[ExI] Faster than light??

[Anders Sandberg]

john clark wrote:
> On *Fri, 9/23/11, Anders Sandberg /<anders at aleph.se>/* wrote:
>
> "The energy of the neutrinos from SN 1987 was measured, and was 10-20 
> MeV [...] The CNGS beam had an average energy of 17 GeV (!). So it had 
> more energetic neutrinos that ought to travel slower if they were 
> tachyons."
>
> I believe that 17 Gev figure refers to the energy of the protons in 
> the beam that produces the neutrinos not to the energy of the 
> neutrinos themselves.
>
Nope, that is the neutrino energy. The protons were more energetic:

> For CNGS neutrino energies, <Eν> = 17 GeV,
> The CNGS beam is produced by accelerating protons to 400 GeV/c with 
> the CERN Super
> Proton Synchrotron (SPS).

John:
>
> "But they had a velocity of around 3 times the speed of light!"
>
> I thought they said they only measured a velocity 20 parts in a 
> million faster than light.
>

Ah, one should not read experimental physics papers too late in the 
evening. (v-c)/c = 2.48e-5 - I missed the hundredthousandth factor.

Redoing my calculation of the mass-square, I now get a squared mass of 
CERN neutrinos as -4.53e-56 kg. That is still 10 orders of magnitude 
"more" than for the supernova neutrinos. So if both are FTL, then they 
have to be very different beasts yet not detect in any different ways.


I noticed that most popular media prematurely claiming Einstein was 
wrong don't notice that there is an even more plausible conclusion if 
these findings are real: causality is wrong. It could simply be that we 
live in a relativistic universe where there is retrocausation going on, 
and paradoxes are avoided by the Novikov self-consistency principle. In 
many ways relativity seems to have a more solid conceptual footing 
(physics is invariant under the Poincare group) than causality (there is 
a strict symmetry breaking along the timelike direction); if I were 
forced to drop one it would be causality.

-- 
Anders Sandberg,
Future of Humanity Institute 
James Martin 21st Century School 
Philosophy Faculty 
Oxford University