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Mespo_Man
2002-Aug-20, 01:01 PM
Is there a simple reason why new chemical elements are not being created naturally?

It seems to me that with the constant recycling of "star stuff" (love that phrase) over countless eons, that heavier and heavier elements would be constructed in the solar furnaces. Unless, of course, such activity would damage the fire-brick lining. /phpBB/images/smiles/icon_smile.gif


(:raig

GrapesOfWrath
2002-Aug-20, 02:05 PM
On 2002-08-20 09:01, Mespo_Man wrote:
Is there a simple reason why new chemical elements are not being created naturally?

It seems to me that with the constant

You got it in one. The fine structure constant (http://scienceworld.wolfram.com/physics/FineStructureConstant.html). 1/137. As the atomic number get closer to 137, it is harder to keep the atom together.

Bob
2002-Aug-20, 03:49 PM
You got it in one. The fine structure constant (http://scienceworld.wolfram.com/physics/FineStructureConstant.html). 1/137. As the atomic number get closer to 137, it is harder to keep the atom together.
[/quote]

The fine structure constant has absolutely nothing to do with atomic number.

New elements have been and still are being formed in stars, including the Sun, since stars first appeared. First generation stars contained only hydrogen and helium. The heavier elements created by fusion within them were scattered by supernovae, so later generation stars formed with hydrogen, helium, and some heavier elements and the process continued.

traztx
2002-Aug-20, 04:02 PM
On 2002-08-20 11:49, Bob wrote:
The heavier elements created by fusion within them were scattered by supernovae, so later generation stars formed with hydrogen, helium, and some heavier elements and the process continued.


Some natural processes also break down heavier elements into lighter ones, right?

Wiley
2002-Aug-20, 04:14 PM
On 2002-08-20 11:49, Bob wrote:
You got it in one. The fine structure constant (http://scienceworld.wolfram.com/physics/FineStructureConstant.html). 1/137. As the atomic number get closer to 137, it is harder to keep the atom together.


The fine structure constant has absolutely nothing to do with atomic number.


I don't know. Since the fine structure constant represents the strength of electromagnetic coupling, I would think that atomic number and the fine structure constant would directly relate to the stability of the atom and it's half-life.

Regardless 99 and above (http://education.jlab.org/itselemental/ele099.html) have very short half-lives. Einsteinium is by far the longest lived with a half-life 471 days, but most are measured in minutes or seconds. We don't find these elements in nature because they decay too fast.




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Bob
2002-Aug-20, 05:22 PM
I don't know. Since the fine structure constant represents the strength of electromagnetic coupling, I would think that atomic number and the fine structure constant would directly relate to the stability of the atom and it's half-life.
/quote]

Nuclei are held together by the strong force, the strongest (duh!) of the fundanental forces, not electromagnetic forces. Since the electromagnetic force between protons is repulsive, the very existence of nuclei was a puzzle until the strong force was figured out.

Wiley
2002-Aug-20, 05:41 PM
On 2002-08-20 13:22, Bob wrote:
Nuclei are held together by the strong force, the strongest (duh!) of the fundanental forces, not electromagnetic forces. Since the electromagnetic force between protons is repulsive, the very existence of nuclei was a puzzle until the strong force was figured out.

I'm not disputing that the strong force holds nuclei together. The issue is decay, or the busting up of the nucleus, which, as your post indicates, is at least partially electromagnetic. On the flip side, beta decay would also be dependent on electromagnetic forces since the electrons and nucleus are attractive.

Bob
2002-Aug-20, 05:55 PM
The main point I wish to make about nuclear physics is the fact that the fine structure constant being approximately equal to 1/137 somehow implies that atomic numbers approaching 137 must be increasingly unstable is numerological hogwash.

Silas
2002-Aug-20, 06:07 PM
On 2002-08-20 13:55, Bob wrote:
The main point I wish to make about nuclear physics is the fact that the fine structure constant being approximately equal to 1/137 somehow implies that atomic numbers approaching 137 must be increasingly unstable is numerological hogwash.


Since Grapes of Wrath is a gentleman ("and so are well all, all honorable people") it might be nicer to say that he made a mistake.

The "curve of binding energy" for atomic nuclei has a minimum at the element Iron. Lighter elements have a tendency (in the right conditions) to build up (fusion) toward that element, and heavier ones have a tendency to split (fission.) Very heavy atoms, beyond Uranium, are so eager to split that they don't exist in stable isotopes at all. There has been speculation that there might be an "island of stability" way out there ("On Beyond Zebra," so to speak...) Last I'd heard, though, the theoretical math suggests the island is only a seamount...

(By the way, the verb form of fusion is "to fuse." What is the verb form of fission? One can't go and say "to fiss" can one?)

For the life of me, I've never been able to work out what the fine structure constant is about. Can someone explain it in appropriately introductory language?

Silas

xriso
2002-Aug-20, 06:16 PM
On 2002-08-20 14:07, Silas wrote:
(By the way, the verb form of fusion is "to fuse." What is the verb form of fission? One can't go and say "to fiss" can one?)



I believe it is "to fissure". At least I think it's a verb as well as a noun.



For the life of me, I've never been able to work out what the fine structure constant is about. Can someone explain it in appropriately introductory language?


I would be interested in hearing about this too. /phpBB/images/smiles/icon_smile.gif

Wiley
2002-Aug-20, 07:51 PM
On 2002-08-20 14:07, Silas wrote:
Since Grapes of Wrath is a gentleman ...

I don't think I've ever heard a more egregious ad hominem attack. /phpBB/images/smiles/icon_smile.gif



(By the way, the verb form of fusion is "to fuse." What is the verb form of fission? One can't go and say "to fiss" can one?)

How about "split"? Or better yet, use cleave. "Cleaving atoms" can be either fission or fusion.



For the life of me, I've never been able to work out what the fine structure constant is about. Can someone explain it in appropriately introductory language?


Try this: PhysLink.com (http://www.physlink.com/Education/AskExperts/ae33.cfm?CFID=239495&CFTOKEN=23948497)

Jim
2002-Aug-20, 08:47 PM
To fish? To fizz? To fizh?

(Rats! Went back to be cute and lost the message.)

Here's another link with what may be a simpler approach. It shows how the angular momentum comes in, and the relationship between Dirac and Bohr's model.

http://members.shaw.ca/quadibloc/science/phyint.htm

In short, it says a simple way to understand alpha is that it is what the ratio of the speed of the electron orbiting the nucleus of a hydrogen atom to the speed of light would normally be. This is shown as:

v/c = e<sup>2</sup> / 2 h c epsilon<sub>0</sub> = alpha

where e = electron charge, h = Planck’s constant, c = the speed of light, epsilon<sub>0</sub> = permittivity of free space.

_____
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Isaac Asimov

<font size=-1>[ This Message was edited by: Jim on 2002-08-20 16:48 ]</font>

<font size=-1>[ This Message was edited by: Jim on 2002-08-20 16:57 ]</font>

Donnie B.
2002-Aug-20, 08:51 PM
I have see the word fission itself used as a verb. I have also heard (but never seen in writing) the usage "to fish". If written, I suppose it should be "to fiss", but that expression doesn't seem to have any formal legitimacy.

Wiley
2002-Aug-20, 09:06 PM
On 2002-08-20 16:51, Donnie B. wrote:
I have see the word fission itself used as a verb. I have also heard (but never seen in writing) the usage "to fish". If written, I suppose it should be "to fiss", but that expression doesn't seem to have any formal legitimacy.


The American Heritage dictionary (http://education.yahoo.com/reference/dictionary/entries/06/f0150600.html) say fission can be used as a verb. No "fiss" entry, and the latin root is fissi (http://education.yahoo.com/reference/dictionary/entries/04/f0150400.html). "Fiss" is probably incorrect, but English is a living language. We can do what we want. So let's everybody take Friday off and go fission.


<font size=-1>[ This Message was edited by: Wiley on 2002-08-20 17:11 ]</font>

Silas
2002-Aug-20, 09:56 PM
On 2002-08-20 17:06, Wiley wrote:
So let's everybody take Friday off and go fission.


I'll bring the dynamite!

Silas

GrapesOfWrath
2002-Aug-21, 12:14 AM
On 2002-08-20 15:51, Wiley wrote:
I don't think I've ever heard a more egregious ad hominem attack.

I'm confident that Silas will soon issue a retraction.

Still, IANANP (I am not a nuclear physicist) but, I have seen analysis supporting my original statement, danged if I know where. Let's see, disregarding relativistic treatments, the approximate velocity of close electrons in atoms of atomic weight Z is Z&alpha;c, where &alpha; is the fine structure constant, 1/137. Is that right?

Donnie B.
2002-Aug-21, 01:00 AM
On 2002-08-20 17:56, Silas wrote:


On 2002-08-20 17:06, Wiley wrote:
So let's everybody take Friday off and go fission.


I'll bring the dynamite!

Silas


Wow, Silas, that's a very clever double-entendre! I'm impressed... /phpBB/images/smiles/icon_smile.gif

Bob
2002-Aug-21, 03:19 AM
On 2002-08-20 20:14, GrapesOfWrath wrote:


On 2002-08-20 15:51, Wiley wrote:
I don't think I've ever heard a more egregious ad hominem attack.

I'm confident that Silas will soon issue a retraction.

Still, IANANP (I am not a nuclear physicist) but, I have seen analysis supporting my original statement, danged if I know where. Let's see, disregarding relativistic treatments, the approximate velocity of close electrons in atoms of atomic weight Z is Z?c, where ? is the fine structure constant, 1/137. Is that right?


I thought this thread was about nuclear forces, but we can talk about orbital electrons as well. The uncertainty principle makes assigning a specific velocity to a subatomic particle like an electron meaningless. The most you can say is that there is a probability distribution for velocities of such particles.

Bob
2002-Aug-21, 03:40 AM
Physics joke (yes, there are such things):

Einstein died and went to heaven. He was greeted by St. Peter who said " Doctor Einstein, as a reward for your contributions to human understanding of physics, God Himself has consented to let you ask him one question." "Lord," Einstein said, "I have only one question: the fine structure constant is 1/137. Why 1/137?" Instantly a blackboard appeared, and God began to explain why this fundamental ratio was what it was. Halfway through, Einstein cried out, "Das ist ganz falsch!" ["That's completely wrong!"].

beskeptical
2002-Aug-21, 04:19 AM
On 2002-08-20 09:01, Mespo_Man wrote:
Is there a simple reason why new chemical elements are not being created naturally?

It seems to me that with the constant recycling of "star stuff" (love that phrase) over countless eons, that heavier and heavier elements would be constructed in the solar furnaces. (:raig

(emphasis mine)


Grapes replied: As the atomic number get closer to 137, it is harder to keep the atom together.


Bob replied: First generation stars contained only hydrogen and helium. The heavier elements created by fusion within them were scattered by supernovae, so later generation stars formed with hydrogen, helium, and some heavier elements and the process continued.

(emphasis mine)


tratz replied: Some natural processes also break down heavier elements into lighter ones, right?


Wiley replied: I don't know. Since the fine structure constant represents the strength of electromagnetic coupling, I would think that atomic number and the fine structure constant would directly relate to the stability of the atom and it's half-life.

Regardless 99 and above have very short half-lives. Einsteinium is by far the longest lived with a half-life 471 days, but most are measured in minutes or seconds. We don't find these elements in nature because they decay too fast.

There seems to be a difference in how Bob interpreted the words 'new elements' from the way Grapes, tratz and Wiley did.

This seems to have caused an apparent disagreement where one might not really exist.

And, the links to the 'fine structure constant' provide more discussion on the value of the constant rather than it's significance. Jim's link has a bit more about significance.

So why am I butting in to this discussion I have only a basic knowledge about? To point out to you all from an outside observer's observations of this thread you might want to clarify whether you are talking about new elements as in more or as in novel.

And for you math speakers, you certainly should be speaking to eachother in math, but you might want to use links that are in common English to explain things to the rest of us.

Now, I don't mean this to be critical, really. And, I could be all wrong, maybe you guys are all on the same page and I'm off. But I just thought I'd say something in case. /phpBB/images/smiles/icon_smile.gif


_________________
For the record, that's Beskeptigal.

<font size=-1>[ This Message was edited by: beskeptical on 2002-08-21 00:21 ]</font>

ZaphodBeeblebrox
2002-Aug-21, 04:20 AM
On 2002-08-20 23:40, Bob wrote:
Physics joke (yes, there are such things):


How about this Riddle:

To which Question, is The Answer, 9W?

Celestial Mechanic
2002-Aug-21, 04:28 AM
In answer to the question about the fine-structure constant:

The fine-structure constant is equal to e^2 / h-bar / c and in suitable units is a dimensionless number approximately equal to 1/137. (Here e is the electrostatic charge unit, not the base of natural logarithms.) There should be a similar fine-structure constant with g_S in place of e.

The problem is that these constants aren't really constant, they are a function of the square of the energy-momentum exchanged by the virtual gluon/photon carrying the field. Because the photon is not confined, we get to see it (literally and figuratively) at lower energies and for a wide range of energies it is slowly varying and effectively constant. We detect gluons very indirectly and only at very high energies where the coupling constant is varying by a significant amount over the range that we are able to measure. The coupling constant is said to "run".

If we could perform particle experiments at energies of about 10^15 GeV we expect to see the strong, electromagnetic, and weak forces have comparable strengths, that is the constants "run" together and are equal at higher energies. This energy scale is called the "Grand Unification Energy".

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Microsoft is over if you want it.

Fixed typo.

<font size=-1>[ This Message was edited by: Celestial Mechanic on 2002-08-21 08:46 ]</font>

Celestial Mechanic
2002-Aug-21, 04:42 AM
What Does the Fine-Structure Constant Have to Do With Nuclear Physics, Anyway?

As mentioned above, the electromagnetic fine-structure constant is about 1/137 while the strong fine-structure constant is (at the energies present in nuclei) about 1. Sorry I can't be more precise about that value. Colloquially we say that the strong force is about 100 times stronger than the electromagnetic force.

Neutrons and protons are bound together into nuclei via the strong nuclear force. The force is attractive and independent of the particle type, that is, proton-proton is the same as neutron-neutron and proton-neutron in strength. This force is limited in range to about 1.3*10^-15m, not much bigger than the nucleons themselves. The neutrons are mostly unaffected by electromagnetic forces (there must be some effect because the quarks are charged, but as a unit the neutron is electrically neutral), but the protons repel one another and there is no limit to the range over which this repulsion acts. At about the atomic number 137 (give or take a few) the electrostatic repulsion between a proton and all the other protons in the nucleus is comparable to the attractive forces of the neighboring nucleons.

_________________
Microsoft is over if you want it.

Oops! Corrected "nuclei" to "nucleons".
<font size=-1>[ This Message was edited by: Celestial Mechanic on 2002-08-21 00:44 ]</font>

<font size=-1>[ This Message was edited by: Celestial Mechanic on 2002-08-22 08:50 ]</font>

GrapesOfWrath
2002-Aug-21, 12:59 PM
On 2002-08-21 00:42, Celestial Mechanic wrote:
At about the atomic number 137 (give or take a few) the electrostatic repulsion between a proton and all the other protons in the nucleus is comparable to the attractive forces of the neighboring nuclei.

That sounds familiar. What about that, Bob?

Silas
2002-Aug-21, 03:31 PM
On 2002-08-21 00:20, ZaphodBeeblebrox wrote:
How about this Riddle:

To which Question, is The Answer, 9W?


"Do you spell your name with a 'V' Herr Valker?"

Are you a P.D.Q. Bach fan?

"What is the question to which the answer is 'Doctor Livingstone I Presume?'"

"What is your full name, Doctor Presume?"

Silas

poorleno
2002-Aug-21, 03:47 PM
That's a simple one ( in regard to "to fiss")

I have never seen such a bunch of clearly intellectual individuals not being able to compute a verb in the area of their expertise. Simple: To undergo fission.

Donnie B.
2002-Aug-21, 04:01 PM
poorleno,

Of course, that verb phrase is used a lot. But the verb there is 'undergo', not 'fission'; it doesn't really fill the bill for a verb that parallels 'fuse'. After all, deuterium also "undergoes fusion" in a thermonuclear reaction.

But I agree, it's not really of much import in the grand scheme of things... /phpBB/images/smiles/icon_smile.gif

Bob
2002-Aug-21, 05:19 PM
On 2002-08-21 08:59, GrapesOfWrath wrote:


On 2002-08-21 00:42, Celestial Mechanic wrote:
At about the atomic number 137 (give or take a few) the electrostatic repulsion between a proton and all the other protons in the nucleus is comparable to the attractive forces of the neighboring nuclei.

That sounds familiar. What about that, Bob?


Last time I looked at a periodic table the balance point seemed to be at N=92.

poorleno
2002-Aug-21, 06:17 PM
Donnie B, (I’m going to adopt your addressing style since you forgot to insert a ©, and my instincts tell me to do so… )

Of course there is a share of truth in that.
My English is far from good so I really shouldn't be discussing this at all. However I still think that the correct term for (incorrect) fiss is to undergo fission. It's a really good question however given that sometime one may find himself puzzled by this wee thing.
I must admit that it’s not exactly parallel to fuse, no. Given the origin of both words (- Latin, one meaning melt and the other cleave), similarities in spelling and pronunciation one very well might think that the correct verb would be similar as well. However fission is spelled, unlike fusion, with a double s; therefore fiss doesn’t “ring” and you are left with a combo-like verb.

Teh enD ?

xriso
2002-Aug-21, 07:32 PM
According to the dictionaries I've just been reading (yes, I cheated!), "fission" is an intransitive and transitive verb as well as a noun (fusion is just a noun - use fuse for a verb). So, you can fission an atom, and an atom can fission. This usage apparently dates back to 1929.

It seems that people rarely want to use a verb form of fission anyway. Though, if you search the web for "fissioned" you will find places that use it.

<font size=-1>[ This Message was edited by: xriso on 2002-08-21 15:35 ]</font>

GrapesOfWrath
2002-Aug-21, 07:54 PM
On 2002-08-21 13:19, Bob wrote:
Last time I looked at a periodic table the balance point seemed to be at N=92.


Balance point?

Bob
2002-Aug-21, 08:16 PM
On 2002-08-21 15:54, GrapesOfWrath wrote:


On 2002-08-21 13:19, Bob wrote:
Last time I looked at a periodic table the balance point seemed to be at N=92.


Balance point?


Ref: a post by Celestial Mechanic: "At about the atomic number 137 (give or take a few) the electrostatic repulsion between a proton and all the other protons in the nucleus is comparable to the attractive forces of the neighboring nuclei"

Although, come to think of it, I don't quite understand what "attractive forces of the neighboring nuclei" are. The neighboring nuclei are positively charged. Perhaps CM means "nucleons" instead of "nuclei," which was my initial interpretation. I was referring to a "balance point" between the attractive strong force and the repulsive electromagnetic force.

<font size=-1>[ This Message was edited by: Bob on 2002-08-21 16:24 ]</font>

Wiley
2002-Aug-21, 10:10 PM
On 2002-08-21 16:16, Bob wrote:
I was referring to a "balance point" between the attractive strong force and the repulsive electromagnetic force.


How does one determine this "balance point"?

Donnie B.
2002-Aug-22, 01:14 AM
Well, among other methods, empirically.

Bob
2002-Aug-22, 01:27 AM
On 2002-08-21 18:10, Wiley wrote:


On 2002-08-21 16:16, Bob wrote:
I was referring to a "balance point" between the attractive strong force and the repulsive electromagnetic force.


How does one determine this "balance point"?



The nuclei become unstable (radioactive)

Kaptain K
2002-Aug-22, 08:04 AM
On 2002-08-21 21:27, Bob wrote:



How does one determine this "balance point"?



The nuclei become unstable (radioactive)

By this criterion, the "balance point" is 83. Bismuth (element 83) is the heaviest element with a stable isotope (Bi 209). Lead (element 82) has four stable isotopes (Pb 204, 206, 207 and 208). No heavier element has any stable isotopes.
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When all is said and done - sit down and shut up!

<font size=-1>[ This Message was edited by: Kaptain K on 2002-08-22 04:06 ]</font>

GrapesOfWrath
2002-Aug-22, 12:07 PM
On 2002-08-21 16:16, Bob wrote:
Ref: a post by Celestial Mechanic: "At about the atomic number 137 (give or take a few) the electrostatic repulsion between a proton and all the other protons in the nucleus is comparable to the attractive forces of the neighboring nuclei"

Although, come to think of it, I don't quite understand what "attractive forces of the neighboring nuclei" are. The neighboring nuclei are positively charged. Perhaps CM means "nucleons" instead of "nuclei," which was my initial interpretation. I was referring to a "balance point" between the attractive strong force and the repulsive electromagnetic force.

Well, that seems to be what CM meant also, although his reasoning for supporting a "balance point" of 137 was a little less numerological. /phpBB/images/smiles/icon_smile.gif

Wiley
2002-Aug-22, 06:15 PM
On 2002-08-21 21:27, Bob wrote:


On 2002-08-21 18:10, Wiley wrote:
How does one determine this "balance point"?



The nuclei become unstable (radioactive)


What I meant is "Is there is a non-empirical way of determining the balance point?" And if so, what?

Silas
2002-Aug-22, 08:09 PM
On 2002-08-22 14:15, Wiley wrote:
What I meant is "Is there is a non-empirical way of determining the balance point?" And if so, what?


This is starting to get a bit circular, since the mass of the pi-meson was determined, in part, by observations of real atoms.

But...once you know the pi-meson's mass, then you can know its lifetime, which gives you the distance over which it can work. Knowing *that* gives you a chance to model the nucleus and to work out, a priori, what sort of atoms are going to be unstable.

But it's a lot easier just to look at atoms in the wild and see if they're stable or not...

Silas

Kizarvexis
2002-Aug-25, 12:06 AM
But it's a lot easier just to look at atoms in the wild and see if they're stable or not...


Silas, that gave me the image of Steve Irwin, aka The Crocodile Hunter, as a nuclear physicist.

"There she is. Cesium-137. Isn't she a beauty?" /phpBB/images/smiles/icon_smile.gif

Kizarvexis
Forgive me, but I do not know how to type an Australian accent. /phpBB/images/smiles/icon_smile.gif

Geo3gh
2002-Aug-25, 06:56 AM
"Crikey! Lookit this beauty of a spec'min of Cesium-137! See how quietly it lies there. This doesn't make good TV, so I'm going to poke it with this stick..."

David Hall
2002-Aug-25, 08:19 PM
/phpBB/images/smiles/icon_lol.gif /phpBB/images/smiles/icon_biggrin.gif /phpBB/images/smiles/icon_lol.gif

Ring
2002-Aug-26, 04:23 AM
Alpha determines the size of atoms and the stability of matter. If alpha were much larger there would be no distinction between matter and radiation. If it were much larger (eg =1) then the atom would be the size of the nucleus. But as far as I know alpha has nothing to do with Z.

Alpha also sets the number of oscillations of an electron, before it will emit a photon, equal to 3 million, and it determines that an the electron will spend alpha of its time as electromagnetic radiation.



<font size=-1>[ This Message was edited by: Ring on 2002-08-26 01:02 ]</font>

Ring
2002-Aug-26, 04:40 AM
<font size=-1>[ This Message was edited by: Ring on 2002-08-26 01:02 ]</font>

Ring
2002-Aug-26, 01:43 PM
Let me see if I can de-garble that last post of mine (it was very late and I was very tired).

Alpha determines the strength of interaction between a charged particle and the electromagnetic field. Therefore if alpha were much smaller the atom would be much larger and vice versa.

Matter can turn into radiation and the probability that an electron will do so is proportional to alpha. In fact an electron spends alpha of its time as radiation and therefore if the interaction were much stronger matter and radiation would be indistinguishable.

But I don't know of any relation between alpha and the mass of the nucleus.

GrapesOfWrath
2002-Aug-26, 03:43 PM
On 2002-08-26 09:43, Ring wrote:
But I don't know of any relation between alpha and the mass of the nucleus.

Alpha being the fine structure constant.

What about the comments by Celestial Mechanic, in this thread?

Ring
2002-Aug-26, 06:16 PM
On 2002-08-26 11:43, GrapesOfWrath wrote:


On 2002-08-26 09:43, Ring wrote:
But I don't know of any relation between alpha and the mass of the nucleus.

Alpha being the fine structure constant.

What about the comments by Celestial Mechanic, in this thread?


Celestial Mechanic seems to be talking about something called the *strong* fine-structure constant. If so, he's talking about something I know nothing about.

In fact, after rereading my above posts it seems I may know nothing about anything at all. My fondest wish is that I would never have posted to this thread in the first place. He who keeps his mouth shut doth not make a fool of himself.


<font size=-1>[ This Message was edited by: Ring on 2002-08-26 14:18 ]</font>