r/theydidthemath • u/Iridium-235 • 2d ago
[Request] is there a chance that this could happen, under the right circumstances? Is it even possible?
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u/Doafit 2d ago
Not a mathematical question but rather a science question.
So physically/chemically speaking, what happens if you cut something? You split a bond. If you cut a a cucumber for example, you will never ever ever "split" an atom. You will probably break hydrogen bonds bonding cellulose molecules and proteins to give it its structure. Those will break before chemical bonds break, since they are much weaker.
Also the tip of your blade, even if incredibly sharp is several 100 to thousands of atoms thick. And the actual force is transmitted by the electrons of the blade atoms repelling those of the cucumber atoms.
Actually nothing ever touches on this nano level.
And when you now think about HOW small in comparison the nucleus of an atom is compared to the size of the whole atom (most of it is the electron "shell") which is smaller than 1/10000, then you see how it is impossible to cut an atom with a blade.
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u/mortadeloyfile 2d ago
You say "the tip of your blade...is several 100 to thousands of atoms thick"
Well wait till you see the
Osmirisium-tipped-blade-knoife™
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u/Lolfapio 2d ago
does it keeeeel?
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u/rubermnkey 2d ago
if you eat too much omelet covered rice it probably will. not sure if eggs are good or bad cholesterol right now, is mercury in retrograde?
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u/Raging-Buddha 2d ago
They obviously haven't heard of the forbidden techniques of blade singing. There is no yokuda anymore
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u/DreamDare- 1d ago
Actually nothing ever touches on this nano level.
Nothing ever happens. <- confirmed.
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u/Humble_Discussion_40 2d ago
Technically atoms don't touch each other because of strong repulsive force between two nuclei. So, whenever you going to cut something it's always going to be at atomic level not at subatomic, or atleast I hope so, or you gonna make world go ka-boom! Haha 😄
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u/Impossible-Option-16 2d ago
So I vaguely remember reading somewhere that we do t ever actually “touch” things we just experience their magnetic field as pressure that our skin detects. So you don’t really cut something with scissors you just separate that magnetic field apart.
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u/WexMajor82 2d ago
Yeah, you don't really "touch" anything in your whole life.
That sent me for a loop when I firstly learnt it. I was 13, TBH.
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u/mark503 2d ago edited 2d ago
My wife just learned that we don’t feel moisture or what we call wet on our skin. We just can’t feel it. We can tell by other means like pressure and temp. It takes multiple senses working together to recognize the body being “wet”.
E: Jesus Christ. I forgot I was on Reddit. It’s not vaginal moisture you jerks, it’s skin moisture. I swear I’m not maga. She gets wet. Y’all are terrible.
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u/Orioniae 2d ago
This is true, and this can be easily spoofed if we use a medical latex glove. Also, our body feels also how "elastic" is the skin based on how much water absorbs by using microcomparations.
The fact that we don't directly feel wetness is based on the fact that our skin is, first and foremost, a protective barrier against outside agents.
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u/PrismaticDetector 2d ago
It tends to be confusing because our intuitive semantics for "you" and "touch" just don't translate to subatomic scales, and translation errors cause you to reexamine your understanding of the words you're using. You're learning something about your understanding of the world as much if not more than you're learning something about physics. Makes it feel good and profound.
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u/calculus9 2d ago
We dont touch things is a bit of a misnomer i feel, as our things don't touch either
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u/AssistanceCheap379 2d ago
It’s also why you can take 2 pieces of metal (same metal) and as long as they are clean (no oxidation or any air between), you can essentially cold weld them together. It’s common enough in space that you need to be somewhat careful with things. Basically, if you have 2 exposed metals that are mostly the same composition, you can touch them together and since the atoms don’t know anything, they just assume the part they’re touching is part of the metal they are a part of and bond to it.
It’s why you either need to apply paint, an oxidation layer or oil to metals in space in order to prevent them from cold welding.
It also has some fantastic qualities for space manufacturing, as you could theoretically make extremely clean manufacturing processes and welds without the enormous amount of energy that can go into it
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u/Impossible-Option-16 2d ago
Ok that actually makes a lot of sense but still that’s absolutely crazy!
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u/Accomplished-Ad-2612 2d ago
When you're dealing with a really good tool and die tech, it's always cool watching them "wring" a freshly made set of matched dies that way. It's impressive watching them stick together with no added materials, just the die cold attaching to the other die.
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u/Bourec98 2d ago
That's why footballers always say "I didn't even touch him" after breaking both of the opponent's legs with a slide tackle
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u/Tiger3Tiger 2d ago
When I learned that, I poked my sister and said "I'm not touching you!"
She didn't think it was as funny as I did, nor did my parents
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u/Fun-Enthusiasm8412 2d ago
Electric field*
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u/PrismaticDetector 2d ago
*electromagnetic field. Electricity and magnetism are not separable phenomena at the level of electrons, since they have charge and constantly move.
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u/TengamPDX 1d ago
What gets real fun is realizing how small the nucleus of an atom is in relation to the space the atom takes up.
Basically put, if you could temporarily disable the forces at play here, you essentially pass through another solid object with fairly minimal if any collisions of nuclei occurring.
You wouldn't want to do this because gravity would still be at play and you'd just sink into the ground or if you were also to disable gravity for yourself, you'd just immediately fly off the surface of the Earth. Either way, it wouldn't be pleasant.
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u/MxM111 2d ago
The touching means that atoms of one surface interact (push away) atoms from another surface. But electrical forces are not enough to split atom. If however you knife is made from radioactive Uranium and you cut another uranium, then yes, you will split some atoms. But not by electrical forces.
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u/Prestigious-Duck6615 2d ago
that's not how it works
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u/PrismaticDetector 2d ago
I mean, nothing says that one of your subcritical masses can't be knife-shaped. It would be (figuratively) pointless, but it would still go boom when you brought them together...
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u/dribrats 2d ago
I always wondered what the statistical chances of walking through a wall would be— when all outside atomic forces are negotiable, but person keeps their integrity. It’s statistically possible!!!
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u/Pomegranate_36 2d ago
Why is 'walking through the door' a thing but 'falling through the floor' isn't?
The probability that someone would fall through the floor should be higher. We're almost never trying to walk through a door..
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u/GovernorSan 2d ago
The atoms of the iron in the blade are larger than the atoms of most things you would cut with it, so even if it was possible for one atom to cut into another, and iron-based blade isn't going to be the one to do it. It would be like trying to cut an apple with the broad side of a frying pan.
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u/Somerandom1922 2d ago edited 1d ago
There are actually a few fundamental misunderstandings here that are important to know.
The first (and most obvious) is the idea of "cutting an atom". You can't, scientists with massive particle accelerators can't "cut" atoms, they can shoot stuff at atoms and break them but it's far messier than "cutting". Even an atomically sharp (1 atom wide) edge on a knife would just result in atoms smooshing against each other with no change to the individual atoms themselves unless you got the knife moving ridiculously fast (as which point you've made a kind of garbage particle acceletor).
The second (less obvious and far more common) misunderstanding is that a single atom splitting causes a boom. This is where the math comes in.
But first, some fundamentals. For atoms larger than iron, when they break they release some of their mass as energy (thanks to E=mc2). It's really a tiny amount of mass compared to even the tiny mass of an atom, but because you multiply the mass by c2 it's a lot of energy.
Importantly though, it's a lot of energy only when you're thinking about the incredibly miniscule scale of an individual atom. A Uranium-235 atom undergoing fission releases about 202.5 MeV or 202 million electron volts of energy, which sounds like a lot, and like I said, it is a lot on the scale of a single atom. However, it's less than 10 billionths of a single joule.
A joule is the energy needed to heat 1ml by 1°C, and a U-235 fission reaction releases less than a 10-billionth of this.
Specifically, a U-235 fission reaction releases 3.24×10−11 J. So heating that ml of water by 1°C requires the fission of ~30,864,197,531 (30 billion) Uranium-235 atoms.
Making a cup of tea by heating 200ml of water from 20°C to 80°c would require approximately 370 trillion U-235 atoms to undergo fusion (and to somehow perfectly capture all of that energy as heat within the water).
That sounds like an insane number of fission reactions just to heat some water, but for a sense of scale those 370 trillion uranium atoms would weigh just 0.14 micrograms, far less than a single E. Coli bacterium, and only a tiny tiny fraction of this mass is actually being converted to energy.
Edit: fixed some things, added some details, and did some additional math.
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u/Sea_Ticket_6032 2d ago
Just curious, why is it only for atoms larger than iron?
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u/thisonedudethatiam 2d ago
The energy input is greater than the output for smaller than iron, causing a net loss of energy to overcome the nuclear force, if I am remembering correctly.
Same but in reverse for fusion, so when stars build up iron they start to die due to the net loss of energy.
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u/Ginden 1d ago
Iron-56 is the most stable isotope in existence, because it has lowest mass per nucleon - it means it has highest mass defect (like all atoms but H-1, Fe-56 is lighter than sum of all its parts).
It means that splitting any atom heavier than Fe-56 releases energy, while fusing atoms lighter than Fe-56 releases energy.
Eventually, all bound matter will convert through quantum tunneling into iron-56 in estimated time 101500 years.
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u/SweatyTax4669 2d ago
So what you’re saying is we’re gonna need to find a really really big atom to split
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u/Catenane 2d ago
I wouldn't call a mL a drop (maybe it's possible to get a mL drop with a very viscous liquid though lol).
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u/Somerandom1922 2d ago
Sure, but honestly that's a smaller difference than some of the other rounding I did in my comment.
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u/Catenane 2d ago
Yeah fair enough. It's also the easiest for me to nitpick on while sitting on my ass on my phone. ;)
Have not done much nuclear chem/physics except for college coursework ages ago, but I've done enough pipetting in my life to have a visceral reaction to seeing 1 mL being described as a drop, hahaha.
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u/Somerandom1922 2d ago
Hahaha fair lol. I'm mostly trying to demonstrate the vast differences in scale, so I definitely fudged just how small 1ml is to help sell the point.
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u/Catenane 2d ago
For sure, I had no real complaint with any of it, and you definitely made the point just fine. Just caught me off guard and it felt like an itch I had to scratch, haha.
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u/DustyScharole 2d ago edited 2d ago
This isn't really a math question, I don't think. First of all, "splitting" occurs because if an instability intentionally created by firing a proton at a large atom. Second of all, I really don't think cutting something with a knife, applying even maximal human strength, would create enough energy to cause the instability required. Humans are very small and weak on a universal scale.
Edit: Acknowledging my math friends who would remind me that all questions can be reduced to "math questions"
Edit 2: Neutron, not proton. Oops.
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u/Kerostasis 2d ago
Generally you fire Neutrons, not Protons, when attempting to cause Fission reactions. Protons are strongly pushed away by the existing nucleus, so it would take far more energy to jam one in hard enough to cause a split (although it would theoretically be possible at high enough energies).
But you’d be surprised on the second point: a human with a knife can generate an energy level higher than the fission energy level, you just can’t focus it precisely enough to land on a single atom (or really, a single neutron, which is even smaller). Atoms and atomic energy levels are really small.
And for very similar reasons, if you managed to cause an atom to fission (or just stood next to one fissioning on its own), you would be totally fine and not even notice. The “boom” doesn’t come from a single atom exploding, it comes from a chain reaction where that first atom triggers two more, which trigger two more each, etc etc until you have millions or billions of atoms all exploding at the same time. And that can only ever happen in a radioactive material like Uranium, so there’s no reason to worry about a stray kitchen knife fission event even if that was likely.
Which is good news, because a stray kitchen knife fission event is likely! Depending on what you are cutting, of course. Cutting a banana? There will probably be a potassium fission! Cutting on a granite countertop? The granite is also (slightly) radioactive! But neither of those can sustain a chain reaction so there’s no worry.
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u/junker359 2d ago
So you're saying I should stop using my uranium knife just to be safe
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u/EternityForest 2d ago
They say smoke detectors are safe, so switching to an americium knife might be better.
Or a cadmium knife, it's not radioactive and it's soft, two common properties of safe items.
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u/Galenthias 1d ago
Your uranium knife is just fine, it's your plutonium countertop that needs to go away.
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u/ScienceKyle 2d ago
Looks like I'll be playing a game of slice the yellow cake with my beryllium knife on my next birthday.
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u/therouterguy 2d ago
If you jump you momentarily exert a larger force than the entire planet exerts on you. So not so insignificant.
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u/PristineCheesecake1 2d ago
what if you just lay down in a ball and cry (asking for a friend)
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u/MD-Independent 2d ago
Well then you become your own planetary body pulling others to you (or so I’ve been told but have yet to experience).
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u/puneralissimo 2d ago
Then you're probably experiencing enough pressure, and maybe shouldn't have any more.
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u/Butterpye 2d ago
That's just proof gravity is extremely weak not that I am extremely strong. Even though I am.
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u/Accomplished-Boot-81 2d ago
Yeh but gravity is the weakest of the 4 fundamental forces so at best we are 4th in a race of 5
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u/soulstrike2022 2d ago
Even if you could produce that much force you don’t have a tool Percise enough
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u/WanderingFlumph 2d ago
Humans are large and powerful on an atomic scale. Ripping apart bonds is as easy as tearing a napkin.
The problem comes from trying to cut something as small as an atom with scissors made of atoms. If we had infinetly sharp scissors the actual force required to split an atom would be miniscule.
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u/Oshester 2d ago
Not possible. Even something like steel is mostly empty space at an atomic level. The fact that we can't even see that empty space, despite it being 99.9999999% empty is a testament to the scale problem within the question.
It would be like trying to cut a grain of sand in half with the sun... That also doesn't seem possible, right?
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u/echo123as 2d ago
Although this is valid the probability ain't the problem here
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u/Oshester 1d ago
It's the trying to cut a grain of sand with the sun part, isn't it?
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u/ConsumeTheBaby 1d ago
No, splitting one atom won’t cause an explosion. You need a material that can have a chain reaction.
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u/HAL9001-96 2d ago
causally? no
an aotm might randomly split though
happens all the time
splititngo ne atom does not cause an explosion
having a material where a chain reaction is inevitbale and septillions of atoms split causes an explosion
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u/Radiant_Dog1937 2d ago
With quantum mechanics? Sure, you might have the universe's most unlucky apple whose atoms randomly decay in an absurd coincidence. It wouldn't have anything to do with the knife though, just you being the unluckiest person in the entire universe. Probably the unluckiest, you're definitely an outlier.
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u/amongnotof 2d ago
No. Unless you are cutting an almost critical mass of highly enriched uranium or plutonium with a knife made of the same materials, then? Yes.
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u/ghost_desu 2d ago
A single atom splitting causes maybe a couple particles to release, so even if it was possible, all it could ever hope to achieve is just trigger a single click on the geiger counter.
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u/Gishky 2d ago
no, not possible. The knife consists of atoms. "Worst" case, which happens every cut, is that there are atoms that directly "hit" each other (which means their fields are perfectly aligned because atoms NEVER touch, except for a black hole maybe who knows). And that doesnt even do anything besides giving the most resistance to cut
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u/sassinyourclass 2d ago edited 2d ago
No, absolutely not. Splitting a single atom absolutely would not cause a nuclear explosion, and the only way split an atom is to fire a neutron into it and that atom has to be a specific isotope. Slicing with a knife uses the electromagnetic force which will never get past the electron cloud of an atom.
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u/Zaros262 2d ago
Even under the right circumstances, splitting an atom releases a practically immeasurably small amount of energy. Since it won't start a chain reaction, you'd never even notice
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u/zeje 2d ago
I can’t say for 100% sure, but no. Even if you had a blade that had a edge sharp enough to contact a single atom, it takes a lot of energy to break molecular bonds.
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u/vtuber-love 2d ago
Even if you did, splitting individual atoms won't even be firecracker level explosions. What makes nukes so powerful is it's a chain reaction that involves millions, even billions of atoms.
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u/Skinnypeed 2d ago
Even millions or billions of atoms would be negligible. Afaik nuclear detonations have chain reactions that involve somewhere on the scale of 1025 atoms splitting
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u/Lily_Thief 2d ago
Yeah. There's a dnd meme about using a cantrip to heat an atom to fusion levels, and I always love to point out how much less effective it is in combat than even warming up a cup of water.
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u/Aggravating-Mix-3813 2d ago
I'm almost 100% certain they are referencing the Fairy OddParents Movie, where Timmy split an atom in an attempt to defeat a fairy powered Crocker.
It's an oversimplification of nuclear fission at its best and a way to scar 10 year olds at its worst
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u/Dreadwoe 2d ago
Nuclear explosion is not JUST splitting an atom.
It is splitting a certain type of radioactive material by firing a particles at it. The splitting releases energy and additional particles that can split more of the same material. This results in an incredibly fast sequence of releases of energy that accelerate in speed as each atom split results and energy and more atom splits until all radioactive material has been split.
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u/crowsgoodeating 2d ago
Are you cutting a barely subcritical ball of Plutonium? If not you should be good, knives don't actually "touch" atoms they cut, they repulse each other. Furthermore, splitting any one atom isn't a big deal. For example splitting one Uranium atom would only release 200 MeV, alot on the atomic scale but you would need specialized equipment to even notice it, let alone it being a serious problem.
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u/DarkMarine1688 2d ago
My favorite bit of random but near impossible chance is if you spap a table there is extremely almost impossible chance your hands atoms.and tables all miss and your hand goes right through
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u/jamesr1005 2d ago
While a single atom splitting releases a lot of energy, it's not enough to create an explosion on its own. You need to split trillions of atoms to create a nuclear explosion
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u/knightlesssword 2d ago
To cut an atom, you need something smaller or sharper than an atom and I don’t think we have an atom splitter 5000 in our regular households
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u/youburyitidigitup 2d ago
It isn’t. The atoms of the two objects don’t touch, in fact, no atoms ever touch unless either they’re part of the same molecule or it’s a really unstable element (like uranium).
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u/Conscious_Avocado225 2d ago
Nikki should be told that there is nothing to worry about when using a knife. Atoms don't get cut like paper or meat. Nuclear explosions are triggered by compressing atoms together. So, please tell Niki to start being worried when using a sledgehammer. BTW, NYP (not your physicist)
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u/Maximum-Country-149 2d ago
You know E = mc^2?
That equation takes the mass deficit of an atom- the amount less mass it has than it "should" if you added up all its components- and describes it as binding energy. C is, of course, the speed of light, which is a very big number. C^2, then, should be a very big number.
And in fairness, it is... proportionally. But the mass, and therefore the mass deficit, of an atom is very, very, very small. To give you an idea, the nuclear binding energy of Lead-208 works out to 7.867 megaelectronvolts per nucleon... or about 1.2 * 10^-12 joules. Even if you completely wiped it out, on the grand scale, it wouldn't make much of a difference.
(That said, the same formula implies it doesn't take much energy, at our scale, to obliterate a lead atom completely. It's just not something we can really do because that's something like trying to pee on a fly from a jet plane.)
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u/WanabeInflatable 2d ago
To do it you'd need a knife working on different physical principles. Even the sharpest knives are just atoms of iron packed in a grid. So when you cut - atoms of knife approach atoms of whatever your cut. They repulse each other by electrical forces as they are in proximity. Not even atomic nuclei, but clouds of electrons around it - collide and push back.
A knife that would do a trick should be operating with different physical forces to be sharper than size of atomic nucleus. No material is capable of it. Even theoretical monomolecular blade can't
A sci-fi solution would be a blade that is tearing space-time continuum
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u/Williamston40gaming 2d ago
Atoms split all the time, its called decay, when it happens, it releases a bit of energy. Specifically splitting in an environment where a whole ton of large, unstable atoms packed together into a critical mass, often with some extra energy added by conventional explosives, could cause a chain reaction that splits a whole ton of atoms all at once that releases a bunch of energy in the form of a nuclear explosion.
Even IF it is possible to split an atom using a knife and physical force, it would be so unlikely to cause a chain reaction that would lead to a nuclear explosion that it likely has never and will never happen anywhere in the entire lifetime of the universe
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u/MDZPlayer25 2d ago
Due to the billions and billions worth of Joules from Coulomb's force connecting the nuclei together, I'm not quite sure your noodle arms are going to tear those atoms apart. I mean, surely, there is a reason nuclear fission happens in a gigantic factory, not a table saw...
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u/Mundane-Tale-7169 2d ago
As atoms are not static it would be impossible to keep it in place long enough to cut it with a knife. Even if you were able to separate it from other atoms and fixate it, the knifes blade would just push it to its left or right side as it is like what? 10very high magnitudes thicker than the atom?
Also splitting atoms doesn’t mean you cut them in half, it means they loose particles releasing a small bit of the energy used to put them together, known as fission energy.
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u/okocims_razor 2d ago
It would be the chance of quantum tunneling causing a fission reaction which is in the realm of 10{40} years or greater, it is longer than the age I’ve the universe plus 10{30} years
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u/PhantomOrigin 2d ago
You can't cut an atom with another atom. The width of the sharpest knife blade on earth is still going to be a LOT of atoms in width at the tip.
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u/Iron_Yuppie 2d ago
On top of everything else, splitting a single atom doesn’t cause a nuclear explosion, it’s the cascading chain reaction. A single atom will release a small amount of energy, but the resulting particles released wouldn’t cascade forward and split additional atom since - presumably - you’re not cutting through uranium (or unstable other materials).
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u/AGoos3 2d ago
No, that’s not how fusion and fission works. Splitting the atom happens because you add a neutron to it and make it become unstable. It’s like you’re knocking down a support pillar in a building. In any case, you wouldn’t be able to split the atom like you’d split an orange or apple. There isn’t anything thin enough yet forceful and wide enough to cut through an atom like that. Most collisions are just repulsion anyway; no two atoms get close enough to the nucleus for one to cut the other, unless you’re talking about fusion (which is a whole different can of worms.)
I’m sure I’m forgetting some wacko elementary particle that is able to exert force directly on the nucleus (I’m only a high schooler who has done some research on this stuff) but even then it wouldn’t like “cut” it.
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u/A_BagerWhatsMore 2d ago
1.) this isn’t really how cutting works, you are mainly pushing atoms apart, the atom will squish into the other atoms around it or move to the side way more easily than it will break you would need both crazy speed and crazy precision to break an atom the kind that would make it very difficult for the knife to hold together in the first place.
2.) one atom breaking doesn’t release that much energy, it’s just that there are a lot of atoms and nuclear bombs start a chain reaction that breaks apart a very very large number of atoms.
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u/Designer_Version1449 2d ago
Aroma split all the time, even if you split an atom of plutonium nothing will happen. You need to split a ton of atoms under highly specific conditions(the center of a powerful explosion for example) in order to cause an explosion.
It's like seeing that pressing a button makes an explosion and gearing anytime you flip a switch your house will explode
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u/AngelThrones4sale 2d ago
It's not just possible, it's guaranteed -but it won't trigger an explosion.
Nuclear explosions happen because of a chain reaction where one atom that splits causes more than 1 other atom to split on average, leading to an exponentially increasing number of atoms splitting. Each one only emits a tiny amount of energy but the cumulative effect of all of them splitting is what gives you the bomb.
Single atoms split all the time. Atoms that are really stable (like carbon, nitrogen, etc.) are unlikely to split, but whenever you cut something with a knife you're forcing huge numbers of atoms to interact with each other. Your knife won't "cut" through an atom (because the blade itself is also made of atoms) but there are always trace amounts of relatively unstable atoms in the lettuce that you're cutting, and during the interaction with your knife the chances that at least one of those atoms will split under the interactions it's undergoing with its environment is essentially 100%.
I mean, it would probably have split anyway, without the knife, but yes. You're splitting atoms all the time.
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u/Former-Hospital-3656 2d ago edited 2d ago
Nuclear physicists here, No. you need to get over electric and magnetic forces generated by the nucleus and electrons before you can split the atom. And knife cutting just doesn’t have that kind of impulse, only way you could make it work is if you make the veggie and knife have a collision at relativistic speeds (millions of times faster than sound) which is what particle colliders do! Matter of fact nothing ever touches anything else, it’s all floating on top of each other elevated by E and M forces. But here’s a fun thing. Just by nature of quantum physics and wave mechanics, an atom is put together and destroyed and in every form it can be at every place in space in every way at the same time and in this very dimension. Just that most of the other “states” of that atom are very “dim” so you don’t see it and the atom is is intact because out of all the forms that one atom exists right now, this happens to be the most “bright”. And with abundant I don’t mean multiple atoms, I’m talking about that one atom you are looking at, say atom john, so John is right now, physically broken up, put together, it is spread around everywhere and nowhere, it is at this very instant at every point in space in this very world. It is true and observable. It’s called the principle of least action. So no, you are not splitting an atom with a knife but… you are not real, and neither is anything else. Life and consciousness as we see it is merely an illusion, a grand big prank by god if you want to put it that way. Veritasium had a good video on it “least action principle”☺️
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u/andrew_calcs 8✓ 2d ago
No. Splitting an atom is not what causes a nuclear explosion. Splitting an atom and having the byproducts of that splitting cause other atoms to split in a self perpetuating chain reaction is what makes a nuclear explosion. That can only happen with very specific materials in very specific physical configurations.
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u/LucidLiving33 2d ago
Only if your knife is full of loose protons that keeping firing into the same atom’s nucleus at astronomical speeds with each chop… then the nucleus of that atom will explode, causing the atom to split, and set off a chain reaction with the atoms around it…
So yeah… I’d be careful
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u/FirstRyder 2d ago
Unless you're using it to press a button attached to an ignition system of an atomic bomb, you are not causing a nuclear explosion with a knife.
Even if you literally cut into a slab of uranium from a nuclear bomb with the sharpest knife imaginable, you aren't causing an explosion. The main danger is the radiation from holding that slab.
Starting one deliberately is hard. The most common mechanism is to surround the core with high explosives and ignite them at so precisely the same time that they need to measure the length of all the wires from the detonators to the ignition points. Starting a nuclear explosion on accident by hand without an existing nuclear bomb is impossible.
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u/okayNowThrowItAway 2d ago edited 2d ago
No. At an atomic level, cutting stuff with a knife is more like squishing material out of the way, rather than cleaving it sharply.
You can keep making your knife sharper and shaper, but there's no such thing as a sharp enough knife to spilt an atom. Not because you can't get knives sharp enough, but because cutting stuff doesn't work that way.
Now, you could conceivably make a device that holds a material in such a way that you could initiate fission by cutting it with a very sharp kitchen knife. But that device would be so exotic that I think we would more reasonably credit the high-tech holder with splitting the atom, not the kitchen knife.
Also, as others have said here, splitting one atom is not something you'd have to worry about too much. It's actually something that happens all around us all the time, and we are barely effected. While splitting an atom does release a large amount of energy relative to the size of the atom, it's still a teeny-tiny amount of heat and radiation. You need to split a large number of atoms all at once to release a dangerous amount of energy.
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u/Dragonxan 2d ago
So, as far as I know, the LHC shoots particles around a loop at near light speed before smacking them into each other, annihilating them, causing massive release of energy.
If a dude could swing a knife at near light speed and did so to slice a carrot, could the same thing happen as in the LHC and the guy accidentally cause a nuclear explosive slicing his veggies?
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u/romulusnr 2d ago
The knife is also made of atoms, and those atoms will push each other away.
The only way to split an atom is with subatomic particles. Not something most of us have readily available (uh, by themselves).
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u/Mr_Woodchuck314159 2d ago
Sure it’s possible, under the right circumstances. The right circumstances would be a knife made out of uranium or plutonium, on a cutting board of uranium or plutonium that when put together reaches a critical mass. Or maybe if the knife was going at least 50% the speed of light </sarcasm>.
But in any normal circumstance, knives and non-relativistic speeds, no, this is not possible. When it gets down to it, if we to enlarge atoms to the size of ball pit balls, you would be taking a two by four the wide way, and pressing it into a bunch of ball pit balls (with more structure and more space between them). When you get down to an atomic scale, a knife isn’t sharp. It’s just stronger than what it’s cutting. Atoms will move to the side.
Now let’s make an assumption that something went terrible wrong. And things lined up perfectly. You squish three atoms together under your plank knife. Either, your knife would dull, or your cutting board would have three atoms pressed into it. The nuclear strong force that holds an atoms nucleus is together is very strong.
Ok, let’s assume you have a magical knife and an atom does split. Let’s assume it’s a carbon atom. And let’s assume it splits so efficiently that it is completely converted to energy (that is where the power of a nuclear blast comes from. After the blast, if you were to measure the weight of all reactants it would weigh less than what it started as. That is where the energy comes from). 1 carbon atom weighs 2*10-23 grams (12/Avogadro’s number). Use Einstein’s e=mc2 equation and we get 1.8 *10-9 J. To power an efficient 10 W led lightbulb for a second, you would need to completely concert 5 billion carbon atoms.
I’m sure I’m missing some large parts of math, but the numbers should be within an order of magnitude. If you had a magical knife that could split atoms eventually you would meet resistance or your knife would heat up, or however the energy chose to release, you need a lot before it would be noticeable. I think a lot of what makes nuclear explosions is how hot they make things. Nuclear bombs also usually need other explosives to get the metals that make them nuclear close enough together for a long enough period to make them explode.
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u/TomatoCo 2d ago
Nope! The knife is sharp at the macroscopic scale but when it comes to atoms they're all the same shape. You can't sharpen an atom, they're all blunt relative to each other. That's why it takes such high energies and such fragile atoms to actually split one.
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u/nonquitt 2d ago
No because a knife isn’t sharp relative to an atom just like the handle isn’t sharp relative to your arm
And also even if it was you’d need to shoot it into the atom at an extremely high speed and probably have a critical mass nearby — not sure exactly
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u/s0ftware3ngineer 2d ago edited 2d ago
Even if you could slicer fast enough, unless the knife is made of plutonium, and the thing your slicing is uranium , the atom you split wouldn't have enough energy to cause a nuclear chain reaction. You would need an atom that can release a lot of neutrons in a very dense region containing other like atoms for the chain reaction to be sustained. Your everyday hydrocarbon molecules that make up much of the organic matter around us would just fizzle out in a matter of microsecond or even nanosecond.
That being said, the laws of quantum mechanics suggest that over a long enough timeline, anything that can happen will eventually happen. So yes, you could technically split at atom by slicing fruit with a knife, but the reaction would be so slight that you wouldn't even be aware that it happened, and the probability of it occurring is so slight that the universe would end before it occured.
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u/palredpastry 1d ago
if the atom is splitting, it's not like the knife had anything to do with it. the blade of a knife is WAY bigger than an atom. imagine it like a huge wall exerting a relatively minor force on a basketball sitting at the base. would that cause the ball to split in half? it might move it around but its not like it has any chance of splitting the ball.
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u/IndividualistAW 1d ago
If you hit a brick composed of 100% U-235 with a hammer is there any chance of a nuclear explosion? Let’s say the tip of the hammer is also made of 100% U-235
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u/7urz 1d ago
No, for multiple reasons, but the biggest one is that a single split atom emits ~10-11 joule, which is huge for a single atom but you need one trillion of them to charge a mobile phone for a couple of seconds.
In a nuclear power plant, around 1020 atoms are split every second, that's why a nuclear power station can produce gigawatts of heat and electricity.
That's still not a nuclear explosion, but just a lot of heat.
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u/Silspd90 1d ago
Not possible. The only reason atoms split in a nuclear reaction is because fast moving neutrons contain enough energy to break the strong nuclear forces holding that heavy unstable nuclei together. You can never provide enough energy to even overcome even the electromagnetic force let alone the strong nuclear force holding an atom together.
Also given the knife is made of iron, not even the nuclear reaction happening at sun can break it apart.
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u/Aerospider 1d ago
True story -
Fellow student: Can't be that hard to split an atom.
My science teacher: Ok, how would you go about it?
Student: With a knife?
My science teacher: So you're going to cut open one atom with something ten atoms wide...?
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u/Infinate_0 1d ago
Everyone in the original post REALLY thinks it can happen. That's sad considering it's on a subreddit where they're making fun of kids for believing and doing stupid things. Adultsarefuckingstupid
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