Science News Nov 15 (Patreon)

 [This is a transcript with links to references.]

Welcome everyone to this week’s science news. Today we have an update on the biggest astrophysics drama of the year, that’s an observation which seems to be ruling out the most popular alternative to dark matter. Then we have a group of geologists who claim that parts of the moon are stuck in the mantle of earth, a new and quite plausible explanation for the sudden dimming and brightening of the star Betelgeuse, plans for a smaller and more energy-efficient particle collider, the first full colour images from the EUCLID mission, earthquakes in the laboratory, a microscopic engine with record efficiency, plans to produce hydrogen with small nuclear reactors, climate scientists who say we’d be better off cooking with synthetic oil, and of course, the telephone will ring.

A group of astrophysicists has presented an analysis of binary star systems and claims that they’ve ruled out the most popular alternative to dark matter, modified Newtonian dynamics, MOND for short. While this isn’t evidence for dark matter in and of itself, it’s basically kicking the main competitor off the market, leaving dark matter as the only game in town.

You see, we know very well how gravity works on earth and in the solar system. We can’t just throw the theory out. The idea of modified gravity is therefore that the law of gravity only changes at small accelerations, which loosely speaking means at weak gravitational fields.

Now, it might seem like the gravitational field of a galaxy should be stronger than that of only one sun, but that isn’t so. It’s because what matters for the strength of gravity is how much the matter is concentrated, not just how much there is in total. The matter in our sun is very concentrated, that in the Milky Way is very spread out. Therefore, you wouldn’t see a modification of gravity in the solar system, but you’d see it in galaxies.

This is why the wide binaries are so interesting. These are cases where two stars orbit around each other, but at a big distance. If they’re close together, you should not see a modification of gravity. If they’re far apart, you should see it. The data come from ESA’s Gaia mission.

We already talked about this in June. Back then, there was a workshop on which several groups presented analyses from wide binary systems. The first paper appeared in April and said that the data are consistent with unmodified gravity for not-so-wide binaries, but the really wide ones seem to prefer modified gravity. This is what you’d expect if MOND was right. The second paper appeared in May and agreed with that. It said that the data provide evidence for the breakdown of standard gravity.

The third was a presentation at the workshop which said there’s no evidence for modified gravity in wide binaries, but rather 16 sigma evidence against it. This means MOND has been ruled out at an incredibly high level of confidence. The news is now that this result has been peer reviewed and published.

The published paper contains an extensive discussion about why the two groups find so wildly different results. To make a long story short, it’s because they use different samples of the data.

The paper that finds evidence for MOND uses pretty much the entire available data. The paper that finds evidence against it throws out data with high uncertainty. They show in the new paper that including this high uncertainty data brings back the evidence for MOND.

I’ve found that to be very interesting because we’ve seen the same thing in data from galaxy rotation curves, that the higher the uncertainty of the data, the better MOND seems to work. This raises the very real possibility that MOND is a systematic artifact coming from data interpretation. I don’t want to jump to conclusions here, but I am sure there’ll be more papers about this in the near future because I know someone who’s working on it, so stay tuned.

For now, little Albert is pleased that he’s been right, once again.

An international team of geologists says the moon formed differently than we thought, and it left pieces behind inside of Earth.

According to the current theory, the moon was formed in the very early stages of the formation of the solar system, when all the planets were still hot and the surfaces only partly solid. About 4 and a half billion years ago, a mars-sized planet named Theia collided with the Earth, sending massive amounts of planetary material into Earth’s orbit. This debris eventually became our moon.

The authors of the new paper now challenge that assumption.

They simulated the Earth’s interior with a sophisticated fluid dynamics model that takes into account both turbulence and material-mixing. They also used new high precision measurements that say the moon and earth have a similar composition. According to the results of their simulation, the debris from the collision orbited around earth for quite some time, and then formed different layers. This process also gives rise to blobs in Earth’s mantle, that are enriched with iron much like lunar rocks.

This agrees well with earlier findings that there are two continent-sized blobs in the Earth’s mantle that slow down seismic waves that move through them.

Another big part of the moon that stayed on earth is otherwise known as central Ohio.

You have probably heard of Betelgeuse. It’s a red supergiant star, about six hundred and forty light years from Earth. It’s made headlines in the past years because its brightness suddenly changed a lot. First it dimmed and then, earlier this year, it suddenly became much brighter. That got a lot of astronomers very excited because a star of this type might well go supernova, which would be quite a spectacle. But it’s remained unclear what Betelgeuse is up to.

A team of astronomers now think they have figured out what’s going on.

According to a new preprint, Betelgeuse might have been part of a two-star system, before it swallowed up its partner. The authors say this would explain why the star is spinning so fast. It would also explain the sudden changes in brightness, because the merger would have left behind a lot of dust and debris that now sloshes around the star.

This means it probably won’t go supernova any time soon. A shame really. Though if you google the topic, the more relevant question seems to be whether the thing’s pronounced beetle-juice or bettle-jazz.

It’s not exactly news that particle physicists really want a bigger particle collider, but a group of them has now put forward plans to make one that’s smaller and more energy efficient than the current ones.

The next bigger collider that particle physicists dream of is what they call a “higgs factory”. Just to make sure there aren’t any misunderstandings, that machine wouldn’t be cloning Peter Higgs, but rather it’d churn out Higgs-Bosons at a high rate to allow physicists to better study them.

The problem is that particle colliders are extremely expensive to build and run. The main reason they’re so expensive is that they’re big. They also create a lot of radiation when they run, so you need to put them underground. Digging long tunnels is the main factor for the high cost of particle colliders. The next biggest factor are the running costs. They mostly come from the extraordinary energy demand for all those magnets and their cooling systems.

In the new study, they looked at a particular type of collider that would be linear rather than circular like CERN. It’d collide electrons with their antiparticles, that’s the positrons. The good thing about colliding electrons and positrons is that they’re elementary particles, not made up of anything else. Colliding them is more efficient to focus energy in the particle collisions, and also makes it easier to extract information from the collision results.

The authors of the new study now advocate a type of collider called the cool copper collider, or sometimes cryogenic copper collider. As the name says, its main ingredients are copper and good cooling.

This technology allows for larger gradients in the magnetic fields that are used to accelerate the particles. This could shrink the length of the new collider to about 8 kilometres, which goes as “compact” among particle physicists. And while the copper must be cooled to about 80 degrees kelvin, it doesn’t have to be cooled as much as the superconducting magnets that are currently being used. That decreases the energy demand.

The authors estimate that the power requirement, and with that also the energy requirement, would go down to about half with the copper design compared to the superconducting magnets.

It’s a good thing that Samsung doesn’t hire particle physicists, otherwise smartphone size would meanwhile be a compact 8 kilometres.

Hello,

Hi Elon,

Wework? The company that wants to elevate the world’s consciousness with office sharing?

They went bankrupt? Ah, such a shame. Guess we’ll have to take the stairs to higher consciousness then. Love you too, bye.

Last week, the European Space Agency releasedthe first full-colour images from the Euclid mission, and they’re even more amazing than the black and white test images we saw in August.

The Euclid mission launched on July first this year, and is now operating in a small orbit around the Sun-Earth Lagrange point two, L2, where it sits alongside other famous space instruments, like the James Webb Space Telescope.

The goal of the Euclid mission is to learn more about the nature of dark energy and dark matter by creating a three-dimensional map of the universe. For this, it takes high-resolution images in the visible and infrared part of spectrum. It can see as far as 10 billion light years away. And the good thing about astrophysics is that even if they don’t find what they’re looking for, at least we get some pretty pictures out of it.

A team of American geologists say they might have found a new way to predict earthquakes by making really small ones in the laboratory.

Scientists have tried for a long time to improve earthquake warning systems to save lives and properties. Part of the problem is that in the most dangerous areas, like the San Andreas fault in California, the earth shakes pretty much constantly, but most of those small earthquakes are harmless. So scientists need to figure out how to tell apart the harmless shaking from the one that precedes a big earthquake.

In the new paper now they report the results of measurements they made in the lab on a mini replica of an earthquake fault. It’s only a few inches long and made of granite blocks. They made the fault slip with hydraulic presses and then measured how the thing shook. They found that for big earthquakes the precursor quakes build up in amplitude and come in shorter intervals. It’s a pattern that could potentially also be identified for fault lines that are a bit larger than a few inches.

Though I think the real world is overrated. I’m sure a tectonic fault line with hydraulic presses would sell very well as LEGO.

A team of researchers from India say they’ve overcome an age-old problem for heat engines.

Their study, published in Nature Communications, uses a tiny heat engine to show that you can both increase power and efficiency.

Heat engine is not a nickname for twitter, it’s a machine that generates mechanical motion from some other kind of energy. A car engine for example creates motion from chemical energy. How well this conversion works is called the efficiency.

Problem is, in realistic systems the irreversible nature of thermal motion means that faster you extract the energy, that is, the higher the power, the less efficient it becomes. However, this problem can in principle be overcome. No one knows how to do it for something as large as a car engine but some ideas for microscopic systems have been floating around for some while.

For this new study, they now realized such a microscopic heat engine that can, for suitable parameters, increase both power and efficiency. Their engine is just about one hundredth the width of a human hair. In this image, these particles here are polymers each about 5 micrometres in diameter. They can be positively or negatively charged, and they’re suspended in water. The researchers then move the particles with a laser. Then they measure how much the laser energy makes the particles move from the current that’s induced. For certain parameter values they find that they can beat the limitations of larger engines.

But in statistical mechanics, what’s possible for microscopic systems often can’t be realized for macroscopic ones, so I doubt we’ll get better cars out of this. However, this kind of efficiency improvement might become useful for microscopic robots.

That an increase in power decreases efficiency is a correlation that I think also holds in politics doesn’t it.
 

Rolls-Royce has announced an expansion to its small modular reactor, or SMR, program. Their plan is to produce hydrogen from the power generated by the small reactors. For this, Rolls Royce will partner with the Dutch nuclear tech company ULC-Energy, and Denmark's Topsoe, a firm that specializes in carbon emission reduction technology.

Rolls-Royce’s contribution to the joint project will be its small modular reactors, which are, well, small, modular, and nuclear reactors –  they’re a fraction of the size of your standard nuclear reactor. You produce them in factories, ship them, and link them together as desired. The idea is that this could bring down construction costs though that remains to be seen.

How small is small? They're not exactly handheld devices, but they're just about small enough to be transported with a truck on a road.

Topsoe will supply the electrolyzer cells, which produce hydrogen using both the electricity and heat produced by the reactor.

The reason for doing this is that hydrogen can be used for transportation, whereas most people, surprisingly enough, don’t want a nuclear reactor in their car.

A group of researchers is arguing that we should switch to synthetic fats because those are more ecologically sustainable.

They calculated the greenhouse gas emissions and land usage for growing oil-rich plants and compared those to the emission that could come from producing those fats synthetically. They found that lab-produced fat would in most cases be more environmentally friendly.

Palm oil produced in Brazil or Indonesia for example, releases about twice as much carbon dioxide-equivalent per kilocalorie than lab-produced one would.

They say that even when the synthetic oil would be produced with the most carbon-emitting energy source possible – coal power – it would still do better in terms of emissions than oil crops in sub-Saharan Africa.

But you’ll probably not see synthetic oils on the shelves any time soon though.  While they might be more environmentally friendly, they’re also expensive to produce, and that’s leaving aside that many consumers simply might not buy them. “Would you like some cold pressed lab oil” just doesn’t have the right ring to it.

The quiz for this video is here.