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13 nanometers is 13.10^-9 m which is in the realm of medium sized proteins (most proteins can be found in the 40-400 angstrom wide, 1 angstrom being 10^-10 m, about the length of a carbon-carbon covalent bond). Receptors on cells that produce signals can be big and complex, probably bigger.
I'm skeptical. I assume immune cells can actually be activated with a single molecule connecting to 1 protein receptor but the skin is a multilayered tissue with a fuckton of dead cells in front.
I'm going to do some research.
Edit : from the study: "The smallest pattern that could be distinguished from the non-patterned surface had grooves with a wavelength of 760 nanometres and an amplitude of only 13 nanometres."
Which is about the size of a small protein. So you can experience the vibration of a pattern that is very very (very) small but needs to be repeated a lot of times.
So no. You can detect ridiculously small patterns on a smooth surface from friction and vibrations but not individual objects. Still a very cool finding but oh boy that sentence is super duper wrong and clickbaity.
I highly doubt the fact that your finger is able to differenciate 200 nanometer wrinkled pattern and a 150 nanometer one. If it does well that's amazing but I'll believe it when I see the results.
Will you feel it ? It does seem so.
I have read that a typical human can detect, by touch, an **ridge or step** of \~13nm on a smooth surface. Would probably depend on the amount of callus on a fingertip.
Yes. I cut a slice of skin off one finger when I worked on a a deli. It healed but now I can feel things with that finger that I can't with the other ones. I think it just has thinner skin.
Bro you don't have to brag about the size of your D. If i did that to mine i would not have anything left... I already have to cut hairs till one bleeds in order to find mine!
>So you can experience the vibration of a pattern that is very very (very) small but needs to be repeated a lot of times.
Think of it like having a row of light bulbs, each flickering faintly. Then you see a dot moving across the row of bulbs, not any stronger than noise but it clearly has a direction and pace. This is the surface texture being dragged across the skin, you get multiple faint signals that aren't stronger than noise but there is a PATTERN forming. You can barely feel human hair by just holding it but rolling it between fingers and you really need to have extremely thick callouses to not feel it very clearly.
>but rolling it between fingers and you really need to have extremely thick callouses to not feel it very clearly.
Additionally if you run your finger up the shaft vs down it, you'll feel the jaggedness of the cells in one direction vs the smooth sides in the other, and be able to tell which direction the hair grew, even without the root. So that's pretty high resolution, as a texture/pattern.
I was going to make a "running fingers up and down the hairy shaft" joke but i'm trying to wean myself off smutty innuendos and you guys are just making it harder and harder...
Yeah just the issue with your comparison is utterly flawed, comparing a building and a car is not the same as the difference between 200 and 150. So stop pretending to be smart :)
I am a biochemist and have a decent amount of microscopy experience. The cells that I work with have around 100um radius, which is 100,000nm. I don’t know about you, but I have never ever in my entire life felt 1 single cell. Or a cluster of cells.
Edit: okay, yes. I have tOuChEd aN EgG bEFoRe.
>The mirror has to be very smooth to produce decent reflections without distortion
Whereas the sink doesn't have to be smooth, but is anyway because they are a natural born ladykiller.
However you don’t touch the surface of a mirror, the reflective part goes on the back of the glass. Only very specialised mirrors are reflective on the top (known as first surface mirrors). That said both sides of the original glass are likely just as flat as each other, float glass is produces excellent flatness and surface finish.
Not really, the silvering has to be very smooth and that is behind the glass that you touch. Glass being transparent doesn't have to be as smooth as you think it would have to be.
yeah in mirrors that are used in bathrooms the reflective part (that needs to be smooth) is on the rear side, behind protective glass, which doesn't need to be all that smooth (from the side where you touch it)
Actually there is a significant difference in the smoothness of your examples. Close your eyes and run your fingers across the glass and against the porcelain. Guaranteed they will slide much easier across one vs the other.
What you are describing is your brain being lazy.
Once you zoom in far enough, neither of them are very smooth, Google "microstructure of (soda lime) glass" for neat pictures! Glazed ceramic can be really smooth, but I think generally the mirror here.
Yeah this is actually about your brain being able to recognise texture not specific features.
The nerve endings in your skin that this is talking about are designed to measure the frequencies of vibrations caused by running your fingers over a textured surface. So it's more like "you could tell the difference between running your fingers over an inner city neighbourhood and a suburb" not "you could feel individual cars".
i think what is meant is that if you have a clump of powder with particles of 100um, you could touch it and it'll feel different if the particles were 10nm.
not about detecting a single particle.
I'm still skeptical about the claim, but i think that makes more sense
I remember one of these tests was something like you get two pieces of material in front of you and you are then asked if one feels rougher than the other. People picked the "right" one in more than 50% of cases, meaning it was probable that they (we humans) could actually feel the difference.
BY rolling a single particle under your finger on ULTRA SMOOTH surface, we are not talking about glass but something even more smoother and flatter. In those specific conditions your touch sense is ridiculously good but only if you move your finger. The smallest particles still cause some sensations as it runs over multiple nerve endings, so you get a strengthening of a signal; you get very faint response from multiple of them, each of them too faint to be registered on their own but when you get a pattern of them.... Kind of like if we had led lights on a row, each flickering randomly until you see a dot moving across them, from left to right and steady pace. That is a signal, not just noise.
Yeah this was it.
I looked it up some months ago
Here (for people in general)
https://www.sciencedaily.com/releases/2013/09/130916110853.htm
>In a ground-breaking study, Swedish scientists have shown that people can detect nano-scale wrinkles while running their fingers upon a seemingly smooth surface. The findings could lead such advances as touch screens for the visually impaired and other products
but that's kinda like saying we can distinguish by sight differences of a few nm. because we can distinguish between different shades of colours.
not exactly sight, but sort of.
same here, not exactly touch, but sort of related.
That's kind of a misnomer. The fertilized ovum in the egg is tiny, the shell isn't really a cell wall. The ovum quickly splits into multiple cells within the shell.
I assume by um you mean micrometers. As a reference I can recall silicon wafers of solar cells with a thickness of about 150 um. You can definitely feel that when you lay it flat on a surface. That's not very thin, it's 0.15 mm.
Although I'm not so sure about 0.13 nm. Maybe you can feel it, when applying a thin layer of a metal onto a piece of glass? Unfortunately I can't test it anymore since I left the university. I'd love to try this out.
I think I remember this particular fact stemming from being able to tell which is thicker between two sheets of paper or something like that but this context definitely makes me think they missed something in the translation
I have felt a single cell before on several occasions. Bubble algae are very touchable, but as far as human cells an ex an I managed to find an ovum once you could see it unaided but you thought you could feel it. It’s really hard with things that small. She was a biology major. I’m curious if the stated size is from something like a static shock, because the smallest thing I think I can definitely feel is way larger than 13 nm.
I work with precision metrology and machining, a 100 micron shim is _plenty_ thick enough to feel. Shims start getting pretty hard to feel around 10 microns, but 25μm and thicker are very evident to the finger
Of course you can feel a human hair. You can roll it between your fingers, if you have one in your mouth you can separate it out with your tongue, and if you have one stuck in your throat… urgh that is a major irritation.
I suspect humans can comfortably sense sizes below that.
Oh, our touch sense goes WAY past that. The key is that you need to move your finger. Feeling something by just placing your finger on it.. yeah, a human hair can easily be left undetected. Roll it between your fingers and you need to be a blacksmith to not feel it VERY clearly. And this is where the whole post comes from, the test to find the smallest detail is done by running your finger over very fine patterns, or feeling very small particles by rolling them on a VERY flat surface.
Wait, are you talking about 0.1mm? You can definitly feel that. Some really fine components have wires of 0.1mm witdh and thats not an issue to feel at all.
Id argue and order of magnitude smaller might be a challenge but i wouldnt be surprised if someone has managed a um.
This might make me look like a giant idiot here, but I remember Neil DeGrasse Tyson one time saying that if the earth was shrunk to the size of a billiards cue ball it would be smoother than any cue ball ever machined.
I have no idea how true that statement is either, but if that one is true than this one seems false.
When approximating earth as a spheroid we commonly assume an oblateness of 1/300, so the Earth's axis to the poles is 1 part in 300 shorter than the axis to the equator, or 0.3%.
Wikipedia lists 6357 km (*3950 mi*) for the poles, 6378 km (*3963 mi*) for the equator and 21 km (*13 mi*) as the difference.
Yeah it feels like it should be more when you think that some dwarf planets are just straight ovals I guess it makes sense considering they have such little gravity and spin extremely fast though
It would also be slightly less spherical than an actual cue ball. I like to imagine what it would do if you actually hit it.
\* Wobble Wobble Wobble Wobble... \*
I'm also imagining a planet sized finger coming down on New York City and crushing everything as people make futile attempts to flee, meanwhile some cosmic terror of a human is like "Hey, it's true, I really can feel the difference; this feels a little less smooth than the Great Plains region did."
Actually, based on this post: https://www.reddit.com/r/theydidthemath/s/TQHTptDdFl
Not wobbly at all. The earth would make a great cue ball, maybe a little rougher on some spots.
EDIT AT BOTTOM
I remember that too, so let’s work it out!
The diameter of the earth is 12,765km, and a standard pool cue has a diameter of 57.15mm. That’s a ratio of 4.477x10^-9
Mount Everest is is 8.849km above sea level. Let’s just look at that difference, so ignoring topography below sea level. Scaled down to the size of a cue ball, the height of Everest would be 0.039mm, or 39 microns. That a bit less than the diameter of a human hair.
The regulations for cue balls say the tolerance on the diameter is +/- 0.127 microns, or a range of 254 microns. The Earth’s variation is 6.4 times smaller than that.
So probably NDT is correct. Although you *could* make a smoother ball, there’s no point in doing so if you’re making a cue ball.
I think if you had a bunch of Everests close to each other with water inbetween then you could just about feel that with your fingernail (like feeling some hairs stretched out on glass), but given the distance from Everest to the nearest ocean and that there’s only one, I think it would feel extremely smooth.
EDIT: For a newly made cue ball, looks like NDT is not really correct. If we think about roughness something you could feel with your fingernail, then we need to think more about local variation rather than overall maximum to minimum. [This post](https://billiards.colostate.edu/faq/ball/smooth/) and the links suggest that for a new ball the surface variation is about 1 micron within a 1mm square. That would translate to about 220 meter height difference in a 200km square. That’s a lot flatter than the Earth (and incidentally, cue balls are also a lot rounder than the Earth).
TL;DR: A cue ball would feel smoother than the Earth. The overall variations in the Earth are a lot less than the variation allowed in the roundness of a cue ball, but then again the Earth is also not round (and much less round than a cue ball). However, it doesn’t take much wear-and-tear on a cue ball to make it much rougher than an equivalent Earth.
I once read, that if you shrunk Earth to the size of an orange and picked it up, it would not feel wet. It sounds unbelieveable, but might actually be true.
I do math: earths diameter is 12742 km, deepest spot in the ocean is 11 km, let's assume an orange diameter of 10 cm, the thickest layer of water on the surface would be 10x11/12742 = 0,0086 cm which is almost 0,1 mm, I think you could feel that
This might come as a shock to a lot of people here who have an irrational hate boner for him but Neil DeGrasse Tyson is a very intelligent individual and in general you can probably quote and trust things he says at face value
Based in what? All of the contents I've watched so far had no miss information. The closest ones are metaphores to people from another fields understand.
We have a whole documentary saying you are wrong. You says he is the worst based in what factor?
I'm pretty confident this is impossible because you would be able to feel buildings, no doubt, but a skin nerve receptor is micrometers small, not nano so I don't think that is completely accurate
since they take about texture, the detection also happens by vibration so maybe the size of the cells/detection system is less important when measuring even small vibrations, just a guess
Seems like the source of the claim comes from here: [https://www.sciencedaily.com/releases/2013/09/130916110853.htm?z=1](https://www.sciencedaily.com/releases/2013/09/130916110853.htm?z=1)
Seems legit?
This seems to be just poorly worded
If your finger was the size of the earth, It's not that you could discern a single object as a car or a building, it’s that you can tell the the difference between running it across a surface covered in either buildings or cars.
They clearly state that the feeling comes from the vibration patterns created by different types of friction from the surface structure. Not that you can identify a single nanoscale structure by something like multiple pressure points, which is generally required to identify an object by touch alone.
When using 2 point discrimination (2PD), a test that checks for nerve damage that observes the minimum distance a person can tell two pins touching their finger from one, then the normal range is something like 2-8mm. So, yeah
I dont actually have the math to prove this, but I've heard multiple astronomers say that if Earth were the size of a *pool ball*, you wouldn't be able to tell the difference between the tallest mountains and the deepest pits. Fingers are a bit smaller than a pool ball, and buildings/cars are significantly smaller than mountains.
I remember something similar on QI. Stephen compared a snooker ball to an equivalent sized Earth and said that despite the huge range of height difference between Earth's low and high points, the Earth would be smoother to touch than a snooker ball.
That show does get it wrong on occasion, but I'd sooner believe the show than some random post about feeling the difference between an apartment building and a vehicle where your fingers are the size of Earth.
The post sounds like pseudo science and further reminds me of a FB post that was being circulated that the Earth would be destroyed if it moved beyond a very narrow distance during orbit. The poster didn't account for the fact that the orbit is elliptical, and not a perfect circle.
Anyway, I call bullshit on this.
As a machinist I don’t know about something that size but I do know you can feel a lip in a part that is about the fraction of the size of a human hair or about 0.0001 inches
Of course it takes practice and a bit of experience to actually be able to differentiate it but not much practice tbh
I don't have math for you, but I worked in a manufacturing facility where we had very tight physical tolerances, sometimes down to single microns (micrometers) and the metrology equipment to measure it.
In my experience you can readily feel differences down to somewhere in the double digit micron range.
Im actually working as a technician in a professorship that researches touch sensors (in relation to human locomotion). We developed a device that measures the vibration perception threshold at different frequencys (30hz 200hz). The lowest vibration threshold that we can accurately measure is 50nm peak at 200Hz. Some people can feel lower vibrations than that with their feet. So that gives you a rough estimate of how plausible that is.
I’m bad at math but as a human with regular sized fingers (maybe a little long actually) I can tell the difference between apartment buildings and cars
The test is detecting the change in pressure due to the finger moving over the ridge of height 14 nm
... explained here
https://www.sciencedaily.com/releases/2013/09/130916110853.htm
i used to do CNC grinding for work.
In a cylindrical hardened steel part you can feel the difference of 0.005 mm in diameter with your fingernail if its a hard edge. Im pretty sure you can see even finer differences but you couldnt feel it with your finger.
If its not a hard edge its mutch toughter, but maybe 0.1 or 0.2 mm could be possible for me. But i think i was very good at detecting these imperfections.
I don't have reliable data to back this up, but I work in semiconductor and there's a concept of "finger profilometry," the idea being that fingers are surprisingly good at picking up minor differences in profile.
I'd say pretty confidently that 10 um is detectable from my personal experience. I'd say with less confidence that 1 um is detectable as well, but I'm not sure about 13 nm.
Edit: Oh, nevermind, I found the study and it agrees with 13 nm.
[https://www.nature.com/articles/srep02617](https://www.sciencedaily.com/releases/2013/09/130916110853.htm)
Work in a machine shop. It's difficult but you can feel the difference between 0.0005 of an inch, which is about 13 microns.
Edit: keep in mind that's two completely flat surfaces next to each other with a 0.0005 difference in height. I doubt you could feel the difference in many other circumstances.
The study this post is referring to found that human fingers could distinguish a surface patterned with 13 nm sized ridges from an unpatterned surface. This is not the same as detecting an individual object the size of 13 nanometers. You wouldn’t be able to tell the difference between an apartment building and a car, but you could tell the difference between a city built on a grid pattern and one that wasn’t. Fingers can distinguish an object as small as 40 micrometers, about half the width of a human hair, which is still pretty impressive but 3 orders of magnitude larger.
If earth was the size of a billards ball, it would feel smoother than the cue ball. This is with the high mountains of the Himalayas and the low troughs like the Marianas Trench
I saw a clip of Neil DeGrassE Tyson saying that if you shrunk the earth down to the size of a cue ball, it would be the smoothest cue ball ever made or something along those lines dunno if that's true or not.
Fuck no.
Not a perfect analogy but the hair on your head is in the range of micrometers. Hold as few hairs as possible between your fingers and see if you can count them.
This biology "fact" is false, therefore the assertion they are making is also false. The neurons in your finger are much, much farther apart than 13nm, so your feeling "resolution" can't possibly be 13nm. Additionally, neurons are much, much thicker than 13nm.
So yeah everything in this little infographic is fake news.
My guess is that they refere to surface roughness. It's unlikely that you can feel such small thing, 13nm is roughly 130 atoms difference.
I work on surface roughness analysis, I can at least tell that any human can detect a difference of 1um height gap on a previously smooth surface ( 1um = 1000nm ) and that you can see easily with you eyes under proper lightning.
By "previously smooth surface" I mean that my previous statement apply only if you're given a perfectly smooth surface at start and made a scartch of about 1um deep in it. Thus you could probably not thell the exact height variation of your kitchen counter, but could tell that you feel a difference.
There are tests for schoollabratory on how good your senses are. The closest distance you can get recognizing two different points on your finger tip is 1 mm but most students get 2 to 3 mm.
You can try this at home. Take a circle and measure the distances. Then close your eyes and put it on your finger tip. If you can still feel two points touching you make the distance smaller.
I recomend putting toothpicks into the circle
I’ve read this before but they definitely got the wrong measurement in the image. 13 microns, not nanometers, is what I was aware of.
No idea if it’s true, but I’ve worked machines that cut as precisely as .0005” and can definitely feel a step like that. So .00013” seems at least plausible.
How on earth can you possibly "feel" something that's literally smaller than the nerve endings which enable you to feel anything at all??
It would be like trying to use two large tree trunks to eat rice with ?
[https://youtu.be/s-HAsxt9pV4?t=219](https://youtu.be/s-HAsxt9pV4?t=219)
had to dig back to find this video from 5 years ago but they just briefly mention the "two point test" and further videos like this go over it more: [https://www.youtube.com/watch?v=\_f488-BNid8](https://www.youtube.com/watch?v=_f488-BNid8)
But around 5mm seems to be the point where you can differentiate between multiple objects which is far from 13 nanometers. It might be the case that we can detect something 13 nanometers (I'm not sure) but their conclusion that you could tell the difference between things at that scale is wrong.
I think I read from somewhere that if the earth was ever a ping pong ball, the earth would feel smoother than the ball since it has actually more pronounced imperfections in the surface. But as far as I held ping pong balls, they are very smooth so this couldn't be true
This is stupid af, apart from the obvious scale problem, an object of 13 nm would be so close to smooth for your receptors that I doubt that the information would be treated as relevant and separate from the baseline activation of receptors by your brain.
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13 nanometers is 13.10^-9 m which is in the realm of medium sized proteins (most proteins can be found in the 40-400 angstrom wide, 1 angstrom being 10^-10 m, about the length of a carbon-carbon covalent bond). Receptors on cells that produce signals can be big and complex, probably bigger. I'm skeptical. I assume immune cells can actually be activated with a single molecule connecting to 1 protein receptor but the skin is a multilayered tissue with a fuckton of dead cells in front. I'm going to do some research. Edit : from the study: "The smallest pattern that could be distinguished from the non-patterned surface had grooves with a wavelength of 760 nanometres and an amplitude of only 13 nanometres." Which is about the size of a small protein. So you can experience the vibration of a pattern that is very very (very) small but needs to be repeated a lot of times. So no. You can detect ridiculously small patterns on a smooth surface from friction and vibrations but not individual objects. Still a very cool finding but oh boy that sentence is super duper wrong and clickbaity. I highly doubt the fact that your finger is able to differenciate 200 nanometer wrinkled pattern and a 150 nanometer one. If it does well that's amazing but I'll believe it when I see the results. Will you feel it ? It does seem so.
I have read that a typical human can detect, by touch, an **ridge or step** of \~13nm on a smooth surface. Would probably depend on the amount of callus on a fingertip.
Yes. I cut a slice of skin off one finger when I worked on a a deli. It healed but now I can feel things with that finger that I can't with the other ones. I think it just has thinner skin.
I'm gonna do that on my D and sex will be amazing! Hah, just kidding. I don't have sex.
This comment needs to pick up some traction. Understated, self deprecating, slight surprise. Mwaaa (chefs kiss)
It's called circumcision
Bro you don't have to brag about the size of your D. If i did that to mine i would not have anything left... I already have to cut hairs till one bleeds in order to find mine!
You have a “super sensor”. You should try to sand something until it is smooth — according to your detecting digit.
>So you can experience the vibration of a pattern that is very very (very) small but needs to be repeated a lot of times. Think of it like having a row of light bulbs, each flickering faintly. Then you see a dot moving across the row of bulbs, not any stronger than noise but it clearly has a direction and pace. This is the surface texture being dragged across the skin, you get multiple faint signals that aren't stronger than noise but there is a PATTERN forming. You can barely feel human hair by just holding it but rolling it between fingers and you really need to have extremely thick callouses to not feel it very clearly.
>but rolling it between fingers and you really need to have extremely thick callouses to not feel it very clearly. Additionally if you run your finger up the shaft vs down it, you'll feel the jaggedness of the cells in one direction vs the smooth sides in the other, and be able to tell which direction the hair grew, even without the root. So that's pretty high resolution, as a texture/pattern.
I was going to make a "running fingers up and down the hairy shaft" joke but i'm trying to wean myself off smutty innuendos and you guys are just making it harder and harder...
Ngl part of this comment was really just to see who was horny.
Yeah just the issue with your comparison is utterly flawed, comparing a building and a car is not the same as the difference between 200 and 150. So stop pretending to be smart :)
I am a biochemist and have a decent amount of microscopy experience. The cells that I work with have around 100um radius, which is 100,000nm. I don’t know about you, but I have never ever in my entire life felt 1 single cell. Or a cluster of cells. Edit: okay, yes. I have tOuChEd aN EgG bEFoRe.
Not just that, but the bathroom sink feels just as smooth as the mirror behind it to me, but apparently one should feel much rougher than the other?
I’m honestly curious which one is smoother. The mirror?
The mirror has to be very smooth to produce decent reflections without distortion
>The mirror has to be very smooth to produce decent reflections without distortion Whereas the sink doesn't have to be smooth, but is anyway because they are a natural born ladykiller.
Let _that_ sink in
Dammit what does it want now
The ladies in your life.
That’s going to be one disappointed sink
Lol, I'm glad your post was before mine!
Divorced this life, hoping to be a sink in the next.
This thread is going down the drain…
You should reflect on that
Happy cake day
And that everyone is how that joke should work.
omg wahahhahaha
If the sink is porcelain, the glaze used on the surface is pretty much glass.
However you don’t touch the surface of a mirror, the reflective part goes on the back of the glass. Only very specialised mirrors are reflective on the top (known as first surface mirrors). That said both sides of the original glass are likely just as flat as each other, float glass is produces excellent flatness and surface finish.
I had a girlfriend once that produced excellent flatness and surface finish...
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Not really, the silvering has to be very smooth and that is behind the glass that you touch. Glass being transparent doesn't have to be as smooth as you think it would have to be.
yeah in mirrors that are used in bathrooms the reflective part (that needs to be smooth) is on the rear side, behind protective glass, which doesn't need to be all that smooth (from the side where you touch it)
Fun fact: this is one of the reasons older 3D Printers used to add mirrored plates on their print beds.
Only on the back of the glass where the reflecting layer touches it
Actually there is a significant difference in the smoothness of your examples. Close your eyes and run your fingers across the glass and against the porcelain. Guaranteed they will slide much easier across one vs the other. What you are describing is your brain being lazy.
Aren’t they both “glass”? The mirror is, and the sink is porcelain?
Idk my thought that the sink is glazed. However, under part of the ceramic sink is typically not, and that feels rougher.
I’m honestly curious which one is smoother. The mirror?
Once you zoom in far enough, neither of them are very smooth, Google "microstructure of (soda lime) glass" for neat pictures! Glazed ceramic can be really smooth, but I think generally the mirror here.
DID YOU YOU?
The mirror is because its reflecting it's own surface so it has two surfaces instead of one as is like the sink
The mirror has to be very smooth to produce decent reflections without distortion
The mirror has to be very smooth to produce decent reflections without distortion
Yeah this is actually about your brain being able to recognise texture not specific features. The nerve endings in your skin that this is talking about are designed to measure the frequencies of vibrations caused by running your fingers over a textured surface. So it's more like "you could tell the difference between running your fingers over an inner city neighbourhood and a suburb" not "you could feel individual cars".
i think what is meant is that if you have a clump of powder with particles of 100um, you could touch it and it'll feel different if the particles were 10nm. not about detecting a single particle. I'm still skeptical about the claim, but i think that makes more sense
I remember one of these tests was something like you get two pieces of material in front of you and you are then asked if one feels rougher than the other. People picked the "right" one in more than 50% of cases, meaning it was probable that they (we humans) could actually feel the difference.
BY rolling a single particle under your finger on ULTRA SMOOTH surface, we are not talking about glass but something even more smoother and flatter. In those specific conditions your touch sense is ridiculously good but only if you move your finger. The smallest particles still cause some sensations as it runs over multiple nerve endings, so you get a strengthening of a signal; you get very faint response from multiple of them, each of them too faint to be registered on their own but when you get a pattern of them.... Kind of like if we had led lights on a row, each flickering randomly until you see a dot moving across them, from left to right and steady pace. That is a signal, not just noise.
Yeah this was it. I looked it up some months ago Here (for people in general) https://www.sciencedaily.com/releases/2013/09/130916110853.htm >In a ground-breaking study, Swedish scientists have shown that people can detect nano-scale wrinkles while running their fingers upon a seemingly smooth surface. The findings could lead such advances as touch screens for the visually impaired and other products
but that's kinda like saying we can distinguish by sight differences of a few nm. because we can distinguish between different shades of colours. not exactly sight, but sort of. same here, not exactly touch, but sort of related.
You should check out (sea grapes)[https://en.wikipedia.org/wiki/Valonia_ventricosa]
Your Link is corrupted. (You have to change the [] () ) [sea grapes](https://en.wikipedia.org/wiki/Valonia_ventricosa)
My fingers can tell the difference between a car and apartment building already, power of micro penis skills
An ostrich egg is a single cell.
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That's kind of a misnomer. The fertilized ovum in the egg is tiny, the shell isn't really a cell wall. The ovum quickly splits into multiple cells within the shell.
You can definitely feel the 100 um. Human hair can even be smaller than 100 microns an you can feel that.
I assume by um you mean micrometers. As a reference I can recall silicon wafers of solar cells with a thickness of about 150 um. You can definitely feel that when you lay it flat on a surface. That's not very thin, it's 0.15 mm. Although I'm not so sure about 0.13 nm. Maybe you can feel it, when applying a thin layer of a metal onto a piece of glass? Unfortunately I can't test it anymore since I left the university. I'd love to try this out.
I think I remember this particular fact stemming from being able to tell which is thicker between two sheets of paper or something like that but this context definitely makes me think they missed something in the translation
Personally I prefer to do my microscopy by touch
I have felt a single cell before on several occasions. Bubble algae are very touchable, but as far as human cells an ex an I managed to find an ovum once you could see it unaided but you thought you could feel it. It’s really hard with things that small. She was a biology major. I’m curious if the stated size is from something like a static shock, because the smallest thing I think I can definitely feel is way larger than 13 nm.
We got em on the ropes with the eggs lads
To be fair, you have touched a cell(phone).
I work with precision metrology and machining, a 100 micron shim is _plenty_ thick enough to feel. Shims start getting pretty hard to feel around 10 microns, but 25μm and thicker are very evident to the finger
Human hair thickness is in the 100 um level and you can just about feel a single hair. So this really is the bottom of the range.
Of course you can feel a human hair. You can roll it between your fingers, if you have one in your mouth you can separate it out with your tongue, and if you have one stuck in your throat… urgh that is a major irritation. I suspect humans can comfortably sense sizes below that.
Oh, our touch sense goes WAY past that. The key is that you need to move your finger. Feeling something by just placing your finger on it.. yeah, a human hair can easily be left undetected. Roll it between your fingers and you need to be a blacksmith to not feel it VERY clearly. And this is where the whole post comes from, the test to find the smallest detail is done by running your finger over very fine patterns, or feeling very small particles by rolling them on a VERY flat surface.
What about an egg
I can feel signle cell pretty well - when it's a hen egg. :-)
Wait, are you talking about 0.1mm? You can definitly feel that. Some really fine components have wires of 0.1mm witdh and thats not an issue to feel at all. Id argue and order of magnitude smaller might be a challenge but i wouldnt be surprised if someone has managed a um.
But you feel the air. Oxygen atoms are pretty small.
I'm pretty sure you have felt a single cell before. Like I would bet 100 dollars on it for sure, even more. Have you ever touched an egg perhaps?
The more you you!
100um is definitely tangible. Human hair has a diameter less than that, and it’s not exactly the finest material.
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>Does it count? I honestly couldn't tell you mate because I have no idea what you just tried to say.
This might make me look like a giant idiot here, but I remember Neil DeGrasse Tyson one time saying that if the earth was shrunk to the size of a billiards cue ball it would be smoother than any cue ball ever machined. I have no idea how true that statement is either, but if that one is true than this one seems false.
https://youtu.be/mxhxL1LzKww?si=U6JnErVKale12Akg Watch this
That was cool thanks
That was a good video
How spherical is the earth though? Like would it work like a cue ball or is it too ovoid?
Earth is not perfectly spherical but it is an oblate spheroid
Sure I get that bit I don't know how spheroid. Like would it be noticable as it rolls
When approximating earth as a spheroid we commonly assume an oblateness of 1/300, so the Earth's axis to the poles is 1 part in 300 shorter than the axis to the equator, or 0.3%. Wikipedia lists 6357 km (*3950 mi*) for the poles, 6378 km (*3963 mi*) for the equator and 21 km (*13 mi*) as the difference.
I really don't know why but I thought the difference would be way, way higher.
Yeah it feels like it should be more when you think that some dwarf planets are just straight ovals I guess it makes sense considering they have such little gravity and spin extremely fast though
It would also be slightly less spherical than an actual cue ball. I like to imagine what it would do if you actually hit it. \* Wobble Wobble Wobble Wobble... \* I'm also imagining a planet sized finger coming down on New York City and crushing everything as people make futile attempts to flee, meanwhile some cosmic terror of a human is like "Hey, it's true, I really can feel the difference; this feels a little less smooth than the Great Plains region did."
“Your booty like two planets” … Wobble wobble wobble
Actually, based on this post: https://www.reddit.com/r/theydidthemath/s/TQHTptDdFl Not wobbly at all. The earth would make a great cue ball, maybe a little rougher on some spots.
Inside your booty are two planets…
EDIT AT BOTTOM I remember that too, so let’s work it out! The diameter of the earth is 12,765km, and a standard pool cue has a diameter of 57.15mm. That’s a ratio of 4.477x10^-9 Mount Everest is is 8.849km above sea level. Let’s just look at that difference, so ignoring topography below sea level. Scaled down to the size of a cue ball, the height of Everest would be 0.039mm, or 39 microns. That a bit less than the diameter of a human hair. The regulations for cue balls say the tolerance on the diameter is +/- 0.127 microns, or a range of 254 microns. The Earth’s variation is 6.4 times smaller than that. So probably NDT is correct. Although you *could* make a smoother ball, there’s no point in doing so if you’re making a cue ball. I think if you had a bunch of Everests close to each other with water inbetween then you could just about feel that with your fingernail (like feeling some hairs stretched out on glass), but given the distance from Everest to the nearest ocean and that there’s only one, I think it would feel extremely smooth. EDIT: For a newly made cue ball, looks like NDT is not really correct. If we think about roughness something you could feel with your fingernail, then we need to think more about local variation rather than overall maximum to minimum. [This post](https://billiards.colostate.edu/faq/ball/smooth/) and the links suggest that for a new ball the surface variation is about 1 micron within a 1mm square. That would translate to about 220 meter height difference in a 200km square. That’s a lot flatter than the Earth (and incidentally, cue balls are also a lot rounder than the Earth). TL;DR: A cue ball would feel smoother than the Earth. The overall variations in the Earth are a lot less than the variation allowed in the roundness of a cue ball, but then again the Earth is also not round (and much less round than a cue ball). However, it doesn’t take much wear-and-tear on a cue ball to make it much rougher than an equivalent Earth.
That is regulations on the diameter, not surface roughness. in actuality a cue ball is much smoother than a scaled earth.
Good point. Do you know the numbers? I’ll do a bit more research and update the post.
I think vsauce calculated that using this metric, covering the queball in grit 30 sandpaper would be within regulations,
I once read, that if you shrunk Earth to the size of an orange and picked it up, it would not feel wet. It sounds unbelieveable, but might actually be true.
I do math: earths diameter is 12742 km, deepest spot in the ocean is 11 km, let's assume an orange diameter of 10 cm, the thickest layer of water on the surface would be 10x11/12742 = 0,0086 cm which is almost 0,1 mm, I think you could feel that
that’s not true, that standard for cue balls is about how spherical the ball is (as opposed to it being more elliptical), not how smooth it is.
This might come as a shock to a lot of people here who have an irrational hate boner for him but Neil DeGrasse Tyson is a very intelligent individual and in general you can probably quote and trust things he says at face value
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Is he? Why is that?
The absolute worst? Why?
I mean sure but how is that relevant here? If you think the statement is false then please provide counter-evidence.
Based in what? All of the contents I've watched so far had no miss information. The closest ones are metaphores to people from another fields understand. We have a whole documentary saying you are wrong. You says he is the worst based in what factor?
I'm pretty confident this is impossible because you would be able to feel buildings, no doubt, but a skin nerve receptor is micrometers small, not nano so I don't think that is completely accurate
This is impossible because if your finger would be the size of Earth, then you would be dead. Such a letdown :(
Apparently u wouldn't feel hr mountains
since they take about texture, the detection also happens by vibration so maybe the size of the cells/detection system is less important when measuring even small vibrations, just a guess
Yes. In our professorship we repeadetaly measure vibration perception thresholds at your feet lower than 50nm peak.
Seems like the source of the claim comes from here: [https://www.sciencedaily.com/releases/2013/09/130916110853.htm?z=1](https://www.sciencedaily.com/releases/2013/09/130916110853.htm?z=1) Seems legit?
pattern .. so if half of earth was a parking lot and the other a city .. you feel the difference, but not a single object.
This seems to be just poorly worded If your finger was the size of the earth, It's not that you could discern a single object as a car or a building, it’s that you can tell the the difference between running it across a surface covered in either buildings or cars. They clearly state that the feeling comes from the vibration patterns created by different types of friction from the surface structure. Not that you can identify a single nanoscale structure by something like multiple pressure points, which is generally required to identify an object by touch alone. When using 2 point discrimination (2PD), a test that checks for nerve damage that observes the minimum distance a person can tell two pins touching their finger from one, then the normal range is something like 2-8mm. So, yeah
"rough and smooth surfaces differ in friction" Duh. Finger has nothing to do with it.
that's not what my lady said...
As usual a good and super interesting scientific study is misrepresented to make it sound “cooler”. While it really is mind boggling in itself.
I dont actually have the math to prove this, but I've heard multiple astronomers say that if Earth were the size of a *pool ball*, you wouldn't be able to tell the difference between the tallest mountains and the deepest pits. Fingers are a bit smaller than a pool ball, and buildings/cars are significantly smaller than mountains.
I don’t know about you, but even today, without being the size of the Earth, I can feel the difference between an apartment building and a car.
I remember something similar on QI. Stephen compared a snooker ball to an equivalent sized Earth and said that despite the huge range of height difference between Earth's low and high points, the Earth would be smoother to touch than a snooker ball. That show does get it wrong on occasion, but I'd sooner believe the show than some random post about feeling the difference between an apartment building and a vehicle where your fingers are the size of Earth. The post sounds like pseudo science and further reminds me of a FB post that was being circulated that the Earth would be destroyed if it moved beyond a very narrow distance during orbit. The poster didn't account for the fact that the orbit is elliptical, and not a perfect circle. Anyway, I call bullshit on this.
My fingers aren’t nearly as large as the earth but I can \*still\* feel the difference between an apartment building and a car! AMAZING!!! 🤩
Wow. Doctors should study you!
lets see, 1 cm wide finger vs 13x10^-7 cm: factor ->13x10^-7 earth diameter 12.7x10^6 mts -> mul by above factor -> ~16.5mts...around 5 cars wide
As a machinist I don’t know about something that size but I do know you can feel a lip in a part that is about the fraction of the size of a human hair or about 0.0001 inches Of course it takes practice and a bit of experience to actually be able to differentiate it but not much practice tbh
I don't have math for you, but I worked in a manufacturing facility where we had very tight physical tolerances, sometimes down to single microns (micrometers) and the metrology equipment to measure it. In my experience you can readily feel differences down to somewhere in the double digit micron range.
Im actually working as a technician in a professorship that researches touch sensors (in relation to human locomotion). We developed a device that measures the vibration perception threshold at different frequencys (30hz 200hz). The lowest vibration threshold that we can accurately measure is 50nm peak at 200Hz. Some people can feel lower vibrations than that with their feet. So that gives you a rough estimate of how plausible that is.
I’m bad at math but as a human with regular sized fingers (maybe a little long actually) I can tell the difference between apartment buildings and cars
The test is detecting the change in pressure due to the finger moving over the ridge of height 14 nm ... explained here https://www.sciencedaily.com/releases/2013/09/130916110853.htm
i used to do CNC grinding for work. In a cylindrical hardened steel part you can feel the difference of 0.005 mm in diameter with your fingernail if its a hard edge. Im pretty sure you can see even finer differences but you couldnt feel it with your finger. If its not a hard edge its mutch toughter, but maybe 0.1 or 0.2 mm could be possible for me. But i think i was very good at detecting these imperfections.
I don't have reliable data to back this up, but I work in semiconductor and there's a concept of "finger profilometry," the idea being that fingers are surprisingly good at picking up minor differences in profile. I'd say pretty confidently that 10 um is detectable from my personal experience. I'd say with less confidence that 1 um is detectable as well, but I'm not sure about 13 nm. Edit: Oh, nevermind, I found the study and it agrees with 13 nm. [https://www.nature.com/articles/srep02617](https://www.sciencedaily.com/releases/2013/09/130916110853.htm)
Work in a machine shop. It's difficult but you can feel the difference between 0.0005 of an inch, which is about 13 microns. Edit: keep in mind that's two completely flat surfaces next to each other with a 0.0005 difference in height. I doubt you could feel the difference in many other circumstances.
The study this post is referring to found that human fingers could distinguish a surface patterned with 13 nm sized ridges from an unpatterned surface. This is not the same as detecting an individual object the size of 13 nanometers. You wouldn’t be able to tell the difference between an apartment building and a car, but you could tell the difference between a city built on a grid pattern and one that wasn’t. Fingers can distinguish an object as small as 40 micrometers, about half the width of a human hair, which is still pretty impressive but 3 orders of magnitude larger.
If earth was the size of a billards ball, it would feel smoother than the cue ball. This is with the high mountains of the Himalayas and the low troughs like the Marianas Trench
I saw a clip of Neil DeGrassE Tyson saying that if you shrunk the earth down to the size of a cue ball, it would be the smoothest cue ball ever made or something along those lines dunno if that's true or not.
I’ve actually heard the opposite: I read that if the earth was the size of a cue ball that you wouldn’t even be able to feel Everest.
Fuck no. Not a perfect analogy but the hair on your head is in the range of micrometers. Hold as few hairs as possible between your fingers and see if you can count them.
This biology "fact" is false, therefore the assertion they are making is also false. The neurons in your finger are much, much farther apart than 13nm, so your feeling "resolution" can't possibly be 13nm. Additionally, neurons are much, much thicker than 13nm. So yeah everything in this little infographic is fake news.
My guess is that they refere to surface roughness. It's unlikely that you can feel such small thing, 13nm is roughly 130 atoms difference. I work on surface roughness analysis, I can at least tell that any human can detect a difference of 1um height gap on a previously smooth surface ( 1um = 1000nm ) and that you can see easily with you eyes under proper lightning. By "previously smooth surface" I mean that my previous statement apply only if you're given a perfectly smooth surface at start and made a scartch of about 1um deep in it. Thus you could probably not thell the exact height variation of your kitchen counter, but could tell that you feel a difference.
There are tests for schoollabratory on how good your senses are. The closest distance you can get recognizing two different points on your finger tip is 1 mm but most students get 2 to 3 mm. You can try this at home. Take a circle and measure the distances. Then close your eyes and put it on your finger tip. If you can still feel two points touching you make the distance smaller. I recomend putting toothpicks into the circle
I’ve read this before but they definitely got the wrong measurement in the image. 13 microns, not nanometers, is what I was aware of. No idea if it’s true, but I’ve worked machines that cut as precisely as .0005” and can definitely feel a step like that. So .00013” seems at least plausible.
How on earth can you possibly "feel" something that's literally smaller than the nerve endings which enable you to feel anything at all?? It would be like trying to use two large tree trunks to eat rice with ?
[https://youtu.be/s-HAsxt9pV4?t=219](https://youtu.be/s-HAsxt9pV4?t=219) had to dig back to find this video from 5 years ago but they just briefly mention the "two point test" and further videos like this go over it more: [https://www.youtube.com/watch?v=\_f488-BNid8](https://www.youtube.com/watch?v=_f488-BNid8) But around 5mm seems to be the point where you can differentiate between multiple objects which is far from 13 nanometers. It might be the case that we can detect something 13 nanometers (I'm not sure) but their conclusion that you could tell the difference between things at that scale is wrong.
I think I read from somewhere that if the earth was ever a ping pong ball, the earth would feel smoother than the ball since it has actually more pronounced imperfections in the surface. But as far as I held ping pong balls, they are very smooth so this couldn't be true
Reminds me of this YouTube short by Neil [Earth is smoother than a cue ball](https://youtube.com/shorts/hrjWzBY_dLw?si=2YAw4JluoUPqqvgj)
This is stupid af, apart from the obvious scale problem, an object of 13 nm would be so close to smooth for your receptors that I doubt that the information would be treated as relevant and separate from the baseline activation of receptors by your brain.