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Thread: A diamond sword so sharp that it can cut through virtually anything?

  1. #1 A diamond sword so sharp that it can cut through virtually anything? 
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    A while ago I finished reading the last Eragon book, Inheritance, which I highly recommend everyone read, because it's awesome. Anyway, an interesting thing in the book was that one of the characters had a sword made of diamond (or at least that's what was implied) that was so sharp that it could cut through virtually anything. It was described as being 'the archetype of an inclined plane'. What exactly that means, I'm not sure, but I'm guessing it means that the thinnest point on the edge of the blade is only one carbon atom thick, and gets progressively thicker to form a perfect slant right down to the atomic level.

    Now, obviously there is no way we could (or would) make such a blade with current technology, but I couldn't help but wonder; if such a blade could be made, and if its edge really was a perfect slant right down to a single row of carbon atoms, is there anyway it could actually do what it could in the book? The thing that most interested me about this sword (which incidentally was named Albitr, or 'Tinkledeath') was that it was implied that it did not need any sort of magical protection (yes, I do know that magic is fiction, but for the purposes of this post it basically means that there is little chance of it being damaged) because the blade was literally so sharp that it would almost never encounter any substantial resistance. Just to put it into perspective, here's an excerpt from the book.

    In the end, he strode over to the altar and swung the blade at one corner of the stone slab. “Not so quickly!” cried Angela. The transparent blade passed through four inches of stone as if the granite were no harder than custard, then continued down toward his feet. Eragon yelped and jumped back, barely managing to stop his arm before he cut himself. The corner of the altar bounced off the step below and then tumbled clacking toward the middle of the room.The blade of the sword, Eragon realized, might very well be diamond after all. It would not need as much protection as he had assumed, since it would rarely meet with any substantial resistance.

    Now, I have no doubt that if we could make such a sword that it could cut through skin and flesh like a scalpel through warm butter, but what about stone and metal? Is that just pure fiction or could there be something to this idea, at least in theory? Even if stretching the limits of what is possible to their limits. I know how absurd this sounds, but I still can't help but wonder whether there is ANY kind of truth to this idea even in principle, whether the sword is made of diamond or not is immaterial, as it is never actually confirmed to be made of diamond in the book.


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  3. #2  
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    your diamond edge would be so thin that is has no structural strength-ie shatter on impact with a hard mass.
    Oh well thats SiFi.


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  4. #3  
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    as with a flint knife, the edge could be one micron thick = sharper than steel

    excellent as a slicing tool, not so much so as a chopping tool
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  5. #4  
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    What many of these sci-fi writers forget is that there is one substance that is just as hard as a diamond: another diamond.
    Some clocks are only right twice a day, but they are still right when they are right.
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  6. #5  
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    Not sure if an-atom-thick diamond can remain stable forever. Maybe it will decay into a weaker substance like graphene and then fall apart. Because the difference between graphene and diamond is just that arrangement of its atoms and this atoms can rearrange itself when heated or agitated.

    Friction could create alot of heat!
    Last edited by msafwan; May 28th, 2012 at 01:20 PM.
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  7. #6  
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    Quote Originally Posted by msafwan View Post
    Not sure if an-atom-thick diamond can remain stable forever. Maybe it will decay into a weaker substance like graphene and then fall apart. Because the difference between graphene and diamond is just that arrangement of its atoms and this atoms can rearrange itself when heated or agitated.

    Friction could create alot of heat!
    Thats exactly true. The diamond structure is in 3 dimensions, if you cut it so thin, it's no longer 3D, it'll no longer be diamond. It'll simply be a layer of carbon. Diamond swords exist in mythology because of the use of diamonds (more like graphite though) filing in the iron. By these methods the iron became a lot stronger, and shined like diamond. So actually, the first real steel blades, were seen as diamond blades by their enemies.

    Though several man made structures with mainly carbon are proven to be stronger then diamond.
    
 Nano-material is harder than diamonds - physics-math - 30 August 2005 - New Scientist
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  8. #7  
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    Quote Originally Posted by Zwolver View Post
    Quote Originally Posted by msafwan View Post
    Not sure if an-atom-thick diamond can remain stable forever. Maybe it will decay into a weaker substance like graphene and then fall apart. Because the difference between graphene and diamond is just that arrangement of its atoms and this atoms can rearrange itself when heated or agitated.

    Friction could create alot of heat!
    Thats exactly true. The diamond structure is in 3 dimensions, if you cut it so thin, it's no longer 3D, it'll no longer be diamond. It'll simply be a layer of carbon. Diamond swords exist in mythology because of the use of diamonds (more like graphite though) filing in the iron. By these methods the iron became a lot stronger, and shined like diamond. So actually, the first real steel blades, were seen as diamond blades by their enemies.

    Though several man made structures with mainly carbon are proven to be stronger then diamond.
    
 Nano-material is harder than diamonds - physics-math - 30 August 2005 - New Scientist
    What the heck are you talking about? Of course it would still be three-dimensional; everything in the known universe exists in at least three dimensions, regardless of our tendency to think of such objects as electrons or singularities as being less than three-dimensional for simplicity sake. The reality is that to say that something is less than 3 dimensional is to say that it has a length/width/depth/diameter, etc of zero, meaning it can't exist.

    At any rate, it seems I must reiterate the question at the heart of my post. The material used to create such a blade is irrelevant; no doubt the author simply chose diamond because of the common misconception that diamond is nearly indestructible. What I was really asking was whether it is even POSSIBLE in theory for a sword/blade to be literally so sharp that it can cut through virtually any material without meeting much if any resistance (and I'm talking about a normal, solid sword. Plasma swords and lightsabers don't count).
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  9. #8  
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    No..............
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  10. #9  
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    What I was really asking was whether it is even POSSIBLE in theory for a sword/blade to be literally so sharp that it can cut through virtually any material without meeting much if any resistance (and I'm talking about a normal, solid sword
    On Mythbusters, they tested the Hollywood myth of a sword cutting through another sword. (If you've seen Kill Bill part 1, you've seen it done). They built a sword swinging arm that generated over ten times the sword speed of a swordmaster, used the finest Japanese katana, against what was essentially a cheap reproduction sword.

    It didn't work.
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  11. #10  
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    Part of the problem is that the two halves of the blade on either side of the cut won't actually spread apart until after you've made it through to the other side. Why would they? Even with a slit going half way through, the blade is still a steel blade. A cutting sword of any sharpness would get pinched into place by the two halves of iron pushing on it from both sides.

    That's also one reason why you can't just hew a tree down in one swing, just by having a sharp enough axe. At a minimum, you'd need to cut some wedges out of the tree first.
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    Some clocks are only right twice a day, but they are still right when they are right.
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  12. #11  
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    Quote Originally Posted by Fanghur View Post
    What the heck are you talking about? Of course it would still be three-dimensional; everything in the known universe exists in at least three dimensions, regardless of our tendency to think of such objects as electrons or singularities as being less than three-dimensional for simplicity sake. The reality is that to say that something is less than 3 dimensional is to say that it has a length/width/depth/diameter, etc of zero, meaning it can't exist.
    He's right, Fanghur. Diamond is a carbon lattice. The cutting edge of the sword would be one atom thick. That isn't diamond, that's graphite. It's pencil lead.

    Quote Originally Posted by Fanghur View Post
    At any rate, it seems I must reiterate the question at the heart of my post. The material used to create such a blade is irrelevant; no doubt the author simply chose diamond because of the common misconception that diamond is nearly indestructible. What I was really asking was whether it is even POSSIBLE in theory for a sword/blade to be literally so sharp that it can cut through virtually any material without meeting much if any resistance (and I'm talking about a normal, solid sword. Plasma swords and lightsabers don't count).
    It isn't possible I'm afraid. The resistance a blade encounters is essentially the electromagnetic bonds which keeps a solid material solid. A thin sharp blade edge minimises the resistance, but doesn't make it go away. And then when you support the leading edge with material behind it, you run into the problem that kojax described.

    I seem to recall reading a science fiction story once that featured something like a "mono-atomic" cheeswire to try to get round this problem. I didn't find it particulary convincing as I recall.
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  13. #12  
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    You might have a hard time with osmium, osmium is harder than diamonds and can scratch or cut them, but diamonds are not hard enough to cut or scratch osmium.

    Diamond tests at approx 443 GPa
    Osmium tests at upto 473 GPa
    Last edited by Ascended; May 30th, 2012 at 01:39 PM. Reason: extra information
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  14. #13  
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    Osmium is not hard enough for anything, it is a brittle metal, that practically corrodes when looked upon. Still At 7.0 Mohrs it's as though as quartz.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  15. #14  
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    He was probably thinking of unobtanium.
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    Quote Originally Posted by Zwolver View Post
    Osmium is not hard enough for anything, it is a brittle metal, that practically corrodes when looked upon. Still At 7.0 Mohrs it's as though as quartz.
    I must differ to my more learned fellow forum member thanks for the correction, seems I have misread the compressive force of osmium diboride as hardness.

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  17. #16  
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    Quote Originally Posted by MeteorWayne View Post
    He was probably thinking of unobtanium.
    Probarbly
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  18. #17  
    Forum Radioactive Isotope sculptor's Avatar
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    differ
    or defer
    (or was that a joke?)
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  19. #18  
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    Quote Originally Posted by sculptor View Post
    differ
    or defer
    (or was that a joke?)
    Unfortunately my spelling is so bad it wasn't. I am so used dictating everything I forget how to spell.
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  20. #19  
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    Spelling is a lost art. It's embarassing what get written these days.
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  21. #20  
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    Quote Originally Posted by MeteorWayne View Post
    Spelling is a lost art. It's embarassing what get written these days.
    I'm not embaressed I had a limited education. Most things are a step up .
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  22. #21  
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    yeh, me too (spelling) added to which is word substitution which is getting more common as i get older
    if i'm thinking of 2 things, i transpose ---wayne spotted one of these earlier
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    Quote Originally Posted by AlexG View Post
    What I was really asking was whether it is even POSSIBLE in theory for a sword/blade to be literally so sharp that it can cut through virtually any material without meeting much if any resistance (and I'm talking about a normal, solid sword
    On Mythbusters, they tested the Hollywood myth of a sword cutting through another sword. (If you've seen Kill Bill part 1, you've seen it done). They built a sword swinging arm that generated over ten times the sword speed of a swordmaster, used the finest Japanese katana, against what was essentially a cheap reproduction sword.

    It didn't work.

    The reason why the katana was so useful as a weapon wasnt coz it was sharp as such but because of the curve on the blade, as the user would strike the curve would reduce the surface area that the force was acting on as only a small area of the blade is connecting at the time. there would be more pressure acting at point of impact.

    this is my first post i dont kno if i did it right
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  25. #24  
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    I stopped reading after the assertion was made about eragon being a recommendable book.
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  26. #25  
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    Quote Originally Posted by omarelt View Post
    Quote Originally Posted by AlexG View Post
    What I was really asking was whether it is even POSSIBLE in theory for a sword/blade to be literally so sharp that it can cut through virtually any material without meeting much if any resistance (and I'm talking about a normal, solid sword
    On Mythbusters, they tested the Hollywood myth of a sword cutting through another sword. (If you've seen Kill Bill part 1, you've seen it done). They built a sword swinging arm that generated over ten times the sword speed of a swordmaster, used the finest Japanese katana, against what was essentially a cheap reproduction sword.

    It didn't work.

    The reason why the katana was so useful as a weapon wasnt coz it was sharp as such but because of the curve on the blade, as the user would strike the curve would reduce the surface area that the force was acting on as only a small area of the blade is connecting at the time. there would be more pressure acting at point of impact.

    this is my first post i dont kno if i did it right
    You didn't do it wrong... But the topic was kind of old...

    Ignore Dywyddyr on this one, his flavor text displays his personality, no offense intended dywyddyr.

    A katana would fail against a european sword, because if the speed increases, the force increases. And if the katana didn't have the ability to cut through it, while deforming from the impact, it will break. Simply because physics will chose a blade because of sturdyness, not sharpness. And a medieval european blade weighs about 4 times as much, which means 4 times more steel is used. The katana never stood a chance.

    It's like driving a truck, headfirst into a volvo. It may be the worlds safest car... It's still a freaking truck..
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  27. #26  
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    Quote Originally Posted by Zwolver View Post
    Ignore Dywyddyr on this one, his flavor text displays his personality, no offense intended dywyddyr.
    Untrue.
    My "text" displays the fact that I replied and then realised I'd replied to the OP and not the last post [1].
    I therefore decided that what I had written was redundant and deleted it.
    So much for your psychological skills.

    1 Because, for some reason, it showed that there was a new post, but only showed me the OP.
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  28. #27  
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    Why would anyone want to waste a diamond on a sword?
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  29. #28  
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    I read that some surgical knives are made from obsidian. Apparently the edge of an obsidian knife can be chipped down to a width of a single atom.
    This is so thin that it actually spreads the skin without slicing throught it and leaves almost no scar tissue.
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  30. #29  
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    It is "The Night of The Living Thread" (when the dead threads rise again to spread terror among the living!)

    Glass and diamond knives are used in microscopy labs for microtomes to cut very thin sections. Mostly useful for electron microscopy.
    It was found steel was too soft to take a fine enough edge to slice very thin sections. The diamond blade can be resharped but the glass blades are usually discarded and new edges broken from the glass sheet.
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    Quote Originally Posted by Write4U View Post
    I read that some surgical knives are made from obsidian. Apparently the edge of an obsidian knife can be chipped down to a width of a single atom.
    This is so thin that it actually spreads the skin without slicing throught it and leaves almost no scar tissue.
    Thanks...next time they cut into my eyes, I'll try to hold that thought.
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  32. #31  
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    Quote Originally Posted by babe View Post
    Quote Originally Posted by Write4U View Post
    I read that some surgical knives are made from obsidian. Apparently the edge of an obsidian knife can be chipped down to a width of a single atom.
    This is so thin that it actually spreads the skin without slicing throught it and leaves almost no scar tissue.
    Thanks...next time they cut into my eyes, I'll try to hold that thought.
    Obsidian Scalpels
    •Blade Shape: Straight
    •Alloy / Material: Obsidian Blade / Wood Handle

    Obsidian is a type of volcanic glass that produces a much finer blade than conventional steel. It is ideal for applications where an extremely fine cutting action is required or where trace metals from ordinary scalpel blades cannot be tolerated. The relatively inexpensive obsidian scalpel is a good substitute for an expensive diamond knife.

    Cautionary note: Obsidian is a very fragile material. Great care should be taken not to exert any lateral pressure on the blade during cutting. Each blade is hand-fashioned, so sizes, shapes and points will vary. While all the blades will have at least one sharp edge, some will have two.
    Fine Science Tools, Inc. - Surgical Instruments for Scientific & Biomedical Research
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