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NlightNd1
∇Δ∇Δ∇Δ∇



Registered: 12/11/07
Posts: 1,883
Loc: Holographic Omniverse
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Snowflake Symmetry
#9266882 - 11/18/08 04:12 PM (15 years, 2 months ago) |
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Can anyone explain to me why snowflakes have symmetry. All six sides of a snowflake are nearly identical. Every snowflake is unique yet all six points on a snowflake form exactly the same. How does this happen. I'm not expecting anyone to actually know the answer to this question so theories are welcome.
-------------------- Turn off your mind, relax and floatdown stream. It is not dying. Lay down all thought, surrender to the void. It is shining. Pink Floyd
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DieCommie

Registered: 12/11/03
Posts: 29,258
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Re: Snowflake Symmetry [Re: NlightNd1]
#9266941 - 11/18/08 04:20 PM (15 years, 2 months ago) |
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Great question! A quick google search revels that the six arms are not indeed 'exactly the same' or symmetrical. The amount of symmetry they do share is likely a result of being exposed to the same conditions.
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Madtowntripper
Sun-Beams out of Cucumbers



Registered: 03/06/03
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Re: Snowflake Symmetry [Re: DieCommie]
#9267130 - 11/18/08 04:45 PM (15 years, 2 months ago) |
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I'm really high, but I have to disagree.
Ice crystals, like any crystals, will grow in a predetermined shape or pattern based on what is at their core. Once the first crystal of ice is formed in a certain pattern, every further addition to that crystal that grows will mirror that original shape. This is how the separated arms of a snowflake can have (generally) the same pattern, because they are both a remnant of the same crystal.
The only reason I know this is because this is crystals of all types perform, not just water.
-------------------- After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action. If you cannot throw it at least you can always drink out of it. - Ernest Hemingway If it is life that you feel you are missing I can tell you where to find it. In the law courts, in business, in government. There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent. -Cormac MacCarthy He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God. - Aeschylus
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Minstrel
Man of Science



Registered: 03/15/05
Posts: 1,974
Loc: Hogtown
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Ah, the wonders of wikipedia:
Ice crystals formed in the appropriate conditions can often be thin and flat. These planar crystals may be simple hexagons, or if the supersaturation is high enough, develop branches and dendritic (fern-like) features and have six approximately identical arms, as per the iconic 'snowflake' popularised by Wilson Bentley. The 6-fold symmetry arises from the hexagonal crystal structure of ordinary ice, the branch formation is produced by unstable growth, with deposition occurring preferentially near the tips of branches.[4]
The shape of the snowflake is determined broadly by the temperature and humidity at which it forms.[3] Rarely, at a temperature of around −2 °C (28 °F), snowflakes can form in threefold symmetry — triangular snowflakes.[5] The most common snow particles are visibly irregular, although near-perfect snowflakes may be more common in pictures because they are more visually appealing.
Planar crystals (thin and flat) grow in air between 0 °C (32 °F) and −3 °C (27 °F). Between −3 °C (27 °F) and −8 °C (18 °F), the crystals will form needles or hollow columns or prisms (long thin pencil-like shapes). From −8 °C (18 °F) to −22 °C (−8 °F) the habit goes back to plate like, often with branched or dendritic features. Note that the maximum difference in vapour pressure between liquid and ice is at approx. −15 °C (5 °F) where crystals grow most rapidly at the expense of the liquid droplets. At temperatures below −22 °C (−8 °F), the crystal habit again becomes column-like again, although many more complex habits also form such as side-planes, bullet-rosettes and also planar types depending on the conditions and ice nuclei.[6]
Interestingly, if a crystal has started forming in a column growth regime, say at around −5 °C (23 °F), and then falls into the warmer plate-like regime, plate or dendritic crystals sprout at the end of the column producing so called 'capped columns'.[3]
There is a widely held belief that no two snowflakes are alike. Strictly speaking, it is extremely unlikely for any two macroscopic objects in the universe to contain an identical molecular structure; but there are, nonetheless, no known scientific laws that prevent it. In a more pragmatic sense, it's more likely—albeit not much more—that two snowflakes are virtually identical if their environments were similar enough, either because they grew very near one another, or simply by chance. The American Meteorological Society has reported that matching snow crystals were discovered in Wisconsin in 1988 by Nancy Knight of the National Center for Atmospheric Research.[citation needed] The crystals were not flakes in the usual sense but rather hollow hexagonal prisms.
Edited by Minstrel (11/18/08 06:13 PM)
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trendal
J♠



Registered: 04/17/01
Posts: 20,815
Loc: Ontario, Canada
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Re: Snowflake Symmetry [Re: NlightNd1]
#9271581 - 11/19/08 10:16 AM (15 years, 2 months ago) |
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Because ice is made of water, and water is just a LARGE collection of H2O molecules, you will always get a kind of symmetry when you build something out of those molecules. An ice crystal is just a whole lot of water molecules stacked together.
Every crystal in nature - and ice is a crystal - shows the same type of similarity.
--------------------
Once, men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.
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DieCommie

Registered: 12/11/03
Posts: 29,258
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Re: Snowflake Symmetry [Re: trendal]
#9272855 - 11/19/08 03:23 PM (15 years, 2 months ago) |
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But that doesnt answer the question... why are two snowflakes different, yet two arms on a single snowflake are the same? Obviously the arms arnt communicating with each other... So the environmental effects that cause two snowflakes to be different should also cause two arms to be different.
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Madtowntripper
Sun-Beams out of Cucumbers



Registered: 03/06/03
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Re: Snowflake Symmetry [Re: DieCommie]
#9273061 - 11/19/08 04:01 PM (15 years, 2 months ago) |
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Because the arms are both exhibiting the structure of the original ice crystal that formed.
Their spatial separation on different arms of the snowflake are irrelevant because both are formed from the same structure.
-------------------- After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action. If you cannot throw it at least you can always drink out of it. - Ernest Hemingway If it is life that you feel you are missing I can tell you where to find it. In the law courts, in business, in government. There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent. -Cormac MacCarthy He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God. - Aeschylus
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DieCommie

Registered: 12/11/03
Posts: 29,258
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Water is water, it all crystallizes the same way in lieu of contaminants and environmental factors. So it doesnt really make sense to claim that the end of a spike on one arm is the same as the end of a spike on another arm because the specific seed crystal.
Here is an interesting depiction of the different types of formations in different conditions.
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Madtowntripper
Sun-Beams out of Cucumbers



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Re: Snowflake Symmetry [Re: DieCommie]
#9273128 - 11/19/08 04:10 PM (15 years, 2 months ago) |
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There are contaminants everywhere in the atmosphere.
-------------------- After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action. If you cannot throw it at least you can always drink out of it. - Ernest Hemingway If it is life that you feel you are missing I can tell you where to find it. In the law courts, in business, in government. There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent. -Cormac MacCarthy He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God. - Aeschylus
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DieCommie

Registered: 12/11/03
Posts: 29,258
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no shit So youre claiming that a contaminant will change the geometry in a seed crystal, but change is symmetrically so that the disturbance propagates through to the end of each arm in exactly the same way? In this way the arms are symmetrical, and snowflakes with different arms are all a functions of that original contaminant? If thats what youre claiming I have to say I simply dont buy it. It doesnt make sense, why would the original contaminant disrupt the lattice in a symmetrical way that propagates equally to each arm? Maybe youre right, it just doesnt make sense to me.
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Madtowntripper
Sun-Beams out of Cucumbers



Registered: 03/06/03
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Re: Snowflake Symmetry [Re: DieCommie]
#9273180 - 11/19/08 04:20 PM (15 years, 2 months ago) |
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I just read something that said it was simply because every arm was under the same conditions at the same time.
But it seems strange that the different arms would form such similar shapes. I'm not sure I believe that.
-------------------- After one comes, through contact with it's administrators, no longer to cherish greatly the law as a remedy in abuses, then the bottle becomes a sovereign means of direct action. If you cannot throw it at least you can always drink out of it. - Ernest Hemingway If it is life that you feel you are missing I can tell you where to find it. In the law courts, in business, in government. There is nothing occurring in the streets. Nothing but a dumbshow composed of the helpless and the impotent. -Cormac MacCarthy He who learns must suffer. And even in our sleep pain that cannot forget falls drop by drop upon the heart, and in our own despair, against our will, comes wisdom to us by the awful grace of God. - Aeschylus
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PhanTomCat
Teh Cat....



Registered: 09/07/04
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Re: Snowflake Symmetry [Re: DieCommie]
#9274533 - 11/19/08 07:47 PM (15 years, 2 months ago) |
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Does the whole snowflake just "grow" out from a drop of water, or does moisture just start collecting on the tips that are "deciding" to grow....?
I know that say salt crystals grow in a super saturated salt-water solution, is it that same type of relationship with air that is "super saturated" with moisture....?
It would be neat to grow a snowflake to the size of a waffle or bigger, or some such.... :ninjathowingstars: Which makes me wonder what the size limiting factor is....
Someone posted this in the Pub a few weeks ago, thought it was pretty cool.... It was coated with something for contrast, if I remember right....

>^;;^<
-------------------- I'll be your midnight French Fry.... "The most important things in life that are often ignored, are the things that one cannot see...." >^;;^<
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ChuangTzu
starvingphysicist




Registered: 09/04/02
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Re: Snowflake Symmetry [Re: PhanTomCat]
#9274894 - 11/19/08 08:50 PM (15 years, 2 months ago) |
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My vision of snowflake formation involves a small nucleus onto which is deposited a seed crystal which undergoes many growth cycles as it is blown up and down through different environments in the atmosphere (much like a piece of hail is layered for the same reason). It makes sense that the arms will look the same because the entire snowflake isn't growing at once. The arms are added to in small layers at a time. So as the snowflake enters a region conducive to growth, an amount of new crystal will be deposited on each arm depending on conditions. Since the conditions are approximately the same for each arm, an equivalent amount is added to each arm at every stage thus giving the appearance of symmetry. This is only approximate though, and as the wikipedia article referenced above notes:
Quote:
The shape of the snowflake is determined broadly by the temperature and humidity at which it forms.[3] Rarely, at a temperature of around −2 °C (28 °F), snowflakes can form in threefold symmetry — triangular snowflakes.[5] The most common snow particles are visibly irregular, although near-perfect snowflakes may be more common in pictures because they are more visually appealing.
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Plasmid
Absent


Registered: 06/01/08
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Re: Snowflake Symmetry [Re: ChuangTzu]
#9275749 - 11/19/08 10:56 PM (15 years, 2 months ago) |
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I suggest you read the Jan-Feb edition of American Scientist 2007. p. 52- 59 is where the article starts The Formation of Snow Crystals
http://www.americanscientist.org/issues/feature/2007/1/the-formation-of-snow-crystals
-------------------- Absent.
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ChuangTzu
starvingphysicist




Registered: 09/04/02
Posts: 3,060
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Re: Snowflake Symmetry [Re: Plasmid]
#9275856 - 11/19/08 11:13 PM (15 years, 2 months ago) |
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Great article, thanks. It seems my vision and theirs are the same. The part on growth kinetics was especially interesting. Caltech is right down the street from my work, maybe I'll go visit these guys and see what kind of equipment they're doing that stuff with...
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Plasmid
Absent


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Re: Snowflake Symmetry [Re: ChuangTzu]
#9276461 - 11/20/08 01:07 AM (15 years, 2 months ago) |
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Crystals are pretty.
-------------------- Absent.
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California
A E S T H E T I C S A T A N


Registered: 12/27/04
Posts: 72,118
Loc: H A U N T E D H O U S E
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Re: Snowflake Symmetry [Re: NlightNd1]
#9276519 - 11/20/08 01:23 AM (15 years, 2 months ago) |
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Quote:
NlightNd1 said: Can anyone explain to me why snowflakes have symmetry. All six sides of a snowflake are nearly identical. Every snowflake is unique yet all six points on a snowflake form exactly the same. How does this happen. I'm not expecting anyone to actually know the answer to this question so theories are welcome.
water molecules have "cellular memmory". I am certain that this has something to do with it.
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ChuangTzu
starvingphysicist




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Re: Snowflake Symmetry [Re: California]
#9276587 - 11/20/08 01:40 AM (15 years, 2 months ago) |
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Quote:
Oregon said: water molecules have "cellular memmory". I am certain that this has something to do with it.
They do not, whatever that is...
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koppie
astral projectile


Registered: 07/23/04
Posts: 2,653
Loc: cloud hidden
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Re: Snowflake Symmetry [Re: ChuangTzu]
#9285997 - 11/21/08 02:58 PM (15 years, 2 months ago) |
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You obviously haven't heard of the work of Masaru Emoto. The snowcrystals form the way they do because of the happy or angry thoughts directed at them. Everybody knows that. 
It must be true because he writes books with pretty pictures in them.
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zouden
Neuroscientist


Registered: 11/12/07
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Re: Snowflake Symmetry [Re: koppie]
#9286731 - 11/21/08 04:51 PM (15 years, 2 months ago) |
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I remember that from that movie What The Bleep Do We Know. They used his work as evidence that positive thoughts can affect the physical world. What a terrible movie.
-------------------- I know... that just the smallest part of the world belongs to me You know... I'm not a blind man but truth is the hardest thing to see
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DieCommie

Registered: 12/11/03
Posts: 29,258
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Re: Snowflake Symmetry [Re: zouden]
#9286995 - 11/21/08 05:24 PM (15 years, 2 months ago) |
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One of the worst part of studying physics is whenever your tell somebody there most likely reaction is "Have you seen what the bleep do we know?". And they say it all excitedly as though its great. Half the time I tell them the movie is crackpottery, the other half I just say no and dont get into it.
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zouden
Neuroscientist


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Re: Snowflake Symmetry [Re: DieCommie]
#9287010 - 11/21/08 05:27 PM (15 years, 2 months ago) |
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It wasn't all crackpottery. Just the last 90%.
-------------------- I know... that just the smallest part of the world belongs to me You know... I'm not a blind man but truth is the hardest thing to see
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DieCommie

Registered: 12/11/03
Posts: 29,258
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Re: Snowflake Symmetry [Re: zouden]
#9287068 - 11/21/08 05:36 PM (15 years, 2 months ago) |
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An anecdote to the hippy crap that has infested our universities... My wife was shown that movie in a university course as though it had relevant scientific information. Pathetic... If the university was held to the same standards as business, we would have demanded our money back for an inferior product.
Another uncomfortable position was when my boss at a community college was praising it. Weird... he was a smart guy I thought, but he bought it. I did manege to find a time where it was appropriate to tell him about the movie. I dont know if he believed me, but I at least gave him a case against it.
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Middleman

Registered: 07/11/99
Posts: 8,399
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Re: Snowflake Symmetry [Re: DieCommie]
#9287535 - 11/21/08 06:58 PM (15 years, 2 months ago) |
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Sorry bro, Ramtha is right and you are wrong.
Everything is conscious and mind does indeed effect matter. 
Thanks for that link Plasmid.
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