New 3D map of Universe could solve dark energy mystery
Visualization shows how DESI built its 3D map of the Universe.
Latest data must still be analyzed but could help determine if dark energy is constant or varies over time.
“DESI’s five-year survey has been spectacularly successful,” DESI director Michael Levi of Berkeley Lab said. “The instrument performed better than anticipated. The results have been incredibly exciting. And the size and scope of the map and how quickly we’ve been able to execute is phenomenal. We’re going to celebrate completion of the original survey and then get started on the work of churning through the data, because we’re all curious about what new surprises are waiting for us.”
As previously reported , Albert Einstein’s cosmological constant (lambda) implied the existence of a repulsive form of gravity. (For a more in-depth discussion of the history of the cosmological constant and its significance for dark energy, see our 2024 story .) Quantum physics holds that even the emptiest vacuum is teeming with energy in the form of “virtual” particles that wink in and out of existence, flying apart and coming together in an intricate quantum dance. This roiling sea of virtual particles could give rise to dark energy, giving the Universe a little extra push so that it can continue accelerating. The problem is that the quantum vacuum contains too much energy: roughly 10 120 times too much.
So the Universe should be accelerating much faster than it is if the dark energy is, essentially, the cosmological constant. Still, all the observations to date indicate that it’s constant. The best theoretical fit thus far is known as the Lambda CDM model , which incorporates both a weakly interacting cold dark matter and dark energy. One alternative theory proposes that the Universe may be filled with a fluctuating form of dark energy dubbed “ quintessence .” There are also several other alternative models that assume the density of dark energy has varied over the history of the Universe.
In its earliest days, the Universe was a hot, dense soup of subatomic particles, including hydrogen and helium nuclei, aka baryons. Tiny fluctuations created a rippling pattern through that early ionized plasma, which froze into a three-dimensional place as the Universe expanded and cooled. Those ripples, or bubbles, are known as baryon acoustic oscillations (BAO). It’s possible to use BAOs as a kind of cosmic ruler to investigate the effects of dark energy over the history of the Universe.
