Read this first: Quantum equation predicts universe has no beginning and has no end.
I think it's about time people start recognizing that the Big Bang is not a fact, merely as a scientific theory based upon facts; one is NOT the other. An eternal Universe would be in line with the Principle of Conservation of Energy, which is the most sound, verified, and tested scientific premise there is. In fact it is THE foundational scientific premise from which nearly all other scientific premises are based upon. That which can never be created or destroyed is eternal. Eternity has no beginning. The Universe as a WHOLE is thus eternal as well from deductive entailment. The Universe as phenomena however is necessarily transitory. The conflation between the two is ubiquitous, erroneous, and fallacious. Do you understand the distinction between Universe as a whole and Universe as phenomena?
By Universe as a whole, I am referring to any and all parts of the Universe. By Universe as phenomena, I am referring to specific phenomenal manifestations of it which require the observation of. Do you get how the Universe as a whole can be deductively entailed to exist eternally based upon the premise of the Conservation of Energy, while the Universe as phenomena is necessarily transitory and finite? Aren't you one of those people who insist that the Big Bang is a bonafide fact? If yes, then I have done my job here.
The Big Bang is a theory. It says so right in the science. However, it is so far an unassailable theory. There is no competing theories that invalidate it, and there is no evidence that disproves it. Nearly all evidence and experimentation supports it, and the evidence that doesn't directly support it can go either way. Theories are made up of facts, but you can't address an entire theory as a fact. That would be a law. Theories are constantly being retested and refined.
Space-time never came into existence. That is a misunderstanding and misrepresentation of the Big Bang theory. Please take a look at what the theory actually states, and show me where it states this space-time coming into existence. Show me a reputable source, such as the original theory as it was first proposed, a textbook, or Wikipedia to back up that the Big Bang theory states that space-time came into existence as a result of it. I double dare you. I've looked into these, and there is no such thing as space-time coming into existence business in the theory itself. The interpretations of the theory is not the theory itself, I'm sorry to tell you.
Space-time as vacuum is filled with energy in the form of vacuum energy. This is verified by experiments (Casimir Effect). Which means space time and energy are inextricably linked. Energy is entailed to be eternal from the Conservation of Energy. Therefore space-time can be deductively entailed to have no absolute beginning or coming into existence. It is phenomenal manifestations that can come into being. Space-time and energy was, is, and always will be there.
You might say, "Show me the scientific papers or research that shows that space and time have always existed, prior to the big bang?" as opposed to me proving it.
From a religion point of view, cum a muslim, I do have faith that God has no end and beginning. Wherever God located or "lived," there must be a space-time where God manifests Himself, and that "place" was included into a "part" of the Whole Universe (not as observable phenomena) as well. God is the Universe. So the Universe has no end and beginning too. God is not a product of existence, God is not a natural being as all beings are. The moment of the Big Bang is not the moment of God coming to be self-aware. God is eternal since existence is eternal, being the being of the singularity of all existence that He is. It is impossible for a material/corporeal/physical object to exist without the space/time continuum. And so, since the space/time contiuum is part of the universe, it implies that matter could not have been the cause of the universe.
If it was not possible for something to come from nothing, then there was something before the quantum singularity, or the singularity always existed. But if it always existed, this raises a serious question: Why expand when it did? Also, it if always existed, that "always" took place outside of time, so it was an eternal but unmoving moment in existence unless there is somehow multiple times within times.
The laws of physics do change, but only as the universe changes. Since the universe changes extremely slowly, we can be confident that the laws of physics we know will hold for a another billion years. Maybe around a trillion years will we see some change. This is why the laws of physics are referred to as "constants," not absolutes.