Simplest explation is: If you take a closer look to Shannon–Hartley theorem https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem#Statement_of_the_theor

Simplest explation is: If you take a closer look to Shannon–Hartley theorem https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem#Statement_of_the_theorem https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theore... you can see, that in theory you can have arbitrarly low signal/nose ratio for message to get trough.