submitted 9 hours ago by kalkulat@lemmy.world to c/science@lemmy.world

Chose a title that reflects what the article actually discusses!

submitted 1 day ago by ptz@dubvee.org to c/science@lemmy.world

A new study by astrophysicist Richard Lieu suggests that gravity can exist without mass, proposing thin, shell-like layers of 'topological defects' as an alternative to dark matter for explaining the gravitational binding of galaxies. This theory posits that these defects create a gravitational force without detectable mass, potentially eliminating the need for dark matter in current cosmological models

Lieu started out trying to find another solution to the Einstein field equations, which relate the curvature of space-time to the presence of matter within it. As Einstein described in his 1915 theory of general relativity, space-time warps around bundles of matter and streams of radiation in the Universe, depending on their energy and momentum. That energy is, of course, related to mass in Einstein's famous equation: E=mc2. So an object's mass is linked to its energy, which bends space-time -- and this curvature of space-time is what Einstein described as gravity, a notch more sophisticated than Newton's 17th-century approximation of gravity as a force between two objects with mass. In other words, gravity seems inextricably linked to mass. Not so, posits Lieu.

In his workings, Lieu set about solving a simplified version of the Einstein field equations that allows for a finite gravitation force in the absence of any detectable mass. He says his efforts were "driven by my frustration with the status quo, namely the notion of dark matter's existence despite the lack of any direct evidence for a whole century." Lieu's solution consists of shell-shaped topological defects that might occur in very compact regions of space with a very high density of matter. These sets of concentric shells contain a thin layer of positive mass tucked inside an outer layer of negative mass. The two masses cancel each other out, so the total mass of the two layers is exactly zero. But when a star lies on this shell, it experiences a large gravitational force dragging it towards the center of the shell. "The contention of my paper is that at least the shells it posits are massless," Lieu says. If those contentious suggestions bear any weight, "there is then no need to perpetuate this seemingly endless search for dark matter," Lieu adds.

The next question, then, is how to possibly confirm or refute the shells Lieu has proposed through observations. "The increasing frequency of sightings of ring and shell-like formation of galaxies in the Universe lends evidence to the type of source being proposed here," Lieu writes in his paper. Although he admits that his proposed solution is "highly suggestive" and cannot alone discredit the dark matter hypothesis. "It could be an interesting mathematical exercise at best," Lieu concludes. "But it is the first [mathematical] proof that gravity can exist without mass."

The study has been published in Monthly Notices of the Royal Astronomical Society.


We haven’t pinned down the masses of any individual neutrino, and we don’t even know which ones are heavier than the others. When it comes to our ability to collect raw data, neutrinos present a triple threat: they’re incredibly lightweight (even the electron weighs over 5 million times more than all the neutrinos combined), they shift their identity as they travel (and their rate of flavor oscillation changes as they travel through different substances, so there’s no one-size-fits-all solution), and they barely interact with anything in the first place...

submitted 5 days ago by Blaze@reddthat.com to c/science@lemmy.world
submitted 5 days ago by ooli@lemmy.world to c/science@lemmy.world

Scientists have traced the ancestry of the modern horse to a lineage that emerged 4,200 years ago and quickly became dominant across Eurasia.


From forming bound states to normal scattering, many possibilities abound for matter-antimatter interactions. So why do they annihilate? There’s a quantum reason we simply can’t avoid.

submitted 6 days ago by saint@group.lt to c/science@lemmy.world

Interesting findings

submitted 6 days ago* (last edited 6 days ago) by realnetag@scribe.disroot.org to c/science@lemmy.world

The video is a group discussion on the necessity to continue exploring particle physics using larger particle energy detectors involving higher energies to achieve further breakthroughs. As conveyed in the video, a project of this size requires a lot of resources both in terms of manpower, architecture and compute, besides a significant amount of money. This post is my personal take on the discussion as a citizen of the world.


Gavin begins with the idea of dark matter, trying to discover it in particle collider experiments using indirect observations. Dark matter cannot be directly discovered as it is not known exactly what we are looking for. As Bjørn points out correctly, dark matter results from the mathematical model of cosmic elements(galaxies, universal expansion) which uses this hypothesis to account for the currently unpredictable behavior of matter at large scales.

Gavin talks about exploring science in avenues previously left untouched. There is a reason for the same – the technology to understand the "particle interactions" exists today, that was not there earlier. It is not a simple matter of one element hits another to measure interactions, simulations are created in computers based on the by-products that are caught in the collider's detection mechanisms. Gavin says to "go and build colliders", but it is difficult to build one that is more massive than the last. People in multiple governments are involved, including contractors who will supply raw materials necessary. Sabine correctly points out the challenges that teams would face in building a significantly better collider, that is much larger than the currently existing ones. Gavin talks about "guaranteed discoveries", and the exciting new breakthroughs that would be unearthed and brought to light. Sabine wrongly talks about the "little output" that these breakthroughs are being referred to from her perspective, whereas the discoveries of particle physics supposedly reveal the fundamental elements in the universe.

Sabine wants to discover more in the realm of quantum mechanics and gravity. These are some of the fields which do not require heavy investments and can be done in regular environments to achieve results that could be used for large-scale enhancements, such as building efficient quantum computers. The understanding of gravity from a quantum perspective is still unclear as to what gives birth to the phenomenon, and this is another field she wants the scientific community to invest their time into.


I think exploring more of particle physics should be delayed. Following are the arguments I propose to justify my point of view.

  • Particle physics require a lot of resources to be built in order to confirm the existence of certain particles beyond reasonable doubt, in the form of colliders. I believe the science behind colliders is simple, but it is resource and compute extensive. Time can be devoted towards coming up with better hacks so as to reduce the amount of resources necessary to get the necessary results, which would be important in the long run. The science behind building an efficient collider may be useful in fields like nuclear fusion, where the energy of initiation is high and containing the reaction is equally important.

  • Particle physics involve working with miniscule, short-lived particles. We may come across new particles which may occur under controlled conditions in a laboratory, a discovery as new as the next bacterium or virus that is synthesized or found out about. Reactions happening at the cosmic level involve high energies occurring in a seemingly random nature(involving huge masses instead of atoms) which is currently beyond understanding. Simulating it on a computer is the best humanity is doing at this point using mathematical models that may not be working at those scales.

  • Physicists might want to print their names on a research paper that comes across the next obscure short-lived particle in the universe, but the path that leads to the discovery is arduous. The architecture necessary to document the observations are expensive. The energy necessary to replicate the data multiple times in order to prove a point beyond reasonable doubt is equally high. These physicists, on the quest for image and recognition in the scientific community do themselves a favour, more than the Earth for whom these discoveries are supposed to benefit.

  • Fields like quantum behaviour, which involve studying entanglement and information exchange better explain the state of the universe we are currently living in(on Earth). Individual experiments may not reveal a huge breakthrough such as the hype that would be created upon discovery of a new particle, but in the long run they would be helpful in building new technology that may end up reducing energy consumption. The knowledge of a new particle may not have immediate benefits as opposed to the energy consumption required to prove existence beyond doubt, whereas quantum science requires much less energy to conduct and observe. Technology keeps on getting better and delaying particle physics exploration by a decade or two may speed up discoveries in the same field in future, where quantum technologies might be used to explore the universe at these scales instead of the traditional approach. We may be in a better position to make sense of these discoveries once we have a better understanding of quantum science.

  • Physicists often justify the field of particle physics by saying that the quest of knowledge is what science is about. This is true, but particle physics is not the only field where this saying is applicable. The hunger for knowledge can be satisfied in the fields of quantum technology, lattice geometry, gene dynamics amongst others which are important from a human perspective. Answering "why the mass of a neutron is what it is" may require answering a question like "under what conditions is the mass being measured as the energy of this particle is supposed to remain same", which may require testing the same under a variety of different conditions and there could be infinite of them. A question like "what energy was used to create a Higgs Boson" may throw off a particle physicist's preconceived notions, as these are nanosecond particles which are infrequent on Earth. [For example, the flavour of an orange may taste different depending upon the soil. Two lead atoms can be different based on their radioactivity]

  • Fields like quantum computing are resource extensive as they require low temperatures and expensive hardware. A.I compute can still be considered beneficial for the common people, but the more people use it, the more energy consumption it clocks. Given this situation, particle physics exploration can also be justified which will obviously involve consuming significantly lesser energy once built, which is why these fields should be subdued as much as possible. The money that is being spent on these resource-hungry technologies can be invested for Earth's welfare projects like afforestation. Incentivized afforestation would make the future a greener and cleaner place to perform exciting experiments that quench human beings' thirst for knowledge.


Lobbying communities and powerful entities is a radical approach and should be prevented if possible, particularly if it upsets the energy balance on Earth. Harvesting energy via Dyson spheres, using quantum technology to solve difficult problems easily sound exciting, but a balanced and patient approach to get there is more important than rushing blindly to find solutions to the universe's mysteries. Current approaches are bearing heavy operational costs that is detrimental for the future generations who are supposed to reap the benefits of the knowledge we are accumulating today.


Clinical relevance of miRNAs as biomarkers is growing due to their stability and detection in biofluids. This study has identified miR-519a-3p as a potential early biomarker for Alzheimer’s, linked to prion protein expression. This molecule is directly associated with the expression of the cellular prion protein located on the surface of nerve cells. miR-519a-3p may potentially be used as a biomarker of preclinical stages of the disease.

https://www.sciencedirect.com/science/article/pii/S0925443924001765?via%3Dihub (open access)

submitted 1 week ago by ooli@lemmy.world to c/science@lemmy.world
submitted 1 week ago by ooli@lemmy.world to c/science@lemmy.world
submitted 1 week ago by jeffw@lemmy.world to c/science@lemmy.world

TL;DR: New method of the mirror test shows self awareness in roosters. General suggestion that the mirror tests that have done in the past may have been misleading/not getting the right picture

submitted 1 week ago by jeffw@lemmy.world to c/science@lemmy.world

There was no group difference in reaction times and accuracy between males and females (using contraception and not). However, within subject analyses revealed that regularly menstruating females performed better during menstruation compared to being in any other phase, with faster reaction times (10ms c.ca, p < .01), fewer errors (p < .05) and lower dispersion intra-individual variability (p < .05). In contrast they exhibited slower reaction times (10ms c.ca, p < .01) and poorer timing anticipation (p < .01) in the luteal phase, and more errors in the predicted ovulatory phase (p < .01). Self-reported mood, cognitive and physical symptoms were all worst during menstruation (p < .01), and a significant proportion of females felt that their symptoms were negatively affecting their cognitive performance during menstruation on testing day, which was incongruent with their actual performance.


cross-posted from: https://lemmy.ml/post/16488358

Scientists Find Plastic-Eating Fungus Feasting on Great Pacific Garbage Patch

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