No, real science has to be able to be tested in real-time. If it can't be it's no different than faith. The problem is, that they put their speculations out there and people take them as facts.
Simply not the case.
The *basic principles* should be testable (so, general relativity, quantum mechanics, chemistry, etc), but that doens't mean the specifics need to be tested in real time. In fact, many phenomena happen on *way* different time scales than what can be done in the lab. Plate tectonics, the 'life cycle' of stars, the dynamics of galaxies, and so on, simply don't happen in the few thousands years of human civilization. But we *can* know about them, test the basic principles, and have reliability of our conclusions.
And, yes, those conclusions reveal *facts* about events that happen over millions or even billions of years. it is not 'just speculation', but data and test driven knowledge.