Huntin’ for quantum gravity

On the tiniest scale, spacetime ain’t flat at all but a-bubblin and a-fizzin with virtual particles leapin in ‘n outta existence. Quantum gravity, say them cosmologists, is a kinda foam.

Ain’t nobody observed quantum gravity. But this week, them astrogawpers say they might have seen some indirect evidence while a-starin and a-gogglin at Markarian 501, an active galaxy 300 million light years from Earth that flared up in 2005.

The thinkin’ is that quantum foam makes life hellish for photons which have to zip through the quantum hills and valleys that it forms, causin’ them to deviate, ever-so-slightly, from the straight and true. That deviation means two photos travellin’ in the same direction from the same place will take different routes. And the difference can be measured in their arrival times over very long distances, like the 300 milion light years from Markarian 501.

So when it flared up in 2005, a few astrobods got out their stopwatches and started a-countin and a-timin the gamma rays as they arrived, using a machine called MAGIC in the Canary Islands.

Now the results have been totted up and published on the arXiv, but no drum rolls please.

The team ain’t sure what they seen. Sure, them photons do seem to get filtered according to NRG, which is what ya’ll expect if quantum foam were playin havoc with em. (The team is able to rule out other dispersion effects on the photons, such as QED plasma refraction, which is kinda excitin’.)

But they still have a problem: ain’t nobody worked out how the flares generate gamma rays in the first place. Maybe the photons ain’t all emitted at the same time, p’raps there is some mechanism in active galactic flares that makes photons look as if they bin filtered by quantum foam.

So we’re left a-hangin. What we need is more data from different kindsa flares. And some a-sweatin and a-toilin by them astrotheorists to tell us what kinda observations will tease all this apart.

Ref: arxiv.org/abs/0708.2889: Probing Quantum Gravity using Photons from a Mkn 501 Flare Observed by MAGIC

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