Our universe might be a giant three-dimensional donut, really

Imagine a universe where you could point a spaceship in one direction and eventually return to where you started. If our universe were a finite donut, then such movements would be possible and physicists could potentially measure its size.
"We could say: Now we know the size of the universe," astrophysicist Thomas Buchert, of the University of Lyon, Astrophysical Research Center in France, told Live Science in an email. 

Examining light from the very early universe, Buchert and a team of astrophysicists have deduced that our cosmos may be multiply connected, meaning that space is closed in on itself in all three dimensions like a three-dimensional donut. Such a universe would be finite, and according to their results, our entire cosmos might only be about three to four times larger than the limits of the observable universe, about 45 billion light-years away.

A tasty problem
Physicists use the language of Einstein's general relativity to explain the universe. That language connects the contents of spacetime to the bending and warping of spacetime, which then tells those contents how to interact. This is how we experience the force of gravity. In a cosmological context, that language connects the contents of the entire universe — dark matter, dark energy, regular matter, radiation, and all the rest — to its overall geometric shape. For decades, astronomers had debated the nature of that shape: whether our universe is "flat" (meaning that imaginary parallel lines would stay parallel forever), "closed" (parallel lines would eventually intersect), or "open" (those lines would diverge).

That geometry of the universe dictates its fate. Flat and open universes would continue to expand forever, while a closed universe would eventually collapse in on itself.
Multiple observations, especially from the cosmic microwave background (the flash of light released when our universe was only 380,000 years old), have firmly established that we live in a flat universe. Parallel lines stay parallel and our universe will just keep on expanding.

But there's more to shape than geometry. There's also topology, which is how shapes can change while maintaining the same geometric rules.
For example, take a flat piece of paper. It's obviously flat — parallel lines stay parallel. Now, take two edges of that paper and roll it up into a cylinder. Those parallel lines are still parallel: Cylinders are geometrically flat. Now, take the opposite ends of the cylindrical paper and connect those. That makes the shape of a donut, which is also geometrically flat.
While our measurements of the contents and shape of the universe tell us its geometry --it's flat — they don't tell us about the topology. They don't tell us if our universe is multiply-connected, which means that one or more of the dimensions of our cosmos connect back with each other.

Look to the light

While a perfectly flat universe would extend out to infinity, a flat universe with a multiply-connected topology would have finite size. If we could somehow determine whether one or more dimensions are wrapped in on themselves, then we would know that the universe is finite in that dimension. We could then use those observations to measure the total volume of the universe.

But how would a multiply-connected universe reveal itself?

A team of astrophysicists from Ulm University in Germany and the University of Lyon in France looked to the cosmic microwave background (CMB). When the CMB was released, our universe was a million times smaller than it is today, and so if our universe is indeed multiply connected, then it was much more likely to wrap in on itself within the observable limits of the cosmos back then. Today, due to the expansion of the universe, it's much more likely that the wrapping occurs at a scale beyond the observable limits, and so the wrapping would be much harder to detect. Observations of the CMB give us our best chance to see the imprints of a multiply connected universe.

The team specifically looked at the perturbations — the fancy physics term for bumps and wiggles — in the temperature of the CMB. If one or more dimensions in our universe were to connect back with themselves, the perturbations couldn't be larger than the distance around those loops. They simply wouldn't fit.

As Buchert explained to Live Science in an email, "In an infinite space, the perturbations in the temperature of the CMB radiation exist on all scales. If, however, space is finite, then there are those wavelengths missing that are larger than the size of the space."

In other words: There would be a maximum size to the perturbations, which could reveal the topology of the universe. 

Maps of the CMB made with satellites like NASA's WMAP and and the ESA's Planck have already seen an intriguing amount of missing perturbations at large scales. Buchert and his collaborators examined whether those missing perturbations could be due to a multiply-connected universe. To do that, the team performed many computer simulations of what the CMB would look like if the universe were a three-torus, which is the mathematical name for a giant three-dimensional donut, where our cosmos is connected to itself in all three dimensions.

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"We therefore have to do simulations in a given topology and compare with what is observed," explained Buchert. "The properties of the observed fluctuations of the CMB then show a 'missing power' on scales beyond the size of the universe." A missing power means that the fluctuations in the CMB are not present at those scales. That would imply that our universe is multiply-connected, and finite, at that size scale.

"We find a much better match to the observed fluctuations, compared with the standard cosmological model which is thought to be infinite," he added.

"We can vary the size of the space and repeat this analysis. The outcome is an optimal size of the universe that best matches the CMB observations. The answer of our paper is clearly that the finite universe matches the observations better than the infinite model. We could say: Now we know the size of the universe."

The team found that a multiply-connected universe about three to four times larger than our observable bubble best matched the CMB data. While this result technically means that you could travel in one direction and end up back where you started, you wouldn't be able to actually accomplish that in reality. We live in an expanding universe, and at large scales the universe is expanding at a rate that is faster than the speed of light, so you could never catch up and complete the loop.

Buchert emphasized that the results are still preliminary. Instrument effects could also explain the missing fluctuations on large scales.

Still, it's fun to imagine living on the surface of a giant donut.

Source: LiveScience

UK consortium leads project to develop the next generation of hydrogen storage tanks for HGV and buses

A consortium of UK companies, Ultima Forma, Lentus Composites and the National Composites Centre (NCC), have joined forces to develop a novel, high-pressure hydrogen storage tank aimed for use in HGV, bus and off-highway applications.

Project HYSTOR has secured funding as part of the Advanced Propulsion Centre’s (APC) Automotive Transformation Fund. The project, led by Ultima Forma, brings together a novel electroformed integrated metallic liner overwrapped with composite that will bring weight reduction and other advantages over current solutions in the market today. The patented thin walled liner provides an impermeable hydrogen membrane onto which structural carbon fibre is wound by Lentus Composites using automated filament winding equipment.

Steve Newbury, MD at Ultima Forma, said:

“We are delighted to be working alongside Lentus and the NCC to bring to market improved storage solutions for high pressure hydrogen. Hydrogen propulsion systems are clearly identified as part of the UK’s Technology Roadmap and will play an increasingly significant role in the energy mix in the coming years. Pressurised storage systems are a key component where the UK supply chain can play an influential role in this growing energy economy.”

The project will undertake analysis, manufacture and initial testing of the vessel design proving feasibility and clear route to industrialisation and exploitation. The prototype vessels will be subjected to tests critical to achieving certification in the future, generating confidence that the product will perform to the challenging standards required in service.

Marcus Walls-Bruck, Chief Engineer for Hydrogen at the National Composites Centre, said:

“Composite materials will have a significant role in the deployment of hydrogen. The NCC are excited to support the development of UK hydrogen supply chains, leveraging the investments the NCC have made in developing composites for hydrogen applications, and the expertise of Ultima Forma and Lentus Composites.”

Daniel Chilcott, Business Development Director at Lentus Composites, said:

“We’re very excited about the opportunity this collaboration offers the UK in developing clean energy such as hydrogen propulsion.”

As well as focusing on HGV applications where there is a compelling case for hydrogen propulsion, the HYSTOR team see opportunities for this technology in the adjacent rail, aerospace and space markets where hydrogen storage and minimal weight are critical requirements.

The project aims to complete in April 2022 at which stage the partners will shift their focus onto commercialization and certification testing of first market-entry products.

Source:www.polartechnology.co.uk

Japan just shattered the internet speed record: 319 Terabits per Second

 How’s your internetworking these days? At a recent conference, researchers from Japan demonstrated a whopping data transmission rate of 319 Terabits per second (Tb/s). Remarkably, the transmission was carried out over a long distance (3001 km / 1864 miles) and using technology that is already available today.

A minute of footage, in high definition, takes about 100 Megabytes. That means that with this speed, you could download around 5,300 hours of footage every second. You could download the entire Spotify library in a few seconds. Wikipedia, you’d download in 0.01 seconds.

This speed is almost double the previous record of 178 Tb/s, and almost seven times the earlier record of 44.2 Tb/s. Meanwhile, NASA’s internet tops out at 91 Gb/s (1 Tb = 1,000 Gb = 1,000,000 Mb) and the fastest home internet you can get is about 10 Gb/s. We at ZME feel fortunate to be working with a 1 Gb/s connection.

The record was achieved with infrastructure that already exists, though researchers did add a few pieces of key equipment. The team used fiber-optic equipped with four “cores” — glass tubes within the cable — instead of the standard one core. To amplify the speed, the researchers divided the signal into different wavelengths. The key innovation seems to be that they employed a rarely-used band of wavelengths.

“In this demonstration, in addition to the C and L-bands, typically used for high-data-rate, long-haul transmission, we utilize the transmission bandwidth of the S-band, which has not yet been used for further than single-span transmission,” the researchers write in the study.

With more bands, researchers were able to take the normal data sending process (which starts with a “comb” laser fired at different wavelengths), and extend it over a much longer distance. After 70 km (43.5 miles), the signal was boosted with optical amplifiers. But the researchers didn’t use regular boosters. They used two novel types of fiber optic amplifies: one doped in thulium and the other in erbium — both materials have been used as boosters before. This amplification process is called Raman amplification. After this, the process is repeated on and on, enabling the signal to span the whopping 3,000 km distance.

Although the researchers did implement a few innovations, the whole structure uses the same diameter as the conventional, single-core fiber optic — which means conventional cables can be replaced with these novel ones. This would make it much easier to transition to a new type of infrastructure.

“The standard cladding diameter, 4-core optical fiber can be cabled with existing equipment, and it is hoped that such fibers can enable practical high data-rate transmission in the near-term, contributing to the realization of the backbone communications system.”

So, what would you use 319 Terabits per Second for?

Source: ZME SCIENCE

Scientists may have found how migrating birds sense Earth’s magnetic field

 Birds migrate thousands of miles without a GPS, using the Earth’s magnetic field to orient themselves. It’s been a long mystery how they were able to do this, but now, scientists may have found the key reason behind it: a molecule in the eye that’s sensitive to magnetism and gives birds a working internal compass. 

A group of biologists, chemists, and physicists tested a 40-years old theory according to which a light-sensitive molecule interacts with the Earth’s magnetic field via a quantum chemical process. To do this, they looked at a light-sensitive protein called cryptochrome 4 (CRY4) from the retina of European robins (Erithacus rubecula).

“We think we may have identified the molecule that allows small migratory songbirds to detect the direction of the Earth’s magnetic field, which they undoubtedly can do, and use that information to help them navigate when they migrate thousands of kilometres,” Peter Hore, researcher and co-author of the paper.

European robins live throughout Europe, Russia, and western Siberia. Some migrate south every northern hemisphere winter, for example from Scandinavia to the United Kingdom, and return in spring. Many migrating robins are faithful to both their summer and winter territories, which may be many hundreds of kilometers apart.

Now, researchers managed to isolate the molecule from robins and showed that it is sensitive to magnetic fields. In the presence of light, electrons can jump between different parts of CRY4 and between it and another molecule called flavin adenine dinucleotide (FAD), ultimately leading to the production of a compound called CRY4-FADH. 

Changes in the level of the compound may allow light-sensitive cells in the eye to alter their output, making the view lighter or darker, depending on the direction and strength of the magnetic field in the bird’s field of vision, Henrik Mouritsen, co-author, told New Scientist. “You may be able to see where north is as kind of a shading on whatever else you would be seeing,” he said. 

For comparison, the researchers also looked at CRY4 proteins from chickens and pigeons, which are not migratory birds but do contain this light-sensitive protein. Each species has a slightly different version of the molecule, and the team found that these two are less affected by magnetism. This suggests that the version of the molecule in migratory birds has been fine-tuned to amplify its sensitivity.

While the findings are exciting, the study hasn’t demonstrated that CRY4 is being used for magnetic sensing in real life. The researchers only looked at this molecule in isolation. Nevertheless, the fact that the molecule is more magnetically sensitive in robins than in birds such as chickens that don’t migrate makes them optimistic about their findings. 

Source:https://lnkd.in/gTKZbuQ

Lockheed Martin Looks To Space With Australian-Developed Composite Tanks

 A collaborative partnership between Lockheed Martin, Australian manufacturer Omni Tanker and UNSW Sydney will look to develop and commercialize world-first composite tank technologies, thanks to a grant from the Federal Government’s Advanced Manufacturing Growth Centre (AMGC).

The co-funded project announced as part of AMGC’s Commercialisation Fund launch and worth a total $AUD1.4 million will utilize two revolutionary home-grown technologies to solve the challenges of using composites for the transportation and storage of liquid hydrogen with applications on the ground, in the air, underwater and in space.  

Combining nano-engineering technology developed by UNSW in partnership with Lockheed Martin and Omni Tanker, and Omni Tanker’s patented OmniBIND™ technology, the collaboration will result in the development of two new operational scale propellant tanks for storing cryogenic liquid fuels for commercial and civil satellite programs: a “Type IV” fluoropolymer-lined carbon fiber composite tank and a “Type V” linerless carbon fiber composite tank, both of which are suitable for high pressures, the extreme cryogenic temperatures required for liquid hydrogen as well as oxygen, hydrogen peroxide, and hydrazine.

Christopher Hess, Head of Industrial Development, Lockheed Martin Australia acknowledged the support of AMGC and welcomed the opportunity for ongoing collaboration with UNSW and Omni Tanker.

“Lockheed Martin invests millions of dollars every year into R&D programs with our Australian industry and research partners to solve real challenges facing our Global Supply Chains,” he said. “We have had a long-standing research collaboration with UNSW and Omni Tanker, and we are grateful for the support of the AMGC as we now look to commercialize these cutting edge, Australian-developed composite tank technologies for a number of Lockheed Martin and NASA applications.” 

David Ball, Regional Director Australia and New Zealand, Lockheed Martin Space, confirmed the development of composite tanks that are lightweight, cost-effective, and resistant to microcracking and permeation represents a unique and innovative technological solution with significant space applications.

“As the world increasingly looks to hydrogen for emission-free energy, containing and transporting it in a safe, cost-effective and economic manner remains extremely challenging,” he said. “The space industry is particularly interested in the development of linerless composite tanks for their weight efficiency and durability, which represent the cutting edge of composite pressure vessel manufacturing.”

“These advances have the potential to support the growth of Australia’s sovereign space capabilities, strengthen exports to space-faring allies and partner nations, and make an important technological contribution to future space missions particularly in on-orbit storage, launch and deep space exploration,”  he said.

“Creating a lightweight vessel for transporting liquid hydrogen at minus 253 degrees Celsius is no simple thing – whether you’re moving it along a highway or to outer space – but it’s Australian know-how that is making it possible,” said Dr Jens Goennemann, Managing Director, AMGC.

“That’s why AMGC is supporting Omni Tanker and its collaborative partners to engineer and manufacture a solution to this problem and offer it globally,” said Dr Goennemann.

The project builds on a recent invention by the research team at UNSW led by Professor Chun Wang, which enables carbon fibre composites to withstand liquid hydrogen temperatures without matrix cracks – a challenge that has, up until now, prevented mass-market adoption of these materials for such applications.

“This new technology is the result of an outstanding collaboration and partnership between UNSW, Lockheed Martin, and Omni Tanker over the past four years. It is wonderful seeing our research achievement is now moving closer towards commercial success and generating social and economic impact in Australia and beyond,” said Professor Wang.

Omni Tanker, with its significant experience in the development and commercialization of strong, lightweight composite transport vessels, has the know-how and technology to translate the recent research innovations for a myriad of applications.

Omni Tanker’s CEO, Daniel Rodgers says: “This next phase in our collaboration with Lockheed Martin and UNSW is a landmark development that sees Omni Tanker’s seamless thermoplastic lining technology enter the aerospace sector. The OmniBIND™ technology has made inroads to revolutionizing the safe and efficient movement of challenging liquids within the chemical transport sector. Now the growing need to decarbonize the energy industry, and the re-usable low-earth-orbit satellite market, have the potential to drive major utilization for these new technologies.”

“We are excited to work with Lockheed Martin and UNSW on this ground-breaking project, which leverages our patented technology. It is also a credit to the talented Australian engineering team that we have assembled at Omni Tanker,” said Omni Tanker’s Chief Technical Officer, Dr Luke Djukic.

Source: LOCKHEED MARTIN