Many scientific models are completely unproven (but not disproven) and are accepted and used because they just seem to fit to reality. Until it is proven that they are wrong, we assume that they are true. That I know of, I can quote the Big Bang theory, the Quantum Theory, the String Theory, the black hole models. In the past, the atom theory (2000 years old, proven since 100).

There is no necessity for a model to be proven true to be accepted. Sometimes proof is just very hard to pin down.