Answer to the first question:
If the universe is expanding then it must have a beginning. If you follow it backwards in time, then any object must come to a boundary of space time. You cannot continue that history indefinitely. It is possible for matter to have a beginning. In a closed universe the gravitational energy which is always negative exactly compensates the positive energy of matter. So the energy of a closed universe is always zero. So nothing prevents this universe from being spontaneously created. Because the net energy is always zero. The positive energy of matter is balanced by the negative energy of the gravity of that matter which is the space time curvature of that matter. There is no conservation law that prevents the formation of such a universe. In quantum mechanics if something is not forbidden by conservation laws, then it necessarily happens with some non-zero probability. So a closed universe can spontaneously appear - through the laws of quantum mechanics - out of nothing. And in fact there is an elegant mathematical description which describes this process and shows that a tiny closed universe having very high energy can spontaneously pop into existence and immediately start to expand and cool. In this description, the same laws that describe the evolution of the universe also describe the appearance of the universe which means that the laws were in place before the universe itself.
But don't take my word for it, take his.
George Wald, Nobel Laureate, responds to the second question:
"There is good reason to believe that we are in a universe permeated with life, in which life arises, given enough time, wherever the conditions exist that make it possible. How many such places are there? Arthur Eddington, the great British physicist, gave us a formula: one hundred billion stars make a galaxy, and one hundred billion galaxies make a universe. The lowest estimate I have ever seen of the fraction of them that might possess a planet that could support life is one percent. That means one billion such places in our home galaxy, the Milky Way; and with about one billion such galaxies within reach of our telescopes, the already observed universe should contain at least one billion billion -- 1018 -- places that can support life
So we can take this to be a universe that breeds life; and yet, were any one of a considerable number of physical properties of our universe other than it is -- some of those properties basic, others seeming trivial, almost accidental -- that life, that now appears to be so prevalent, would become impossible, here or anywhere.
I can only sample that story here and, to give this account a little structure, I shall climb the scale of states of organization of matter, from small to great.
But first, a preliminary question: How is it that we have a universe of matter at all?
Our universe is made of four kinds of so-called elementary particles: neutrons, protons, electrons, and photons, which are particles of radiation. (I disregard neutrinos, since they do not interact with other matter; also the host of other particles that appear transiently in the course of high‑energy nuclear interactions.) The only important qualification one need make to such a simple statement is that the first three particles exist also as antiparticles, the particles constituting matter, the anti-particles anti-matter. When matter comes into contact with anti-matter they mutually annihilate each other, and their masses are instantly turned into radiation according to Einstein’s famous equation, E = mc2, in which E is the energy of the radiation, m is the annihilated mass, and c is the speed of light.
The positive and negative electric charges that divide particles from anti-particles are perfectly symmetrical. So the most reasonable expectation is that exactly equal numbers of both particles and anti-particles entered the Big Bang, the cosmic explosion in which our universe is thought to have begun. In that case, however, in the enormous compression of material at the Big Bang, there must have occurred a tremendous storm of mutual annihilation, ending with the conversion of all the particles and anti-particles into radiation. We should have come out of the Big Bang with a universe containing only radiation.
Fortunately for us, it seems that a tiny mistake was made. In 1965, Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in New Jersey discovered a new microwave radiation that fills the universe, coming equally from all directions, wherever one may be. It is by far the dominant radiation in the universe; billions of years of starlight have added to it only negligibly. It is commonly agreed that this is the residue remaining from that gigantic firestorm of mutual annihilation in the Big Bang.
It turns out that there are about one billion photons of that radiation for every proton in the universe. Hence it is thought that what went into the Big Bang were not exactly equal numbers of particles and anti-particles, but that for every billion anti-particles there were one billion and one particles, so that when all the mutual annihilation had happened, there remained over that one particle per billion, and that now constitutes all the matter in the universe -- all the galaxies, the stars and planets, and of course all life..."
