This is the biggest mystery of all times. Scientists and their jargon is often too technical to comprehend for most of us. I tried to make some sense and what little I could glean is presented here.
Scientific view point
The Big Bang Theory(BBT) and its related Inflation Universe Theories (IUTs) are today's dominant scientific conjectures. According to these interrelated notions, the universe was created between 13 and 20 billion years ago from the random, cosmic explosion (or expansion) of a subatomic ball that hurled space, time, matter and energy in all directions. Everything - the whole universe -- came from an initial speck of infinite density (also known as a "singularity"). This speck (existing outside of space and time) appeared from no where, for no reason, only to explode (start expanding) all of a sudden. Over a period of approximately 10 billion years, this newly created space, time, matter and energy evolved into remarkably-designed and fully-functional stars, galaxies and planets, including our earth. (http://www.allaboutthejourney.org/origin-of-the-universe.htm)
Cosmologists envision two possible fates for the Universe: The Big Freeze or the Big Crunch.
The scientific thesis is riddled with a number of still unexplained issues that include boundaries of space, time and matter. This made me look at the different myths about the beginning of this world. I share with you here the Pauranic myth relating to our earth and universe.
Hindu Myth
Vishnu is the Lord of creation, preservation and destruction. Before creation there was no day, night, no land or sky. Only Brahm (eternal truth) was everywhere.
Lord Vishnu first created the waters. Then he sowed the seeds of Brahmanda (universe) in the waters. From these seed there developed a Golden Egg which began to float on the waters. From the egg Lord Brahma created himself. Since he created himself (svayam sambhuta), Brahma is also known as Svayambhu.
Having created himself, Brahma stayed inside the egg for an entire year. And at the end of the year, he split the egg into two. One part of the egg formed the heavens, the other the earth. And in between the two parts of the egg, Brahma created the sky.
Brahma next established the earth on the waters and made the ten directions. He created time, lightning, thunder, clouds, rainbows, words and anger. To ensure that yajnas could be performed, texts of the Rig Veda, the Yajur Veda and the Sama Veda emerged from his body.
From the powers of his mind, Brahma created seven sons (manas putras). Their names were Marichi, Atri, Angira, Pulastya, Pulaha Kratu and Vashishtha for populating the world but this effort failed (details some other time).
Prithu was the first king crowned by Brahma. From Prithu the earth came to be known as Prithivi.
(Source: BrahmVaivarta Purana)
The earth (Prithivi or Bhuloka) extends upto those hieghts of the sky that can be lit up by the rays of the sun and the moon. The expanse from there to the solar circle is known as Bhuvarloka and holy sages live there. Above the solar circle is the lunar circle and beyond it, in succession, come the regions of Mercury (Budha), Venus (Shukra), Mars (Mangala), Jupiter (Brihaspati), Saturn (Shani), the Great Bear constellation (Saptarshi) and the Pole Star (Dhruva). The region from the solar circle to Dhruvaloka is known as heaven (Svargloka or svarga). Beyond Dhruvaloka is Maharloka and further away are Janaloka, Tapaloka and Satyaloka.
At the end of a kalpa, all the three lokas (regions) of Bhuloka, Bhuvarloka and Svargloka are destroyed. But the four lokas of Maharloka, Janaloka, Tapaloka and Satyaloka are not destroyed.
The earth is divided into seven regions (dvipas). Their names are Jambudvipa, Plakshadvipa, Shalmaladvipa, Kushadvipa, Krounchadvipa, Shakadvipa and Pushkaradvipa. These regions are surrounded by seven oceans and their names are Lavana, Ikshu, Sura, Sarpi, Dadhi, Dugdha and Jala.
Jambudvipa is in the center of earth and right in the middle of Jambudvipa is Mount Sumeru. To the south of Sumeru are the mountains Himavana, Hemakuta and Nishadha and to the north of Sumeru are the mountains Nila, Shveta and Shringi. Jambudvipa itself is divided into several regions (varshas). For example, Sumeru is in the middle of Ilavritavarsha. Braratavarsha is to the south of Sumeru. To the east of Sumeru is Bhadrashvarsha and to the west is Ketumalavarsha. Harivarsha lies to the south and Ramyakavarsha to the north. Still further north is Hiranmayavarsha and beyond that, Uttara Kuruvarsha.
Brahma's city is on the peak of Sumeru. The river Ganga descends from heaven here and gets divided into four tributaries. Sita flows eastwards, Chakshu westwards, Bhadra Northwards and Alakananda southwards into Bharatavarsha.
There are seven major mountain ranges in Bharatavarsha and their names are Mahendra, Malya, Sahya, Shuktimana, Riksha, Vindhya and Pariyatra. Bharatavarsha itself is divided into nine regions.. The ninth region is completely surrounded by the ocean in all directions. To the east of Bharatavarsha live the Kiratas and to the west the Yavanas.
Below the earth lie the seven regions of the underworld (Patala). Their names are Atala, Vitala, Nitala, Sutala, Talatala, Rasatala and Patala. The daityas, danavas and the snakes (sarpa) live there.
The underworld is a wonderful place, more beautiful than heaven itself. Below the underworld sleeps a great snake, known as Shesha or Ananta. It has a thousand hoods, all covered with jewels.
Also part of the world are hells (naraka), presided over by Yama, the god of death.
(Source: Agni Purana)
Some stray thoughts
Prof Stephen Hawking's in one of his speech said “We showed that if General Relativity was correct, any reasonable model of the universe must start with a singularity. This would mean that science could predict that the universe must have had a beginning, but that it could not predict how the universe should begin: for that one would have to appeal to God.”
Lord Vishnu sowing the seeds of Brahmanda ……..sounds like the singularity that scientists mention.
The universe started with creation of Water and we all know it is the essence of life.
Prithvi refers to our solar system/galaxy rather than the planet. Other galaxies many thousands of light years away are referred to as other lokas.
The technicalities of time and space are adequately addressed by the myth in context of BBT.
The seven seas and seven continents sounds very familiar.
The wise has always accepted that the hells are here and now.
According to the Big Bang model, the universe expanded from an extremely dense and hot state and continues to expand today. A common and useful analogy explains that space itself is expanding, carrying galaxies with it, like raisins in a rising loaf of bread. General relativistic cosmologies, however, do not actually ascribe any 'physicality' to space. The concept of Brahm meets this criteria (in absence of will and thought what remains is truth..as is what is……eternally)
This myth is better tuned to the scientific thoughts of today as compared to other myths regarding the origin of universe.
As of date BBT partially explains the origin of Universe and leaves too many questions unanswered. A thorough and open minded examination of the Vedas may provide insights and ideas towards a scientifically and thelogically acceptable hypotheses.
Finally, the problem of the origin [of the universe] involves a certain metaphysical aspect which may either appeal or revolt a person, but to swallow it as such does need hajmola.