| Topic: |
Science > Physics |
| User: |
"Joe D." |
| Date: |
16 Jan 2005 12:48:26 PM |
| Object: |
Sun's core "pinhead" illustration in error |
There's a common illustration of the sun's power which is in error.
This is notable since it's widely used in many books, science web
sites, etc. Any comments welcome.
The illustration is a 15 million degree C pinhead of the Sun's core if taken
to earth would kill someone 160km away. If you search on "sun", "core" and
"pinhead", you'll see it repeated everywhere. I can't tell where this first
started.
I questioned this when I first heard it, and finally did some research and
it seems drastically wrong.
Consider the Russian "Tsar Bomba" 57 megaton H bomb. It converted 2.7 kg of
matter to energy at 100 million C, released 2.4 x 10E17 Joules, yet it
wouldn't kill someone 160 km away. In fact the manned aircraft dropping it
was only 45km away at detonation.
If 2.7kg of matter converted 100% to energy won't kill someone at 160km, how
could a pinhead of the sun's core? You can't get more energy from matter
than E=mc^2. The solar core density about 150 times water.
1 mm^3 of hydrogen at that pressure is about 0.15 grams.
In actuality the core's fusion power density is not uniform but increases
toward the center. If we take the absolute highest power density at the very
center, that's 276.5 watts per m^3, or 2.76 x 10E-7 watts per cubic
millimeter, or .28 microwatts per cubic millimeter. It's actually remarkably
low.
A cubic mm pinhead of solar core material producing 0.28 microwatts isn't
going to hurt anyone standing adjacent, much less someone 160km away.
However what about the stored energy based on specific heat?
We must assume it's kept confined to 1 mm^3, else it's
not a pinhead. Also the illustration is about radiant energy, not blast. If
de-confined there would be significant blast effects as the hydrogen is
under 250 billion atmospheres.
The specific density of hydrogen at sun's core is 150. The specific heat of
hydrogen is 14304 Joules per kg per degree K. Core temp is 15 million C.
So 1 mm^3 hydrogen at that pressure is 0.15 grams, and specific heat is
14.304 Joules per g per degree K.
14.304 J/g/K * 15e6 K * 0.15 g = 32 megajoules.
By comparison gasoline contains 45 megajoules per kg.
So the pinhead of core material contains about the energy of 1 liter of
gasoline. That's not fatal at 160km, nor even 1 km.
Apparently, whoever contrived this "pinhead" illustration merely
took 1 mm^3, 15 million C, and plugged those into the Stefan-Boltzman
equation:
P=epsilon*sigma*A(Tr^4 - Ts^4), where
P=radiated power
epsilon = emissivity (1 for ideal blackbody)
sigma = Stefan's constant (5.67E-8 watt/m^2 K^4)
A = radiating area
Tr = temp of radiator
Ts = temp of surroundings
Plug in those numbers and you get 1.7E16 watts. At 160km the flux is still
52 kilowatts/m^2, or 52x solar intensity, which is lethal.
However 1 mm^3 of core material doesn't have that much energy!!
That's like taking 1 mm^3 from the ITER fusion reactor which is 100
million C (7 times hot as the sun's core), plugging that into the
Boltzman equation and getting 3.4E19 watts. Behold! Each pinhead
of ITER plasma is 1000 times as deadly as the sun's core!
That's obviously absurd.
There are so many good illustrations that could have been used, and which
would have been accurate.
E.g. using the same illustration but saying "grapefruit size" instead of
pinhead might work. A grapefruit-sized chunk of solar core would
contain 4.7E14 joules, or the equivalent of 174 million kg of TNT,
if liberated in the same timeframe. That would probably kill someone
at 10 km. Something like that.
Or each square meter of the sun's core constantly produces 1.6 gigawatts,
the same as a large power plant.
Or each second the sun converts 4.4 billion metric tons of matter to energy,
and the largest H bomb only converted 2.7 kg.
It's very unfortunate when technically incorrect or scientifically
misleading illustrations are used, often in a misguided attempt to simplify
or impress.
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| User: "LingChow" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 01:12:46 PM |
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"Joe D." <joe@nospam.invalid> wrote in message
news:hAyGd.53356$zy6.10555@bignews5.bellsouth.net...
<snip>
How does the example have any real world relevance? Who is going to go get
the "pinhead" at the center of the Sun, which is not Hydrogen anyway, and
bring it back to earth and put it next to someone?
Rather, look at Chernobyl where the question of how long, how close, how
deadly was answered by thousands.
I have a pinhead of Radium in an old Spinthariscope, which you put up to
your eye, about 1/3 inch away to see.
If you swallow it, and it gets stuck inside you will probably have cancer in
3 -15 years or so.
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| User: "Road Kill" |
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| Title: Re: Sun's core "pinhead" illustration in error |
22 Jan 2005 02:12:09 AM |
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The call of the pinhead is strong!
LingChow wrote:
"Joe D." <joe@nospam.invalid> wrote in message
news:hAyGd.53356$zy6.10555@bignews5.bellsouth.net...
<snip>
How does the example have any real world relevance? Who is going to go get
the "pinhead" at the center of the Sun, which is not Hydrogen anyway, and
bring it back to earth and put it next to someone?
Rather, look at Chernobyl where the question of how long, how close, how
deadly was answered by thousands.
I have a pinhead of Radium in an old Spinthariscope, which you put up to
your eye, about 1/3 inch away to see.
If you swallow it, and it gets stuck inside you will probably have cancer in
3 -15 years or so.
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| User: "Everett Hickey" |
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| Title: Re: Sun's core "pinhead" illustration in error |
18 Jan 2005 02:34:52 PM |
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"Joe D." <joe@nospam.invalid> wrote in message
news:hAyGd.53356$zy6.10555@bignews5.bellsouth.net...
There's a common illustration of the sun's power which is in error.
This is notable since it's widely used in many books, science web
sites, etc. Any comments welcome.
The illustration is a 15 million degree C pinhead of the Sun's core if
taken
to earth would kill someone 160km away. If you search on "sun", "core" and
"pinhead", you'll see it repeated everywhere. I can't tell where this
first
started.
I questioned this when I first heard it, and finally did some research and
it seems drastically wrong.
Consider the Russian "Tsar Bomba" 57 megaton H bomb. It converted 2.7 kg
of
matter to energy at 100 million C, released 2.4 x 10E17 Joules, yet it
wouldn't kill someone 160 km away. In fact the manned aircraft dropping it
was only 45km away at detonation.
If 2.7kg of matter converted 100% to energy won't kill someone at 160km,
how
could a pinhead of the sun's core? You can't get more energy from matter
than E=mc^2. The solar core density about 150 times water.
1 mm^3 of hydrogen at that pressure is about 0.15 grams.
Nuclear bombs don't convert anywhere remotely close to 100% of their matter
to energy. Not even antimatter can accomplish that feat, and antimatter
weapons would be orders of magnitude more powerful. All a nuke does is
reduce the resulting matter by a small fraction, and the process of
unbinding the particles is what releases the energy, not the conversion
process. E=mC2 is the raw conversion of mass to energy, but the actual
calculation for a nuclear bomb is considerably more complicated, as you have
to take into account the expected efficiency, and the nature of the
reaction. Hydrogen bombs are more efficient than simple atomic bombs, and
are thus incredibly powerful in comparison. And that's just converting a
slightly higher miniscule fraction of mass to energy. Then again, the sun
does the same thing - ie it's not very efficient in conversion.
In actuality the core's fusion power density is not uniform but increases
toward the center. If we take the absolute highest power density at the
very
center, that's 276.5 watts per m^3, or 2.76 x 10E-7 watts per cubic
millimeter, or .28 microwatts per cubic millimeter. It's actually
remarkably
low.
There is no fusion at the center of the sun. The core is primarily helium,
with traces of other elements (including some unprocessed hydrogen that
escaped fusion, though a very very low figure). The actual fusion process
occurs in a slowly expanding shell around the core, at the boundry point
between helium and hydrogen. As the hydrogen is slowly fused into helium
(releasing energy as a tiny tiny bit of mass is lost in the fusion process),
the helium collects in the center. It doesn't fuse because the temperature
is not remotely close to what's required to fuse helium.
The density does increase, because of the pressure. But there is no power
density involves as it's merely exceptionally hot helium plasma, and the
center is not very close at all to the area where fusion is actually
occuring (thousands upon thousands, (or even millions?), or kilometers away
from center.
A cubic mm pinhead of solar core material producing 0.28 microwatts isn't
going to hurt anyone standing adjacent, much less someone 160km away.
However what about the stored energy based on specific heat?
We must assume it's kept confined to 1 mm^3, else it's
not a pinhead. Also the illustration is about radiant energy, not blast.
If
de-confined there would be significant blast effects as the hydrogen is
under 250 billion atmospheres.
I'd think that alone would do the job. It would cool as it expanded, but
the intense heat combined with ravaging blast would kill for a great radius.
How big a radius I have no clue or care.
The specific density of hydrogen at sun's core is 150. The specific heat
of
hydrogen is 14304 Joules per kg per degree K. Core temp is 15 million C.
I won't argue the figures as that's my weak suit, but what is hydrogen doing
in any great quantity in the central core? Isn't the core defined more or
less as the fusion shell, inside of which there is negligible hydrogen
content?
So 1 mm^3 hydrogen at that pressure is 0.15 grams, and specific heat is
14.304 Joules per g per degree K.
14.304 J/g/K * 15e6 K * 0.15 g = 32 megajoules.
By comparison gasoline contains 45 megajoules per kg.
So the pinhead of core material contains about the energy of 1 liter of
gasoline. That's not fatal at 160km, nor even 1 km.
Somehow that doesn't add up. I've played with Astrolite (chemical
explosive), which has a considerable expansion rate. That rate is still
nothing compared to the equivilant of 250 billion atm expanding almost
instantly. And one cubil milimeter of astrolite (at normal density) has
destructive power that I'd rate as higher than a liter of gasoline (which
would be difficult to ignite in one instant reaction anyway except as an
aerosol).
I won't support the destruction radius mentioned, but regardless of the
figures quotes, a cubic milimeter of solar core material would carry some
absolutely devastating effects.
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
18 Jan 2005 06:27:27 PM |
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"Everett Hickey" <everett@ev1.net> wrote in message
news:10uqsqtlsbf7v6e@corp.supernews.com...
Nuclear bombs don't convert anywhere remotely close to 100% of their
matter
to energy. Not even antimatter can accomplish that feat, and antimatter
The statement was in the Soviet 57 Mt bomb, 2.7 kg of matter was
100% converted to energy, NOT that the whole bomb was.
There is no fusion at the center of the sun. The core is primarily
helium,
with traces of other elements (including some unprocessed hydrogen that
escaped fusion, though a very very low figure). The actual fusion process
occurs in a slowly expanding shell around the core, at the boundry point
between helium and hydrogen.
Thanks for that point. However I used the core center because (a)
density is highest there, giving the illustration a better chance, and
(b) The below chart had specific numbers for various core radii
http://fusedweb.pppl.gov/CPEP/Chart_Pages/5.Plasmas/SunLayers.html#Bib
If
de-confined there would be significant blast effects as the hydrogen is
under 250 billion atmospheres.
I'd think that alone would do the job. It would cool as it expanded, but
the intense heat combined with ravaging blast would kill for a great
radius.
How big a radius I have no clue or care.
The previously-listed calculations show how much specific heat is
contained in 1 mm^3 of hydrogen at core density. Helium has
only about 1/3 the specific heat capacity (5190 J/kg) of Hydrogen,
so would do much less heat damage.
Regarding energy released by de-confining 1 mm^3 of a gas at 250 billion
atmospheres, the illustration states pinhead so precludes this.
However just for kicks let's calculate that energy release. The formula
is that for adiabatic expansion. It's complex, but there's an on-line
calculator at:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/adiab.html#c3
1 mm^3 of hydrogen at specific density 150 contains .15 grams
by weight. Hydrogen is 0.084 kg/m^3 at normal atmospheric conditions,
so the tiny pinhead has 1.78 cubic meters crammed into it.
How much potential energy is stored in that? Plugging the numbers
into the above calculator, we see de-confining 1 mm^3 of hydrogen
at about 250 billion atmospheres and 15 million C releases 2.8E7 Joules,
or about the energy of 10 kg of TNT. That's a nice bang, but it
won't kill someone 160 km away, 1 km away, or probably
2 city blocks away.
I won't argue the figures as that's my weak suit, but what is hydrogen
doing
in any great quantity in the central core? Isn't the core defined more or
less as the fusion shell, inside of which there is negligible hydrogen
content?
That's a good point. I used the central core since pressure and
(by one reference) fusion energy density was highest. These
were the most liberal possible choices to try and make the illustration
work. It doesn't.
So 1 mm^3 hydrogen at that pressure is 0.15 grams, and specific heat is
14.304 Joules per g per degree K.
14.304 J/g/K * 15e6 K * 0.15 g = 32 megajoules.
By comparison gasoline contains 45 megajoules per kg.
So the pinhead of core material contains about the energy of 1 liter of
gasoline. That's not fatal at 160km, nor even 1 km.
Somehow that doesn't add up. I've played with Astrolite (chemical
explosive), which has a considerable expansion rate. That rate is still
nothing compared to the equivilant of 250 billion atm expanding almost
instantly. And one cubil milimeter of astrolite (at normal density) has
destructive power that I'd rate as higher than a liter of gasoline (which
would be difficult to ignite in one instant reaction anyway except as an
aerosol).
I won't support the destruction radius mentioned, but regardless of the
figures quotes, a cubic milimeter of solar core material would carry some
absolutely devastating effects.
The 32 megajoules in 1 mm^3 of Hydrogen is from specific heat
only. It didn't include pressure effects, since the illustration states
it remains in pinhead form.
However your point was interesting so I did the additional
calculation (in this post, above) to examine how much potential
energy was in the hyper-pressure gas.
1 mm^3 of Hydrogen at 250 billion atmospheres and 15 million C
when released produces energy equal to about 10 kg of TNT.
That's a nice big bang, but it's hardly devastating.
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| User: "John Popelish" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 01:43:13 PM |
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"Joe D." wrote:
There's a common illustration of the sun's power which is in error.
This is notable since it's widely used in many books, science web
sites, etc. Any comments welcome.
The illustration is a 15 million degree C pinhead of the Sun's core if taken
to earth would kill someone 160km away. If you search on "sun", "core" and
"pinhead", you'll see it repeated everywhere. I can't tell where this first
started.
(snip)
It's very unfortunate when technically incorrect or scientifically
misleading illustrations are used, often in a misguided attempt to simplify
or impress.
I agree that such descriptions are misleading, at best. How would
your opinion of the account change if it were changed to something
like:
A pinhead sized black body radiator, if it could maintain the
temperature of the core of the Sun, would eventually produce deadly
consequences for someone exposed to its radiation from 160 kM distance
with no absorbent or reflective material between them and the
radiator.
I think this is the sort of thing they are clumsily trying to express.
--
John Popelish
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 08:18:04 PM |
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"John Popelish" <jpopelish@rica.net> wrote in message
news:41EAC3D1.26BEBBB4@rica.net...
I agree that such descriptions are misleading, at best. How would
your opinion of the account change if it were changed to something
like:
A pinhead sized black body radiator, if it could maintain the
temperature of the core of the Sun, would eventually produce deadly
consequences for someone exposed to its radiation from 160 kM distance
with no absorbent or reflective material between them and the
radiator.
I think this is the sort of thing they are clumsily trying to express.
John I agree your wording "patches up" the technical inaccuracies.
However the presumed goal was illustrate the sun's power in
a compelling and accurate way.
While it's true a 15 million C blackbody radiator would kill someone
160 kM away, it requires 1.7E16 watts to do that.
The ENTIRE SUN only produces 4E26 watts. The illustration requires
vast power perpetually funneled through that cubic millimeter -- power
that the sun doesn't have. Yet the goal was illustrate the sun's power.
The ITER fusion reactor's low density plasma is 100 million C.
If you blindly plug that into the Boltzman equation, you get
3.4E19 watts in EACH mm^3.
ITER's plasma volume is 837 m^3, or 837 billion cubic mm.
Based on that ITER should output 10,000 times the power of
the sun!!!
That's absurd beyond belief, yet that is EXACTLY what the
sun core "pinhead" illustration does.
There are many good illustrations of the sun's power. This
isn't one of them.
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| User: "John Popelish" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 08:34:17 PM |
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"Joe D." wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:41EAC3D1.26BEBBB4@rica.net...
I agree that such descriptions are misleading, at best. How would
your opinion of the account change if it were changed to something
like:
A pinhead sized black body radiator, if it could maintain the
temperature of the core of the Sun, would eventually produce deadly
consequences for someone exposed to its radiation from 160 kM distance
with no absorbent or reflective material between them and the
radiator.
I think this is the sort of thing they are clumsily trying to express.
John I agree your wording "patches up" the technical inaccuracies.
However the presumed goal was illustrate the sun's power in
a compelling and accurate way.
I think the point of the exercise is to illustrate what the fourth
power of temperature and the tremendous temperature at the center of
the Sun means for energy exchange through small areas.
While it's true a 15 million C blackbody radiator would kill someone
160 kM away, it requires 1.7E16 watts to do that.
Yes. isn't it amazing what can pass through a pinhead size area when
such temperatures are involved.
The ENTIRE SUN only produces 4E26 watts. The illustration requires
vast power perpetually funneled through that cubic millimeter -- power
that the sun doesn't have. Yet the goal was illustrate the sun's power.
We disagree, there.
The ITER fusion reactor's low density plasma is 100 million C.
If you blindly plug that into the Boltzman equation, you get
3.4E19 watts in EACH mm^3.
ITER's plasma volume is 837 m^3, or 837 billion cubic mm.
Based on that ITER should output 10,000 times the power of
the sun!!!
That's absurd beyond belief, yet that is EXACTLY what the
sun core "pinhead" illustration does.
There are many good illustrations of the sun's power. This
isn't one of them.
I don't think the exercise is about the Sun's power at all.
--
John Popelish
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 10:02:59 PM |
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"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB2429.567A6A44@rica.net...
I don't think the exercise is about the Sun's power at all.
I assume you mean it's intended only as an illustration of
the sun's core temperature, not its power?
-- Joe D.
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| User: "John Popelish" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 10:15:07 PM |
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"Joe D." wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB2429.567A6A44@rica.net...
I don't think the exercise is about the Sun's power at all.
I assume you mean it's intended only as an illustration of
the sun's core temperature, not its power?
Exactly. It is an attempt to give a feel for the physical effects of
that kind of temperature.
--
John Popelish
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 11:18:03 PM |
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"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB3BCB.A6E041E2@rica.net...
"Joe D." wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB2429.567A6A44@rica.net...
I don't think the exercise is about the Sun's power at all.
I assume you mean it's intended only as an illustration of
the sun's core temperature, not its power?
Exactly. It is an attempt to give a feel for the physical effects of
that kind of temperature.
I understand what you're saying and I accept what the
originator of that illustration was attempting.
My problem is he apparently just blindly plugged 15 million C into
the Stefan-Boltzman equation. That produces a POWER
output which in turn determines lethal range. The impact of
the illustration centers on power, regardless of whether
temperature was the goal. Without power you have no
lethal range. Yet that power doesn't exist in the stated
volume.
The Voyager space probe detected temperatures
of ONE BILLION degrees in the Uranus magnetosphere.
Plug that into the Boltzman equation and it spits out
3.4E23 watts!!!
By the exact same illustration, using the exact same
technique, a pinhead of material from the Uranus magnetosphere
would kill someone 100,000 km away (I just did the math).
Obviously you can't just convert temperature to radiant
power with that equation and have it mean something.
Yet that's what the original illustration does.
The only reason it slips by is the sun is viscerally hot, so
everybody figures that's accurate.
If I'm in error, let me know.
BTW there's a nice on-line calculator for the Stefan-Boltzman
equation at http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2
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| User: "John Popelish" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 11:58:34 PM |
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"Joe D." wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB3BCB.A6E041E2@rica.net...
"Joe D." wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:41EB2429.567A6A44@rica.net...
I don't think the exercise is about the Sun's power at all.
I assume you mean it's intended only as an illustration of
the sun's core temperature, not its power?
Exactly. It is an attempt to give a feel for the physical effects of
that kind of temperature.
I understand what you're saying and I accept what the
originator of that illustration was attempting.
My problem is he apparently just blindly plugged 15 million C into
the Stefan-Boltzman equation. That produces a POWER
output which in turn determines lethal range. The impact of
the illustration centers on power, regardless of whether
temperature was the goal. Without power you have no
lethal range. Yet that power doesn't exist in the stated
volume.
The Voyager space probe detected temperatures
of ONE BILLION degrees in the Uranus magnetosphere.
Plug that into the Boltzman equation and it spits out
3.4E23 watts!!!
Not a black body radiator, I'll wager.
By the exact same illustration, using the exact same
technique, a pinhead of material from the Uranus magnetosphere
would kill someone 100,000 km away (I just did the math).
Obviously you can't just convert temperature to radiant
power with that equation and have it mean something.
Yet that's what the original illustration does.
The only reason it slips by is the sun is viscerally hot, so
everybody figures that's accurate.
If I'm in error, let me know.
BTW there's a nice on-line calculator for the Stefan-Boltzman
equation at http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2
Thanks.
--
John Popelish
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| User: "Sam Wormley" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 11:32:41 PM |
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Joe D. wrote:
The Voyager space probe detected temperatures
of ONE BILLION degrees in the Uranus magnetosphere.
Reference please.
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 11:44:10 PM |
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"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:Z5IGd.10908$OF5.9106@attbi_s52...
Joe D. wrote:
The Voyager space probe detected temperatures
of ONE BILLION degrees in the Uranus magnetosphere.
Reference please.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
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| User: "Sam Wormley" |
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| Title: Re: Sun's core "pinhead" illustration in error |
16 Jan 2005 11:47:38 PM |
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Joe D. wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:Z5IGd.10908$OF5.9106@attbi_s52...
Joe D. wrote:
The Voyager space probe detected temperatures
of ONE BILLION degrees in the Uranus magnetosphere.
Reference please.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
Thank you.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
"I bring this up because there can be ridiculously high temperatures in
the Universe, but they don't mean much! For example, the Voyager probe
measured a temperature of over one billion degrees in the magnetosphere
of Uranus. Imagine! But really what it was measuring were particles
moving extremely quickly. If you stood (well, floated) in Uranus'
magnetosphere, you wouldn't suddenly vaporize. On the contrary, you'd
freeze! The particles may be very very hot, but there simply aren't
enough of them for them to heat you up."
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
17 Jan 2005 12:27:06 AM |
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"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:_jIGd.10927$OF5.9745@attbi_s52...
.....
Thank you.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
"I bring this up because there can be ridiculously high temperatures in
the Universe, but they don't mean much!
And that is exactly my point. It would be absurd to plug that
temperature (OR the 100 million C from the ITER fusion reactor)
into the Boltzman equation, look at resultant watts, and
make conclusions about lethal distance.
Yet that is what the original illustration does.
The Boltzman equation is an accurate translation of temperature to radiant
power, assuming perfect emissivity, plus infinite power is available to
maintain the temperature of the 1 mm^3 pinhead on earth.
It is not in any way reflective of what a pinhead of solar core material
would do on earth, any more than a pinhead of ITER plasma or a
pinhead of Uranus magetosphere.
.
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| User: "Sam Wormley" |
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| Title: Re: Sun's core "pinhead" illustration in error |
17 Jan 2005 12:30:53 AM |
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Joe D. wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:_jIGd.10927$OF5.9745@attbi_s52...
.....
Thank you.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
"I bring this up because there can be ridiculously high temperatures in
the Universe, but they don't mean much!
And that is exactly my point. It would be absurd to plug that
temperature (OR the 100 million C from the ITER fusion reactor)
into the Boltzman equation, look at resultant watts, and
make conclusions about lethal distance.
Yet that is what the original illustration does.
The Boltzman equation is an accurate translation of temperature to radiant
power, assuming perfect emissivity, plus infinite power is available to
maintain the temperature of the 1 mm^3 pinhead on earth.
It is not in any way reflective of what a pinhead of solar core material
would do on earth, any more than a pinhead of ITER plasma or a
pinhead of Uranus magetosphere.
And the density of the plasma at the center of the sun is?
And the temperature of the plasma at the center of the sun is?
.
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| User: "Joe D." |
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| Title: Re: Sun's core "pinhead" illustration in error |
17 Jan 2005 12:41:48 AM |
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"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:xYIGd.11291$eT5.8148@attbi_s51...
Joe D. wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:_jIGd.10927$OF5.9745@attbi_s52...
.....
Thank you.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
"I bring this up because there can be ridiculously high temperatures in
the Universe, but they don't mean much!
And that is exactly my point. It would be absurd to plug that
temperature (OR the 100 million C from the ITER fusion reactor)
into the Boltzman equation, look at resultant watts, and
make conclusions about lethal distance.
Yet that is what the original illustration does.
The Boltzman equation is an accurate translation of temperature to
radiant
power, assuming perfect emissivity, plus infinite power is available to
maintain the temperature of the 1 mm^3 pinhead on earth.
It is not in any way reflective of what a pinhead of solar core material
would do on earth, any more than a pinhead of ITER plasma or a
pinhead of Uranus magetosphere.
And the density of the plasma at the center of the sun is?
And the temperature of the plasma at the center of the sun is?
As stated previously in this thread, specific density of
the sun's core is 150 grams/cm^3. Temperature is 15 million C.
.
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| User: "Sam Wormley" |
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| Title: Re: Sun's core "pinhead" illustration in error |
17 Jan 2005 12:50:13 AM |
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Joe D. wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:xYIGd.11291$eT5.8148@attbi_s51...
Joe D. wrote:
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:_jIGd.10927$OF5.9745@attbi_s52...
.....
Thank you.
http://www.madsci.org/posts/archives/aug97/872692372.As.r.html
"I bring this up because there can be ridiculously high temperatures in
the Universe, but they don't mean much!
And that is exactly my point. It would be absurd to plug that
temperature (OR the 100 million C from the ITER fusion reactor)
into the Boltzman equation, look at resultant watts, and
make conclusions about lethal distance.
Yet that is what the original illustration does.
The Boltzman equation is an accurate translation of temperature to
radiant
power, assuming perfect emissivity, plus infinite power is available to
maintain the temperature of the 1 mm^3 pinhead on earth.
It is not in any way reflective of what a pinhead of solar core material
would do on earth, any more than a pinhead of ITER plasma or a
pinhead of Uranus magetosphere.
And the density of the plasma at the center of the sun is?
And the temperature of the plasma at the center of the sun is?
As stated previously in this thread, specific density of
the sun's core is 150 grams/cm^3. Temperature is 15 million C.
Your figures are not much different than mine.
1.6 x 10^7 K
1.6 x 10^5 kg/m^3
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