I do not believe it to be true that scientists believe only what can be directly experienced. There are numerous theories and laws in science about things which cannot be directly experienced, such as black holes, human evolution, and infinity. Scientists may believe in these theories because they serve as the best explanation to date.
Black holes have never been directly experienced by humans, yet there are many theories about them. There are even theories about "worm holes,"ÃÂ which are supposedly two connected black holes which can, if you were in "Mario Land,"ÃÂ transmit you through a pipe to a different place and level in a "warp zone."ÃÂ In human land, it would be traveling through space and time to a different place, perhaps galaxies away and millions of years in the future.
Another theory which cannot be directly experienced is the theory of human evolution. No one can certainly and definitely state that we did not just spontaneously appear on the earth about 40,000 years ago, and from there learn to use the things the Earth provided.
On the same note, no one can certainly and definitely state that humans had evolved "ÃÂ we only say they did because that is what all the signs lead us to believe, because it is the only explanation for all the fossils found and is the best explanation to date.
No one has ever reached infinity. You can try counting to infinity, but you keep counting and counting. Even if you had counted from the moment you had been conceived until the moment of your death you would not reach infinity, although you would end up with a really high number in the end. Infinity is only a theory, which we believe in, although we have never experienced it directly.
In conclusion, I think that scientists do not believe only what can be directly experienced. They believe what is the best explanation for the phenomena to date, such as the theories of black holes, wormholes, human evolution, and infinity.