  We have detected astrophysical neutrinos in IceCube that can be used to probe
astrophysical sources at ultra high scales. Here we report a search for
anomalous space time effects using astrophysical neutrino flavor data in
IceCube. New effective operators are introduced to drive non-standard neutrino
flavor mixing which modify the flavor ratios compared to standard cases. Using
the High Energy Starting Events sample (HESE) 7.5-year data for this analysis,
we found no evidence of such flavor anomalies. However, we are expecting to set
limits from this new approach which goes far beyond any known techniques.
Importantly, we achieve the necessary precision to probe new physics using
neutrino flavor expected by Planck scale theories.
