Physicists detect signs of neutrinos at Large Hadron Collider

Neutrinos are produced by radioactive decay, and they interact very weakly with ordinary matter, making them extremely difficult to detect.

Seems like the exact opposite qualities of something you'd want to use for communication.

While neutrinos are not very difficult to generate, they are extremely, astoundingly difficult to detect. Unless we discover a new type of matter that interacts more strongly with neutrinos, we're stuck with cavern-sized detectors that can detect single-digit numbers of neutrinos (out of many trillions), unreliably.

The 'good reason' to use them for communication, if it were practical, is that they interact so weakly, you don't have to worry about pesky things like planets or stars getting in the way of your signal (though gravity is still a thing).

I've wondered the same about gravitons. Notwithstanding the need for likely-huge sensing equipment for the first N years of development...

We can collect enough over hundred of days to make a picture of the sun*. Bear in mind the absolutely unimaginable quantities of neutrinos the sun is producing every femtosecond just in our direction and we can barely detect them with a giant apparatus.

https://apod.nasa.gov/apod/ap980605.html

There have been (theoretical) proposals to use them to communicate with submarines: http://www.physics.ucla.edu/~hauser/neutrino_communication_p...

> Neutrinos have many properties that would make them superior even to the extremely low radio frequencies. Because neutrinos are nearly unaffected by matter, a neutrino beam could traverse directly through the earth from the transmission site to the submarine. A directional beam would allow confidential information to be passed only to the intended recipient. Neutrino communications would also be totally jam-proof. As an additional benefit, a neutrino message could be received in the deepest of waters, leaving a submarine less vulnerable to enemy attacks.

You can tell the tale. It has happened to you!

That pesky sun doing it’s pesky fusion.

That depends on the energy of the neutrino, for lower energies there will be some momentum exchange, but since neutrinos are extremely light, this may be neglected depending on your experimental setup.

At higher energies (>GeV) depending on the interaction type (whether a W-boson or a Z-boson is exchanged), a charged lepton comes out, which can be an electron, muon or tau (the tau decays very fast) and this is the same as the neutrino flavor. Or a hadronic shower if a nucleon is hit.

Of course it's always more complicated than that: for lower energies (sub-GeV) you get resonance scattering, where the nucleus will emit a meson (quark-anti-quark particle), or deep-inelastic scattering, where the nucleus is broken up and hadronic particles create a cascade of more particles.

Edit: see https://en.wikipedia.org/wiki/Particle_shower for more on these cascades. It's a bit bare-bone, I don't have a nice reference right now.

Usually the neutrino will interact with a nucleus and what happens is the reverse of a beta decay, i.e. either a proton will be changed into a neutron or a neutron into a proton, with the emission of an electron or a positron.

So one atom will be converted into an atom of another element, which is a neighbor to it in the periodic table.

Because one neutral lepton goes in and one charged lepton goes out, you might say that the neutrino snatches an electric charge from a nucleus, transmuting it into the nucleus of another element. However this interaction happens extremely seldom. In most cases the neutrino passes by without any effects.

Nevertheless, there has been a proposal to generate extremely powerful neutrino beams, with which to destroy any hidden nuclear weapons.

The trillions of neutrinos going through you are low energy neutrinos from the sun. We've been able to detect those for decades, and with only moderately pricey technology.

The neutrinos in the article are high energy ones produced from proton collisions at the LHC. Although we have ways of producing neutrino beams from accelerators, the LHC is not set up for that, and these neutrinos are sparsely produced, incidentally to the high energy hadron collisions being produced there.

In any case, the LHC cost at least an order of magnitude less than a trillion dollars. And the FASER experiment in particular which runs parasitically on existing LHC infrastructure runs on a shoestring budget, largely privately funded.

It’s interesting that you class dark energy (the thing accelerating universal expansion) as, “We don’t know,” but don’t put gravity into that same category. They are both aspects of general relativity that we have failed to integrate with our other most successful fundamental theories, but if you asked an average person on the street I’m sure they’d put them in very different categories of understanding, as you did.

>Nobody says what goes through my body but me!

That's selfish! Mandatory trip to Chernobyl!

If you think science has you stomach untenable ideas, it's got nothing on what a lack of science will stick you with.

> seems like a lame excuse for saying “we don’t know”.

Dark matter/energy aren’t excuses, they’re labels for things that behave like matter and energy but whose nature is unknown.

In all seriousness, I found myself wondering about those numbers before; but consider that there's on the order of 10^27 atoms in your body. So, if we assume a trillion neutrinos in your body, that indicates that for each neutrino in your body, there are 10^15 atoms - that's one part per quadrillion! A machine capable of detecting neutrinos in your body would need to be _unimaginably_ sensitive, before even considering the intrinsic difficulty in detecting them due to low mass and neutral charge.

John Updike wrote a poem about the crassness of neutrinos:

http://www.physics.mcgill.ca/~crawford/PSG/PSG21/204_97_L21....