https://www.space.com/universe-unpartic ... -expansion
You can hear it now ... Ka-Ching Ka-Ching!Scientists widely acknowledge that the universe is expanding, though the cause of that expansion remains elusive. One of the most popular proposed explanations is a mysterious entity called dark energy in the form of a cosmological constant, which leads to expansion at a rate independent of the age of the universe and the temperature of matter and radiation. However, recent astronomical observations challenge this hypothesis, prompting physicists to explore alternatives to what dark energy could be.
Now, in a new paper, researchers analyzed the idea that dark energy is instead made of a theoretical form of matter called unparticles. They found that this theory aligns better with observations than the prevalent standard cosmological model, which assumes a cosmological constant.
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For now, there is no empirical evidence to back up this theory. However, the authors are confident that, in the next decade or so, the accuracy of astronomical measurements will improve enough to determine whether the unparticle theory is correct.