You haven't asked an answerable question. The question, as you asked it, contains innumerable hidden assumptions about the nature of time and existence.
The simple answer, according to physicists is that the observable universe has a point in its history beyond which the ordinary definition of time loses its meaning.
But physics also knows that it doesn't know everything and hasn't observed everything. There are observable effects on galaxies that imply we haven't observed or meaningfully described more than a fraction of what we call matter and energy.
So even at the level of observable, physical reality, your question is unanswerable.
Why are you afraid of answering my question?
I gather some of our correspondents believe that to ask whether or not the universe had a beginning is a senseless question (including you it seems). But I wonder, if the question is senseless, why is Stephen Hawking working so hard to show that the universe had no beginning? Obviously, an answer is important to him, specifically an answer that denies divine creation. In short, he starts with a presupposition, and aims to prove it. But here’s the problem: the presupposition may be wrong, in which case even if you can come up with a “mathematical proof” of it, that won’t make the presupposition “right.”
I’d like to excerpt a few passages from Timaeus, beginning at the citation that cornelis provided earlier on [28] that sheds light on an alternative to Hawking’s “answer”:
We must in my opinion begin by distinguishing between that which always is and never becomes from that which is always becoming but never is. The one is apprehensible by intelligence with the aid of reasoning, being eternally the same, the other is the object of opinion and irrational sensation, coming to be and ceasing to be, but never fully real. In addition, everything that becomes or changes must do so owing to some cause; for nothing can come to be without a cause. Whenever, therefore, the maker of anything keeps his eye on the eternally unchanging and uses it as his pattern for the form and function of his product the result must be good; whenever he looks to something that has come to be and uses a model that has come to be, the result is not good.The “gods” to whom Timaeus refers here are the Olympians and their forebears – the intracosmic gods, not the creator god “beyond the cosmos” who also created the intracosmic gods. Because they are created, they “are not entirely immortal and indissoluble." They seem to be somewhat analogous to the Christian idea of angels (God created them too). But I digress.As for the world – call it that or cosmos or any other name acceptable to it – we must ask about it the question one is bound to ask to begin with about anything: whether it has always existed and had no beginning, or whether it has come into existence and started from some beginning. The answer is that it has come into being; for it is visible, tangible, and corporeal, and therefore perceptible by the senses, and, as we saw, sensible things are objects of opinion and sensation and therefore change and come into being. And what comes into being or changes must do so, we said, owing to some cause. To discover the maker and father of this universe is indeed a hard task, and having found him it would be impossible to tell everyone about him. Let us return to our question, and ask to which pattern did its constructor work, that which remains the same and unchanging or that which has come to be? If the world is beautiful and its maker good, clearly he had his eye on the eternal; if the alternative (which is blasphemy even to mention) is true, on that which is subject to change. Clearly, of course, he had his eye on the eternal; for the world is the fairest of all things that have come into being and he is the best of all causes. That being so, it must have been constructed on the pattern of what is apprehensible by reason and understanding and eternally unchanging; from which again it follows that the world is a likeness of something else. Now it is always most important to begin at the proper place; and therefore we must lay it down that the words in which likeness and pattern are described will be of the same order as that which they describe. Thus a description of what is changeless, fixed and clearly intelligible will be changeless and fixed – will be, that is, as irrefutable and uncontrovertible as a description in words can be; but analogously a description of a mere likeness of the changeless, being a description of a mere likeness will be merely likely; for being has to becoming the same relation as truth to belief. Don’t therefore be surprised, Socrates, if on many matters concerning the gods and the whole world of change we are unable in every respect and on every occasion to render consistent and accurate account. You must be satisfied if our account is as likely as any, remembering that both I and you who are sitting in judgment on it are merely human, and should not look for anything more than a likely story in such matters. [italics added for emphasis]
Hearing the above statements from Timaeus, Socrates invites him to develop his main theme. Which essentially is that the creation is a work of reason whose motive is to make a world that is a unique copy “of a unique, perfect and eternal model.” In short, the creation is an image or likeness of the god Beyond, the “unseen god” of Acts (my supposition here).
Anyhoot, in Timaeus’ account the cosmos the god created is an ensouled, intelligent living being. “For god’s purpose was to use as his model the highest and most perfect of intelligible things, and so he created a single visible living being, containing within itself all living beings of the name natural order.” The cosmos is ONE:
Are we then right to speak of one universe, or would it be more correct to speak of a plurality or infinity? ONE is right, if it was manufactured according to its pattern; for that which comprises all intelligible beings cannot have a double. There would have to be another being comprising them both, of which both were parts, and it would be correct to call our world a copy not of them but of the being which comprised them.Follow the logic: This is an exercise in apperception (reasoning, intelligence), not perception (direct observation, sense impression).
In conclusion, I am warm for Plato’s “likely story” – his aletheia logos -- his cosmology of divine creation.
It sure beats a theory of dumb matter accidentally bootstrapping itself into life and intelligence by pure chance in an eternal universe!
Speaking of matter: Science hasn’t even defined what it is. It hasn’t offered so much as a definition for time. Einstein – the father of space-time – had a sort of non- definition: “Time is that which we measure with clocks.” And correspondingly, “space is that which we measure with rods [measuring sticks or rulers].” Yep, that really sheds a whole lot of light on things!
The fact is, science really can’t answer questions like, “What is matter? What is time? What is space?” It just takes them all for granted, and moves on to its business.
Same thing with the question of the origin of life, or the origin of the universe. Probably these are not really “scientific questions” at all.