[151555] in North American Network Operators' Group
Re: $1.5 billion: The cost of cutting London-Tokyo latency by 60ms
daemon@ATHENA.MIT.EDU (Marshall Eubanks)
Sat Mar 24 08:37:39 2012
In-Reply-To: <CAK__Kzu33pw3RSqcKECGsMtksb9M07-Bah3KjnDH_RZoowB08Q@mail.gmail.com>
Date: Sat, 24 Mar 2012 08:36:55 -0400
From: Marshall Eubanks <marshall.eubanks@gmail.com>
To: George Herbert <george.herbert@gmail.com>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Sat, Mar 24, 2012 at 12:51 AM, George Herbert
<george.herbert@gmail.com> wrote:
> On Fri, Mar 23, 2012 at 7:11 PM, Marshall Eubanks
> <marshall.eubanks@gmail.com> wrote:
>> On Fri, Mar 23, 2012 at 5:14 PM, =A0<Valdis.Kletnieks@vt.edu> wrote:
>>> On Fri, 23 Mar 2012 13:16:59 -0700, George Herbert said:
>>>> The physics is not conducive to improving the situation a lot.
>>>>
>>>> There's probably $1.5 billion in the ground already in neutrino
>>>> detectors; the total combined detector bit rate is pretty poor. =A0One
>>>> experiment looking at neutrinos coming off the Fermilab accelerator
>>>> had 473 million accelerator pulses with under 1.1 million detected
>>>> neutrinos.
>>>
>>> Note that each pulse was probably millions or even billions of neutrino=
s, so
>>> the detection rate was even worse than you'd think. =A0I saw a statisti=
c that
>>> every second, 50 trillion neutrinos pass through your body. =A0And the =
number
>>> that will interact is well into the single digits.
>>>
>>
>> Small detection numbers are not, per se, fatal to communication. What
>> fraction of the photons generated by a GPS satellite are captured by
>> your phone?
>
> Much higher fraction than with neutrinos. =A0Remember their MFPs are
> measured in light-years...
Actually, at the energy they used it's more like 0.1 light seconds.
>
>> The neutrino interaction rate increases with neutrino energy, and sea
>> water makes a good neutrino detector. You could, for a billion
>> dollars, do
>> a LOT better than they did.
>
> On the detector end, sure. =A0On the transmitter end, it's just not a
> well collimated beam due to physics, and no matter how hard you try
> the generation of neutrinos is a low-efficiency process.
>
The beam width was < 2 meters after 1 km, equivalent to ~12 km after 1
Earth radius. The beam can be made tighter by going to
higher energy and using more or better post collision focusing
magnets. The KM3NeT detector in the Mediterranean will be more
sensitive, 3 km across and will cost order 200 million euros. With
better magnets, the existing beam could be made to be the size of that
detector at 1 Earth radius. So, existing technology could certainly
communicate across the Atlantic or the Pacific. The real question,
again, would be what it would take to get the bit rate up.
Regards
Marshall
>> By the way, here is the original paper : http://arxiv.org/pdf/1203.2847v=
1.pdf
>
> Yep. =A0I meant to include the URL but forgot.
>
>
>
> --
> -george william herbert
> george.herbert@gmail.com
