We can't be sure who first asked the question: "why is there something rather than nothing," although it has been attributed to the German philosopher Gottfried Wilhelm Leibnitz (1646 -1716). Given the age and culture which shaped Lebnitz's thinking his explanation, naturally, was in summary that the universe exists because God exists and made the Creation so.

Before commencing an examination of the subject it may be helpful to distinguish between reasons and causes. For example, if someone was to ask why Jack asked Jill to a movie that person would be seeking to understand Jack's reasons what was going on in his mind (his desires, hopes and so on) that led him to ask Jill in the first place.

The questioner isn't looking for an explanation of the physiological causes — the neurochemical reactions occurring in Jack's brain, although this would explain how he was able to ask the question, but probably not the reasons why. By contrast if someone were to ask: "why does the Earth orbit the sun?" they are seeking a causal explanation — facts that describe and account for planetary motion.

So, is the question "why is there something rather than nothing" about reasons or causes? This depends on whether your starting point is God or not. If God is evoked as the creator then the question primarily concerns reasons — God desired the universe to exist and it was so. By what means or causes it was made to be so is not explained. The will of God magically crystallizes into matter, (or that the Universe is a manifestation of God, or that God is incarnate in the universe) and that is all that can be said.

But is the theological answer really an answer? If there is a God (and what definition of God shall we accept?) and God preexisted the Creation, then why is there a God at all? Theologians may attempt to resolve the difficulty by postulating that God is his own reason and cause, thus eliminating the need for any additional explanation. But what evidence do they have that this assumption is true?

I think a more profitable line of enquiry is to look for causes rather than reasons, for a reason implies the existence of a will either in or behind nature in a similar way that there was a will behind Jack asking Jill to a movie, and as Nature is non¬conscious it is doubtful that it has a will, unless of course one embraces panpsychism — the view that the entire Cosmos is permeated by degrees of consciousness.

The best theory we have to date (and I must point out that a theory is not a guess, but is derived from the evidence of nature) is that of the Big Bang. In summary the Big Bang states that the universe came into existence approximately 13.8 billion years ago, a time when all matter was compressed into a singularity of infinite density and intense heat whose expansion eventually gave rise to the cosmos we see today.

Below is a brief timeline of the process of cosmic evolution that has been formulated through astronomical observations of the deep universe, experiments employing particle accelerators and high energy states, and the testing of theoretical principles through advanced mathematics.


Singularity Epoch: Point 0 to approximately 10^-43 seconds



Inflation Epoch 10^-32 seconds



Cooling Epoch: Circa 10^-11 seconds



Structure Epoch: Several billion years post Singularity to the present


The aforementioned is a very brief and simplified outline of the consensus of cosmologists, but it is certainly not the final explanation of how things came to be. The role of dark matter and dark energy has yet to be fully elucidated, and there may yet be further discoveries that will necessitate additional refinement of the theory.

Naturally, this leads to the question of whether we will ever really know the full answer to the question: "why is there something rather than nothing." In my opinion there is no guarantee for the following reasons (although I admit I could be wrong).

Firstly, what happened before the Big Bang? If time and space emerged as a result of the Big Bang, then it is meaningless to talk about what came before, for the simple reason that without time there was no "before," no prior causative agency, at least as we understand the term. Of course this hasn't stopped cosmologists from attempting to answer the question, and below are some of the theories they have formulated:

1.    It's entirely possible that there was no previous era. Assuming that this is true, it means that matter, energy, space, and time began abruptly. Perhaps this abrupt change sprang from a collision with a parallel universe. Or maybe something else. We really don't know.
2.    Another theory is "Quantum Emergence." According to this view, space and time developed out of a primeval state described by a quantum theory of gravity. Notably, we don't have an explanation for quantum gravity just yet. So we can't say much beyond that.
3.    There's the landscape multiverse of string theory, which deals with differences of quantum tunnelling and quantum fluctuations between different energy states.
4.    There's also the cyclic universe. In this theory, the Big Bang is just the latest "big bang" in an endless stream of big bangs — in the continual expansion, collapse, and renewed expansion of space and time.
(https://futurism.com/cosmology-the-timeline-of-everything-we-know/)

At the moment there isn't a final candidate for any of the above, so it isn't possible to give a definitive answer.

Secondly, our investigations are limited by the sensitivity of the instruments we can construct. To discover the ultimate answer we may need an instrument — say a particle accelerator the size of Jupiter — which is beyond our capacity to build.

Thirdly, our brains may be unable to deduce the answer due to physical limitations. For example: a chimpanzee could never have discovered calculus — its brain is simply not structured in a way that would enable it to do so. When it comes to answering the ultimate question we, too, may lack sufficient intellect.

Fourthly, even if we can augment our brainpower by constructing a quantum computer possessing artificial intelligence and sufficient processing capacity to solve the problem; the machine, with its vastly superior intellect, may be the only one who can really understand the answer.

Science will continue to progress, but in the end it may prove unable to answer the question. If so then does this bring us back to the claims of religion as a possible solution? I think not for the simple reason that all the theologians can say is that "God exists and created the universe."

Some of the more sophisticated theologians may attempt to appeal to probability — they may argue that our Universe is improbable and therefore requires a guiding intelligence to explain its origins.

I think the problem here is that in order to determine probability one needs a series of repeatable events — the toss of a coin for example. The universe, however, is a one off event from our perspective and so it is impossible to tell how likely or unlikely it is. There may have been an infinite series of universes preceding ours, as some cosmologists speculate. At the moment there is simply no way of knowing.

Another appeal might be to the fundamental physical constants of nature that make the universe conducive to life. The argument here is that if anyone of these constants varied then life would be impossible, and that this fact requires the postulation of an intelligent designer.

Again, we have the same problem of only one example — life as we know it. A universe with different constants may still give rise to life, but not the kind of life we are familiar with.

In the end the universe, for us, might simply be an expression of natural laws — a brute fact bereft of a human centered meaning. For example, 66 million years ago an asteroid impact was instrumental in the extinction of the dinosaurs. With their demise the mammals were able to evolve into the vacant ecological niches, one of which was the precursor of humanity. The extinction event (without which Earth's history would have been very different) wasn't predetermined, it wasn't foreordained. It was just bad luck for the dinosaurs, and good luck for us.



http://www.askanastronomer.co.uk/darkmatterenergybigbang.php

https://www.independent.co.uk/news/science/dinosaurs-survive-extinction-asteroid-minutes-event-research-scientists-a7744031.html

http://theconversation.com/answering-the-biggest-guestion-of-aII-why-is-there-something-rather-than-nothing-65865

https://www.philosophytalk.org/blog/why-there-something-rather-nothing

https://futurism.com/cosmology-the-timeline-of-everything-we-know/

https://www.physicsoftheuniverse.com/topics_bigbang_timeline.html

https://www.universetoday.com/54756/what-is-the-big-bang-theory/