If it is not real, it is an extremely scary ghost story. Unfortunately, the phenomena we call dark energy is real. If it plays out on its current course, we are going to be alone, all alone. The billions upon billions of other galaxies holding the promise of planets with life like ours will be gone. The universe will be much like what they taught our grandparents at the beginning of the Twentieth Century. It will consist of the Milky Way galaxy. All the other galaxies will have moved beyond our cosmological horizon, and be lost to us forever. There will be no evidence that the Big Bang ever occurred.

Mainstream science widely accepts the Big Bang as giving birth to our universe. Scientists knew from Hubble’s discovery in 1929 that the universe was expanding. However, prior to 1998, scientific wisdom was that the expansion of the universe would gradually slow down, due to the force of gravity, and eventually all mass in the universe would collapse to a single point in a “big crunch.” We were so sure that the “big crunch” model was correct, we decided to confirm our theory by measuring it. Can you imagine our reaction when our first measurement did not confirm our paradigm, namely that the expansion of the universe should be slowing down?

What happened in 1998? The High-z Supernova Search Team (an international cosmology collaboration) published a paper that shocked the scientific community. The paper was: Adam G. Riess et al. (Supernova Search Team) (1998). “Observational evidence from supernovae for an accelerating universe and a cosmological constant.” Astronomical J. 116 (3). They reported that the universe was doing the unthinkable. The expansion of the universe was not slowing down—in fact, it was accelerating. Of course, this caused a significant ripple in the scientific community. Scientists went back to Einstein’s general theory of relativity and resurrected the “cosmological constant,” which Einstein had arbitrarily added to his equations to prove the universe was eternal and not expanding. Einstein considered the cosmological constant his “greatest blunder” when Edwin Hubble, in 1929, proved the universe was expanding.

Through high school-level mathematical manipulation, scientists moved Einstein’s cosmological constant from one side of the equation to the other. With this change, the cosmological constant no longer acted to keep expansion in balance to result in a static universe. In this new formulation, Einstein’s “greatest blunder,” the cosmological constant, mathematically models the acceleration of the universe. Mathematically this may work, however, it does not give us insight into what is causing the expansion.

The one thing that you need to know is that almost all scientists hold the paradigm of “cause and effect.” If it happens, something is causing it to happen. Things do not simply happen. They have a cause. That means every bubble in the ocean has a cause. It would be a fool’s errand to attempt to find the cause for each bubble. Yet, I believe, as do almost all of my colleagues, each bubble has a cause. Therefore, it is perfectly reasonable to believe something is countering the force of gravity, and causing the expansion to accelerate. What is it? No one knows. Science calls it “dark energy.”

That is the state of science today. The universe’s expansion is accelerating. No one knows why. Scientists reason there must be a cause countering the pull of gravity. They name that cause “dark energy.” Scientists mathematically manipulate Einstein’s self-admitted “greatest blunder,” the “cosmological constant,” to model the accelerated expansion of the universe.

Here is the scary part. In time, we will be entirely alone in the galaxy. The accelerated expansion of space will cause all other galaxies to move beyond our cosmological horizon. When this happens, our universe will consist of the Milky Way. The Milky Way galaxy will continue to exist, but as far out as our best telescopes will be able to observe, no other galaxies will be visible to us. What they taught our grandparents will have come true. The universe will be the Milky Way and nothing else. All evidence of the Big Bang will be gone. All evidence of dark energy will be gone. Space will grow colder, almost devoid of all heat, as the rest of the universe moves beyond our cosmological horizon. The entire Milky Way galaxy will grow cold as the stars eventually run out of fuel and die. All life will end. How is that for a scary story?

This post is based on my book, Unraveling the Universe’s Mysteries (2012).