The universe may not expand forever as scientists once believed. According to new calculations by Cornell physicist Henry Tye, the cosmos is approaching the midpoint of its 33-billion-year life and could eventually collapse in a catastrophic \u201cbig crunch.\u201d <\/p>\n
The prediction comes from fresh data collected by dark-energy observatories in both the northern and southern hemispheres.<\/p>\n
Tye, the Horace White Professor of Physics Emeritus, used these observations to update models involving the cosmological constant, a concept introduced by Albert Einstein over a century ago. <\/p>\n
\u201cFor the last 20 years, people believed that the cosmological constant is positive, and the universe will expand forever,\u201d Tye said. <\/p>\n
\u201cThe new data seem to indicate that the cosmological constant is negative, and that the universe will end in a big crunch.\u201d <\/p>\n
Universe could collapse in 20 billion years<\/p>\n
The universe<\/a> is currently 13.8 billion years old and expanding. According to Tye\u2019s updated model, its future depends on the sign of the cosmological constant. A positive constant would mean eternal expansion. <\/p>\n A negative constant, however, would cause the universe to stop growing, reach a maximum size, and then contract until it collapses to zero.<\/p>\n The physicist\u2019s calculations indicate the latter scenario is likely. \u201cThis big crunch defines the end of the universe,\u201d he wrote<\/a>. The model estimates this collapse will occur roughly 20 billion years from now. The universe, in effect, would snap back like a stretched rubber band, returning to a single point.<\/p>\n Dark Energy observatories provide critical data<\/p>\n This year\u2019s major advance comes from the Dark Energy Survey (DES) in Chile and the Dark Energy Spectroscopic Instrument (DESI) in Arizona. <\/p>\n These observatories measure dark energy<\/a>, which makes up 68% of the universe\u2019s total mass and energy. Their observations suggest dark energy is not just a simple cosmological constant.<\/p>\n Tye and his collaborators proposed a hypothetical low-mass particle that acted like a cosmological constant early in the universe\u2019s history but behaves differently today. This model aligns well with the new data and points to a negative underlying cosmological constant. <\/p>\n \u201cPeople have said before that if the cosmological constant is negative, then the universe will collapse eventually. That\u2019s not new,\u201d he mentioned. \u201cHowever, here the model tells you when the universe collapses and how it collapses.\u201d<\/p>\n More observations are coming<\/p>\n