Disputing Sean Carroll on the beginning of the universe

Physicist Sean Carroll has argued that we do not know that the Universe had a beginning and he thinks it is likely it did not. I saw his argument presented here https://www.youtube.com/watch?v=FgpvCxDL7q4  on "Closer to Truth", a great show which explores life's big questions which arise out of philosophy, science and religion. Carroll claims that the prediction that the universe has a space-time beginning is based upon the space-time theorems which predict the existence of a Big-Bang singularity. Carroll gives two arguments why we cannot conclude that a Big Bang singularity exists: we do not think singularities exist as infinities do not occur in nature, and general relativity which is used to predict the existence of a Big Bang singularity is wrong as it is incompatible with quantum mechanics (quantum mechanics being correct and general relativity being wrong), so its prediction of a Big Bang singularity is incorrect.

Physicist Sean Carroll sees the Big Bang as just a placeholder

Carroll's claim that singularities do not exist as infinities do not occur in nature is more of a preference than an argument- one thing which is clear is that Carroll's own views on the topic of infinity in nature are not consistent- he is willing to believe in the existence of a multiverse where time is infinite but he is not willing to grant the existence of singularities which have more evidence and possibility to be experimentally verified. In fact, the question as to whether a Big Bang singularity exists is being experimentally tested by experimenters at Penn state and they will hopefully have results within the next two years. It seems to me that Carroll main problem with the existence of a Big Bang singularity is that its occurrence cannot be explained within a naturalist framework. This is because the laws of physics break down at a singularity, it not possible to apply the laws of physics to it. Fred Hoyle commenting on this said that it is appropriate to think of the laws of physics as arising from the Big Bang singularity rather than being applicable to it. A model of the universe which entails that space-time, matter and energy have an absolute beginning at the Big Bang singularity therefore fits very well with the Christian idea of creation, what scientists identify as a Big Bang singularity having the properties of God as a supernatural being who brings into being the universe. This does not fit well with Carroll who wants to explain the natural world in natural ways, so he just claims that singularities do not occur. 

As to Carroll's claim that the prediction of a Big Bang singularity cannot be demonstrated to exist as it is based upon General Relativity which is incompatible with quantum mechanics meaning it cannot be right he seems to misunderstand what it is that classifies a theory as correct. General Relativity produces a wide range of predictions which have been experimentally verified and one of these predictions is the existence of a Big Bang singularity. This was shown by Roger Penrose and Stephen Hawking in the 1970s. The way that science works is by having theories about the natural world which account for the facts about the natural world, science advancing by developing theories which account for more facts and disregarding theories which account for fewer or make an inaccurate case for a description of the world. General Relativity is one of our best theories for accounting for these facts however some of its account conflicts with Quantum Mechanics account which is also one of our best theories. A theory which describes nature in the light of this conflict is being searched for by Physicists, and Carroll's argument is that once such a theory is found it will invalidate General Relativity and therefore its prediction for the existence of a Big Bang singularity. This is not accurate to how science progresses, in fact our best theories have retained throughout history. Any new theory of physics will not invalidate General Relativity's accurate predictions, just in the same way that General Relativity did not invalidate Newtonian Gravity, a detailed mathematical proof that Newtonian gravity is curvature available in Gravitation, a book which Carroll happens to have reviewed with praise. As such one cannot simply assert that General Relativity's predictions are false as it is incompatible with Quantum Mechanics. 

A model of the universe like this one with an initial singularity is what Carroll disputes

This is a question that will ultimately be settled by experiment- further study of the Cosmic Microwave Background Radiation by experimenters at Penn State may give us the definitive answer as to whether a Big-Bang singularity exists which is what gives me issue with Carroll's hope for a theory which explains our universe's existence with reference to another universe in a multiverse somehow causing it to exist- there is no way that direct observational tests of the multiverse are possible, as other universes cannot be seen by any observations whatever, and the assumed underlying physics is also untested and indeed probably untestable. It seems to me therefore that Carroll's claims are ideals of explaining away the Big Bang singularity and allowing for a natural explanation, not scientific ones which give an accurate portrayal of the literature in support of the case for a beginning of the universe.  As physicist Alexander Vilenkin has claimed all the evidence we have says that the universe had a beginning.