Technologies

What Is Dark Matter? The Answer to Universe’s Greatest Mystery Could Be Axions

The saga of how an odd hypothetical particle became a star dark matter candidate.

Physics is permeated by conundrums, and in a sense, that’s what keeps the field going. These mind-bending puzzles foster a race toward truth. But of all the dilemmas, I’d say two of them unquestionably fall under priority A.

First off, when scientists look up at the sky, they consistently see stars and galaxies traveling farther from our planet, and from each other, in every direction. The universe kind of looks like a bubble blowing up, which is how we’ve come to know it’s expanding. But something doesn’t make sense.

Space doesn’t seem to have enough stuff floating around in it — stars, particles, planets and all else — for it to inflate so swiftly. In other words, the universe is expanding way faster than our physics says it can, and it’s even picking up speed as you read this. Which brings us to problem two.

Per experts’ best calculations, galaxies are spinning so incredibly quickly as everything zips around that we’d expect the spirals to behave like out-of-control merry-go-rounds flinging metal horses off the ride. There doesn’t seem to be enough stuff in the universe to anchor them together. Yet the Milky Way isn’t drifting apart.

So… what’s going on?

As blanket terms, physicists call «missing» stuff pushing the cosmos outward dark energy, and pieces holding galaxies together — presumably in a halo-like form — dark matter. Neither interacts with light or matter we can see, so they’re essentially invisible. Combined, dark matter and dark energy make up a whopping 95% of the universe.

Zeroing in on dark matter’s portion, the authors of a recent review, published in the journal Science Advances, write that «it may well consist of one or more types of fundamental particle … although part or all of it might consist of macroscopic lumps of some invisible form of matter, such as black holes.»

Black holes or not, dark matter is totally elusive. In an effort to decode its secrets, scientists have picked a handful of suspects out of the cosmic lineup, and one of the most wanted particles is an odd little speck called the axion.

The wide-eyed hypothesis of axions

You might’ve heard of the Standard Model, which is pretty much the holy grail, ever-strengthening handbook of particle physics. It outlines how every single particle in the universe works.

However, as the Science Advances review points out, some «particle physicists are restless and dissatisfied with the Standard Model because it has many theoretical shortcomings and leaves many pressing experimental questions unanswered.» More specifically for us, it leads right into a paradox regarding a well-established scientific concept dubbed CPT invariance. Aha, the physics puzzles continue.

Basically, CPT invariance states that the universe must be symmetrical when it comes to C (charge), P (parity) and T (time). For that reason, it’s also called CPT symmetry. If everything had the opposite charge, was left-handed instead of right-handed and traveled through time backward instead of forward, it states the universe should remain just the same.

For a long while, CPT symmetry seemed unbreakable. Then 1956 came around.

Long story short, scientists found something that violates the P part of CPT symmetry. It’s called the weak force, and it dictates things like neutrino collisions and element fusion in the sun. Everyone was shocked, confused and scared.

Nearly every foundational concept of physics relies on CPT symmetry.

About a decade later, researchers discovered the weak force violating C symmetry, too. Things were falling apart. Physicists could just hope and pray that even if P is violated… and CP is violated… maybe CPT still isn’t. Maybe weak forces just need the trio to uphold CPT symmetry. Thankfully, this theory seems correct. For some unknown reason, the weak force follows total CPT symmetry despite C and CP blips. Phew.

But here’s the issue. If weak forces violate CP symmetry, you’d expect strong forces to as well, right? Well, they don’t, and physicists don’t know why. This is called the strong CP problem — and precisely where things get interesting.

Neutrons — uncharged particles within atoms — abide by the strong force. Plus, allowing for simplification, their neutral charge means they violate T symmetry. And «if we find something that violates T symmetry, then it must also violate CP symmetry in such a way that the combination CPT is not violated,» the paper states. But… that’s weird. Neutrons don’t because of the strong CP problem.

And so the idea of the axion was born.

Years ago, physicists Roberto Peccei and Helen Quinn suggested adding a new dimension to the Standard Model. It involved a field of ultralight particles — axions — that explained the strong CP problem, thereby relaxing the conditions for neutrons. Axions appeared to fix everything so well that the duo’s idea became the «most popular solution to the strong CP problem,» the paper states. It was a miracle.

To be clear, axions are still hypothetical, but think about what just happened. Physicists added a new particle to the Standard Model, which outlines specks of the entire universe. What might that mean for everything else?

The key to dark matter?

Per the Peccei-Quinn theory, axions would be «cold,» or very slowly moving through space. And… the study researchers say «the existence of [dark matter] is inferred from its gravitational effects, and astrophysical observations suggest that it is ‘cold.'»

The paper also states, «there are experimental upper limits on how strongly [the axion] interacts with the visible matter.»

So, basically, axions that help explain the strong CP problem also seem to have theoretical properties that align with those of dark matter. Extremely well.

The European Council for Nuclear Research, better known as CERN, which runs the Large Hadron Collider and is leading the charge for antimatter studies, also underlines «one of the most suggestive properties of axions is that, in a natural way, they could be produced in huge numbers soon after the Big Bang. This population of axions would still be present today and could compose the dark matter of the universe.»

There you go. Axions are among the hottest topic in physics because they seem to explain so much. But once again, those sought-after bits are still hypothetical.

Will we ever find axions?

It’s been 40 years since scientists began hunting for axions.

Most of these searches are «mainly exploiting the action field interaction with the electromagnetic fields,» say the authors in that recent review published in Science Advances.

For instance, CERN developed the Axion Search Telescope, a machine built to find a hint of the particles produced in the sun’s core. Inside our star, there are strong electric fields that could potentially interact with axions — if they’re really there, that is.

But the quest has so far faced a few pretty big challenges. For one, «the particle mass is not theoretically predictable,» the authors write — that is, we have very little idea of what an axion might look like.

Right now, scientists are still searching for them while assuming a vastly wide range of masses. Recently, however, researchers offered evidence that the particle is likely between 40 and 180 microelectron volts. That’s unthinkably small, at about 1 billionth the mass of an electron.

«In addition,» the team writes, «the axion signal is expected to be very narrow … and extremely feeble due to very weak couplings to Standard Model particles and fields.» In essence, even if minuscule axions try their very best to signal their existence to us, we might miss them. Their cues could be so weak we’d barely notice.

Despite these hurdles, the axion search marches on. Most scientists argue that they must be out there somewhere but they seem too good to be true when it comes to fully explaining dark matter.

«Most experimental attempts assume that axions compose 100% of the dark matter halo,» the study authors emphasize, suggesting that perhaps there’s a way to «look into axion physics without relying on such an assumption.»

Though they may be the star of the show, what if axions are just one chapter of dark matter history?

Technologies

Scientists Are Using AI to Help Identify Dinosaur Footprints

The Dinotracker app was trained on eight major characteristics of dinosaur footprints to quickly determine the species.

An international team of researchers has devised a futuristic tool to examine the footprints left by dinosaurs in our ancient past. The AI-powered app, Dinotracker, can identify dinosaur footprints in moments.

The research comes from a joint project by the Helmholtz-Zentrum research center in Berlin and the University of Edinburgh in Scotland. The Proceedings of the National Academy of Sciences published the paper on Monday.

Don’t miss any of our unbiased tech content and lab-based reviews. Add CNET as a preferred Google source.

Identifying a dinosaur species from a footprint isn’t always easy. The footprint is hundreds of millions of years old, often preserved in layers of rock that have shifted over the eons since the track was laid.

Also, we still have a lot to learn about dinosaurs, and it’s not always clear which species left a footprint. Subjectivity or bias can come into play when identifying them, and scientists don’t always agree with the results.

Gregor Hartmann of Helmholtz-Zentrum, who led the project, told CNET that the research team sought to remove this propensity from the identification process by developing an algorithm that could be neutral.

«We bring a mathematical, unbiased point of view to the table to assist human experts in interpreting the data,» Hartmann said.

Researchers trained the algorithm on thousands of real fossil footprints, as well as millions of simulated versions that could recreate «natural distortions such as compression and shifting edges.»

How AI is being used on dinosaur tracks

The system was trained to focus on eight major characteristics of dinosaur footprints, including the width of the toes, the position of the heel, the surface area of the foot that contacted the ground and the weight distribution across the foot.

The AI tool uses these traits to compare new footprints to existing fossils, and then determines which dinosaur was most likely responsible for the footprint.

The team tested it against human expert classifications and found that the AI agreed with them 90% of the time.

Hartmann made it clear that the AI system is «unsupervised.»

«We do not use any labels (like bird, theropod, ornithopod) during training. The network has no idea about it,» Hartmann said. «Only after training, we compare how the network encodes the silhouettes and compare this with the human labels.»

Hartmann said that the hope is for Dinotracker to be used by paleontologists and that the AI tool’s data pool grows as it’s used by more experts.

Bird vs. dinosaur

Using Dinotracker, the researchers have already uncovered some intriguing possibilities on the evolution of birds. When analyzing footprints more than 200 million years old, the AI found strong similarities with the foot structures of extinct and modern birds.

The team says one possibility is that birds originated tens of millions of years earlier than we thought. But it’s also possible that early dinosaur feet just look remarkably like bird feet.

This evidence, Hartmann notes, isn’t enough to rethink the evolution of birds, since a skeleton is the «true evidence» of earlier bird existence.

«It is essential to keep in mind that over these millions of years, lots of different things can happen to these tracks, starting from the moisture level of the mud where it was created, over the substrate it was created on, up to erosion later,» he said. «All this can heavily change the shape of the fossilized track we find, and ultimately makes it too difficult to interpret footprints, which was the motivation for our study.»

Dinotracker is available for free on GitHub. It’s not in a download-and-use format, so you’ll have to know a bit about software to get it up and running.

Technologies

Belkin Is Ending Support for Wemo Smart Home Devices. Here’s What That Means for You

If you own certain Belkin Wemo devices, they’ll stop working as soon as Jan. 31. Here’s what to know before it happens.

Belkin is ending support for most of its Wemo smart home devices, a move that will shut down the Wemo app and cloud services and significantly reduce the functionality of many popular smart plugs, switches and sensors.

The change takes effect at the end of January, so you have only a few days to migrate compatible devices or start planning for replacements.

You can see the full list of affected devices on Belkin’s support page. Once support ends, features that rely on the cloud — including remote access, schedules and integrations with Amazon Alexa and Google Assistant — will stop working. Those Wemo devices will no longer function as «smart» products, even if the hardware still powers on.

Since Belkin will also stop releasing firmware updates, affected devices won’t receive bug fixes or security improvements.

Belkin’s decision highlights a growing issue in the smart home world: Devices can stop being «smart» long before the hardware wears out.

Apple Home users get a limited lifeline

There is one major exception. Some Wemo devices that are compatible with Apple Home and HomeKit can continue working after the Wemo app shuts down, but only if you migrate them before the end-of-support deadline.

«Since the Wemo app will be ending, it’s very important that users switch to Apple Home/HomeKit by the end of the month,» says CNET smart home editor Tyler Lacoma. «Belkin has a long-term partnership with Apple, so for compatible devices, that transition is usually pretty simple.»

However, Lacoma warns that older Wemo products may not support Apple Home at all.

«If someone has a Wemo device that’s not on the list of Apple-compatible products, it won’t have much functionality left,» he says. «It won’t get firmware updates to fix bugs or improve security, so at that point, it makes sense to factory reset it and recycle it before the end of the month, then look for a replacement.»

Belkin has published a list of Wemo devices that support Apple HomeKit, and users need to complete the setup process before the Wemo app is retired. The following products will continue to work through Apple HomeKit:

Wemo Smart Light Switch 3-Way (WLS0403, WLS0503)
Wemo Wi-Fi Smart Light Switch with Dimmer (WDS060)
Wemo Smart Light Switch (WLS040)
Wemo HomeKit Bridge (F7C064)
Wemo Dimmer Light Switch (F7C059)
Wemo Mini Plugin Switch (F7C063)
Wemo Outdoor Plug (WSP090)
Wemo Mini Smart Plug (WSP080)
Wemo Stage Smart Scene Controller (WSC010)
Wemo Smart Plug with Thread (WSP100)
Wemo Smart Video Doorbell (WDC010)

What about refunds?

Belkin says customers with Wemo devices that are still under warranty when support ends may be eligible for a partial refund. You can find the warranty period for each device in the list of devices on Belkin’s support page linked above. Refund requests won’t be processed until after the end-of-support date, and eligibility will depend on the product and purchase date.

Because many Wemo products were released years ago, most people should not expect to qualify for a refund. We’ve reached out to Belkin to ask whether other products will lose support in the near future. We haven’t heard back at the time of publishing.

What Wemo owners should do now

If you own Wemo devices, the clock is ticking. Here’s what to do next:

Check whether your Wemo products support Apple Home and migrate them as soon as possible.
If your devices don’t support Apple Home, plan to replace them before support ends.
Consider recycling unsupported devices once they lose smart functionality.
Remove the Wemo app after services shut down to avoid confusion.

If you’re shopping for replacements, this is a good time to look at CNET’s list of the best smart plugs and review our guide on what to do when smart home devices lose support.

Technologies

Today’s NYT Strands Hints, Answers and Help for Jan. 28 #696

Here are hints and answers for the NYT Strands puzzle for Jan. 28, No. 696.

Looking for the most recent Strands answer? Click here for our daily Strands hints, as well as our daily answers and hints for The New York Times Mini Crossword, Wordle, Connections and Connections: Sports Edition puzzles.

Today’s NYT Strands puzzle is a bit of an odd one, but it might calm you down — hint, hint. If you need hints and answers, read on.

I go into depth about the rules for Strands in this story.

If you’re looking for today’s Wordle, Connections and Mini Crossword answers, you can visit CNET’s NYT puzzle hints page.

Read more: NYT Connections Turns 1: These Are the 5 Toughest Puzzles So Far

Hint for today’s Strands puzzle

Today’s Strands theme is: Zen state

If that doesn’t help you, here’s a clue: Mellow out.

Clue words to unlock in-game hints

Your goal is to find hidden words that fit the puzzle’s theme. If you’re stuck, find any words you can. Every time you find three words of four letters or more, Strands will reveal one of the theme words. These are the words I used to get those hints but any words of four or more letters that you find will work:

COIL, COIF, COIFS, MATE, TAME, TAMED, CONE, CODE, NEST, NETS, LENS, TIED, DIET, MIND

Answers for today’s Strands puzzle

These are the answers that tie into the theme. The goal of the puzzle is to find them all, including the spangram, a theme word that reaches from one side of the puzzle to the other. When you have all of them (I originally thought there were always eight but learned that the number can vary), every letter on the board will be used. Here are the nonspangram answers:

FOCUS, RELAX, LISTEN, NOTICE, BREATHE, MEDITATE

Today’s Strands spangram

Today’s Strands spangram is MINDFULNESS. To find it, start with the M that’s the first letter on the top row, at the far left, and wind down and then over and up.

Don’t miss any of our unbiased tech content and lab-based reviews. Add CNET as a preferred Google source.