Big Rip

The possibility of sudden rip singularity occurs only for hypothetical matter (phantom energy) with implausible physical properties.

The model implies that after a finite time there will be a final singularity, called the "Big Rip", in which the observable universe eventually reaches zero size and all distances diverge to infinite values.

Observations of galaxy cluster speeds by the Chandra X-ray Observatory seem to suggest the value of w is between approximately −0.907 and −1.075, meaning the Big Rip cannot be ruled out.

Based on the above equation, if the observation determines that w is less than −1 but greater than or equal to −1.075, the Big Rip would occur in approximately 152 billion years at the earliest.

[3] More recent data from Planck mission indicates the value of w to be −1.028 (±0.031), pushing the earliest possible time of Big Rip to approximately 200 billion years into the future.

[4] In their paper, the authors consider a hypothetical example with w = −1.5, H0 = 70 km/s/Mpc, and Ωm = 0.3, in which case the Big Rip would happen approximately 22 billion years from the present.