Like with flat Earthers and moon landing deniers give them the at home experiments. Science is never to be trusted. It can be tested and proves itself.
However... You're friend isn't entirely wrong to be skeptical... What we know is subject to change at any new discovery. And a lot of what we have been taught has been manipulated to facilitate the industrial way of life... So much of what we have been told and corralled into is lies. And our understanding of what you and I may call "basic" or "common knowledge" has been corrupted throughout the years.
As I said, look up easy to prove home experiments in response to your friend's skepticism.
Like with flat Earthers and moon landing deniers give them the at home experiments. Science is never to be trusted. It can be tested and proves itself.
However... You're friend isn't entirely wrong to be skeptical... What we know is subject to change at any new discovery. And a lot of what we have been taught has been manipulated to facilitate the industrial way of life... So much of what we have been told and corralled into is lies. And our understanding of what you and I may call "basic" or "common knowledge" has been corrupted throughout the years.
As I said, look up easy to prove home experiments in response to your friend's skepticism.