum of the spiritual three and the material four The seven ages of man, the seven seas, the seven deadly sins (p 1592), the seven league boot, seventh heaven, the seven wonders of the world, the seven pillars of wisdom, Snow White and the seven dwarves, 7-up.... There are an awful lot of sevens around. Numerologists see seven as the sum of the spiritual three and the material four, signifying creation. The Old Testament tells us that the world was created in seven days. The seventh generation after Adam produced Lamech, who lived for 777 years and was to be avenged 77 fold. Psalm 90 sets the human life span at seven decades. Solomon's temple has seven steps, and Noah's dove returns after seven days. In the Hippocratic tradition the number seven governs the ailments of the body. In Germany it was believed that people would not catch swine fever if they spent seven days drinking and bathing in water containing asphodel. A Jewish cure for fever involved taking "seven prickles from seven palmtrees, seven chips from seven beams, seven nails from seven doors," and so on up to "seven hairs from the beard of an old dog."1 And in this issue of the BMJ a long but neglected tradition alleging seven year cycles in human development is vindicated in Jos Verhulst and Patrick Onghena's finding of a circaseptennial (roughly seven year) rhythm in the growth of male human ears (p 1597).2 In Iranian folklore the cat has seven, not nine, lives and carries her kittens seven times to seven different places.1 "To do the work of seven mullahs" means to accomplish absolutely nothing. In ancient India the most important numbers were three and seven. The ancient Indian text Rigveda talks of seven stars and seven streams of soma (the drink of the gods).1 Indra, the rain god, is "the seven-slayer," the ocean has seven depths, and there are seven concentric continents. The sacred cow has 21 names--three times seven. In ancient Greece, seven was associated with Athena, the virgin goddess, because it is neither producing nor produced--that is, it has no multiple in the first decade (1-10) and also no divisor (other than 1). The first property has little mathematical importance, but the second tells us that seven is a prime number--having no divisors other than itself and one. It is the second Mersenne prime--one less than a power of two.3 Seven numbers suffice to colour every map on a torus--a surface shaped like a doughnut with a central hole--so that no two adjacent regions have the same colour. The smallest regular polygon that cannot be constructed using ruler and compasses is the heptagon, with seven sides. All sufficiently large whole numbers are the sum of seven perfect cubes. And it you want to get more esoteric, the unit sphere in a multidimensional space has the greatest surface area when the space has dimension seven. Seven is an astronomical number. The week has seven days because successive phases of the moon occur roughly seven days apart. Other astronomical sevens include the "seven sisters," the stars of the constellation of the Pleiades, and--in ancient times only--the seven planets: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn. In Douglas Adams's The Hitch Hiker's Guide to the Galaxy the answer to the "Great Question of Life, the Universe, and Everything," is 42 (six times seven).4 In November 1996 the Independent reported the latest measurements of Hubble's constant--a fundamental physical quantity that determines the rate of growth of our expanding universe.5 "Dr Richard Saunders," the newspaper wrote, "sounded a trifle abashed by the result. 'We have taken two measurements for the constant, and the average of them is, well, it's 42.'"