But how do we know that energy/matter was created by 'external' causes?
We observe a universe of dependent existences/causes, therefore there must be an independent, uncaused, first cause.
Ptolemy observed that planets, observed form the earth, apparently make "loops" so he devised a navigational system based on that observation. It's the observer problem. We observe the world and conclude that it had to be created by an external source the way Ptolemy observed and concluded the planets run in "epicycles".
His system factually flawed, because it is based on the geocentric model of the universe, but it still works because its systematic and because we still observe form the earth. Nevertheless, just because science creates a working model doesn't mean that model represents reality.
Today we have the Big Bang (a relatively recent theory) leading us all the back to the initial event, but it doesn't tell us that this was the first or the nteenth repetition of a newly created world ex nihilo or the perpetuum mobile one without the beginning or the end.
Ancients knew that the sun, in the course of a year, makes "figure 8" (analemma) in the sky (and some probably thought it was a "sign").
But they didn't know that this was a relative, local, perspective and that the sun is stationary with repsect to us.
So, when you insist on "dependent existence" I wonder how do we know that energy and spacetime didn't exist all along. Let's not forget that all cosmological theories (scientific or theological) are just thattheories, or, if you will, modern-day "epicycles."
This would be a big step above pure imagination, especially when we have a hypothesis based on observation and logic.
Observations can be flawed, limited, distorted,etc. Logic is still valid, but the conclusions aren't necessarily true.
Chose one that fits observation and reason/logic.
And end up with another Ptolemaic system?
But, friend, I don't think you've found one yet...Your hole has to be found there.
Sometimes admitting that we don't know is the most truthful thing we can do. There is no more reason to have eternal energy then an eternal "outside" source.
Two hundred years from now, if the earth and humanity are still around, people will be saying about us "did they really believe that?" It's really an eye-opener to read what people believed in 18011.
As I said earlier, the first cause argument is not in the same category as firm scientific proof. It's an argument, and a good one, for why anything exists - using observation and logic.
Nevertheless, just because science creates a working model doesn't mean that model represents reality.
In a way it does. It, to some degree of accuracy models what is observed - that is the way in which it works.
Until a more accurate model, Ptolemy's ruled. It wasn't enough for someone to say: "there will be a more accurate model," they had to create it - and it had to "work", to a greater degree of accuracy, be a better model of what is observed.
The same with Newtonian physics until Einstein and so on.
I can agree that a model of reality will likely be replaced with another based on new knowledge or a better modeler. I can even believe that all man's model's are lacking.
However, that is not the same as proving the current model wrong.
I think it should be clear that Aquinas Cosmological Argument is more in the sphere of philosophy than science - although all philosophy still relies on the physical accuracy, the sense observation, being true. It draws conclusions and arguments from science.
It could be undermined by new science; however, it is not reliant on much else in science than cause and effect. Until this part of science is changed firmly, it has a good chance of holding. For example, it is immune to the changes you explain in the orbits of the planets. And I do appreciate your posts and points on this aspect, on science and on man's limitations in general. In general I agree: science only names, describes and models reality - and any model could be wrong.
thanks very much for your reply.
Your post reminded me of the quote attributed to statistician George Box:
“All models are wrong, but some are useful.”