The photons and other particles that traverse the galaxy to reach our observatories provides a continuous stream of information and matter. If there was some way to travel up the beam, which is an old science fantasy concept, faster than the speed of light through the spooky action at a distance of entanglement, then we could explore the universe as far as we can see it.
If there is quantum entanglement between the deuterium and neutrino in the p-p chain of stellar fusion, and recognizing that the neutrino emerges to travel unimpeded across the galaxy to reach our location, and then that our observation of the state of the neutrino tells us about the condition of the deuterium in the stellar core.
(Disclaimer: these are mental wanderings through physics that are only first thoughts and so require analysis…)