True exponentials exist very rarely. What we are used to call exponential is often at most quadratic and even then the trend usually exists only for some limite

True exponentials exist very rarely. What we are used to call exponential is often at most quadratic and even then the trend usually exists only for some limited time window. I wouldn't dare to make prediction about mankind 1000 years from now based on a relatively short time window of technological growth. There are many huge obstacles in the way.