Certainly we can imagine this Russel’s teapot universe, where pink unicorns frolic between the stars smiling conspiratorially while hiding from human senses and tools. These kinds of universes exist in human imagination, and are useful in some contexts, but not in physical research. Certainly a lot of physicists, contrary to what Sabine is saying, mean more than “the predictions obtained with the hypothesis agrees with observations” when they say that something exists. Hence all the interpretations of quantum mechanics, for example. My charitable interpretation of what you quoted is something like following Occam’s razor, which would imply that there is no need to add Omega to the mix, or assume that the universe is wildly different beyond the cosmological horizon, unless there is a relevant hypothesis with enough predictive power.
Certainly we can imagine this Russel’s teapot universe, where pink unicorns frolic between the stars smiling conspiratorially while hiding from human senses and tools. These kinds of universes exist in human imagination, and are useful in some contexts, but not in physical research. Certainly a lot of physicists, contrary to what Sabine is saying, mean more than “the predictions obtained with the hypothesis agrees with observations” when they say that something exists. Hence all the interpretations of quantum mechanics, for example. My charitable interpretation of what you quoted is something like following Occam’s razor, which would imply that there is no need to add Omega to the mix, or assume that the universe is wildly different beyond the cosmological horizon, unless there is a relevant hypothesis with enough predictive power.
What these thought experiments are useful for is emphasising the lack identity between prediction and correspondence.