The biggest mystery of the Standard Cosmological Model is dark energy, the matter that “probably” drives the acceleration of the universe and which makes up 65 to 70 percent of the entire universe. Dark energy forms the backbone of the idea of the “cosmological constant,” first coined by Albert Einstein in his General Theory of Relativity to disprove the idea that the universe was actually static and neither expanding nor contracting.
When researchers discovered in the 1990s that the universe was not only expanding, but accelerating its expansion, Einstein’s “universal constant” (which he called lambda or Λ) took on surprising relevance once again. By plugging in the equations used to understand the growth of the universe after the big bang (known as the Friedmann equations), scientists arrived at the modern “cosmological constant”. However, there are a few problems: scientists have never actually observed dark energy (hence the nickname “dark”) and the cosmological constant is pretty poor at explaining the observed phenomena.
Since science hates an epistemological vacuum, astrophysicists have explored other theories that might explain what is going on in the universe. In one of these theories, published in Journal of Cosmology and Astroparticle Physics In December 2023, astrophysicist Jan Ambjørn of the University of Copenhagen and Yoshiyuki Watabiki of the Tokyo Institute of Technology explored a new idea that does not require yet-to-be-discovered dark energy to explain the acceleration of the universe, and which also denies the need for a cosmological constant.
Instead, according to this new paper, our universe is absorbing “child universes” as it expands.
“The main finding of our work is that the accelerated expansion of our universe caused by mysterious dark energy could have a simple intuitive explanation,” says Ambjørn. LiveScience“merging with so-called infant universes, and that a model for this can fit the data better than the standard cosmological model.”
The idea is seemingly simple: as our universe grows, it absorbs other universes in its path, thereby “accelerating” its limits. According to our telescopes, this would appear to be another acceleration of cosmic expansion. The researchers say that when Ambjørn and Watabiki performed the calculations for this “baby universe” theory, they were more consistent with real-life observations than those using the standard cosmological model.
The paper also attempts to answer another mystery of the early universe called “cosmological inflation,” in which the early universe expanded rapidly for an unknown reason. Current theory suggests that a hypothetical field called the “inflaton field” was driving this expansion, but this new paper suggests that another mechanism may have been at play.
“The fact that the universe expanded… in a very short period of time leads us to believe that this expansion was caused by a collision with a larger universe, that is, it was actually our universe that was swallowed up by another universe. father,” the document says. “It’s hard to judge whether such a scenario could play out in a way that would actually solve the problems that inflation was meant to solve, but the interesting aspect of such a scenario is that there is no need for an inflationary field.”
This is not the only theory that rules out the need for a cosmological constant. In July 2023, another paper claimed that the expansion of the universe could simply be a mirage caused by the evolution of electrons and protons on an immensely long time scale.
So far, no alternative theory has dethroned dark energy and the cosmological constant as the best explanation for universal acceleration. However, it is always important to keep a cautiously open mind, especially in a science as cutting-edge as universal expansion. Sometimes interesting and useful ideas can come from very strange places. Never say never.
Darren lives in Portland, has a cat, and writes/edits about science fiction and how our world works. You can find his previous stuff on Gizmodo and Paste if you look hard enough.
