Having looked at the paper, I'm possibly misreading it as saying that the deviation from c is proportional to the energy divided by the Planck mass, or it is proportional to the square of that same ratio. This is one data point, so you can draw any line you like through it, but the implication is that the deviation is linearly proportional, and at a few TeV, is enough to provide a 240 second delay over a 140 quadrillion second flight (roughly a part in 10¹⁵).

I think that there will come a time in the near future when MAGIC, or a similar installation, will have observed similar flares from a different more distant BL Lac object, and the numbers will be more clear.

As a first observation of this sort, this is very exciting news.

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Forming opinions as we speak