The void is changing. Something invisible is shaping the fate of the universe — and we don’t know what it is.

For decades, scientists believed that dark energy — the mysterious force making up about 70% of the cosmos — was constant, a kind of unchanging “vacuum energy” driving the universe’s accelerated expansion.

But new research from the University of Chicago suggests otherwise. Using combined data from the Dark Energy Survey, the DESI instrument, and the Planck space telescope, researchers found that the standard cosmological constant doesn’t fully fit the observations.

Instead, dynamic models — where dark energy evolves over time — seem to match the universe better.

This means dark energy may not be fixed. It could be slowly changing. In fact, the analysis shows its density might have dropped by about 10% over the past few billion years.

One possible explanation: an entirely new, ultra-light particle — far lighter than the electron — influencing the cosmos in ways we’ve never seen before.

If this is true, it’s not just a tweak to equations. It’s a new frontier in physics. Dark energy doesn’t just control how the universe expanded in the past. It may determine its ultimate fate.

We know how much of it there is. But what it actually is — remains the greatest mystery in science.