“…with, of course, no noticeable effect.” was the rest of the sentence regarding interactions. First, a single photon interaction in the eye would be effectively filtered out as noise by the retina itself. Second, if it were instead in the optic nerve and a signal was triggered, the brain would filter out that one-off event, normally. If not, the higher brain functions would still tend to ignore a minute dot flashing, ever so briefly.
Astronauts see flashes all the time, the difference is, they’re frequent, hence are noticed. The reason astronauts see flashes is due to ionizing radiation though, not neutrinos. It is thought that the flashes are caused by ionizing radiation directly stimulating the optic nerve.
The article speaks of that million people having an interaction. Even money, it was a statistical calculation on the probability of interaction. It would also include an interaction counting ANYWHERE in the body.
Assuming the average person has a mass of 50 kg, the figure of 100 neutrinos interacting with an eye scales up to 1.25 million.
Huh? Where, exactly?
It probably wouldn’t be a single photon, though, but a Cherenkov ring thereof on the retina, provided you’re looking in the right direction.
I think that is what Robert Parks is referring to, from his email newsletter:
While, once again, the most likely explanation for an extremely unusual observation is that the observation is somehow in error (until and unless it is replicated by other labs), this argument strikes me as nuts. Essentially it is saying: “the observation does not fit some aspect of how I currently think the universe works therefore the observation must be wrong.”
Not how science works.
Okay, so see my post a few up. A few dozen even.
A few million people had an interaction. Both eyes together weigh about 50 to 60 grams of the 50 to 60 kg average human, so we are down to a few thousand individuals who had an eyeball that had an interaction. Of those it would be potentially perceptible in only those individuals who were awake, in pitch black, with the reaction falling on an area relatively densely covered in rods rather than the cone rich center of the eye, and then only to the point of being slightly better than chance at guessing whether or not a stimulus occurred when asked. The percent of a day the average person is awake in absolute pitch blackness? Guess with me. I’m guessing less than .001%. Ach, guess up by a factor of ten.
So, yes, *maybe *one or two people … if you are very generous with how define “flash.”
Discounting the result of an experiment because of other experimental results that outweigh it (in this case, the experiments supporting the theory of the weak interaction) is a perfectly reasonable way to do science.
It’s exactly how science works. The most likely, but not the only explanation at present is measurement error. That doesn’t prevent testing to confirm or refute it.
Newton’s laws were pretty well established when Einstein came along, and it took extraordinary evidence to overturn or modify Newton, but we got it, and it accumulated. This is no different.
“Discounting”, yes. Requiring a high standard of evidence, such as multiple replications in different labs, yes. Assuming that a result must be in error because it does not fit extant theory, no.
(Andrew Cohen and Sheldon Glashow did not “make the observation that superluminal neutrinos would radiate by the same effect as Cerenkov radiation when particles exceed c/n” … they hypothesized such as what would be expected of superluminal neutrinos according to their current understandings. This is not just being pedantic; it is a big difference.)
In practicality yes, much to the detriment of us all.
Please note the difference between what you are saying, that something outside of standard understanding requires a large burden of evidence to accumulate before we consider significant changes to accepted paradigms, and the statement you quoted:
Not is very likely wrong. Not would require much replication to be believed. No, we already know it must be wrong. “Observations” of what superluminal neutrinos would do have been made, doncha know?
‘Wrong’, just as ‘right’, always comes with error bars in science – results are rejected or accepted up to a certain level of confidence. It’s really not worth getting worked up over someone’s phraseology.
Here is a hopefully clarifying post on supernova neutrinos and eyeballs, in which I walk through the relevant numbers in more detail.
Neutrino detection, and the Kamiokande-II detector
Supernova 1987a led to 11 detected neutrinos in the Kamiokande-II detector. Here’s how.
Kamiokande-II was a detector consisting of a tank of 2,140 metric tons of water surrounded by optical-photon detectors called photomultiplier tubes (PMTs). When a charged particle (like an electron) moves at relativistic speeds through water, it produces Cherenkov light that propagates through the water to the PMTs. The Cherenkov light has a spatial pattern to it that reveals the direction of travel of the charged particle. While this directional feature is only loosely relevant for this discussion, it is quite striking and worth mentioning. This picture shows what a 492-MeV (energy) electron looks like in the similar (but larger) Super-Kamiokande detector. This electron was traveling toward the center of that circle of light detected at the wall. The electron did not reach the wall at all – only the Cherenkov light that it produced did. The electron itself (and its knock-on effects from banging into atoms) only lasted across 6% or so of the tank’s width before running out of steam and stopping.
The high-energy electron “seen” in that image was created by the interaction of a neutrino. This neutrino would have passed quietly into the tank, but unlike the jillions of its breathren that then quietly exited, this one happened to interact. There are multiple ways the interaction may have proceeded, but the most probable for the image above is this:
(electron-type neutrino) + neutron –> electron + proton
In this reaction, the neutrino has turned into an electron by swapping charge with the was-neutron/now-proton via the weak interaction. That is, the detected electron wasn’t present in the water before the interaction occurred.
You could also get these sister reactions if the neutrino flavor were different:
muon neutrino + neutron –> muon + proton
tau neutrino + neutron –> tau + proton
However, the incoming neutrino needs to have enough energy to make up the rest mass of the muon or tau particle that it would become. Supernova neutrinos, which have energies in the 30 MeV ballpark, do not have enough energy for this. Thus, only the electron neutrinos from a supernova can undergo this reaction.
To complicate matters more, the binding energy of the oxygen nucleus (which is 15 MeV or so) makes the above reaction hard even for electron neutrinos from a supernova, and when they do overcome the binding energy, the resulting electron is often below detection threshold. Thus, the reaction that leads to most of the supernova events in water is actually:
(anti-electron-type neutrino) + proton –> positron + neutron
Because the protons are not part of a bound nucleus (i.e., they are from hydrogen), there is no binding energy to overcome, and this reaction can proceed smoothly.
There is also the possibility that a neutrino interacts with an electron instead of a neutron (or proton). This reaction:
neutrino + electron –> neutrino + electron_with_lots_of_energy
can be induced by any flavor neutrino, but the interaction rate is much lower than the nucleon-target reactions. (Well, except for with muon and tau neutrinos, where this is the only reaction possible due to the rest mass limitations on the other reactions.)
Number of visible Cherenkov photons produced in a single supernova neutrino event
The Kamiokande-II detector’s PMTs covered 20% of the surface of the tank, so if a photon reached the wall of the tank, it had a 20% change of hitting one of the PMT’s active surfaces. However, each PMT’s surface was only 30% efficient at photon detection. Thus, 0.2*0.3 = 6% of Cherenkov photons that were produced were detected. (We can safely assume that the water was perfectly clear.) On average, 26.3 PMTs fired for a 10 MeV electron. Thus, a 10 MeV electron produced around 440 visible photons. I say “visible” here because the wavelength acceptance band of the PMTs matches the visible range pretty well. Just like the human eye, these PMTs are blind to (far) UV and IR. (This ~440 number will be reduced below.)
One can calculate the number of photons (and their wavelength spectrum) from first principles, but we can skip that step here because the Kamiokande-II detector has already effected the calculation for us.
Rate of neutrino interactions in the eye
While Kamiokande-II saw 11 events, these were all above the detection threshold. Of note, an electron (or positron) with energy 8.5 MeV would only get noticed 50% of the time, and an electron of energy 4 MeV would rarely be noticed. This threshold is not relevant for our eye, and we must count all the interactions above about 2 MeV. This adjustment is around a factor of 2, meaning there were around 22 relevant underlying events, which I will round to a clean 20.
These 20 interactions happened within 2,140 tons of water. The fluid in a human eye weighs about 4 grams, so each person has about 8 grams of fluid available for neutrino interactions, which means there are about 50,000 metric tons of eyes out there. This means that roughly 20 * 50000 tons / 2140 tons = 470 supernova neutrino interactions occurred within eyeballs.
Low energy electrons passing through a fluid. These neutrino interactions would yield electrons or positrons of several MeV (~2 to 30 MeV). However, only those electrons below about 3 MeV in energy will spend their entire time within the eye. The higher energy electrons will exit, leaving only 3-MeV’s worth of light behind. Thus, we can treat all the electrons as having ~3 MeV of energy as far as the eye is concerned.
Aside: Note that this means that a 30 MeV electron can start outside the eye and travel through it, which means that the eyeball interaction rate calculated above is an underestimate of what we want. Rather than 470 interactions in eyeballs, we want the number of interactions that can lead to an electron passing through the eyeball. This correction is again likely around a factor of 2, but I’ll leave it out and mention it here only as a curiosity.
Amount of light produced in each interaction
Our 3-MeV-effective electron passing through the eyeball will produce within the eyeball three-tenths the Cherenkov radiation of the 10 MeV electrons in Kamiokande-II (3 MeV / 10 MeV = 0.3). Thus, the number of visible photons is about 440 * 0.3 = 132. Call it an even 100, since the PMT wavelength acceptance does go down a bit below the visible range (to 300 nm or so).
Summary
Something around 500 people (an underestimate by possibly 2x, per above) will have had neutrino interactions in their eyes and neighboring tissues that would yield high-energy electrons (or positrons) passing through the eye. Such an electron would produce about 100 visible photons of light directed in a conical pattern. From geometric considerations, about one third of these events would leave all 100 photons directed toward the retina, well above visual threshold for adequately dark-adapted observers; another third would leave about half of the light on the retina; and a final third would miss most of the retina.
This calculation ignores any direct stimulation of the optic nerve through ionization, which I take as cheating.
I’m happy to expand on any of the statements or calculations above, as desired.
Would objects moving faster then the SoL increase velocity as they lose energy?
Good point, but I think (as a non-expert) what this paper assumes is that these neutrinos aren’t tacyons as such, instead they are “Lorentz-violating particles”. So it assumes that Lorentz symmetry (the basic symmetry of special relatvity) is not really a fundamental symmetry, instead it’s just the limit of some other symmetry under certain situations (e.g. low energy). The basic argument is that neutrinos as Lorentz-violating particles is inconsistant with other experiments.
Pretty much the bottom line I already came to. So about 150 to 200 individuals across the globe would have an event that if it occurred while they were both fully dark adapted and awake could be possibly perceived. Now of those 150 to 200 individuals, how many do you think were both fully dark adapted and awake at that precise moment? Any?
In the case that this query is directed my way: I make no attempt at addressing the sociological factors. I only wanted to allay any confusion introduced by physics misinformation up-thread, while adding some additional background information. Also, a more careful treatment of the photon count leads me to a higher yield than I guessed before.
I can see that my request for a temporary halt in eyeball discussions was well-received. 
But the whole OP boils down to eyeballs, after all.
Try asking a mod to alter the title to include eyeballs. It is a subtopic about the nature of neutrinos and observing them.
Well we can take a vote as to whether or not discussion has has concluded to the satisfaction of we pupils of both physics and psychophysics … and I take it the ayes have it.
I’ll hide now.
Very good post, Pasta. Thanks for going through the trouble.