We have countless mechanical sensors and detectors that can sense just about everything there is in this universe, even neutrinos. Even if we magically manage to detect half of that it wouldn't show us anything we don't already know. Although it would be trippy to see the full EM spectrum.
"just about everything" includes detecting perturbations in the intensity and frequency of light that Occam's Razor suggests is due to unaccounted mass and energy. Moreover, that the unaccounted-for amount would exceed the light and mass we can detect (75:25, roughly? Maybe less, depending on the model). Our best explanations all sound dubious -- dark matter & dark energy? Hardly an explanation. Extra torsion of the space in each galaxy due to the effect on space from black holes? That's a pretty big rounding error. WIMPs that we've left out of the Standard Model? Recent experiments have left little room for that possibility.
There may indeed be things which we can't detect, even with our best instruments, that we don't have a suitable explanation for.
I would go as far as to say it's a certainty there are things we can't detect yet... but probably not that many of them. Dark matter is funny because it's actually something that we can detect [0], at least indirectly but can't explain yet. But just like there are the EM and Higgs fields there could be countless other fields that don't affect our day to day reality in any way, but in that sense they might as well not exist.
> But just like there are the EM and Higgs fields there could be countless other fields that don't affect our day to day reality in any way, but in that sense they might as well not exist.
Then you also have to accept that you're not talking about objective reality in any way but isolated to human experience and limited by our cognitive and experimental abilities.
