Neutrino flux YASID

[Lee Gleason]

A recent XKCD "What If" discussed whether it is possible to be killed by
neutrino flux, and under what circumstances that might occur.

I dimly recall reading an SF story or novel where there was a stellar event
so intense that death by neutrino flux occurred, but can't recall any more
than that.

Anyone recall story or author where this happened?

--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.g...@comcast.net


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[pete...@gmail.com]

On Thursday, November 28, 2013 12:10:11 PM UTC-5, Lee Gleason wrote:
> A recent XKCD "What If" discussed whether it is possible to be killed by
> neutrino flux, and under what circumstances that might occur.

> I dimly recall reading an SF story or novel where there was a stellar event
> so intense that death by neutrino flux occurred, but can't recall any more
> than that.

> Anyone recall story or author where this happened?

Charles Stross: "Iron Sunrise"

pt

[David Mitchell]

On 28/11/13 17:10, Lee Gleason wrote:
> A recent XKCD "What If" discussed whether it is possible to be killed
> by neutrino flux, and under what circumstances that might occur.
>
> I dimly recall reading an SF story or novel where there was a stellar
> event so intense that death by neutrino flux occurred, but can't recall
> any more than that.
>
> Anyone recall story or author where this happened?

Not death, IIRC, but severe damage to the ship in Greg Bear's _Anvil of
Stars_

--
=======================================================================
= David --- No, not that one.
= Mitchell ---
=======================================================================

[pete...@gmail.com]

Now that I think about it, the neutrino flux didn't actually kill them
vg qvqa'g unir gvzr; gurl (naq gurve cynarg) cbbsvat vagb cynfzn nf
gur ryrpgebzntargvp enqvngvba sebz gur fnzr (gevttrerq) fhcreabin juvpu
perngrq gur arhgevab syhk tbg gurz svefg.

Guvf vf npghnyyl ernyvfgvp; gur pber pbyyncfr bs gur fha perngrf n arhgevab
syhk, zhpu bs juvpu yrnirf gur fha vzzrqvngryl ng whfg orybj p, ohg ohyx bs
gur RZ naq vbavmvat enqvngvba unf gb jbex vgf jnl guebhtu gur bhgre
ynlref bs gur fgne. Gur svefg aba-arhgevab enqvngvba jbhyq or sebz
fgryyne znggre va gur cubgbfcurer urngrq hc ol nofbeovat n cbegvba bs
gur arhgevabf, fb gur fha jbhyq or frra gb oevtugra fvzhygnarbhf jvgu gur
arhgevab chyfr.

Zl erpbyyrpgvba bs Fgebff'f fgbel vf gur gur arhgevab syhk uvg svefg, naq gur
fha oevtugrarq rabhtu gung rirelguvat vg fubja ba vtavgrq. Crbcyr vaqbbef, be
ba gur avtug fvqr jrer fvpx, ohg nyvir. Gura gur znva aba-arhgevab enqvgvba
neevirq....

pt

[William December Starr]

In article <50b65331-5100-4e63...@googlegroups.com>,
pete...@gmail.com said:

> pete...@gmail.com wrote:
>
>> Charles Stross: "Iron Sunrise"
>
> Now that I think about it, the neutrino flux didn't actually kill
> them

[ rot13 spoiler block omitted ]

If I recall correctly, the first interstellar ship arriving at the
system after the catastrophe -- just hours after it happened, also
iirc -- made contact with the system's traffic control station which
was located a large distance further out than the populated planet,
and was basically told "Turn around and save yourselves (and spread
the word to anybody you meet who are still on incoming courses)"
because they (the traffic-control crew) figured that while they'd
physically survived the main event they'd still taken a lethal dose
of neutrino flux from it and were going to die anyway.

-- wds

[JRStern]

On Fri, 29 Nov 2013 06:29:52 +0000, David Mitchell
<david.robo...@gmail.com> wrote:

>On 28/11/13 17:10, Lee Gleason wrote:
>> A recent XKCD "What If" discussed whether it is possible to be killed
>> by neutrino flux, and under what circumstances that might occur.
>>
>> I dimly recall reading an SF story or novel where there was a stellar
>> event so intense that death by neutrino flux occurred, but can't recall
>> any more than that.
>>
>> Anyone recall story or author where this happened?
>
>Not death, IIRC, but severe damage to the ship in Greg Bear's _Anvil of
>Stars_

With some casualties.

J.

[pete...@gmail.com]

My readings of this introduced me to unit of energy I hadn't previously
encountered: the "foe", recently renamed the "Bethe".

One 'foe' is 10^51 ergs, or 10^44 joules (f.o.e == (10^)Fifty One Ergs.

A supernova dissipates about 1 foe of kinetic energy, with much less luminous
radiation, and up to 100 foe in neutrino energy (in a core-collapse supernova).

If the sun spent its entire 10 billion year lifetime at its current brightness,
it would emit about 1.2 foe.

A second interesting factoid: Neutrinos from the 1987a supernova in the Greater
Magellanic Cloud were detected 2-3 hours before brightening was observed, matching the notion that the neutrinos leave the core immediately, but the
other radiation has to propagate via shockwave to the surface before it becomes
visible.

pt

[Scott Fluhrer]

"Lee Gleason" <lee.g...@comcast.net> wrote in message
news:529778fd$0$47731$862e...@ngroups.net...

> A recent XKCD "What If" discussed whether it is possible to be killed by
> neutrino flux, and under what circumstances that might occur.
>
> I dimly recall reading an SF story or novel where there was a stellar
> event so intense that death by neutrino flux occurred, but can't recall
> any more than that.
>
> Anyone recall story or author where this happened?

In addition to the stories mentioned elsethread, it is also referenced in
_Diaspora_ by Greg Egan. We don't actually see it (the protagonists go
elsewhere before it hits them), however there is a Galactic core event so
mammoth that:

"Arranging to be in the shadow of a planet could shield could shield the
polises from gamma rays, but the neutrino flux would be unavoidable, and
intense enough to damage even the most robust molecular structures."

Hmmmm, while copying this, it occurred to me that staying in the shadow of a
large sun ought to be enough. I remember hearing that it takes N million
years for a neutrino to make its way from the stellar core to the
photosphere, hence a star would appear to be mostly neutrino opaque. Of
course, that's not the story that Egan wanted to write...

--
poncho

[pete...@gmail.com]

Umm, no. It's photonic energy that takes a lot of time to get out, since photons are absorbed and emitted again and again. Neutrinos just leave.

When supernova 1987a went off, its neutrinos were picked up 2-3 hours before
the star brightened. Even when the core of a star explodes, it take a while
for the shockwaves to propagate up to the photosphere. The neutrinos were more
prompt.

pt

[Robert Carnegie]

On Tuesday, 3 December 2013 20:18:18 UTC, Scott Fluhrer wrote:
> Hmmmm, while copying this, it occurred to me that staying in the shadow of a
> large sun ought to be enough. I remember hearing that it takes N million
> years for a neutrino to make its way from the stellar core to the
> photosphere, hence a star would appear to be mostly neutrino opaque. Of
> course, that's not the story that Egan wanted to write...

Apparently you remember wrong and that was photons - roughly.
<http://en.wikipedia.org/wiki/Neutrino> : "Whereas photons
emitted from the solar core may require 40,000 years to diffuse
to the outer layers of the Sun, neutrinos generated in stellar
fusion reactions at the core cross this distance practically
unimpeded at nearly the speed of light."

So, it's a worry.

[Michael F. Stemper]

That's really too bad. I *liked* the idea of hiding in the shadow
of a really big sun.

--
Michael F. Stemper
This sentence no verb.

[David DeLaney]

Which is one portion of the mechanism for shell supernovae; once the innermost
shell runs out of fuel and the center starts collapsing and the temperature
rises incredibly, when it gets to the point where pair production of neutrinos
is more than unlikely, they suddenly abscond with a good fraction of the
remaining core energy, causing a REAL collapse, igniting every bit of fuel left
in the OTHER shells all at once. {BOOM}

Dave, and there was light

PS: We don't know of much that COULD protect against neutrino flux. A few yards
of neutronium would probably help, as would a perfectly-placed black hole...
but other than that you have to start looking for things like Arcot, Wade,
and Morey's 'cosmium'.
--
\/David DeLaney posting thru EarthLink - "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

[pete...@gmail.com]

So, while you can't hide from a neutrinos behind a star, if you can put a neutron star between you and the flux, you might stand a chance.

pt

[Robert Carnegie]

Is a neutron star any better for stopping neutrinos than the
conventional star that it was before it collapsed? Or is the
chance of any given neutrino going right through it, just
the same?

And with a black hole, some of them will fall in and stop, but
some will pass by the black hole but get pulled around in behind
it, where you're hiding.

[pete...@gmail.com]

On Wednesday, December 4, 2013 5:27:41 AM UTC-5, Robert Carnegie wrote:
> On Wednesday, 4 December 2013 03:28:35 UTC, pete...@gmail.com wrote:
>> On Tuesday, December 3, 2013 10:09:00 PM UTC-5, David DeLaney wrote:
>>> PS: We don't know of much that COULD protect against neutrino flux. A few yards
>>> of neutronium would probably help, as would a perfectly-placed black hole...
>>> but other than that you have to start looking for things like Arcot, Wade,
>>> and Morey's 'cosmium'.
>>
>> So, while you can't hide from a neutrinos behind a star, if you can
>> put a neutron star between you and the flux, you might stand a chance.
>
> Is a neutron star any better for stopping neutrinos than the
> conventional star that it was before it collapsed? Or is the
> chance of any given neutrino going right through it, just
> the same?

The amount of matter didn't change. However, a larger fraction of
the mass is between you and a point source on the far
side. But running the numbers, it looks like you need kilometers of
neutronium, not meters, to help you.

The neutrino absorption numbers are actually all over the shop;
google 'lightyears of lead' and neutrinos, and you'll find
half-absorption numbers of 1.5, 10, 50, 1000, and 3500 in the
first page of results. Neutrinos can also vary in energy, and the
more energetic ones are more easily absorbed.

Neutronium is roughly 3.5 x 10^13 times the density of lead; collapse a light
year of lead down to neutronium, and you get a layer about 3.7 km (check;
this feels too high).

A 1.5 solar mass neutron star is 10-15 km across, depending on who you ask.
so at the upper (1.5 ly) end of the absorption scale, you'd get at most a
6 fold factor of attenuation, which could be quite helpful.

That's at the *most* *favorable* numbers. But it turns out the neutrinos
interact with protons and electrons far more easily than they do with
neutrons, so the degenerate neutronium, kilo for kilo, is a lousy
neutrino shield.

I think you're still dead.

> And with a black hole, some of them will fall in and stop, but
> some will pass by the black hole but get pulled around in behind
> it, where you're hiding.

You'd have to calculate the focal length, and be closer or farther, but
not so far the BH doesn't eclipse the neutrino source.

pt

[J. Clarke]

In article <6176bf26-f878-44e9...@googlegroups.com>,
rja.ca...@excite.com says...

>
> On Wednesday, 4 December 2013 03:28:35 UTC, pete...@gmail.com wrote:
> > On Tuesday, December 3, 2013 10:09:00 PM UTC-5, David DeLaney wrote:
> > > PS: We don't know of much that COULD protect against neutrino flux. A few yards
> > > of neutronium would probably help, as would a perfectly-placed black hole...
> > > but other than that you have to start looking for things like Arcot, Wade,
> > > and Morey's 'cosmium'.
> >
> > So, while you can't hide from a neutrinos behind a star, if you can
> > put a neutron star between you and the flux, you might stand a chance.
>
> Is a neutron star any better for stopping neutrinos than the
> conventional star that it was before it collapsed? Or is the
> chance of any given neutrino going right through it, just
> the same?

On density considerations alone there shouldn't be much difference--a
neutron star doesn't actually interpose any more mass than a regular
star for paths through the center, and it's small enough compared to the
regular star that to a rough approximation all paths through the neutron
star would be "through the center" of the regular star.

On the other hand, if one wants to wank up a shield, one could make up
some treknobabble about capture cross sections--there's debate in
physics over the detailed makeup of the interior of a neutron star and
the cross sections for neutrino capture by some of the possible
components are not well established if they are established at all, so
there may be something in there that sucks up neutrinos like an old
Hoover.

> And with a black hole, some of them will fall in and stop, but
> some will pass by the black hole but get pulled around in behind
> it, where you're hiding.

The black hole should make things worse. What you'll get is everything
that passes through an annulus around the black hole at whatever
distance leads to its being deflected into your position. That annulus
I would expect to have a lot more area than you do, so you'll get a lot
more exposure than if you were just out in space.

[David DeLaney]

Yesbut ... As demonstrated by the aforementioned AWM, if you're close enough
to the neutron star to have it protect you? You're either already on its
surface and suffering from several milliom gees, ABOUT to be on its surface
within much less than a second or so ... or orbiting around it several times
a second. So you'd still get hit with the neutrino flux unless it was exactly
correctly pulsed AND you had incredible timing.

So not a very good solution...

Dave

[David DeLaney]

On 2013-12-04, Robert Carnegie <rja.ca...@excite.com> wrote:
> On Wednesday, 4 December 2013 03:28:35 UTC, pete...@gmail.com wrote:
>> On Tuesday, December 3, 2013 10:09:00 PM UTC-5, David DeLaney wrote:
>> > PS: We don't know of much that COULD protect against neutrino flux. A few
>> > yards
>> > of neutronium would probably help, as would a perfectly-placed black
>> > hole...
>> > but other than that you have to start looking for things like Arcot, Wade,
>> > and Morey's 'cosmium'.
>>
>> So, while you can't hide from a neutrinos behind a star, if you can
>> put a neutron star between you and the flux, you might stand a chance.
>
> Is a neutron star any better for stopping neutrinos than the
> conventional star that it was before it collapsed? Or is the
> chance of any given neutrino going right through it, just the same?

The neutron star is, essentially, a giant atomic nucleus with a foot or two of
crushed more-ordinary matter on top; it's neutrons, basically in contact with
each other. It would be about as effective as the average atomic _nucleus_ at
stopping neutrinos, and would be able to wield the very-short-range-but-not-
quite-that-short weak force with a good deal of efficiency at interaction.

In contrast, the star it was was ordinary matter, albeit an electrical plasma
thereof, with separate nuclei and a compressed electron soup they were
floating in. The neutron star doesn't have the electron soup any more, as such,
and its nuclei are at contact range, making them all merge.

> And with a black hole, some of them will fall in and stop, but
> some will pass by the black hole but get pulled around in behind
> it, where you're hiding.

Well yeah. But there'd be a focussing effect such that you'd have spots where
the flux wasn't. But again the gravity and rapid orbiting would complicate
things such that this would probably not work well either.

Dave

[pete...@gmail.com]

On Wednesday, December 4, 2013 1:01:02 PM UTC-5, David DeLaney wrote:
> On 2013-12-04, Robert Carnegie <rja.ca...@excite.com> wrote:
>> On Wednesday, 4 December 2013 03:28:35 UTC, pete...@gmail.com wrote:
>>> On Tuesday, December 3, 2013 10:09:00 PM UTC-5, David DeLaney wrote:
>>>> PS: We don't know of much that COULD protect against neutrino flux. A few
>>>> yards
>>>> of neutronium would probably help, as would a perfectly-placed black
>>>> hole...
>>>> but other than that you have to start looking for things like Arcot, Wade,
>>>> and Morey's 'cosmium'.
>>>
>>> So, while you can't hide from a neutrinos behind a star, if you can
>>> put a neutron star between you and the flux, you might stand a chance.
>>
>> Is a neutron star any better for stopping neutrinos than the
>> conventional star that it was before it collapsed? Or is the
>> chance of any given neutrino going right through it, just the same?
>
> The neutron star is, essentially, a giant atomic nucleus with a foot or two of
> crushed more-ordinary matter on top; it's neutrons, basically in contact with
> each other. It would be about as effective as the average atomic _nucleus_ at
> stopping neutrinos, and would be able to wield the very-short-range-but-not-
> quite-that-short weak force with a good deal of efficiency at interaction.

That turns out not to be the case. Check
http://www.reddit.com/r/askscience/comments/1kkion/can_neutrinos_pass_through_neutron_stars_like/

TLDNR: The extreme conditions in a neutron star discourages neutron/neutrino interactions.

pt

[Bill Dugan]

On Wed, 04 Dec 2013 11:55:40 -0600, David DeLaney
<davidd...@earthlink.net> wrote:

>On 2013-12-04, pete...@gmail.com <pete...@gmail.com> wrote:
>> On Tuesday, December 3, 2013 10:09:00 PM UTC-5, David DeLaney wrote:
>>> Dave, and there was light
>>
>>> PS: We don't know of much that COULD protect against neutrino flux. A few
>>> yards
>>> of neutronium would probably help, as would a perfectly-placed black hole...
>>> but other than that you have to start looking for things like Arcot, Wade,
>>> and Morey's 'cosmium'.
>>
>> So, while you can't hide from a neutrinos behind a star, if you can put a
>> neutron star between you and the flux, you might stand a chance.
>
>Yesbut ... As demonstrated by the aforementioned AWM, if you're close enough
>to the neutron star to have it protect you? You're either already on its
>surface and suffering from several milliom gees, ABOUT to be on its surface
>within much less than a second or so ... or orbiting around it several times
>a second. So you'd still get hit with the neutrino flux unless it was exactly
>correctly pulsed AND you had incredible timing.
>
>So not a very good solution...
>
>Dave

To get to the neutron star in time, you'd need both advance warning
and FTL transport. If you have those, run a few hundred LY away from
the neutrino source and consider the problem at leisure.

[David DeLaney]

On 2013-12-04, pete...@gmail.com <pete...@gmail.com> wrote:

> That turns out not to be the case. Check
> http://www.reddit.com/r/askscience/comments/1kkion/
can_neutrinos_pass_through_neutron_stars_like/
>
> TLDNR: The extreme conditions in a neutron star discourages neutron/neutrino
> interactions.

Fair enough ... though I'd want to see somewhere else that compared the rate
of discouragement from degeneracy causing all the lowest-energy states to be
filled (and note that neutrinos from a supernova might, some of them, have
higher energy than you'd think) versus the rate of encouragement due to atomic-
matter densities vs nuclear-matter densities. But yeah, not as simple as
density comparison, ah well.

[JRStern]

On Tue, 03 Dec 2013 21:09:00 -0600, David DeLaney
<davidd...@earthlink.net> wrote:

>PS: We don't know of much that COULD protect against neutrino flux. A few yards
> of neutronium would probably help, as would a perfectly-placed black hole...
> but other than that you have to start looking for things like Arcot, Wade,
> and Morey's 'cosmium'.

In "Anvil of Stars" they mostly can but never say quite how, it may be
by warping space in such a way they (mostly) just can't find you.

J.