This post is slightly tongue in cheek, there is obviously no way anyone can prove or disprove the existence of God. But the ideas, although still highly speculative, do allow one to assign some kind of probability to God's existence, and that is at the very least interesting. Or I think it is...
In what follows, by God with a capital G I mean a God who has created the Universe for the sole purpose of us to live in. This is a rather self important belief, but it is one that you will find in most religions that involve a Creation Myth.
The most I will do is to question this belief, by putting forward some ideas that, whilst a tad speculative, show that it is vanishingly unlikely that a God exists who has created a whole blinking and whirring Universe solely for our comfort and perusal.
This question is based on the fact that, as our knowledge increases, there is every indication that we are less and less important in a cosmological sense. There are no contradictory indications to this trend.
In other words, the arrow of science seems to have taken an unequivocal Copernican direction, ie, it seems hell bent to knock us off our pedestal on centre stage. This bent, or direction, is based on observation, logic and mathematics, not subjectivity, and it is not, as we shall see, flattering to our cosmic importance.
If God has created the Universe and everything in it just for us, then we need to be unique in the Universe and what you might call Cosmologically Important.
Therefore, if we can show that we are NOT Cosmologically Important, then that goes some way to showing that God (with capital G) as we "know" and worship him, does not exist.
Let's start our 'proof' with Copernicus and take a spin through subsequent increments in our knowledge and understanding of the Cosmos that we live in.
Copernicus showed that Earth is not the centre of the Universe. The Earth revolves around the Sun and therefore the Sun is the centre of the Universe, not the Earth. That leaves us still cosmologically close to the heart of things, give or take a few light minutes. But we are no longer in situ at plumb centre.
However, a few centuries later, along comes the post Copernican realisation that the Sun is just one of hundreds of billions of stars that rotate around a massive black hole at the centre of the Milky Way. Fortunately, we are NOT at the centre of our galaxy, otherwise we would be inside said massive black hole, which would not be fun. Instead, it seems we are very much out on a limb of our spiralised galaxy.
But we have not stopped there. Next came the 20th Century observation that the Milky Way is not the only galaxy in the Universe, but instead is just one of hundreds of billions of galaxies, each with hundreds of billions of stars like the sun.
Anyone with an open mind will begin to concede that we are not exactly centre stage.
In consequence, we are now beginning to look seriously comsomologically insignificant.
But hold on, could not the Milky Way still be at the centre of the Universe?
Hubble answered that question with his observation that there is no 'centre of the Universe'. Space is expanding and each point is rushing away from its neighbour. Mathematically, that means that there is no centre to the Universe.
All this is pretty established. We live out our lives on an insignificant spec of dust in a bubble of space that is fifteen billion light years in diameter that mathematically or in any other sense has no centre. We are small. Very small. And very, very insignificant.
But let's not stop there.
All the Horrors of the Multi-Verse
As science brings maths to bear on the first instants of the Universe, a new and ugly speculation raises its hideous head.
The maths and the logic seem to imply that there is not just a Universe, but instead a Multi-Verse made up of lots and lots of Universes, some similar to our own, some potentially very different. Our 15 billion light years bubble is just an insignificant spec of dust in a unthinkably vast multi-verse constituted by every mathematically possible bubble. In most of these bubbles life would not be possible, as the constants of nature would not allow for galaxy formation. However, in a number of bubbles that is vast even by cosmological standards, galaxies would indeed form and so life would indeed be possible. Given such large numbers, life would happen, billions of times in billions of different galaxies in billions of different bubble universes.
In a Cosmos that is not a Universe, but a Multi-Verse, it follows that our Earth bound species is not in any reasonable sense cosmologically significant. We would be just one of billions upon billions of sentient species in the Multi-Verse.
Therefore God (capital G) does not exist.
The Anthropic Principle
Amen, you might well say.
If you apply Steven Weinberg's use of the anthropic principle in conjunction with a Multi-Verse cosmology populated by bubble universes generated by quantum jitters in the inflaton field to gauge the cosmological significance of mankind, the probability of your Amen being heard by an interested creator is vastly less than 1 divided by 10 to the power of 500, according to some speculative mathematics.
Ie, 0 followed by at least 500 decimal places before you get a significant digit (ie, a digit different from 0).
Ie, the probability is smaller than a ridiculously small number.
But hey, it ain't zero so git down on yo' there knees and say Hallelujah, Praise the Lord!
God bless all you folks sittin' at yo' computers tonight.
Computers that wouldn't work if quantum mechanics wasn't right. And it is nothing if not Quantum Mechanics that leads us, slowly but surely, to the notion that there are billions upon billions of other Universes out there beyond our own, none lesser nor greater than the other, all just being, just existing, some expanding forever till the night sky goes dark and cold, others growing first only to cave in upon themselves before eternity has but blinked an eye. Billions upon billions upon billions of Universes, not solar systems or galaxies but entire Universes, with billions upon billions of galaxies in the billions upon billions of them that have a cosmological constant small enough to allow galaxy formation.
And all the time, the inflaton field jitters away and new bubbles erupt from the Multi-Verse vacuum, billions of them in just an instant, each with the Cosmological violence of a Big Bang. Let there be light. A lot of it.
So many Universes that the meaning of the numbers begins to escape our reach. Hallelujah, indeed.
And in each of the galaxies in each of the Universes with a cosmological constant that allows galaxy formation, hundreds of billions of stars, with billions of planets, of which there will be millions of planets with ideal conditions for life like ours to trigger and survive. In just one galaxy. Let alone all the galaxies in all the universes of the multiverse.
If you look at it from that angle, there will be innumerate billions of planets teeming with life, with evolution driven by natural selection selecting that will eventually select intelligence over brawn, until you get a self aware species (well, partially self aware) that can look up at the night sky and wonder why. The answer to their question why will not be immediately apparent.
So each of those species will sooner or later write a book that beings with the line:
"And God said: Let there be light."
And they will believe that they are the chosen ones, the ones at the centre, the ones with the truth. Just like we did.
Until one day, from too much looking up at the sky and wondering why, they begin to figure out the answer.
And the answer isn't flattering.
What about gods without a capital g?
So much for God with a capital G. But what about plain old gods with a small, lower case g?
The alternatives to God are gods who are not in the least bit interested or involved with OUR existence.
Worshiping such a god can be shown to be somewhat pointless, so the uninterested god can be excluded from human spirituality:
God based religions fail if mankind is not cosmologically important, and so rather than believe in some other alternative god, you might as well believe in Father Christmas and the tooth fairy.
But things aren't as grim as all that, there is still refuge available for the spiritually inclined.
You can still give buddism a spin or join the Hare Krishna. Personally, I think the Dalai Llama is one of the greats of our time, along with the likes of Nelson Mandela (but then I am not in power in China nor am I a Boer). Maybe you should try the Tao?
Go East, young man (or woman). Or not.
Your options are reduced to finding a religion without a creation myth at its core.
The problem for belief in a god that does NOT have the power to create the universe, is that said god becomes disappointingly parochial. And if a deity is parochial, then what is the point? What answers to Humanity's existential questions will he (with a lower case h) provide?
If you accept that your god didn't create the cosmos, then can he change the result of battles, or football matches? Can said god intervene in personal illness or distress? If not, what is the point of prayer? If there is no point in prayer, what is the point of religion?
And if our parochial god was able to intervene in such things, then our planet Earth would be a most unusual part of the cosmos (the place where a god can intervene in football matches) which to the best of my knowledge it isn't. Leicester City doesn't usually win the Premiership.
So if mankind is NOT cosmologically significant then you are left, at best, with the possibility of a god who is not in the least bit interested in you.
Most people's god is a god who is interested in them, and with whom they can hotline by means of prayer. All the above leaves such beliefs in a rocky place.
A Speculative Loophole
The problem with this disproof of God (capital G) is that the physics it is based on is still highly speculative.
However, speculative or not, it is derived from current lines of enquiry into Cosmology, and dovetails with the unrelenting Copernican trend in the direction of scientific knowledge to dislodge us from centre stage.
Given that the Multi-Verse is still a highly speculative notion, ultimately, this proof is definitely not watertight. That will be a blessing to some.
In my case, however, Galileo's alleged words, as the Inquisition led him away, still echo in my mind:
Eppur si muove, said Galileo, and stamped his foot, indicating the Earth beneath him.
Still it moves, whatever the clerics have made me say.