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Researchers have discovered how to make a new kind of metamaterial reconfigure itself without tangling itself up in knots, opening up the possibility of a broad array of space applications. Metamaterials are a hot topic in engineering. These are materials inspired from biological systems. Many living structures start from simple, repeatable patterns that then grow into large, complex structures. The resulting structures can then have properties that the small subcomponents don’t. For example, individual bone cells or coral polyp skeletons aren’t very strong, but when they work together they can support huge animals or gigantic underwater colonies. One promising kind of metamaterial is known as a Totimorphic lattice. This lattice starts from a triangular shaped structure. On one side is a fixed beam with a ball joint in the center. An arm attaches to that ball joint, and the other end of the arm is attached to the ends of the fixed beam with two springs. Many of these shapes attached together can morph into a wide variety of shapes and structures, all with very minimal input, giving the Totimorphic lattice incredible flexibility. In a recent paper, scientists with the European Space Agency’s Advanced Concepts Team found a way to reconfigure Totimorphic lattices without having them tangle up on themselves. They discovered this using a series of computer simulations, creating an optimization problem for the algorithm to solve. With the algorithm in hand, they could then take any configuration of the lattice and change it to another in an optimal, efficient way. The researchers showed off their technique with two examples. The first was a simple habitat structure that could change its shape and stiffness, which could allow future astronauts to deploy the same kind of metamaterial to build a variety of structures, and reconfigure them as mission needs changed. The second example was a flexible space telescope that could change its focal length by adapting the curvature of its lens. This would enable a single launch, with a single vehicle, to serve a variety of observing needs. As of right now, this is all hypothetical. Totimorphic lattices don’t exist in practice, only as curious mathematical objects. But this research is crucial for advancing humanity into space. The cost and difficulty of launching materials into space mean that we need flexible, adaptable structures that are cheap to launch and easy to deploy. This research is yet another example of how we can draw inspiration from nature, in this case investigating the surprising properties of metamaterials, to bring ourselves into a future in space. The post A Flexible, Adaptable Space Metamaterial appeared first on Universe Today.

According to new research, the earliest seeds of structures may have been laid down by gravitational waves sloshing around in the infant universe. Cosmologists strongly suspect that the extremely early universe underwent a period of exceptionally rapid expansion. Known as inflation, this event expanded the universe by a factor of at least 10^60 in less than a second. Powering this event was a new ingredient in the cosmos known as the inflaton, a strange quantum field that ramped up, drove inflation, and then faded away. Inflation didn’t just make the universe big. It also laid down the seeds of the first structures. It did so by taking the quantum foam, the subatomic fluctuations in spacetime itself, and expanding that along with everything else. Slowly over time those fluctuations grew, and hundreds of millions of years later they became the first stars and galaxies, ultimately leading to the largest structure in the universe, the cosmic web. But mysteries remain. We do not know the identity of the inflaton, or what powered it, or why it turned off when it did. And we have no conclusive evidence that inflation actually happened. So researchers are always looking for alternatives, especially ones that don’t invoke some new and mysterious ingredient. In a recent paper, a team of astrophysicists describe a model where inflation happens, leading to the large-scale structure of the universe, all without an inflaton. The model described by the researchers is set in the backdrop of an expanding universe that is accelerating in its expansion, just like the modern-day universe is. In that expanding universe, the quantum foam releases gravitational waves. Those ripples in space spread outwards, colliding with each other and amplifying themselves. Gravitational waves usually can’t create structures on their own, but the researchers found that in certain special cases the gravitational waves can amplify each other in just the right way. When that happens, the imprints they make in space are nearly the same at a wide variety of length scales. This is precisely what cosmologists observe in the cosmic microwave background, the leftover light from the early universe. This radiation contains a faint impression of the echoes of inflation, and it shows that whatever set the seeds of structure, it had to have that kind of pattern. There are slight differences between the kinds of structures generated in this inflation-without-inflaton scenario and traditional inflation. In this first paper, the researchers did not yet calculate how strong those differences are, but an important next step is to explore the observational consequences of this model and see if it’s worth investigating further. The post Space Itself May Have Created Galaxies appeared first on Universe Today.

Dark matter may have to go on a diet, according to new research. By now we have a vast abundance of evidence for the existence of dark matter. That’s because cosmological observations just aren’t adding up. All our measures of luminous matter fall far short of the total gravitational effects we see in galaxies, clusters, and the universe as a while. Dark matter far outweighs the regular matter in the cosmos, but we still don’t know the identity of this mysterious particle. Because of that, it could have a wide variety of masses, anything from a billionth of the mass of the lightest known particles to mass ranges far, far heavier. Most searches for dark matter have focused on masses roughly in the range of the heavier known particles, because several extensions to known physics predict particles like that. But those searches have thus far come up short, making physicists wonder if the dark matter might be much lighter than expected…or much heavier. But heavier dark matter runs into some serious issues, according to a new paper appearing on the preprint server arXiv. The problem is that we expect to dark matter to at least sometimes, rarely, interact with normal matter. In the extremely early universe, dark matter and regular matter talked to each other much more often. But as the cosmos expanded and cooled, the interactions broke down, freezing out dark matter and leaving it behind as a relic background. Almost all models of dark matter predict that it talks to normal matter through some interaction involving the Higgs boson, the famous particle finally detected by the Large Hadron Collider in 2012. The Higgs boson is responsible for the mass of many particles. But interactions in physics are two-way streets. Many particles acquire their mass through their interaction with the Higgs, and in turn the mass of the Higgs is modified by its interaction with the other particles. But those particles are so light that the back-reaction isn’t very strong, so usually we don’t have to worry about it. But if the dark matter is much heavier, somewhere around ten times the mass of the heaviest known particles, then its own interactions will cause the Higgs to balloon up in mass, making it far heavier than measurements suggest. There are possibilities to get around this restriction. The dark matter might not interact with regular particles at all, or through some exotic mechanism that doesn’t involve the Higgs. But those models are few are far between, and require a lot of fine-tuning and extra steps. This means that the dark matter, whatever it is, might just be an ultra-light particle, rather than an ultra-heavy one. The post Dark Matter Can’t Be Too Heavy appeared first on Universe Today.

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