how did the energy and matter cause the big bang and create earth? How come there is only one earth?

Question: how did the energy and matter cause the big bang and create earth? How come there is only one earth?
- Keywords:
  big bang,
  earth,
  planet,
  universe
Asked by whitd112 to Claire on 27 Jun 2013.
- Claire Lee answered on 27 Jun 2013:
  
  Well, nobody really knows what caused the big bang. In fact, energy and matter was actually created in the big bang! As Terry Pratchett wrote: “In the beginning there was nothing, which exploded”. That pretty much sums up what we know of it!
  
  As for Earth, well, there are a lot of planets around other stars. A lot of them look like they could be habitable too. Earth is probably not really even unique, over the whole universe. But if you want to get anthropic then you could argue that there is only one Earth for us, because that is where we evolved. On this particular one 🙂

Question: how did the energy and matter cause the big bang and create earth? How come there is only one earth?