
A major physics experiment just detected a particle that shouldn't exist - tosh
https://www.nbcnews.com/mach/science/major-physics-experiment-just-detected-particle-shouldn-t-exist-ncna879616
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tehwalrus
Interesting, but almost certainly a systematic error. We have a lot of
experiments over the last few decades detecting neutrinos, and only 2
detecting "sterile" ones (i.e. slightly too many) seems like the outlier.

(These experiments are usually buried underground or similarly crazy in their
location, so if they got something wrong about the setup/geology, e.g. If the
rocks are slightly radioactive, that could skew the results like this in
exactly this way.)

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imglorp
4.5 sigma is not an outlier. It might still be system error of course.

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ncallaway
I think they were saying the experiments themselves were outliers, rather than
the data within them.

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mathewsanders
There was a plot line in The Three Body Problem where aliens sabotaged
particle physics experiments to limit human technological advancement while
they were making the journey to earth.

Amazing series and even friends that don’t enjoy science function enjoyed
reading them.

[https://en.m.wikipedia.org/wiki/The_Three-
Body_Problem_(nove...](https://en.m.wikipedia.org/wiki/The_Three-
Body_Problem_\(novel\))

~~~
poopchute
I was just wondering what to listen to next, now that I finished the expanse
series (until the next book at least). Thanks for the recommendation; I'll
check it out

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sctb
Previously:
[https://news.ycombinator.com/item?id=17210982](https://news.ycombinator.com/item?id=17210982).

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coldacid
How can we detect something that doesn't interact with anything?

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qubex
In the article it is mentioned that the ’detection’ occurs by subtraction:
three types of neutrino (electron, muon, and tau) can be detected; a known
number is being sent by the source and the neutrinos oscillate between the
states as they travel. However the total comes up short, indicating that they
are also transmuting into some other variety, nicknamed ’sterile’. Since the
neutrinos we know about interact by means of gravity and the weak nuclear
force, and the latter is how we detect them, it can be summarised that the
missing neutrinos must have oscillated into a sterile state that does not
interact through the weak force.

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snowwrestler
This is what I thought too, but the article pretty clearly states that they
detected too many neutrinos, not too few.

> Both experiments have now reported more neutrino detections than The
> Standard Model's description of neutrino oscillation can explain the authors
> wrote in the paper.

I had the same question you did: if the defining characteristic of a sterile
neutrino is non-interaction, how does it get detected? My best guess is that
NBC's summary of the definition of a sterile neutrino is probably wrong in a
some subtle way.

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yk
In short quantum stuff. With additional kinds of neutrinos, you get different
patterns of oscillation, and the experiment is located at a spot were sterile
neutrinos change the oscillation pattern in such a way that you get additional
neutrinos, instead of less as one would expect if they would just have another
classical oscillation mode.

Perhaps a good analogue is the double slit experiment, the wavefunction
interferes with itself and you get more photons at the peaks, not only less at
the dark patches of the interference pattern, as one would expect in case of
just blocking some of the light.

