And Will Medicare Cover My X-Ray Eyes?

In comments to my post on the absurdity of the infinite-horizon, TJon writes:

Why don't Democrats use this to mock Republicans. Use the infinite model to calculate how much SS will cost between 4050 and 4100. Ask Republicans if they agree with that prediction. Ask them details about it. How many workers will there be per retiree? How much will a retiree get in 2005 dollars? Will that cover the toll lanes on the commute from Mars to Venus? Economists can't predict what is going to happen next year, much less 75 years from now. Its a joke and we need to start mocking it.