Cosmic 'big crunch' may end universe in 20 billion years: Physicist

Cornell physicist Henry Tye has proposed that the universe, currently 13.8 billion years old and expanding, may not continue expanding indefinitely as previously thought. Using new data from dark energy observatories—the Dark Energy Survey (DES) in Chile and the Dark Energy Spectroscopic Instrument (DESI) in Arizona—Tye updated cosmological models involving the cosmological constant, a concept introduced by Einstein. Contrary to the long-held belief that the cosmological constant is positive, implying eternal expansion, the new observations suggest it is negative. This would cause the universe to stop expanding, reach a maximum size in about 11 billion years, and then begin contracting, ultimately collapsing in a "big crunch" approximately 20 billion years from now. Tye and his collaborators introduced a model involving a hypothetical low-mass particle that behaved like a cosmological constant in the early universe but has changed behavior over time, aligning well with the latest data. This model not only supports the idea of a negative cosm