Our universe may not expand forever. Based on evolving dark energy data, physicists now propose a model in which the cosmos could stop expanding and collapse into a “Big crack” in about 20 billion years. This scenario depends on whether dark energy actually evolves over time – a possibility that some recent results seem to support.
The theory, developed by physicists Hoang Nhan Luu, Yu-Cheng Qiu and Henry Tye, describes a limited lifespan for the universe. They estimate a total age of 33.3 billion years, which leaves less than 20 billion years before everything starts contracting. This model, if confirmed, challenges the widely accepted idea that the universe will continue to expand indefinitely.
Revisiting the cosmological constant
At the center of this model is Einstein’s cosmological constant (λ), a term originally added to the equations of general relativity to account for the expansion of the universe. For decades, scientists believed that λ was positive, implying a constant outward push resulting in eternal expansion. However, according to Scientific alertnew calculations point to a small negative λ, suggesting instead a force pulling inward.
Physicist Henry Tye of Cornell University explains that “for 20 years, people believed that the cosmological constant was positive,” but “new data seems to indicate that the cosmological constant is negative.” This change means that gravity could eventually overcome expansion, leading to a cosmic reversal.
Although current evidence does not eliminate the possibility that λ is zero, the best-fitting model used by the research team incorporates a small negative value. This could be enough to stop and reverse the expansion of the universe if other conditions align.
The role of axions in cosmic dynamics
Another element of the model is the axion, a hypothetical ultralight particle. Rather than acting as individual particles, axions can form a smooth field throughout space. First introduced to solve problems in particle physics, they are now used to explain the influence of dark energy on cosmic behavior.
According to the study, in the early universe, the axion field provided a slight outward force. This helped drive the initial expansion phase. Today, this dynamic continues, albeit at a slower pace. Tye and his colleagues suggest that in about 11 billion years, this external force would weaken enough that the internal pull of the negative cosmological constant would dominate.
This transition point would mark the end of the expansion. From this point, the universe would begin to shrink, only to contract into a singularity approximately 8 billion years later – a phenomenon known as the Big Crunch.
An uncertain but possible result
The Big Crunch scenario remains theoretical. Although the model is consistent with recent indications of the evolution of dark energy, the researchers stress that it is not a prediction. As stated in t, “much more data analysis will be needed to determine whether dark energy is indeed evolving.”
Tye points out the broader philosophical interest: “For all life, you want to know how life begins and how life ends…it’s also interesting to know, does (the universe) have an end?“For decades, cosmology operated on the assumption that expansion would continue indefinitely. Today, if dark energy is dynamic rather than constant, this assumption may no longer be valid.
For now, the paper offers a possible framework – not a definitive prediction – for how the universe might ultimately end. More observations and theoretical refinements will be needed to determine whether this scenario reflects the true trajectory of the cosmos.
