Παρασκευή, 30 Οκτωβρίου 2009

Einstein wins this round...

Με αφορμή αυτό το post, Lone Starr's Quest: Το Fermi καταγράφει φωτόνια μετά από 7.3 δισ. χρόνια, έλαβα γνώση των παρακάτω:

Stanford researchers: Gamma-ray photon race ends in dead heat; Einstein wins this round

A pair of gamma-ray photons – one possessed of a million times the energy of the other – arrived at virtually the same instant at NASA's orbiting Fermi Gamma-ray Space Telescope, where the Large Area Telescope, for which Stanford's Peter Michelson is principal investigator, detected them after a 7.3 billion year race across the universe. Some proponents of alternatives to Einstein's theory of gravity would have predicted that the more energetic would have interacted with more matter along the way and thus been much farther behind the less energetic one. They were wrong – Einstein wins this round.


Universe's quantum 'speed bumps' no obstacle for light

Backreaction: The Photon and its Cousins

Αυτό το θέμα, δεν μπορούσα να το αφήσω να περάσει ασχολίαστο...

Νανόπουλος MAGIC (Addendum) (κλπ...)

Thanks Citronella...

3 σχόλια:

vaggelis84 είπε...

Πάλι άδεια πήραμε;
ΟΛΑ στο Νανόπουλο :)

Vagelford είπε...

Οχι... εξοδούχος...

lazopolis είπε...

Our new limit, MQG,1/MPlanck ≥ several (see Table 2), is much stronger than the previous
best limit of this kind (MQG,1/MPlanck ≥ 0.1 from GRB080916C20) and fundamentally
more meaningful. Since, in most quantum gravity scenarios, MQG,n <~ MPlanck, even our
most conservative limit (Table 2; (a)) greatly reduces the parameter space for n=1
models [26,27]. Our intermediate limits (Table 2; (b)–(d)), and even more so, our least
conservative limit (Table 2; (e): MQG,1/MPlanck > 102), based on associating the 31 GeV
photon with the contemporaneous low-energy spike, makes such theories highly
implausible (models with n > 1 are not significantly constrained by our results).

bibliography:
...
26. Ellis, J., Mavromatos, N. E. & Nanopoulos, D. V. Derivation of a vacuum refractive
index in a stringy space time foam model. Phys. Lett. B, 665, 412–417 (2008).
27. Zloshchastiev, K. G. Logarithmic nonlinearity in theories of quantum gravity:
Origin of time and observational consequences. arXiv:0906.4282 (2009).