What is dark energy, and has the XENON1T experiment found it?

admin November 5, 2021
Updated 2021/11/05 at 9:33 AM

For decades, physicists and astronomers have been fascinated by dark energy, a mysterious type of energy that makes up about 68 percent of the universe. Dark energy has been described as “science’s most profound mystery.” Scientists have discovered some hints concerning it thanks to improved technology and fresh tests, and an international team of researchers achieved the first suspected direct detection of dark energy last week.

They observed some unusual findings in an underground experiment and speculate that dark energy is responsible. The XENON1T experiment, which was conducted deep down at the INFN Laboratori Nazionali del Gran Sasso in Italy, is the world’s most sensitive dark matter experiment.

The discovery also indicates that dark energy may be detected using experiments like XENON1T, which are intended to detect dark matter.

Dark matter vs. Dark energy

Everything we see — planets, moons, huge galaxies, you, me, and this website – accounts for less than 5% of the whole universe. Dark matter makes up around 27% of the universe, whereas dark energy makes up 68%. Dark matter attracts and keeps galaxies together, while dark energy repels and causes our universe to expand.

“Despite the fact that both components are invisible, we know a lot more about dark matter since its presence was proposed as early as the 1920s, while dark energy wasn’t found until 1998,” said Sunny Vagnozzi of Cambridge’s Kavli Institute for Cosmology, the paper’s lead author. “Large-scale experiments like XENON1T are intended to directly detect dark matter by looking for evidence of dark matter ‘hitting’ conventional matter, but dark energy is much more difficult to detect.”

What method did they use to make the discovery?

The XENON1T experiment revealed an unexpected signal last year. In the announcement, co-author Luca Visinelli of Frascati National Laboratories in Italy stated, “These kinds of excesses are typically flukes, but once in a while they may also lead to important findings.”

Dr. Vagnozzi stated in an email to indianexpress.com, “Basically there’s some background noise and the electrons in XENON1T will on average move a little on their own even with no dark matter or dark energy present just by virtue of “kicks” owing to this background.” “At energies about 2 keV, we found that there are much more occurrences than one would anticipate solely owing to noise, which may be related to dark energy.”

In the press release, Vagnozzi said, “It was very surprised that this excess could in theory have been generated by dark energy rather than dark matter.” “It’s very wonderful when things come together like that.”

However, some astronomers have their own reservations. Alexei Filippenko, an astronomer at the University of California, Berkeley, who was not involved in the research, told inverse.com, “If it’s accurate, it’s a remarkable finding.” “However, there is still a lot more work to be done to verify if it is true.”

What if the signal was triggered by something else?

The researchers developed a physical model that utilised chameleon screening to demonstrate that dark energy particles generated by the Sun’s strong magnetic fields may explain the signal observed in XENON1T.

In our world, there are four basic forces, and speculative ideas have suggested a fifth force that cannot be described by the four. Many dark energy models use specific techniques to conceal or screen this fifth component.

“Imagine two individuals carrying something, one hefty item and the other a light one,” Dr. Vagnozzi describes how the chameleon screening works. Most likely, the individual carrying the light item will make it farther. Similarly, in this crowded environment, the fifth force carried by this hefty chameleon doesn’t go very far.”

When will we be able to detect dark energy directly?

Dr. Vagnozzi says he’s been considering novel approaches to finding dark energy. The team is optimistic that upcoming upgrades to the XENON1T experiment, as well as similar experiments like LUX-Zeplin, a next-generation dark matter experiment at the Sanford Underground Research Facility, and PandaX-xT, a project at China Jinping Underground Laboratory, will allow them to directly detect dark energy within the next decade.

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