A new study has come to an immensely disappointing conclusion about the nature of dark matter, which is believed to make up the vast majority of matter in the known universe.

Dark matter has been incredibly elusive to mankind, and we’ve only been able to detect it indirectly by observing its gravitational effects. But scientists were hopeful that there was some additional interaction, a way that dark matter might mess with normal matter and produce a recoil from a collision, but a huge new experiment has come to the conclusion that dark matter may be almost completely invisible to us, according to a Lawrence Berkeley National Laboratory.

The LUX Collaboration, or the Large Underground xenon experiment, performed the longest and most sensitive search for dark matter ever devised, using 370 kilograms of liquid xenon and a detector that ran for 20 straight months, but it was unable to detect a single dark matter collision.

Dark matter is necessary to explain galaxy rotation curves and the bending of light around star clusters, so we know it’s out there. We can even observe dark matter separating from normal matter when two galaxy clusters smash into each other.

But unfortunately, we are no closer to understanding the particle nature of dark matter because we haven’t figured out how to see it interact with normal matter, and this latest experiment is a huge disappointment that throws into question whether it’s possible for us to observe this.

“LUX has delivered the world’s best search sensitivity since its first run in 2013,” said Rick Gaitskell, professor of physics at Brown University and co-spokesperson for the LUX experiment. “With this final result from the 2014-2016 run, the scientists of the LUX Collaboration have pushed the sensitivity of the instrument to a final performance level that is 4 times better than originally expected. It would have been marvelous if the improved sensitivity had also delivered a clear dark matter signal. However, what we have observed is consistent with background alone.”