This is a good topic, in the sense that it is an issue that is sometimes raised.
I rather like the way Admin rephrased the issues, so I will comment on them in that form.
Could the physical laws of the universe have been different in the past?
I'm assuming that this has to do with how the universe works, rather than with how physicists say that it works. How scientists say that it works as changed, as science has learned more.
Yes, sure, in principle it is possible that things could have changed. In practice, this seems very unlikely. I look at the Bible and at other ancient literature. I see reports of people living similarly to the way that primitive peoples still live today. I see reports of animals (cattle, sheep, etc). To me it seems highly implausible that things could have changed enough that the YEC version of creationism could be true, yet that they have changed so little that the same biological organisms (humans, cattle, sheep, doves, etc) could have been well enough adapted to that world to be able to survive.
Could there be such a thing as an alternate reality that is undetectable?
Well that's always possible. Maybe there's an alternative universe with elves, gnomes, tooth fairies and the like. But if it is undetectable, then it has no important effects on the world of our experience, so it has no relevance to us.
This had the potential to be a good discussion, though it failed to meet that potential.
It is, of course, possible that the physical nature of the universe has changed since older time. And foreveryoung is wanting to rely on that, so that he can protect his religion from the clear evidence of science.
The big problem for foreveryoung is this: How can the physics have changed so much as to allow the possibility that the Bible stories are literally true, yet have changed so little that homo sapiens could have continued to thrive in spite of the change. That was the issue that I attempted to raise in Message 8, but foreveryoung has not successfully answered it.
If foreveryoung wants his religion to be consistent with science, then he is going to need to make some modifications to his religious commitments. The attempt to keep his religion fixed, and make the changes only in science, is not going to work.