In our universe:
Could there be such a thing as “dark light?” Science writer Tibi Puiu tells us at ZME Science that some physicists think that the mysterious dark matter of the universe is made out of dark photons: “A new study found that hypothetical particles called dark photons can explain discrepencies in the ‘cosmic web’.” (December 14, 2022) “First introduced in 1986 by physicist Bob Holdom, dark photons, also known as ‘heavy photons’ or ‘hidden photons’, are supposed to be gauge bosons for dark matter. Dark photons and regular photons are expected to mix, such that the dark photons can convert into low-frequency photons. If that’s the case, these converted photons should heat up the cosmic web but in a much more efficient and diffuse manner across non-dense regions of intergalactic space, as opposed to other astrophysical heating mechanisms, such as star formation and galactic winds.”
The researchers say that they saw this happening in the Cosmic Origin Spectrograph (COS) data from the Hubble Space Telescope. The paper is open access.
We also learn from Stony Brook astrophysicist Paul Sutter, featured in the video above, that our universe may be more unstable than we think: “When physicists first calculated the stability of the universe, as determined by the Higgs boson’s ability to maintain the separation of the electroweak force, they didn’t know the mass of either the Higgs itself or the top quark. Now we do: The top quark weighs around 175 GeV, and the Higgs around 125 GeV.”
“Plugging those two numbers into the stability equations reveals that the universe is… metastable. This is different than stable, which would mean that there’s no chance of the universe splitting apart instantly, but also different than unstable, which would mean it already happened.” (Astronomy News, December 16, 2022)
He thinks the universe could remain in its present state indefinitely but if perturbed in an unfortunate way, “it would transform to a new ground state.” There would be new laws of physics, new particles, and new forces of nature. They would not, he expects, be friendly to life. He worries that it might have already happened in a far part of the universe and be spreading outward at the speed of light. The speed of light? Wait. It takes light years to get anywhere in our own galaxy. We probably have millions of years yet in which other worries are more pressing.
In our galaxy:
The big story just now is water worlds and potentially habitable exoplanets. Université de Montreal astronomers have discovered strange twin planets, 218 light-years away in the constellation Lyra, that may be water worlds, unlike any in our solar system: Called Kepler-138c and Kepler-138d, they are thought to be water worlds because, on analysis, up to half of them seems to be made of materials lighter than rock but heavier than hydrogen or helium — and the most common such candidate is water. “‘We previously thought that planets that were a bit larger than Earth were big balls of metal and rock, like scaled-up versions of Earth, and that’s why we called them super-Earths,’ explained [Björn] Benneke. ‘However, we have now shown that these two planets, Kepler-138c and d, are quite different in nature: a big fraction of their entire volume is likely composed of water. It is the first time we observe planets that can be confidently identified as water worlds, a type of planet that was theorized by astronomers to exist for a long time.’” (Eurekalert, December 15, 2022) The paper requires a fee or subscription.
What about life? One hitch, the researchers say, is that the temperature on the planets is likely above the boiling point of water and the their atmospheres may be steam.
Meanwhile, two potentially habitable Earth-like worlds have been found orbiting a star “in our cosmic backyard,” according to science writer Robert Lea: “They are located in the ‘habitable zone’ of their star, GJ 1002, defined as the shell around a star that is neither too hot nor too cold to support liquid water, a vital ingredient for life.”
“‘Nature seems bent on showing us that Earth-like planets are very common,’ study author Alejandro Suárez Mascareño of the Instituto de Astrofisica de Canarias (IAC) said in a statement(opens in new tab). ‘With these two we now know seven in planetary systems quite near to the sun.’” (Space.com, December 20, 2022)
The habitable zone is very important, of course, for identifying planets to focus on in the search for life. But at Universe Today, space journalist Evan Gough tells us that we may be dismissing the ones that lie outside the habitable zone too quickly: “Terrestrial planets that lie outside their star’s habitable zone are largely dismissed when choosing targets for further study. But a new paper published in Nature shows how water might exist, and persist, on these cold exo-Earths. On planets with ice sheets, there could be enough heat to create a persistent layer of liquid water under the ice or trapped between layers of ice.” (December 14, 2022) The paper is open access.
Only one way to find out…
In our solar system:
At Space.com, science writer Sharmila Kuthunur tells us that “Europa’s icy crust may let more material into hidden ocean than thought.” Researchers found that “The icy shell of Jupiter’s moon Europa is marked with craters, most of which are from small impacts that dent the moon’s surface but are not big enough to penetrate all the way to its underlying ocean. Now, researchers have shown that impacts that penetrate even halfway through the ice shell accumulate enough meltwater to sink through the rest of the ice and into the underlying ocean.” (December 20, 2022) Here’s the researchers’ statement (University of Texas).
Right next door:
Experimentalists at Washington University in St. Louis have found that, contrary to earlier research, no oxygen was required to make manganese oxide on Mars: “Scientists discovered that under Mars-like conditions, manganese oxides can be readily formed without atmospheric oxygen. Using kinetic modeling, the scientists also showed that manganese oxidation is not possible in the carbon dioxide-rich atmosphere expected on ancient Mars.” (Newswise, December 21, 2022) That doesn’t show that there was never any oxygen on Mars but rather that the presence of manganese oxide doesn’t demonstrate it. The paper requires a fee or subscription.
Here on Earth:
At Universe Today, writer Andy Tomaswick notes that a commonly suggested site for a permanent lunar base is the lava tubes scattered through the lunar mare. But a Chinese research team has suggested using karst caves on Earth to roughly simulate the environment:
“Simulating the exact environment of lunar lava tubes is likely impossible on Earth. The higher gravity and constant weather changes of our planet would probably collapse them. However, they have been stable on the Moon for billions of years and offer an ideal place to hide humanity’s first infrastructure. That is because they protect explorers from three major hazards on the lunar surface: radiation, meteorites, and thermal shock.” (December 10, 2022) The paper is open access.
One reason to keep searching is that the universe appears fine-tuned for life: For example, from Steve Meyer’ The Return of the God Hypothesis, “We now know that many other constants of physics also exhibit fine tuning as a condition of a life-permitting universe. The electromagnetic force constant exhibits moderate fine tuning of 1 part in 25. The strong nuclear force constant is fine-tuned to 1 part in 200. Moreover, the ratios of the values of the different force constants also require significant fine tuning. For example, the ratio of the weak nuclear force constant to the strong nuclear force constant had to have been set with a precision of 1 part in 10,000. If the weak force had been weaker or stronger by that small fraction, stars powered by hydrogen fusion, required for life, would not have existed. – Stephen C. Meyer, Return of the God Hypothesis, HarperCollins, Kindle Edition, pp. 219–220.
You may also wish to read: The search for extraterrestrial life 14. According to a new study from the University of Copenhagen, 4.5 billion years ago, there was enough water on Mars to cover the planet in an ocean 300 metres deep. Meanwhile, the James Webb Space Telescope keeps finding galaxies that may require substantial revisions to current models of the universe.