If dark energy is decreasing, is the big crunch back on the menu?

For generations, humans have gazed at the stars and wondered about the ultimate fate of the universe. Will it expand forever into the cold emptiness, or meet a more dramatic end?

A study published on the arXiv preprint server by physicists from Cornell University, Shanghai Jiao Tong University, and other institutions suggests we may finally have an answer, and it’s surprisingly specific.

Using data from a number of astronomical surveys, including the Dark Energy Survey and the Dark Energy Spectroscopic Instrument, the researchers have developed a model that predicts our universe will end in a “Big Crunch” in approximately 33.3 billion years. Since the universe is currently 13.8 billion years old, this gives us roughly 20 billion years before the curtain falls!

This prediction challenges the long-held assumption that the universe will expand forever. Instead, it suggests that after reaching maximum expansion in about 7 billion years, the universe will begin contracting until everything collapses back into a single point.

The key lies in understanding dark energy, the mysterious force that makes up about 70% of the universe and drives its expansion.

It’s long been assumed that dark energy behaves like a cosmological constant, maintaining a steady pressure that pushes space apart indefinitely. However, recent observations suggest dark energy might actually be dynamic. The researchers propose a model involving an ultra-light particle called an axion, combined with what’s known as a negative cosmological constant.

Think of it like a great big rubber band. Initially, the universe expands as this “rubber band” stretches. But eventually, the elastic force becomes stronger than the expansion, causing everything to snap back together.

According to the new model, the universe continues expanding but at a gradually slowing rate until reaching maximum size, about 69% larger than today, in roughly 7 billion years. Then gradual contraction begins as gravitational forces and the negative cosmological constant take over, leading to rapid collapse in the final moments.

It’s important to note that this prediction comes with significant uncertainty. The researchers acknowledge their model has large margins of error due to limited observational data. The negative cosmological constant that drives their prediction remains highly speculative, and alternative scenarios including eternal expansion are still possible.

What makes this research particularly exciting isn’t just the prediction, but that we may soon be able to test it. Several major astronomical projects launching in the coming years will provide much more precise measurements of dark energy’s behavior, potentially confirming, refining, or ruling out the Big Crunch scenario entirely, once and for all.

Even if confirmed, a 20 billion-year countdown hardly constitutes an immediate crisis. For perspective, complex life on Earth has existed for only about 600 million years. Twenty billion years represents a timespan so vast that the sun will have died and our galaxy will have collided with Andromeda long before any cosmic collapse begins.

Nevertheless, this research represents a remarkable achievement in our understanding of the cosmos. For the first time, scientists have developed a specific, testable prediction about the ultimate fate of everything that exists, giving us a concrete timeline for the most dramatic event possible; the end of the universe itself.