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Are Neutrinos Their Own Evil Twins? Part 2: The Weak Left-Hander
(This is Part 2 of a series on neutrinos, Majorana fermions, and one of the strangest open questions in physics. Read Part 1 first.)
What I’m about to say may be some small comfort for those of you who are left-handed and feel like the world isn’t constructed with you in mind. When it comes to fundamental particles, the universe doesn’t care if you’re left- or right-handed. It doesn’t make any difference. Think of all the forces of nature and the ways they interact. Gravity and mass. Electromagnetism and charge. Strong force and color charge. Left-handed? Nobody cares, nobody notices, everything is the same. Right-handed? Same deal.
An electron buzzing around is constantly flitting back and forth between left- and right-handed identities — the massless twins that when combined give us an electron. When it hits you, you don’t care if it’s left- or right-handed mode. You feel its mass and charge. That’s it.
Oh, right, except for the weak nuclear force.
Ahem, right, so, weak nuclear force. The quirky cousin in the family of the forces. The eccentric one. The one living in its own little world, to the beat of a different drum. Or accordion. Or vuvuzela.
The weak force REALLY cares about handedness. It cares SO MUCH that it ONLY, and I mean ONLY, talks to left-handed particles. It’s BLIND to right-handed particles. It’s like some sort of germaphobe that will ONLY shake hands with left-handed people.
Famed physicist and all-around curmudgeon Wolfgang Pauli once quipped, “I cannot believe God is a weak left-hander.”
He said that because even though the weak force is the odd one out, it’s absolutely critical for most of the universe as we know it. One of its superpowers is beta decay, which allows it to reach inside a neutron, grab one of its quarks, and change it, transforming the neutron into a proton. That transformation makes nuclear fusion and fission possible, which is responsible for, among other things, making stars shine.
Pauli spent years disparaging, in typical Pauli fashion, the experiments conducted by Chinese-American physicist Chien-Shiung Wu — known as Madame Wu, the first lady of physics — who conclusively demonstrated that the weak force only works with left-handed particles. Her experiments showed that radioactive decay of cobalt-60 tended to prefer one direction over another. When she first made the announcement, nobody liked it because it broke up the nice and tidy picture of the universe we had been so meticulously cultivating for decades. But evidence is evidence, and Madame Wu was exceptionally good at getting it, so even the old curmudgeon relented.
Okay, that’s weird. Fine, universe, whatever. In most cases this doesn’t matter at all, ever. That’s because every particle, like an electron, is constantly flitting between left- and right-handed states. If the weak nuclear force wants to talk to the electron, it just — in a sense — “waits” for the left-handed version to show up (which isn’t very long at all), and grabs it. It doesn’t need the right-handed version.
To torture this analogy even further: if our germaphobe only shakes hands with left-handed people, that would normally be incredibly restrictive and largely unfriendly…except this germaphobe happens to live in a world filled with ambidextrous people.
So it doesn’t matter.
Oh, right, except for the neutrinos.
Neutrinos are exceptionally selective when it comes to the forces. They have no electric charge, so they don’t interact via electromagnetism. They have no color charge, so the strong force is out for them. They feel gravity because if you exist in this universe you don’t get a choice about that.
But the weak force? Oh, they LOVE the weak force. They’re the one kind of particle our left-hand-only germophobic force will actually SEEK OUT at an event. They speak the same language. They eat the same kinds of foods — with their left hands, of course.
And this is where the story comes screeching to a halt. Because there are ONLY left-handed neutrinos.
Seriously. Every single neutrino we have ever observed, ever, in every physical reaction, is only left-handed. They don’t flit back and forth. They don’t switch identities. They just…are left-handed.
Now the antineutrinos? Those exist, but those are ONLY right-handed.
This is completely unlike any other particle. Any other massive particle has both left- and right-handed identities that constantly swap back and forth. But the neutrino? Only left-handers for neutrinos, only right-handers for antineutrinos. That’s it. Trillions of neutrinos passing through your thumb every single second — not a one is right-handed.
For a long time, this was classified under “weird but fine.” We thought neutrinos were massless. And massless particles, like the photon, are locked in either left- or right-handed mode forever. There was weirdness — we see both left- and right-handed photons in equal measure, but ONLY left-handed neutrinos and right-handed antineutrinos — but that was tagged as “problem for another day.”
And then we discovered that neutrinos have mass.
Massless particles are locked into one hand. Massive particles swap back and forth. The neutrino is both massive AND locked.
I don’t know about you, but this sounds like a problem.
In Part 3, we look at the most straightforward fix — and what it quietly hides.
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Why now? Because that’s how trauma works. Get over it

Why now? Why now?
Every time a woman comes forward with her story of sexual assault, this is the first question she faces. OK, maybe the second — after some variation of “Are you a lying slut?”
At least we are consistent. But on behalf of all survivors everywhere, of any gender, identity or age, let me give you some blanket answers to “Why now?”
Survivors come forward now, whenever now is, because they have reached the point in their recovery when facing the inevitable “lying slut” accusation is less terrible than watching their abuser strut around as if that person is not a dangerous, cruel predator who is almost certainly going to hurt someone else if they are not stopped.
Whether it’s in Congress, on a movie set, in the halls of their school — wherever that predator is just living their life without consequence — there is a survivor who has been cowering in the shadows of her own life, in pain, wanting to scream to the world that this person is not what they seem.
But the price of that honesty has always been steep. Too steep. Even after #MeToo.
Ask Cassie Ventura. Ask Jennifer Siebel Newsom. Ask E. Jean Carroll. Dolores Huerta. Simone Biles.
Even powerful women can’t escape the blowback, the fear. Even powerful women are steamrolled over and over again by the overwhelming presumption that they are lying, and there is an ulterior motive for coming forward at this particular moment.
Imagine just being an average person holding that secret. Who are any of us to stand up alone against a rich and powerful man whose very freedom will depend on crushing our credibility?
P. Diddy. Harvey Weinstein. Donald Trump. Cesar Chavez. Larry Nassar. Eric Swalwell.
Those men know power, and know how to use it.
“He thought he was untouchable. He acted with total impunity. He never thought that the consequences of his actions would follow him,” Ally Sammarco, one of the women who has spoken out about Swalwell (who has previously denied allegations of misconduct), told CBS.
It’s why the women of the Epstein files stayed silent for so long. It’s why there are thousands of rape survivors out there right now who have never said a word about what they endured, and maybe never will.
“Why now?” is just a more palatable version of “lying slut,” a question based on ignorance about how trauma — and society — works. A question meant not to elicit fact, but to feed the Jezebel frenzy men always use in their attempt to escape justice.
Here’s the truth about sexual assault: There is no right way to respond to it, no right time. There is no one reaction that proves it happened or that creates the perfect scenario that will protect the survivor’s reputation while delivering justice upon the predator. In fact, there is really no way at all to respond to a sexual assault that won’t bring secondary trauma.
Wait years and face disdain — that it didn’t happen, wasn’t serious, is only coming out now for some agenda, like politics or money.
Report it immediately and be prepared for every move, every smile, every sip of a drink, to be examined for signs that this was, if not consensual, somehow deserved — a gray area of shared responsibility.
Imagine, at a moment of crushing vulnerability, when your body has been violated and your mind is reeling trying to find safe ground, being bludgeoned by these accusations, stated or implied, that you brought this on yourself.
“Why now?” becomes “Why would you?”
Even when the scenario is one in which there can be no defense — such as the UCLA gynecologist, James Heaps, who on Tuesday pleaded guilty to sexually abusing five of his patients during exams — the cost of reporting is terrible. That case has wound on for years, leaving each of the victims to constantly relive their worst moments, constantly fear that all of their courage would come to nothing.
Which is why survivors don’t always come forward. Maybe they need time to put themselves back together, even just a little bit. Maybe the fear of all that societal scrutiny is just too much. Maybe they fear they won’t be believed, and their attacker will be free to harm them again.
Maybe they just want it to all go away. Maybe they do blame themselves, and are paralyzed by an unfounded shame.
There are so many reasons why survivors stay silent — and none of them are because it didn’t happen, or because they are lying.
Lonna Drewes, the Beverly Hills model who came forward Tuesday with an accusation that Swalwell drugged and raped her in 2018, summed up the experience of many, many survivors.
“I did not want to live anymore,” she said of how she felt after the attack. “I cried all the time for years.”
So here’s the real answer to “Why now?” from a victim’s statement that one of Heap’s survivors read in court.
“What you intended to break, you did not,” she said.
That is the answer to “Why now?” Because the bravery and courage at the heart of the survivor was bruised but not defeated.
Because she doesn’t want it to happen to anyone else.
Because she deserves to be free of his secrets: Ones she has been forced to keep out of fear of him, but also of us.
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Middle East War Will Slow Global Economic Growth, I.M.F. Warns
The conflict could also fuel another bout of inflation, according to the International Monetary Fund.
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Are Neutrinos Their Own Evil Twins? Part 3: Dirac’s Direct Solution
(This is Part 3 of a series on neutrinos, Majorana fermions, and one of the strangest open questions in physics. Read Part 1 and Part 2.)
Neutrinos have mass. We know this. And massive particles — ALL massive particles, as we established in Part 1 — flicker between left- and right-handed states. That flickering IS the mass. The constant Higgs handshake, the endless switching. That’s the deal. That’s what makes it all hang together.
But neutrinos don’t flicker. Left-handed neutrinos stay left-handed. Right-handed antineutrinos stay right-handed. No switching. No flickering. Nothing. And yet they have mass.
So either everything we just said about mass is wrong — and I’m pretty confident it isn’t — or something very strange is going on with the neutrino.
The most straightforward solution is this: the right-handed neutrinos ARE there. They exist. We just can’t see them.
Here’s why that works. Think about the electron. The electron has two completely independent ways to describe it. One: handedness. Left or right. But we’ve found that for a massive particle this is just the flickering — transient, constantly changing. It’s not a permanent label. Handedness for an electron is almost…incidental. It doesn’t define what the electron fundamentally IS.
But there’s another way to describe an electron: particle versus antiparticle. Electron versus positron. And THIS one is permanent. Important. Pinned open by electric charge. An electron has charge. A positron has the opposite. If they meet, they annihilate in a flash of pure energy. The universe treats this distinction as sacred, because charge is conserved, and the universe does not mess around with conserved quantities.
So for the electron: handedness flickers and doesn’t really matter. Particle versus antiparticle is locked and fundamental and really, REALLY matters. Two descriptions. One important, one not.
This gives us what we can reasonably call the Dirac picture — named after Paul Adrien Maurice Dirac, who first worked out the mathematics of relativistic quantum particles. In this picture, the neutrino works exactly the same way as the electron. Two options for handedness, two options for charge. Four total combinations.
Left-handed neutrino: we see them, the weak force loves them. Right-handed antineutrino: we see them too, the weak force produces them in beta decay. Those are the observable ones.
Then there are the other two. Right-handed neutrino. Left-handed antineutrino. These exist in the theory. They just don’t interact with anything. Our germaphobic weak force won’t touch them — wrong hands, remember? They have no electric charge, so electromagnetism ignores them. No color charge, so the strong force ignores them. The only force they EVER feel is gravity. They are, in the most complete and total sense imaginable, invisible. Not hard to detect. Not rare. Not shy. INVISIBLE. Completely, permanently, in-principle undetectable by any instrument we could ever conceivably build.
They could be in this room RIGHT NOW and we have no way of detecting them.
And look — it works. The math is consistent. It explains why we only see left-handed neutrinos.
There’s even something genuinely beautiful hiding in it. If those right-handed neutrinos exist and are ENORMOUSLY massive — and I mean absurdly, almost comically massive, like ten to the fifteen times heavier than a proton — then something elegant falls out of the mathematics. Their mass and the mass of ordinary left-handed neutrinos end up inversely linked. Make the right-handed partner heavier, and the left-handed neutrino gets lighter. It’s called the seesaw mechanism. Push one end down, the other goes up. And it would explain why neutrino masses are so vanishingly, almost insultingly tiny. The lightness of the neutrino would be a direct echo of the enormousness of something we can never directly observe.
That’s nice.
But here’s the thing. When it comes to the electron, its two descriptions — handedness and particle-versus-antiparticle — are kept independent by electric charge. Charge is what forces them apart. Charge is what insists that “electron” and “positron” are categorically different things that cannot be confused or collapsed into each other.
But the neutrino has no electric charge. We have bookkeeping devices that keep neutrinos distinct from antineutrinos in our equations — but unlike electric charge, they’re not sacred. They’re not protected by any deep principle. They’re accidental. The universe didn’t mandate those rules. They just fell out of the math, because we designed the math that way.
Here’s the thing: nothing is FORCING the distinction between “neutrino” and “antineutrino” to be fundamental.
And that’s the crack in the door that Ettore Majorana walked through.
In Part 4, we get to Majorana’s last paper — and the experiment that might finally answer the question he left behind.
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