Firstly, before starting I would like to applaude my opponent for accepting this debate. Hopefully he isn't some brainwashed idiot and will actually use some good points. Just don't cuss or insult me, and this will be a stimulating debate.
Background info: I am currently studying Theoretical Physics at uni, so I will use Physics mainly as a way to defend my position. Also, I'm new to this website, so please have some patience if I need some prompting when trying to open new rounds etc...
Here is my argument, or better, here is my proof that all arguments showing that the Christian God is necessary for the universe to exist are erroneous.
Firstly, most Christians use the "Fine Tuning argument" as an excuse to prove that God must exist. For those of you who don't know what the fine tuning argument is, it states that if the parameters of the universe at its beginning were different by a minimal margin (along the lines of billionths of percent), then the universe would not have been hospitable. This is quite similar to chaos theory: a small change in the initial state of a system has great effects in the state of the system later in time. Watch this yt video for some extra background if needed
There are various counter arguments, which all are supported by hundreds of papers (which, for the sake of you, I have chosen to be open access so that you may view them as well). I will use three:
1) The whole reasoning that changing the universal parameters by a "very small amount" would make the universe hostile to human existence is , in truth false. These universal parameters can be changed simultaneously. Just read this article: https://arxiv.org...
Not only that, the four fundamental forces were actually UNIFIED at the beginning of the big bang, and split up due to assymetry... (according to the standard model, also this unification was shown for the electromagnetic and weak nuclear force, still a very undiscovered area of physics, very exciting!)
I also have to point out that there are countless other parameters which, for someone who hasn't had a rigorous background in physics (i'm not talking about you), may seem fine tuned, but actually aren't.
For example, consider the Rate of Expansion of the universe and the cosmological constant (consider it as the energy density of a vacuum). Theists believe that it was tuned to 1 part in 10^60. Cosmologists believed this as well, before EFE came (Einstein Field Equations). Using GR, they found out that the probability is 1. Not 1%, 1 out of 1. This can be easily seen observing a typical Galaxy Power Spectrum to Lambda CCD prediction graph. This is at the base of Quantum Loop Cosmology, but let's not get into too many details...
The cosmological constant seems to be fine tuned to 120 orders of magnitude! that's INSANE. Indeed, one has to fine-tune _5;B to a precision of 122 decimal places to cancel the huge vacuum energy density to match the observations.
There is one HUGE fallacy in this logic, it forces vacuum energy density to be constant, IT'S NOT. Another paper, this one I will explain since it is quite difficult: https://arxiv.org...
The vacuum energy density is fundamental in calculating the cosmological constant, and forcing it to be constant is a mistake. WHy? Because yes, vacuum is an eigenstate (pretty much, an eigenstate in QM is a state for which, if an operator acts on it, it only multiplies it by a scalar quantity) of the Hamiltonian Operator, but NOT OF THE ENERGY DENSITY TENSOR!!!! This means that it may fluctuate according to its expectation value, which is HUGE. Even if you fine tuned the cosmological constant to 120 orders, the universe would still expand too quickly because of these fluctuations, the constant would get rid of the expectation value but not its fluctuation... Then the papers goes into some pretty heavy mathematics, but pretty much gives a relation for the effective cosmological constant showing how not fine tuned it is...
So what causes the acceleration of the universe you might ask... quantum fluctuations of the stress energy tensor, the very thing that shows how fine tuning is not needed. I suggest you read the paper, since it is quite difficult to explain and reformulate.
All those "slightly off" arguments for fine tuning are easily proven wrong using EFE, GR AND QFT.
2) The second argument, which is more abstract to understand, but very powerful if understood, is what i call the "What are the odds that my legs would be precisely the right length to reach the floor?" argument. The reason we observe the universe to be habitable is because, well, we exist! If you were to observe the universe, would you expect a universe that can sustain life, or a universe that doesn't sustain life? Obviously the former option! A universe that can't produce observers isn't observable, it makes sense that these parameters allow for human existence. Let's do a quick thought experiment. You have 100 cats, and you have 100 meals for them. 99 of these meals are poisoned, one is normal. After feeding your cats, you realize that 99 of them have died, only one has survived, that's a statistical certainty. The fine tuning argument is analogous to saying "wow look at that cat who survived!". It's just wrong, because 99 other cats have died. Similarly, who knows how many cosmic oscillations our universe has gone through before it was able to produce observables: one, a hundred, maybe a billion? Then out of these billion oscillations, if only one survives (just like in the cat analogy) a fine tuner would say: "wow, what are the odds of the universe being so fine tuned?". 999 999 999 universes weren't hospitable before, the odds are quite low actually XD
3) I will now present the weakest argument, since it has little scientific evidence to support it. According to the fine tuning argument, the universe was made perfectly to sustain human life, or any carbon-based life form. But what about other life forms, maybe made of different type of ma
tter? Then isn't this universe non-fine tune for them? What if in another universe these other types of life forms, survive, but we don't. Then the universe is not fine tuned for us, but the other "alien" civilisation will say that it is fine tuned. So who's correct? No one, because as I said in the two earlier points no universe is fine tuned.
To conclude, these are my three points to argue against fine tuning. There is just no neccessity for god to intervene.