Measuring back in time and distance (to the left of “today”) can inform how the Universe will evolve and accelerate/decelerate far into the future. We can learn that acceleration turned on about 7.8 billion years ago with the current data, but also learn that the models of the Universe without dark energy have either Hubble constants that are too low or ages that are too young to match with observations. If dark energy evolves with time, either strengthening or weakening, we will have to revise our present picture. (SAUL PERLMUTTER OF BERKELEY)

5 Ways That Dark Energy Might Not Determine The Fate Of Our Universe

It could evolve, strengthen, decay, or not be alone.

Our known Universe contains matter, radiation, and dark energy.

While matter (both normal and dark) and radiation become less dense as the Universe expands owing to its increasing volume, dark energy, and also the field energy during inflation, is a form of energy inherent to space itself. As new space gets created in the expanding Universe, the dark energy density remains constant. (E. SIEGEL / BEYOND THE GALAXY)

As it expands, matter and radiation dilute, but dark energy persists.

When we plot out all the different objects we’ve measured at large distances versus their redshifts, we find that the Universe cannot be made of matter-and-radiation only, but must include a form of dark energy: consistent with a cosmological constant, or an energy inherent to the fabric of space itself. (NED WRIGHT’S COSMOLOGY TUTORIAL)

As time progresses, only dark energy remains cosmically important.

Various components of and contributors to the Universe’s energy density, and when they might dominate. Note that radiation is dominant over matter for roughly the first 9,000 years, then matter dominates, and finally, a cosmological constant emerges. (The others do not exist in appreciable amounts.) However, dark energy may not be a pure cosmological constant. (E. SIEGEL / BEYOND THE GALAXY)

It determines our fate, but these five scenarios could irrevocably change it.

If dark energy were to decay from its current energy state to a lower-energy one, the fundamental constants would change and all matter in that transition region would become unstable, and would immediately be destroyed. A “bubble of destruction” would propagate outwards in all directions at the speed of light. We’d never see our own demise coming. (EU’S COMMUNICATE SCIENCE)

1.) Vacuum decay. Dark energy, the zero-point energy of empty space, possesses a positive, non-zero value.