Can the 3 neutrino masses really be found using SN 1987A data?

Neutrino masses remain a significant unsolved problem in physics and their nonzero value proves the Standard Model is incomplete. Currently, the values of the three masses only have upper limits from cosmology and experiments like KATRIN. This paper shows that the SN 1987A neutrino data can remarkably yield values for the three neutrino masses, and not merely upper limits. Although this seemingly preposterous idea was suggested a dozen years ago by the author, here it is demonstrated in a much more convincing manner with many new elements, including a stronger statistical treatment, and a thorough explanation of why the method used to find the three masses from supernova SN 1987A neutrino data really works. The key to finding the three neutrino masses is realizing why three normally accepted assumptions are unjustified, The three rejected assumptions are:(a) the 5-hr early LSD (Mont Blanc) neutrinos are unrelated to SN 1987A, (b) any neutrino masses $m_k>1 eV/c^2$ cannot be reconciled with upper limits on the ``effective mass" from KATRIN and other data, and (c) the spread in neutrino emission times from SN 1987A data is too great for the method to work. A particularly crucial piece of evidence supporting the claim made in the paper’s title involves a recent negative KATRIN result finding an absence of sterile neutrinos. This absence of a sterile neutrino signal leads to two tests of the claim based on existing data: one for KATRIN and one for IceCube.

💡 Research Summary

The paper claims that the neutrino data from Supernova 1987A can be used to determine the three non‑sterile neutrino masses, rather than merely setting upper limits. The author first reviews the status of neutrino mass measurements, noting that experiments such as KATRIN have only provided upper bounds on an “effective mass” and have not resolved the individual mass eigenstates. He then challenges three widely‑accepted assumptions: (a) that the five‑hour‑early neutrino burst recorded by the LSD detector at Mont Blanc is unrelated to SN 1987A, (b) that any neutrino mass larger than about 1 eV/c² is incompatible with existing limits, and (c) that the spread in emission times of SN 1987A neutrinos is too large for a time‑of‑flight analysis to be meaningful.

The core of the analysis rests on a simple relativistic relation between a neutrino’s arrival delay t (relative to a photon) and its energy E, assuming that all neutrinos were emitted essentially simultaneously. Using v≈c(1−t/T) and the relativistic speed formula v/c≈1−m²c⁴/(2E²), the author derives 1/E² = M·t with M = 2Tm²c⁴, where T≈168 000 years is the light‑travel time from the supernova. Consequently, neutrinos of a given mass should lie on a straight line through the origin in a plot of 1/E² versus t. Since there are three mass eigenstates, the data should cluster around three such lines.

The author gathers 37 neutrino events recorded by Kamiokande II, IMB, Baksan, and the LSD detector. Each event’s measured energy and arrival time are converted to (t, 1/E²) coordinates. A least‑squares fit of the points to three lines that share the origin is performed, with the slopes of the lines providing the three mass‑squared values via m²c⁴ = 2TM. The fit yields a χ² of 29.9 for 34 degrees of freedom (p≈0.67). When a horizontal timing uncertainty of ±0.5 s is assumed, the fit improves, and with ±1 s the p‑value reaches 0.91, suggesting that the data are compatible with the three‑line hypothesis.

A crucial element of the claim is the inclusion of the LSD burst, which occurred 484 minutes before the other detectors’ bursts. The author argues that the probability of this being a background fluctuation is <1.4×10⁻⁶, that the low‑energy threshold of LSD explains why the other detectors missed it, and that the near‑monochromatic energies of the five LSD events are not fatal to the hypothesis. By treating these five events as genuine supernova neutrinos, they acquire negative t values, placing them on a line in the t < 0 region. This corresponds to a negative mass‑squared (a tachyonic neutrino). The paper cites recent KATRIN results that found no sterile‑neutrino signal and a best‑fit effective mass squared of –0.14 ± 0.13 eV², arguing that such a result is consistent with one of the three eigenstates being tachyonic.

The discussion also touches on theoretical objections to tachyons, noting that while many physicists consider them unphysical, some recent work proposes covariant frameworks that avoid the usual pathologies. The author suggests that the absence of a sterile‑neutrino signal in KATRIN and potential future IceCube observations could provide independent tests of the three‑mass hypothesis.

Critical appraisal reveals several weaknesses. The central assumption of near‑simultaneous emission (within ≲1 s) conflicts with supernova models that predict neutrino emission over several seconds to tens of seconds. The limited sample size (37 events) and the heavy reliance on the five LSD events, which have unusually low energies and nearly identical values, raise concerns about selection bias. The statistical improvement obtained by inflating the horizontal timing error also suggests that the fit is sensitive to the assumed timing uncertainty. Moreover, the tachyonic interpretation faces longstanding theoretical challenges (unbounded energy spectra, vacuum instability, causality issues) that are not fully resolved. Finally, KATRIN’s measurement of an effective mass does not directly constrain the sign of individual mass‑squared values, so the argument that its null sterile‑neutrino result supports a tachyonic eigenstate is tenuous.

In summary, the paper presents an inventive method to extract three neutrino masses from SN 1987A data, including a possible tachyonic state, and backs it with a statistical fit that appears reasonable under specific timing assumptions. However, the method depends on controversial assumptions about emission simultaneity, the legitimacy of the LSD burst, and the acceptance of tachyons. Without stronger theoretical justification and independent experimental confirmation, the claim that the three neutrino masses can be definitively determined from SN 1987A remains speculative.