The dark side (2/16/23)

Happy Thursday. Seven’s an especially lucky number this week. Over the weekend, a meteoroid was spotted before impacting Earth’s atmosphere for only the seventh time in history. Seven hours after detection, the meteoroid streaked across the sky over the English Channel, treating viewers across the UK and France to a stunning show.

If you were lucky enough to A) see the fireball and B) snap a photo, send it to your friendly local space reporter who’s always in the wrong place at the wrong time (me) as a consolation prize.

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Seeing the Dark Side

We know less about the vast, mysterious universe we live in than we can even begin to comprehend. For thousands of years, astronomers have looked out to the heavens to try to make sense of it all, and bit by bit, we’ve increased our understanding of how it all works.

Now, researchers may have made a dent in understanding one of the universe’s most ubiquitous and least understood forces: dark energy.

The study, published yesterday in The Astrophysical Journal Letters by researchers at the University of Hawai’i, STFC RAL Space, and Imperial College London, includes the first empirical evidence of “cosmological coupling,” a theory first predicted in Einstein’s theory of general relativity. It suggests black holes increase in mass more quickly than they accrete mass, and that the expansion of black holes is “coupled” to the universe’s expansion. 

Dark energy as a “vacuum force” produced by the black hole could explain that bonus increase in mass.

The universe we live in: For a long time, the prevailing theory of the universe's expansion explained that the Big Bang exerted an incredible force that pushed the edges of the universe outwards. Eventually, scientists expected the gravitational forces from all the mass in the universe to slow that growth.

“That’s the universe we thought we lived in until the late 1990s,” Dr. Chris Pearson, a coauthor on the paper and researcher at STFC RAL Space, said in a video about the research findings. In 1998, Hubble observations revealed that the universe is indeed expanding, but that instead of slowing down, it's actually speeding up. Some unknown force is pushing cosmological objects apart.

The dark energy problem: The idea of dark energy emerged as a response to this finding. “Dark energy pervades the whole of space, and kind of acts like negative pressure,” Pearson said. “So dark energy is actually pushing things apart rather than keeping them together.”

Scientists believe that only about 5% of the universe is made up of the regular bits of stuff we’re used to (i.e. atoms). Nearly 70%, on the other hand, is dark energy.

Finding the source: The researchers set out to study the evolution of black holes over time. They turned their focus on distant giant elliptical galaxies that have stopped forming stars, as the supermassive black holes at the center of these galaxies have access to comparatively little matter for accretion. 

Distant supermassive black holes, the researchers found, increased in mass more quickly than could be explained by standard astrophysical processes. To explain this, the researchers introduced the idea that dark energy exists within the black holes, and found that this explanation evades the concept of a singularity—a phenomenon where a black hole crushes mass to infinite density, which violates the theory of relativity.

According to the paper, the amount of dark energy that would need to have been produced in supermassive black holes to balance the mass discrepancy is consistent with the theorized amount of dark energy in the universe.

Looking ahead: This is only the first observational evidence that could explain the mysterious origin of dark energy. Now, astronomers can use these findings as a framework to check and double-check the estimates made in this paper, and experimentally verify its findings. 

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Other News from the Cosmos

• JWST observers submitted a loooooooot of proposals for observation time, representing 7.3 times more than the available time on the telescope, and 20% more than the most popular Hubble observation cycle.

• Two probes, BepiColombo and Solar Orbiter, conducted flybys of Venus within a day of one another in 2021. Together, the probes collected evidence that Venus’ induced magnetic field helps to protect its atmosphere from the solar wind.

• The Chelyabinsk asteroid, which exploded 14 miles above the ground and blew out windows across ~200 square miles, entered the atmosphere ten years ago yesterday.

• Blue Origin revealed two science initiatives: Blue Alchemist, which has been producing solar cells and transmission wire from lunar regolith simulants for the past two years, and a launch agreement for the ESCAPADE mission led by UC Berkeley. (Via Payload.)

• Lunar Flashlight, a NASA CubeSat mission, was unable to enter its planned lunar orbit due to thruster issues, but the agency is investigating other ways to use the craft.

• Four classes of planetary systems exist across the universe. A paper published in  Astronomy & Astrophysics detailed the ways solar systems are typically organized.

• CSIC, aka the Spanish National Research Council, completed a network of seven robotic observatories across five continents.

• China’s Mars rover Zhurong imaged a five-meter-deep region of the Red Planet’s subsurface and found a large body of underground ice.

Rachael's Recs

🚀 “Those F*cking New Guys”: The Apollo era of astronauts made history, putting humanity's first steps on the Moon. Looking back, though, it’s hard not to notice what they all shared in common as white male test pilots. Now, as NASA prepares for the Artemis era and the first woman and person of color on the moon, Nature magazine remembers the 1978 astronaut class—the first to include civilians, women, and Black men in its ranks.

👻 Not so spooky: Just saying the words “quantum entanglement” conjures the idea of two particles mimicking one another’s movements from a distance, seemingly with no connection between them. In an op-ed for Scientific American, Chris Ferrie, a faculty member of the Center for Quantum Software and Information at the University of Technology Sydney, argues that we need to drop this idea of “spooky action at a distance” to clear a path toward real understanding of the quantum realm.

The View from Space