Not even arguing the science here, why does this Law exist? How do we account for laws of science?
Any theories, rules, laws or whatever of science can be one of two things: Either a definition of what it is talking about, in which case, it doesn’t teach us anything new and is a tautology (like saying 1 = 1) - but useful for modelling and etc., or it could be an attempt to explain observations, a currently accepted theory because it matches the evidence, which might be the truth of how things really work, or might be wrong but we never find out, or might be discarded when we find evidence of it being false.
An example of the first case is something like “mass is the property of an object that causes it to have inertia [ie, resistance to force]”. This statement is undeniably true, because it is a definition of mass. So it can be used to prove things, like that all objects which have mass have inertia. But that doesn’t actually “mean” anything in a real sense because it’s just based upon our definitions, just used to serve our current model.
An example of the second case, well this would be most scientific theories, such as the first 2 laws of thermodynamics. These actually do have a “real” meaning, because they are trying to explain real events we can observe. But thing is, they can’t actually be used to “prove” anything, because they are just theories, only accepted because they support the evidence found thus far, but they could possibly be ditched. No serious scientist denies this fact, that theories are just theories.
A conclusion we can draw, then, is that science can’t be used to prove anything with real meaning or in the real universe. It can prove things in our models, and it can make suggestions or possible explanations in the real universe, though. So you can’t prove or disprove God with science.
That being said,
Just because theories are only theories, doesn’t mean we should dismiss them completely. Many people complain about how some Christians dismiss these so easily, because to do so is to present science’s greatest strength as its greatest weakness. The point is that the theories are good theories because they are supported by centuries of observations / evidence. They are much better than the ‘theories’ of the old woman who claims that the world is supported on the back of a giant turtle, because while that could possibly be true, there is no reason or observations to believe that it should be so.
Observations are real important to the human experience. In most cases they are a big part of how we form our beliefs. So many prehistoric tribes believed in gods not because they thought it would be a cool idea, but because they looked at the world around them that they had not built, they saw the rain come every now and then and the movement of the planets and figured there must be a reason for it, something behind it. They felt their consciences and wondered where they came from. Etc.
So in our attempt to explain God, to evangelise, etc., we can still call on science. Even though we can’t be sure that the theories of today are true, we can say that they’re backed up by the obersvations of millions over centuries. The fact that there is so much support for second law of thermo, even if I haven’t seen this first hand, means that there is a lot of support for the universe having had a beginning. Others will testify that they saw the ‘proof’ of the universe having a beginning with their own eyes - you can doubt their testimony if you like, but what if they’re right?
Others will testify that they saw a man cure the blind and raise the dead back to life. You can doubt their testimony if you like, but what if they’re right?
Christianity - it ain’t such a blind faith after all.