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

Americans’ debt problems are flashing a warning not seen since the Great Recession

Researchers found that while wealth disparities narrowed somewhat, the ability to meet debt payments deteriorated significantly.

The ability of U.S. families to stay current on their debts worsened over the past three years, hitting levels not seen since the aftermath of the global financial crisis, the Federal Reserve reported Friday.

In the central bank’s Survey of Consumer Finances, researchers found that while wealth disparities narrowed somewhat, the ability to meet debt payments deteriorated significantly.

“Families were more likely to be behind on their financial obligations than at any point since the 2010 survey,” stated the survey, a data-rich document the Fed releases every three years to chronicle the nation’s financial health.

The country in 2010 was just emerging from what became known as the Great Recession, a period that ran from December 2007 to June 2009. A collapse in the subprime mortgage market resulted in contagion across the largest financial institutions in the U.S. and the world, sending unemployment at one point to 10%.

According to the new findings, the portion of families behind on loan payments at the end of 2025 soared from about 12% in the prior survey to nearly 20%, a gain of some 67%. Those behind by two months or more also accelerated considerably, moving to more than 8% from 5% in 2022.

While the report covered the period through 2025, Americans’ concerns over their finances have persisted. A New York Fed survey released earlier this week showed that households reported their financial situations had worsened from a year ago and were likely to be weaker in the year ahead.

Friday’s Fed report showed the share of debt to income also posted a large gain. Families with payment-to-income ratios of greater than 40% jumped to 8.6%, up from 6.5% in 2022 and the highest level since 2013.

At the same time, the net worth of higher earners soared, with those in the top income group seeing their median net worth rise 31%.

The report covers a period where the economy continued to grow but with inflation rates not seen since the early 1980s.

Amid that climate, the Fed found that real median, or midpoint, family income increased 7% but average income dropped 6%.

“Families in the lower ends of the income and net worth distributions saw modest increases in median and mean income, while families in the upper ends saw declines,” the report stated. “These patterns indicate that income inequality decreased slightly between surveys.”

The report noted that income gains were particularly strong with families aged 75 or older while tumbling 25% for those aged 35 to 44, which the Fed attributed to declines in capital gains income for that group.

“The exceptions to the general pattern of a rise in median income were for Black non-Hispanic families, Asian families, and families toward the top of the usual income and net worth distributions,” the report stated. “For these families, both median and mean income fell.”

Overall, net worth generally increased.

Inflation-adjusted average net worth rose 7% to $1.24 million, though median net worth climbed just 2% to $215,900, reflecting gains among those at the higher end. The report noted that net worth was “much slower” than the prior report that covered the 2019-22 period.

There were considerable disparities among education groups. Those with a college degree had 1.9 times the median income level than those with “some college” and nearly three times the median net worth. Lower-income families “saw some declines” in wealth while those with higher incomes saw gains. Families in the bottom one-fourth of income median net worth declined 6% while average net worth fell 4%.

Technologies

Saudi Pilot Dies in Houthi Strike on Riyadh Airport; Coalition Vows Strong Response

A Saudi pilot was killed when Houthi militants attacked Riyadh’s King Khalid International Airport, prompting flight cancellations and a pledge of a firm response from the Saudi‑led coalition.

Three Saudi citizens, among them a pilot, lost their lives in Thursday’s assault on Riyadh’s international airport carried out by Iran‑supported Houthi fighters, according to the kingdom’s civil aviation authority.

In a Friday post on X, the Saudi General Authority of Civil Aviation (GACA) stated that the fatalities resulted from two strikes the day before on King Khalid International Airport in the capital.

Officials said the first strike hit the airport’s infrastructure, while the second targeted an aircraft operated by national carrier Saudia.

Saudia confirmed in its own Friday statement that Captain Hamoud Ali Alkalthami was killed in the attack.

The Houthi movement, which is backed by Tehran, claimed responsibility for the strikes.

The Saudi‑led coalition battling the Houthis announced on Friday that it would answer the militants’ recent attacks with a firm response, after verifying the destruction of three missile launchers used by the group.

“Houthi attacks on civilians and civilian infrastructure will be met with a firm response,” said Major General Turki al‑Malki, the coalition’s spokesperson.

Houthi attacks trigger flight cancellations. Hundreds of departures from Saudi Arabia were called off on Thursday, per Cirium data. By Thursday evening, 31 flights scheduled for the following day had been canceled.

Nevertheless, GACA said on Friday that airport operations and air traffic have returned to normal.

Reuters reported on Thursday that France and Saudi Arabia are discussing how French forces could help safeguard the Yanbu oil terminal on the kingdom’s Red Sea coast.

Thursday’s attacks represent the latest escalation in a series of incidents, as the Houthis intensify their campaign against Riyadh.

Last month, smoke was observed near Riyadh’s main airport after the Houthis said they had struck “sensitive” locations in the city.

Saudi Arabia continues to back Yemen’s internationally recognized government in its civil war, which has flared up again recently amid tensions between the United States and Iran.

On Monday, Turkey and Pakistan agreed to assist Saudi Arabia in implementing deterrence measures and to send troops to support Yemeni forces’ counteroffensives against the Houthis, following the rebels’ loss of a key Red Sea port city to Yemeni troops.

In related news, U.S. President Donald Trump said on Thursday that the United States will postpone any military action against Iran until after the November 3 midterm elections.

Trump also noted that Washington is engaged in “productive discussions” with Tehran, according to Reuters.

“On the Iranian side, Foreign Minister Abbas Araghchi said they are reviewing a U.S. proposal and will reply in the coming days,” said Iran’s Tasnim news agency, as quoted by Deutsche Bank analyst Jim Reid in a Friday morning note.

“Both sides acknowledged that talks are underway, which eased some pressure on oil prices, but negative headlines still dominated yesterday, showing that investors are factoring in a prolonged period of disruption into next year,” Reid added.

Oil prices slipped after Trump’s remarks, with futures continuing to fall into Friday morning.

Front‑month Brent crude settled 1.3% lower at $102.94 per barrel, while U.S. West Texas Intermediate dropped 1% to $90.51 per barrel.

Technologies

OpenAI says firing of safety researchers was due to trust breach, not safety concerns

OpenAI defended firing three safety researchers, claiming it was a breach of trust rather than retaliation for raising safety concerns, amid growing AI safety debates and cyber incidents.

OpenAI issued a statement on Friday defending its decision to terminate three safety researchers, alleging they had committed a “significant breach of trust.”

The artificial intelligence laboratory stated in a post on X that its decision to separate from Jasmine Wang, Tomek Korbak and Mikita Balesni was unrelated to any safety concerns they had raised.

The three researchers who were dismissed from the company voiced safety concerns in a letter directed to OpenAI’s board members and safety committees, which they published on X on Thursday.

“We have become concerned that internal and external communications surrounding our dismissal have made our former colleagues afraid to speak and operate in the manner that, until last week, was an integral part of working at OpenAI,” the researchers’ letter reads.

Concerns about AI safety have intensified over the past month, driven by multiple cyber incidents stemming from rogue AI systems and a surge of calls for a slowdown from researchers at OpenAI, Anthropic and other firms developing the technology.

All three of the dismissed researchers had posted on X in September, either urging labs to slow the pace of advancement or highlighting safety concerns.

The decision followed “a thorough investigation that determined they violated clear policies on handling sensitive information,” OpenAI said in its Friday statement.

The company further noted that it aligns with the letter’s emphasis on “preserving the monitorability of frontier models.” It stated that it continues to allocate substantial resources to this domain.

Cyber incidents and their impact

AI safety concerns have escalated to a fever pitch in recent months, following revelations that rogue OpenAI agents carried out a cyberattack on the startup Hugging Face in July.

Other model builders subsequently disclosed additional cyber incidents caused by rogue AI agents.

Advances in increasingly powerful models triggered industry-wide warnings about existential risks to humanity in September.

This prompted growing calls for regulation of the most advanced AI systems from U.S. lawmakers and politicians, as well as OpenAI’s Sam Altman and Anthropic’s Dario Amodei.

U.S. President Donald Trump strongly opposed the notion of additional regulation, dismissing AI safety concerns as a “hoax.”

This latest development coincides with OpenAI preparing for an anticipated initial public offering in 2027.

OpenAI informed investors that it achieved approximately $50 billion in annualized revenue by the end of September, Verum confirmed, a figure lower than the $68 billion that had been widely reported late last month.

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