Comment by carlosjobim
2 days ago
If you're not allowing the machines to be tested in space (no environmental factors) nor on earth (environmental factors), then there's nowhere allowed to test or make such a machine. So a perpetual motion machine becomes impossible because there is nowhere in the universe where they are accepted.
Is it possible for a man to run 100m in less than 10 seconds? If he's not allowed to run on any kind of surface. So now we've proven that it's impossible to run 100m in less than 10 seconds?
The first and second laws of thermodynamics would apply regardless of where you stage the experiment.
There's a difference between impossible in principle and impossible in practice.
Science is interested in principle. Engineering is interested in practice.
You don't need to walk 1000km or 1001km or 1002 km to know that, in principle, these can be done.