If dark energy were to significantly increase or decrease, what outcome could this have on the universe?

A) In case of dark energy increasing significantly,  the universe would accelerate its expansion at an ever-increasing rate which later on may result in "Big Rip".

B) In case of dark energy decreasing significantly, the universe would decelerate its expansion which later on may result in "Big Crunch".

Explanation:

In case of significant increase in dark energy, the universe would accelerate its expansion at more increasing rate. Ultimately the expansion would result in scale factor  becoming infinite within a finite period of time.  As a result due to the repulsive dominance of dark energy the whole universe  would come apart resulting in a situation called "Big Rip"

If dark energy were to decrease significantly enough with time, the accelerating expansion of the universe that is observed now would  start to decelerate as the mass once again dominates over dark energy. It will result in universe reversing its expansion resulting in its collapse, a situation called "Big Crunch".

Hope it helps!!!

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