Physicists searching for signs of quantum gravity have long faced a frustrating problem. Even if gravity does have a quantum nature, its effects are expected to show up only at extremely small distances, far beyond the reach of experiments. A new theoretical study by Benjamin Koch and colleagues at the Technical University of Vienna in Austria suggests a different strategy. Instead of looking for quantum gravity where space–time is tiny, the researchers argue that subtle quantum effects could influence how particles and light move across huge cosmical distances.

Their work introduces a new concept called q-desics, short for quantum-corrected paths through space–time. These paths generalize the familiar trajectories predicted by Einstein’s general theory of relativity and could, in principle, leave observable fingerprints in cosmology and astrophysics.

General relativity and quantum mechanics are two of the most successful theories in physics, yet they describe nature in radically different ways. General relativity treats gravity as the smooth curvature of space–time, while quantum mechanics governs the probabilistic behavior of particles and fields. Reconciling the two has been one of the central challenges of theoretical physics for decades.

“One side of the problem is that one has to come up with a mathematical framework that unifies quantum mechanics and general relativity in a single consistent theory,” Koch explains. “Over many decades, numerous attempts have been made by some of the most brilliant minds humanity has to offer.” Despite this effort, no approach has yet gained universal acceptance.

Deeper difficulty

There is another, perhaps deeper difficulty. “We have little to no guidance, neither from experiments nor from observations that could tell us whether we actually are heading in the right direction or not,” Koch says. Without experimental clues, many ideas about quantum gravity remain largely speculative.

That does not mean the quest lacks value. Fundamental research often pays off in unexpected ways. “We rarely know what to expect behind the next tree in the jungle of knowledge,” Koch says. “We only can look back and realize that some of the previously explored trees provided treasures of great use and others just helped us to understand things a little better.”

Almost every test of general relativity relies on a simple assumption. Light rays and freely falling particles follow specific paths, known as geodesics, determined entirely by the geometry of space–time. From gravitational lensing to planetary motion, this idea underpins how physicists interpret astronomical data.

Koch and his collaborators asked what happens to this assumption when space–time itself is treated as a quantum object. “Almost all interpretations of observational astrophysical and astronomical data rest on the assumption that in empty space light and particles travel on a path which is described by the geodesic equation,” Koch says. “We have shown that in the context of quantum gravity this equation has to be generalized.”

Generalized q-desic

The result is the q-desic equation. Instead of relying only on an averaged, classical picture of space–time, q-desics account for the underlying quantum structure more directly. In practical terms, this means that particles may follow paths that deviate slightly from those predicted by classical general relativity, even when space–time looks smooth on average.

Crucially, the team found that these deviations are not confined to tiny distances. “What makes our first results on the q-desics so interesting is that apart from these short distance effects, there are also long range effects possible, if one takes into account the existence of the cosmological constant,” Koch says.

This opens the door to possible tests using existing astronomical data. According to the study, q-desics could differ from ordinary geodesics over cosmological distances, affecting how matter and light propagate across the universe.

“The q-desics might be distinguished from geodesics at cosmological large distances,” Koch says, “which would be an observable manifestation of quantum gravity effects.”

Cosmological tensions

The researchers propose revisiting cosmological observations. “Currently, there are many tensions popping up between the Standard Model of cosmology and observed data,” Koch notes. “All these tensions are linked, one way or another, to the use of geodesics at vastly different distance scales.” The q-desic framework offers a new lens through which to examine such discrepancies.

So far, the team has explored simplified scenarios and idealized models of quantum space–time. Extending the framework to more realistic situations will require substantial effort.

“The initial work was done with one PhD student (Ali Riahina) and one colleague (Ángel Rincón),” Koch says. “There are many things to be revisited and explored that our to-do list is growing far too long for just a few people.” One immediate goal is to encourage other researchers to engage with the idea and test it in different theoretical settings.

Whether q-desics will provide an observational window into quantum gravity remains to be seen. But by shifting attention from the smallest scales to the largest structures in the cosmos, the work offers a fresh perspective on an enduring problem.

The research is described in Physical Review D.

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Academics who switch to hybrid working and remote collaboration do less impactful research. That’s according to an analysis of how scientists’ collaboration networks and academic outputs evolved before, during and after the COVID-19 pandemic (arXiv: 2511.18481). It involved studying author data from the arXiv preprint repository and the online bibliographic catalogue OpenAlex.

To explore the geographic spread of collaboration networks, Sara Venturini from the Massachusetts Institute of Technology and colleagues looked at the average distance between the institutions of co-authors. They found that while the average distance between team members on publications increased from 2000 to 2021, there was a particularly sharp rise after 2022.

This pattern, the researchers claim, suggests that the pandemic led to scientists collaborating more often with geographically distant colleagues. They found consistent patterns when they separated papers related to COVID-19 from those in unrelated areas, suggesting the trend was not solely driven by research on COVID-19.

The researchers also examined how the number of citations a paper received within a year of publication changed with distance between the co-authors’ institutions. In general, as the average distance between collaborators increases, citations fall, the authors found.

They suggest that remote and hybrid working hampers research quality by reducing spontaneous, serendipitous in-person interactions that can lead to deep discussions and idea exchange.

Despite what the authors say is a “concerning decline” in citation impact, there are, however, benefits to increasing remote interactions. In particular, as the geography of collaboration networks increases, so too does international partnerships and authorship diversity.

Remote tools

Lingfei Wu, a computational social scientist at the University of Pittsburgh, who was not involved in the study, told Physics World that he was surprised by the finding that remote teams produce less impactful work.

“In our earlier research, we found that historically, remote collaborations tended to produce more impactful but less innovative work,” notes Wu. “For example, the Human Genome Project published in 2001 shows how large, geographically distributed teams can also deliver highly impactful science. One would expect the pandemic-era shift toward remote collaboration to increase impact rather than diminish it.”

Wu says his work suggests that remote work is effective for implementing ideas but less effective for generating them, indicating that scientists need a balance between remote and in-person interactions. “Use remote tools for efficient execution, but reserve in-person time for discussion, brainstorming, and informal exchange,” he adds.

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There are 12 questions in total: blue is your current question and white means unanswered, with green and red being right and wrong. Check your scores at the end – and why not test your colleagues too?

How did you do?

10–12 Top shot – congratulations, you’re the next John Hopfield

7–9 Strong skills – good, but not quite Nobel standard

4–6 Weak performance – should have asked ChatGPT

0–3 Worse than random – are you a bot?

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More molecules and compounds vital to the origin of life have been detected in asteroid samples delivered to Earth by NASA’s OSIRIS-REx mission. The discovery strengthens the case that not only did life’s building blocks originate in space, but that the ingredients of RNA, and perhaps RNA itself, were brought to our planet by asteroids.

Two new papers in Nature Geoscience and Nature Astronomy describe the discovery of the sugars ribose and glucose in the 120 g of samples returned from the near-Earth asteroid 101955 Bennu, as well as an unusual carbonaceous “gum” that holds important compounds for life. The findings complement the earlier discovery of amino acids and the nucleobases of RNA and DNA in the Bennu samples.

A third new paper, in Nature Astronomy, addresses the abundance of pre-solar grains, which is dust that originated from before the birth of our Solar System, such as dust from supernovae. Scientists led by Ann Nguyen of NASA’s Johnson Space Center found six times more dust direct from supernova explosions than is found, on average, in meteorites and other sampled asteroids. This could suggest differences in the concentration of different pre-solar dust grains in the disc of gas and dust that formed the Solar System.

Space gum

It’s the discovery of organic materials useful for life that steals the headlines, though. For example, the discovery of the space gum, which is essentially a hodgepodge chain of polymers, represents something never found in space before.

Scott Sandford of NASA’s Ames Research Center, co-lead author of the Nature Astronomy paper describing the gum discovery, tells Physics World: “The material we see in our samples is a bit of a molecular jumble. It’s carbonaceous, but much richer in nitrogen and, to a lesser extent, oxygen, than most of the organic compounds found in extraterrestrial materials.”

Sandford refers to the material as gum because of its pliability, bending and dimpling when pressure is applied, rather like chewing gum. And while much of its chemical functionality is replicated in similar materials on our planet, “I doubt it matches exactly with anything seen on Earth,” he says.

Initially, Sandford found the gum using an infrared microscope, nicknaming the dust grains containing the gum “Lasagna” and “Neapolitan” because the grains are layered. To extract them from the rock in the sample, Sandford went to Zack Gainsforth of the University of California, Berkeley, who specializes in analysing and extracting materials from samples like this.

Platinum scaffolding

Having welded a tungsten needle to the Neapolitan sample in order to lift it, the pair quickly realised that the grain was very delicate.

“When we tried to lift the sample it began to deform,” Gainsforth says. “Scott and I practically jumped out of our chairs and brainstormed what to do. After some discussion, we decided that we should add straps to give it enough mechanical rigidity to survive the lift.”

By straps, Gainsforth is referring to micro-scale platinum scaffolding applied to the grain to reinforce its structure while they cut it away with an ion beam. Platinum is often used as a radiation shield to protect samples from an ion beam, “but how we used it was anything but standard,” says Gainsforth. “Scott and I made an on-the-fly decision to reinforce the samples based on how they were reacting to our machinations.”

With the sample extracted and reinforced, they used the ion beam cutter to shave it down until it was a thousand times thinner than a human hair, at which point it could be studied by electron microscopy and X-ray spectrometry. “It was a joy to watch Zack ‘micro-manipulate’ [the sample],” says Sandford.

The nitrogen in the gum was found to be in nitrogen heterocycles, which are the building blocks of nucleobases in DNA and RNA. This brings us to the other new discovery, reported in Nature Geoscience, of the sugars ribose and glucose in the Bennu samples, by a team led by Yoshihiro Furukawa of Tohoku University in Japan.

The ingredients of RNA

Glucose is the primary source of energy for life, while ribose is a key component of the sugar-phosphate backbone that connects the information-carrying nucleobases in RNA molecules. Furthermore, the discovery of ribose now means that everything required to assemble RNA molecules is present in the Bennu sample.

Notable by its absence, however, was deoxyribose, which is ribose minus one oxygen atom. Deoxyribose in DNA performs the same job as ribose in RNA, and Furukawa believes that its absence supports a popular hypothesis about the origin of life on Earth called RNA world. This describes how the first life could have used RNA instead of DNA to carry genetic information, catalyse biochemical reactions and self-replicate.

Intriguingly, the presence of all RNA’s ingredients on Bennu raises the possibility that RNA could have formed in space before being brought to Earth.

“Formation of RNA from its building blocks requires a dehydration reaction, which we can expect to have occurred both in ancient Bennu and on primordial Earth,” Furukawa tells Physics World.

However, RNA would be very hard to detect because of its expected low abundance in the samples, making identifying it very difficult. So until there’s information to the contrary, “the present finding means that the ingredients of RNA were delivered from space to the Earth,” says Furukawa.

Nevertheless, these discoveries are major milestones in the quest of astrobiologists and space chemists to understand the origin of life on Earth. Thanks to Bennu and the asteroid 162173 Ryugu, from which a sample was returned by the Japanese Aerospace Exploration Agency (JAXA) mission Hayabusa2, scientists are increasingly confident that the building blocks of life on Earth came from space.

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