Since Edwin Hubble noticed that galaxies are moving away, scientists have been refining the expansion rate of the universe. Today, two main methods give different numbers. One relies on the ancient light of the cosmic microwave background, the other on the explosions of distant supernovae, whose brightness was measured by Adam Riess and Saul Perlmutter. It's like a car with the tachometer and GPS showing different speeds. Apparently, a hidden turbo boost kicked in early on — early dark energy.
New research links this "booster" to dark matter — an invisible substance that holds galaxies together. The idea is supported by string theory, where such interactions are natural. Using data on galaxy redshift, ancient light, and supernovae, along with machine learning and computer simulations, physicists calculated two scenarios — with different strengths of interaction between the dark entities.
Result: if the connection exists, then dark energy wasn't always constant. This reduces the discrepancy in measurements and hints that the universe's expansion might someday slow down. An unexpected conclusion: the power of that primordial "turbo energy" turned out to be perfectly calibrated. Had it deviated by a tiny fraction — and neither galaxies nor stars would have formed.
The Hubble constant is so finely tuned that the slightest shift would make the universe dead: either an instant collapse or emptiness without a single star.
In Liu Cixin's "The Dark Forest," dark energy becomes a weapon. In reality, it's more mysterious: whether the universe expands forever or quietly fades away depends on it.