Whether you're a paleontologist digging for fossils, or a cosmologist staring into the depths of the universe, some knowledge is simply lost to time.

Like, no matter how much we look at dinosaur bones, we'll just never see a dinosaur sneeze. And we'll never truly know just how many would-be planets Jupiter flung out of our solar system.

Those moments have passed and your feelings of FOMO are valid. But it turns out, that thanks to gravity the universe itself has, like, a sort of memory. Massive objects leave subtle but lasting marks in the fabric of spacetime, like grooves on a vinyl record. So far, we can't play those memories back like a record, but scientists do have a starting point for where to look for them.

And as out technology improves, these messages carved in spacetime could help us get to the bottom of some of the universe's biggest mysteries.

Just like a bunch of other brain-bendy cosmological phenomena, the idea that the universe has some kind of memory traces its roots back to Einstein's theory of general relativity. In 1916, Einstein predicted that an object with any amount of mass should give off gravitational waves as it accelerates through spacetime. In other words, it should pinch and stretch the fabric of space itself, much like the ripples moving across the surface of a pond. Except the kind of pinching and stretching we can detect here on earth is a far, far more subtle effect.

I'm talking, like, subatomic scales. So scientists didn't actually detect gravitational waves until 2015, but that didn't stop them from trying way earlier than that. Take the physicist Joseph Weber; back in the 1950s and 60s, he constructed giant aluminum bars that were supposed to act like tuning forks, and were meant to start vibrating as soon as a strong enough gravitational wave washed over them. In 1969, Weber declared that he'd finally detected the signals he was looking for, which set the physicists scrambling.

People all over the world built their own giant tuning forks to see if they could reproduce Weber's cosmic hum, but there was nothing but silence. No gravitational waves, nothing to be heard, except for Weber's insistence that his signals were real. So a few years into this particular scientific tea, one pair of physicists were like, "Okay, let's ignore Weber's results for a moment and lets just calculate how sensitive would a device like this need to be in order to detect gravitational waves?"

They used Einstein's general relativity to run the math on some hypothetical scenarios involving objects like black holes that could send out some of the most powerful gravitational waves in the universe. And well basically, there was just no way that Weber's device picked up what he claimed it had. Those super-powerful gravitational waves were far, far too weak for his fancy little tuning fork to pick up. But while they were calling Weber's bluff, there was another little nugget that turned up in their findings. The math revealed that as a gravitational wave passes through two objects that are at rest relative to each other, they don't return to the exact same positions they were in before, and instead, they're slightly just displaced. That meant that gravitational waves didn't just wrinkle up spacetime and then return it to its previous state, like ocean waves rolling under a boat - they changed spacetime in a lasting way. In other words, the universe remembers every gravitational wave that moves through it, whether it's from two black holes spiraling towards each other or you waving at your neighbor. But not every gravitational memory forms the same way. Physicists recognize a few different origin stories. One reason has to do with the way objects with mass curve spacetime around them. Up in space, you might imagine a scenario where two black holes briefly swing by each other and fling each other off in different directions. And two things are happening here: they radiate gravitational waves because they're accelerating, but by merely existing, each also creates like this sort of dip in spacetime like a marble sitting on a mattress. This curving of spacetime is their gravitational field, and as they move through space, like accelerating or not, that dip moves with them. So to ground this, let's pretend that you're at the beach, floating just offshore in your favorite inflatable, when a wave rolls through. That wave picks you up and puts you right back down, so you'd expect to end up in the exact same place where you began, except this is the ocean and right now the tide is going out. So in the time that the wave took to roll underneath you, the water level has dropped ever so slightly, which means you're not quite in the same position as where you began. Now in the case of gravitational waves, the motion that creates the wave is also what creates this shift in the fabric of spacetime.