It's not ind doubt so much as there is little intrinsic reason to support either side, and scant evidence. Maybe the laws of physics worked differently in the early universe -- how would you know?
The answer of course is astronomical observations -- it's the only window into the past that we have, other than a few historical events like the OP, as the GP points out. But how do you interpret astronomical observations? By using the currently understood laws of physics, of course, so it becomes a bit of a circular argument.
If you assume that certain constants change over time, that does help explain away current mysteries like inflation & dark energy, under some models. However too much deviation would contradict other observable evidence.
> But how do you interpret astronomical observations? By using the currently understood laws of physics, of course, so it becomes a bit of a circular argument.
One of the best ways to measure this is to use quasar absorption spectroscopy to probe the precise energy level spacing of atoms (like iron, magnesium, and so on) from billions of years ago with the energy level spacings found in the same atoms of today.
If the fine-structure constant (for example) were different by some amount in the distant past, its effect is calculable -- and the spectroscopic signature of a different fine-structure constant is distinct from any other physical effect (redshift of the spectrum, etc.).
There are some intriguing results that have come out over the past decade or so, with new information coming in all the time.
The answer of course is astronomical observations -- it's the only window into the past that we have, other than a few historical events like the OP, as the GP points out. But how do you interpret astronomical observations? By using the currently understood laws of physics, of course, so it becomes a bit of a circular argument.
If you assume that certain constants change over time, that does help explain away current mysteries like inflation & dark energy, under some models. However too much deviation would contradict other observable evidence.