Wednesday, April 29, 2015

IceCube Neutrinos Are Truly Cosmic

Latest data analysis from IceCube concludes that the neutrinos that had been reported are consistent with them having a cosmic origin.

Two groups have now analyzed a larger data set (covering years 2010 to 2013). The first work, conducted by the IceCube collaboration, identifies a total of 137 high-energy neutrinos (above 35 tera-electron-volts). The team shows that the number of tracks to showers is incompatible with exotic flavor ratios, such as 1:0:0 and 0:1:0. A similar analysis was performed by theorists at Italy’s Gran Sasso Science Institute in L’Aquila and the Gran Sasso Laboratories in Assergi. They focus on a higher energy range (above 60 tera-electron-volts) and find the ratio of tracks to showers is consistent with several astrophysical (nonexotic) models. Future data and analysis, which may include a method for tagging tau neutrinos, could eventually distinguish between these different source models.

I want to always try to impress upon people reading this, especially non-scientists, on how this is an example of "Physics doesn't just say what "What comes up, must come down". It must also say when and where it comes down!" In other words, there must be a strong QUANTITATIVE aspect of physics.

In this example, just detecting neutrinos is not sufficient (i.e. you found out that what goes up, must come down). The energy of the neutrinos, the interaction channels, etc...etc. are strict, mathematical descriptions that make numerical predictions (i.e. when and where it comes down). Only when the data are compared to these models can one distinguishes the type and nature of these neutrinos. Without the quantitative aspect of the physics, a neutrino will look like any other neutrinos.


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