> Historically, science has predicted lots of true things about the universe that could not be observed at the time.

Just some examples I could think of:

The neutrino[1], predicted in 1930 due to missing mass in beta decays, discovered in 1956.

Gravitational waves[2], predicted by Einstein in 1916, indirectly detected via pulsars in 1974 and directly by LIGO in 2015.

Higgs boson[3], predicted in 1964 to solve the problem of the Standard Model at the time requiring particles to be massless, which we knew they weren't. Hints from LEP at the turn of the millennium, detection by the LHC in 2012.

Cosmic microwave background[4], predicted in 1948 as a consequence of the expanding universe on the early radiation. Detected by accident in 1964.

Gravitational lensing[5] was first proposed in 1801 as a consequence of Newtonian corpuscular theory of light. Einstein realized in 1915 that GR predicted a larger value. Weak lensing by the sun was observed in 1919. Strong lensing by a distant galaxy of an object behind the galaxy was was predicted in 1937, and first observed in 1979.

[1]: https://en.wikipedia.org/wiki/Neutrino#Pauli's_proposal

[2]: https://en.wikipedia.org/wiki/Gravitational_wave#History

[3]: https://en.wikipedia.org/wiki/Higgs_boson#History

[4]: https://en.wikipedia.org/wiki/Cosmic_microwave_background#Hi...

[5]: https://en.wikipedia.org/wiki/Gravitational_lens#History