Hi! I'm not sure if my post is in the correct sub-forum, but I think 'Quantum Physics' will result in more detailed answers.. I'm not a physicist, i'm a mathematician and dont know too much about Quantum Theory, just the basics. I've read some stuffs about the issue, introdutory books, this forum, got information from internet, etc.. The theory of quantum fluctuations and inflation seemed very concise and plausible for me since the beginning. I just finished reading Hawking's A Brief History of Time and that Lineweaver's article (http://arxiv.org/abs/astro-ph/0305179) Marcus posted in some thread. Instead of clarifying my mind, it put a little 'disorder', so I have a few questions (mainly the 5th).. 1) That idea of the Big Bang as a singularity is already dead, or there is some research trying to hold it nowadays? 2) The theory of the universe originating from quantum fluctuations (with the subsequent inflation) is the most 'acceptable' nowadays? There are any known flaws in it? 3) The theory in the previous question is a consensus here in the forum? Are you all talking about the same theory when you talk about quantum vacuum, quantum fluctuations, zero-point energy, inflation, etc.? 4) There is any plausible alternative for the quantum fluctuations at the moment that doesnt have any known contradictions or flaws? 5) Assuming that the universe originated from quantum fluctuations, what prevents or avoid that the quantum fluctuations in the existing universe 'evolve' and inflate to other universe(s)? If there are certains 'conditions' that avoid it, isnt it right to assume that there was(were) no universe(s) containing that 'original' quantum vacuum (or it wouldnt 'generate' our universe)? Sorry if I said something wrong about Quantum Physics and for my not so good English. Thank you very much for your attention and comprehension!