Nonsense. Economics is the study of how people exchange goods and services.
Yes, but apparently a 'successful' economy is one which is always growing...
Sure it is. But the AC assumes that growth inevitably means increasing consumption of natural resources. It can mean that, but that actually only works in a context where the natural resources in question are abundant. Once they become scarce (perhaps artificially), then growth comes from finding ways to use resources more efficiently.
A successful economy is one which is improving the standard of living of the people in it. There is no reason why that process cannot be endless... though the definition of what constitutes improvement absolutely will change over time.