Pondering the infinitely large and small, … there’s the neutrino. Grok this:
“The sun is emitting neutrinos like mad, so that about a hundred trillion of them pass through your body every second , …” — Carroll, Sean (2016-05-10). The Big Picture: On the Origins of Life, Meaning, and the Universe Itself (p. 177). Penguin Publishing Group. Kindle Edition.
[Wikipedia] “About 65 billion (6.5×10^10) solar neutrinos per second pass through every square centimeter perpendicular to the direction of the Sun in the region of the Earth.”
So, I got out a ruler and drew a square on a piece of paper, each side 1 centimeter long. Which looked like less surface area than the nail on my little finger. Imagine seeing 65 billion things passing through that space. Like crazy invisible “hail ” everywhere. All the time.
And an amazing property: currently the neutrino’s speed is effectively the speed of light (within measurement error) and likely has non-zero mass! — maybe one millionth that of the electron . And it comes in flavors. And maybe neutrinos do not interact with each other, just like photons.
As far as size, that’s spooky: “… , it does not have a size in the same sense as everyday objects.”
The saga continues with the Big Bang model and research on the cosmic microwave background; also the Standard Model of particle physics. Chasing the ghost particle.
 Neutrino mass inferred from “the experimentally established phenomenon of neutrino oscillation.”
Update March 7, 2017
Supernova 1987A: “This was the first time neutrinos known to be emitted from a supernova had been observed directly, which marked the beginning of neutrino astronomy. The observations were consistent with theoretical supernova models in which 99% of the energy of the collapse is radiated away in the form of neutrinos.”
Update May 19, 2020
Regarding supernovas, observational astronomy has really advanced since 1987.
Symmetry Magazine > “The supernova that keeps on giving” by Shannon Hall (04/28/20).
Although astronomers now spot thousands of supernovae every year, an explosion close enough to be seen with the unaided eye is still a rare event. In fact, the cosmic explosion—dubbed SN1987A or just 87A for short—remains the closest supernova that has been seen in nearly four centuries.
Before 1987, however, much of our understanding of supernovae was based solely on theory.
[When] a type II supernova erupts … the bulk of the star comes crashing down toward its core, forcing it to collapse into one of the densest astrophysical objects known, a neutron star.
At least that was the theory. If true, the action would release a huge stream of particles called neutrinos. And because they would pass through the bulk of the star unimpeded, they would arrive at Earth even before the explosion could be seen as a blast of light. (In fact scientists now think that it’s not the bounce that blows up the star, but the neutrinos.)
[Launched in 1990, Hubble Space Telescope’s] early images revealed what other telescopes had only hinted at: a thin ring of glowing gas that encircled the dying ember that 87A left behind, with two fainter rings above and below. These were clues that the star had dumped a lot of gas into space tens of thousands of years before it exploded. A previous outburst, likely from a red supergiant, could have whittled the star down to expose its hotter, bluer innards. Or perhaps two stars had collided together; this would have shed a lot of gas and left behind a hot mess.
16 thoughts on “Neutrino madness”
So, how is neutrino flux determined? Where does the astounding figure of “65 billion neutrinos per second” come from? Measured or estimated? If measured, how? If estimated, based on what model?
Historically, the neutrino is part of a fascinating chapter in the development of modern physics and our confidence in the Standard Model. Early 20th century studies of beta decay indicated possible violation of conservation of energy (and momentum). Even Niels Bohr hypothesized a real glitch in the law. Wolfgang Pauli, on the other hand, (in 1930) hypothesized an as yet unseen particle. That particle — the neutrino — was later experimentally confirmed (in 1956).
Fermilab’s “Doc Don” presents an overview of the neutrino in this YouTube 5 minute video “Neutrinos: Nature’s Ghosts?”
Published on Jun 18, 2013
Dr. Don Lincoln introduces one of the most fascinating inhabitants of the subatomic realm: the neutrino. Neutrinos are ghosts of the microworld, almost not interacting at all. In this video, he describes some of their properties and how they were discovered. Studies of neutrinos are expected to be performed at many laboratories across the world and to form one of the cornerstones of the Fermilab research program for the next decade or more.
The YouTube video of Nobel laureate Art McDonald’s public lecture “A Deeper Understanding of the Universe from 2 km Underground” at the Perimeter Institute for Theoretical Physics on April 13, 2016, provides a good overview of neutrino research. McDonald shared the 2015 Nobel prize in physics “for the discovery of neutrino oscillations, which shows that neutrinos have mass.” He presents an overview of his personal journey studying the “ghost particle” and establishing the underground research facility for that purpose.
7-22-2017 – Here’s an article about the latest planned advance in neutrino research: Creating the largest neutrino detectors in the world.
Space.com posted another article yesterday about neutrino research at the IceCube lab in Antarctica: “Ghostly Cosmic Neutrinos Are Stopped Cold by Planet Earth, New Study Shows.”
So, what makes some neutrinos so much more energetic? (How is the energy bundled differently? What does the Standard Model say?)
Another update on neutrino research by Don Lincoln (Senior Scientist, Fermi National Accelerator Laboratory; Adjunct Professor of Physics, University of Notre Dame) in this Space.com article (June 19, 2018) [originally published on Live Science], “The 4th Flavor? Scientists Close in on a New Kind of Neutrino.”
This Symmetry Magazine article (10/25/2018) also summarizes neutrino particle research and the Standard Model: “Already beyond the Standard Model — We already know neutrinos break the mold of the Standard Model. The question is: By how much?”
… in the search for physics beyond the Standard Model, one area of notably keen interest continues to be neutrinos.
This extra neutrino — suggested by results from the Liquid Scintillator Neutrino Detector and the MiniBooNE experiment — wouldn’t match up with the generations of particles in the Standard Model. It would be “sterile,” meaning it likely wouldn’t interact directly with any Standard Model particles. It might even be a form of dark matter.
Meanwhile, other oscillation experiments will continue to understand what gave neutrinos their mass in the first place — one of the first hints we have had of physics beyond the Standard Model.
This Gizmodo article summarizes the results of a recent neutrino experiment:”Dark Matter Detector Makes Incredible Neutrino Observation” by Ryan F. Mandelbaum (4-25-2019).
Space.com: “The Quest to Find One of the Most Elusive Particle Decays in the Universe” by Paul Sutter (April 26, 2019).
This U.S. Department of Energy podcast / article “S3 E7: DUNE: The Neutrinos Must Flow” (May 7, 2019) discusses the key role neutrinos play in the Standard Model regarding explaining why anything exists — why the symmetries of the Big Bang did not just result in matter and anti-matter annihilating, leaving nothing — as least no matter, only a “bath of energy.” This article contains some interesting pictures and [visualization] videos, as well as a transcript of the podcast. Over a 1000 scientists from around the world … a “megascience” experiment.
Fermilab: “Long-Baseline Neutrino Facility pre-excavation work is in full swing” (May 2, 2019).
Fermilab > Youtube: “Small Particles, Big Science: The International LBNF/DUNE Project” (March 28, 2016).
Phys.org > Theorists discover the ‘Rosetta Stone’ for neutrino physics by Stephen Parke, Fermi National Accelerator Laboratory (September 24, 2019).
Gizmodo > A Huge Experiment Has ‘Weighed’ the Tiny Neutrino, a Particle That Passes Right Through Matter by Ryan F. Mandelbaum (9/18/2019)
As previously noted, neutrino research is quite an active field. Big science. In particular, addressing a question posed in the cosmological model of the Big Bang theory: why does the universe contain something (matter) rather than nothing (a mere void from matter-antimatter annihilation). One of the unsolved problems in physics – matter–antimatter (baryon) asymmetry.
This Quanta Magazione article (among others) discusses accumulating evidence of a key imbalance between neutrinos and antineutrinos.
Quanta Magazine > “Neutrino Asymmetry Passes Critical Threshold” by Natalie Wolchover (April 15, 2020).
More articles on neutrinos.
• Phys.org > “Where neutrinos come from” by Moscow Institute of Physics and Technology (May 13, 2020) – The Russian RATAN-600 telescope helps to understand the origin of cosmic neutrinos.
• History of the Neutrino > Neutrino properties
Although “every neutrino and antineutrino we’ve ever observed moves at speeds so fast they’re indistinguishable from the speed of light,” are there slower neutrinos? Especially if neutrino energy varies?
• Forbes > “Ask Ethan: Do Neutrinos Always Travel At Nearly The Speed Of Light?” by Ethan Siegel, Senior Contributor (Aug 28, 2020)
Here’s an overview of how the DUNE project makes neutrino “beams.” Sort of the trick to herding cats (which tend to move in all directions). And using the stopping power of planet Earth for a cleaner detector signal.
• Big Think > “Ask Ethan: How can physicists make neutrino beams?” by Ethan Siegel (July 8, 2022) – The ghostly neutrino rarely interacts with matter, so how well can we truly make “beams” out of them?
DUNE’s CENTER-OF-MOMENTUM (COM) FRAME
Image credit: DOE/Fermilab
• DUNE – digging for neutrinos, not spice
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