Researchers used ancient starlight to randomize an experiment, but still found quantum entanglement.
For decades, physicists contended that demonstrations of quantum entanglement were biased by observation. In an ingenious twist on an old experiment, researchers turned to ancient starlight from distant quasars to randomize the polarity of the particles used in the experiment. The results, however, stayed the same:
The colors of these photons were decided hundreds of years ago, when they left their stars, increasing the chance that they (and therefore the measurement settings) were independent of the states of the photons being measured. And yet, the scientists found that the measurement outcomes still violated Bell’s upper limit, boosting their confidence that the polarized photons in the experiment exhibit spooky action at a distance after all.
The experiment doesn't rule out an alternative entirely, but the primary exception would be a little bit spooky itself: determinism. If the state of the universe now is dependent on the state of the universe when the quasar emitted the photon used to randomize the experiment, that would also explain the results.
So we may have to pick between believing in a) a concept Einstein found so reprehensible he basically disowned it; b) a totally deterministic universe depends on the one before it; c) time travel.