Do Atoms Ever Touch?

Professor Philip Moriarty expresses his displeasure with oft-repeated belief that atoms do not physically touch each other.
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From Brady on this video...
In anticipation of questions and comments, I thought I'd write this in the description (where no-one will ever see it!!!)
Prof Moriarty and I have discussed the issue of "atoms touching" many times off camera.
We've shared different views on the best definitions and tools used by various online "explainers" over the years.
Clearly it is an issue close to Professor Moriarty's heart because it involves his main area of research.
And I am mindful he is a professional on the topic. I am not.
We jointly decided to make a Sixty Symbols video that reflected our previous discussions, so included more than my usual fill of provocative questions.
And regardless, I see it as my role to be a "devil's advocate" and ensure we challenge our scientists and get the best possible explanations.
I can assure everyone it was done in good spirit and we had a laugh afterwards.
Oh and by the way, Prof Moriarty is now on Twitter... / moriarty2112

[@Bnio]

Watching Prof. Moriarty in this discussion was like watching a Ferrari stuck in city traffic.

[@victorselve8349]

pure comedic gold

[@JNeverMindMe]

But the analogy breaks down!

[@bikerchrisukk]

Bnio The guy behind the camera probably wouldn't ask about the definition of 'traffic' :-)

[@AuroraNora3]

Perfect analogy

[@casaxtreme2952]

I'm waiting for him to go like: "FFUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU..."

[@fen4554]

So passionate... I love how enthusiastic Phil always is.

[@kamel3d]

I love him

[@MrUfojunkiedavid]

Friendly Metroid he's a charlatan

[@ScottBrown124]

David That seems harsh, why do you think that?

[@30l0l3]

Some parts of the internet hate him (he used to have a blog where, among other things, he tried to debate with the anti-"feminazi" crowd)

[@AnaICarnaval]

David just like priest in your church

[@bertlowry7668]

I think we all need to admire Brady’s ability to embody the casual physics fan’s questions and beliefs.

[@sixtysymbols]

In anticipation of everyone getting a bit upset about the "debate" nature of this video, I wrote something in the video description, but of course no-one reads the full video description.... It says: In anticipation of questions and comments, I thought I'd write this in the description (where no-one will ever see it!!!) Prof Moriarty and I have discussed the issue of "atoms touching" many times off camera. We've shared different views on the best definitions and tools used by various online "explainers" over the years. Clearly it is an issue close to Professor Moriarty's heart because it involves his main area of research. And I am mindful he is a professional on the topic. I am not. We jointly decided to make a Sixty Symbols video that reflected our previous discussions, so included more than my usual fill of provocative questions. And regardless, I see it as my role to be a "devil's advocate" and ensure we challenge our scientists and get the best possible explanations. I can assure everyone it was done in good spirt and we had a laugh afterwards. Oh and by the way, Prof Moriarty is now on Twitter... twitter.com/Moriarty2112

[@joerobinson7564]

I am far from being a scientist and far from understanding the precise physics behind atoms but if you say the atoms are not touching would you not have to ignore the electrons and components of the atoms and the forces they apply on each other? I mean those forces are part of the atoms themselves and as such are an extension of the atoms so they would in fact be touching each other, just not in a way you could physically see, (kind of moot considering you can't see it anyway) I guess my point is the force would be a part of the atoms themselves which would mean they would in fact be touching would they not?

[@Tethloach1]

Joe Robinson that is like saying that my words touched you, and whence we just made contact. the idea of touching doesn't apply to the small objects they remain the same. the question would be if they don't touch what is changing, energy is what touches everything. atoms don't touch because it would be chaos. energy is what moves threw space sand time. some things lose energy while other things gain energy. that is far more scientific than touching. the idea of atoms touching is like the idea of truth. truth is too abstract to be of any use to science or math. the language is too limited to describe the universe in its perfect form. that is like you trying to map PIE( 3.14.......) using language. it won't happen, the laws of nature don't allow you to do it. language is limited that is why scientist use math, because math is more precise than words like truth or touch.

[@Ana_crusis]

Sixty Symbols I see. :) I thought you sounded a bit dense although I did wonder while watching the video if you weren't doing it deliberately as it was unlike you. It's a very interesting video and clears up that question once and for all. Thanks.p.s.

[@afrog2666]

Sixty Symbols "Prof Moriarty and I have discussed the issue of "atoms touching" many times off camera." LoL! It shows..

[@koshhe]

Sixty Symbols If the standard definition of contact on the atomic scale has the same meaning it does at the human scale, why is that a problem?

[@whirled_peas]

His explanation and solution to the problem of the definition of "touching" is spot on. Our brains try to turn everything into objects, specifically, atoms into solid spheres, but science tells us absolutely nothing is actually that simple. The traditional definition of 'touch' doesn't make sense on this scale. I love how animated he gets trying to get through to the cameraman :D.

[@whirled_peas]

I think another, simpler explanation is that well, no interaction in physics is binary, on or off.

[@JohnDoe-zl6qw]

+samthepoor Agreed. The problem results from the limits of our perception; we want - as you say - to turn everything into objects. Or - put in a more physics-y way - we want to apply a perceptual bias in favor of matter. But the universe isn't just matter; it's matter and energy (or - if you'd rather - it's all the same stuff and matter and energy are simply two expressions of that "stuff"). Just because we have difficulty perceiving and conceptualizing the energy doesn't mean the energy is any less significant in defining the point of "contact". As Professor Moriarty challenged the interviewer, "Let's define what you mean by touching. Do you mean the nuclear cores come together?" To define it in this matter is reductionism and a failure to understand how matter and energy interact and are inseparable. In this context, you can't have a discussion of one without including the other. The Van Der Waals force causing two molecules to attract each other are every bit a part of the molecule as the electrons, protons, or neutrons. Likewise, the repulsive force of the electrons being brought into close proximity to one another is equally a part of the whole system of the respective molecules. We don't get to cherry pick and discount one or the other simply because it doesn't fit within the limits of our perceptual or cognitive framework. Once the balance point between these forces are reached, that's the definition of contact; period. Can we go beyond those forces? Sure; just look to neutron stars where you have neutrons physically/mechanically "touching" one another. If one wants to use that as their benchmark of contact, then certainly the interactions we experience in our day-to-day lives wouldn't qualify under that definition. Of course, one could claim there's no true contact between neutrons, either, since they're made of quarks which do not come into contact with the quarks in an adjacent neutron. Using the previous paragraph as their definition, one can then rightly claim that at the energies at which human life is possible, then - no - nuclear cores never touch one another; therefore there is no true "contact". As stated earlier, though, that argument completely invalidates the role of energy and the interactions between molecules. The interviewer also needs to come to an understanding that contact is a fluid definition. Standing on the surface of the Earth at normal pressure, temperature, etc., the nuclei of two atoms will never touch; their point of contact is when the Van Der Waals and electron repulsive forces balance one another. Return to the example of the neutron star and the point of contact is when neutron nuclei start bumping up against one another. He's going to have to be more precise in his assumptions, criteria, and limiters in forming a definition of contact before making a blanket proclamation that nothing ever really touches. In the interactions between molecules, energy is just as valid as matter in defining the point of contact. That's what Professor Moriarty is trying to explain to the interviewer and which the interviewer is rejecting due to a bias in favor of matter over energy. One won't get very far in understanding how our universe works if they dismiss the contribution of energy.

[@JGunlimited]

John Doe Oh I see! Your comment helps clear up what Moriarty was saying. I was on Brady's side, but reading what you are saying about energy...I kinda get now why Morirarty says that that is the contact point.

[@JohnDoe-zl6qw]

+Evi1M4chine I wouldn't say he's a moron. I'd say he's representative of the perceptual limits of the human organism. It's a very difficult concept to wrap one's head around because what physics and quantum mechanics tells us is happening at the micro scale flies in the face of everything we experience at the macro scale. The universe/physics doesn't function at the micro scale the way we perceive it at the macro scale; or - more correctly - our perceptions of the how the universe/physics works at the macro scale is not an accurate representation of what's really occurring at the micro scale. That's not a failing on our part; that's simply the hand we've been dealt by evolution and our biology. I'm sure thesis-level dissertations could be written concerning the overlap of physics and biology. I won't attempt to take on that challenge in a KZbin comments section, but suffice to say it would probably fill a book. What's incredible is that we can surpass the limitations of what we experience with our senses and begin to understand how the universe really works. That's one of the real values of science. The interviewer can be forgiven for rejecting the notion that what physics and quantum mechanics says about reality flies in the face of everything he experiences with his senses. It's a huge cognitive leap and I think it will be many, many generations (if ever) before we as a species accept that what our senses tell us is not an accurate representation of what's really happening; especially when those senses have served our survival so well.

[@lumburgapalooza]

You do realize the ignorance was feigned, right? He's attempting to challenge him as the average person would who has no scientific background in order to illicit a more thorough debunking of classical, sensory perceptions of reality... Devil's Advocate if you will. Even if it were real though your antagonistic attitude towards those you consider to be intellectually inferior is the sign of a troubled and insecure mind. I suggest you rid yourself of this kind of self-bias and ego to the best of your ability.

[@Mrgiveupufail]

'when common sense meets quantum physics'

[@kigozimuhammad]

+The Stacker dude that sound more like a threat when u put it that way .lol

[@kigozimuhammad]

+The Stacker I like the way u politely threatened him . Shows how nice u are .

[@garielmartir9876]

Jajajajaja yes

[@saturdyl5711]

I'm sorry guys. I'm infatuated with fundamental particles and i'm too cowardly to inform the public in fear of ridicule or opinion.

[@Bix12]

"when common sense meets quantum physics" - in the quantum world, never the twain shall meet.

[@ahadicow]

My burning question whenever come to Prof Moriarty is do he always keep two footballs in his office specially for this purpose?

[@nibblrrr7124]

It would be annoying to always have to borrow Prof. Poliakoff's dog toys.

[@jcollins519]

I'm sure he keeps all kinds of props around for demonstrations and analogies during his lectures

[@tammyplatte328]

I think he juggles them like knockers in his free time

[@MozartJunior22]

I find this video...touching.

[@aurelia8028]

wow...

[@frysause934]

hahaha

[@tuneboyz5634]

Theirs nothing emotional here to be touched

[@donpcmartin]

But who’s right tho? Now to the experts here in KZbin comments

[@sc4r3d0ntf34r]

Nope a video can't touch you

[@mewepede]

One hundred percent understand what Mr. Teacher is getting at. Thank you both for playing your parts to clear this up and make the destinctions clear.

[@ThePurza]

Yes, if election 'shells' are more a cloud of probability than anything defined, I can't see how anyone could say - 'yep they are touching now'. You need to define an arbitrary point, I would have thought an arbitrary measure of "overlapping electron density" would be as close as us laymen could possibly get

[@Cheesepuff]

There are 4 fundamental quantities in physics: 1. Energy 2. Mass 3. Force 4. etc.

[@Mic_Glow]

In classical physics at least...

[@nagarmalsharma9992]

Idiot, there are 8...time, mass, temperature, current, length, luminous intensity, mole,

[@57thorns]

I was so hoping for "passion" there at #4.

[@koroko999]

@@ombelle5284 Well done ;-) I was thinking the same!!

[@FrancoisTremblay]

Especially the etc

[@GravisTKD]

"... the problem is, you can't extend what the normal person thinks about touching down to the quantum level..." BINGO. Quantum mechanics is, by its nature, not intuitive. Our minds did not evolve in such a way that we dealt with quantum phenomena in our daily lives. We are evolved for the macro. As Prof. Moriarty says, the analogies break down. That statement he made is worth listening to again and again until it's internalized. This stuff is much more readily understood when we let go of our preconceived notions of how we think things *should* behave. Brilliant video.

[@noob94884]

It is also like saying ' can you read the text on the screen' :D if you move your eye up VERY CLOSE to the screen, you will only see the red green blue dots, so of course, you CANNOT read the text, that is made up of hundreds of those dots.. :D :D

[@sarge1176]

excellent analogy for this phenomenon

[@Yutani_Crayven]

Geoff Futch Then use a different descriptive term that doesn't run into this problem. Seems easy enough.

[@philipjohnson2986]

Isn't this what religious people would argue tho? To quote what Geoff Futch said... for example...... That statement he made is worth listening to again and again until it's internalized. This stuff is much more readily understood when we let go of our preconceived notions of how we think things should behave. Brilliant video. Please correct me if i'm wrong. Thanks.

[@fu886]

analogies "break down" because that what analogy means - symbol that is not identical with the symbolized but exemplify aspect of what being symbolized. it is not because "in the quantum level" or anything like that any derivative use of language "break down" at some point but have merit in other.

[@tomasdelatoba7572]

His reaction at 8:06 is the international sign of "WTF DUDE" lol

[@IceMetalPunk]

I have to agree with Professor Moriarty on this one. To define "contact" as "the point at which there is no space, not even a Planck length, between two objects" is an extreme exaggeration that doesn't apply to anything. You can't put a piece of paper between the two "contacting" footballs, but you CAN put a sheet of graphene (ignoring the logistics of alignment). You can't put even graphene between two close-enough atoms, but you CAN put an electron. Etc. So that definition doesn't apply to anything on any scale. And since particles aren't really volumetric points...there's the issue of "what does it mean to be 'that close' to another electron when electrons have no defined position?" In the end, the common ideas of contact don't actually apply to the real world on any scale, and so the only way to talk about contact factually is to define it in a way that does--which the Professor has done here.

[@Ana_crusis]

IceMetalPunk Absolutely correct. (I'm afraid some people haven't really understood the video).

[@SmartAlx]

Yes. But I'm not one of them.

[@synapse349]

IceMetalPunk Yeah, and I shudder to think about contact between the quarks that make up the protons and neutrons, etc. And what exactly happens when particles collide at high energy? Do they THEN touch? Even ever so briefly? Oh if I never find out, I'll still die happy, I suppose.

[@BrooklynZeeBKZ]

How you scientifically measure an "extreme exaggeration"? And to say that it doesn't apply to anything when it applies to this discussion is disinforming. It was an accurate definition of "touch" especially in terms of classic physics. However, to talk about particle interactions on the quantum level is pointless when those particles actually behave like waves. The answer to this discussion was given when the professor talked about Attractive and Repulsive forces. The whole discussion should have been around forces and waves since those are what matters most at the actual level of atomic interactions.

[@WeeWeeJumbo]

"I agree, but you have to be kerrful!"

[@kellyjackson7889]

eye

[@pairot01]

A perfect example of two people arguing about two different things.

[@skinny55772]

Cocaine or a double dose of Vyvanse.

[@cassiopeia9701]

then you missed both points completly :D maybe rewatch the argumentation of prof Moriarty. It is exactly the issue of the whole discussion. If you see his point there is no need for such and therefor it is perfect counter argument for bradies (or the internet questions he represents)

[@cidfacetious3722]

@@cassiopeia9701 there's a reason no one responded to you just stop it he didn't miss anything the question answer was asked by the Common Man would be answered no by Professor Moriarty if you understood what was being asked but he took it as a science question asked by somebody who has a basic understanding of quantum physics but that's not what was being asked but Professor Moriarty did answer the question and it's no it is impossible it would be immediate Fusion as he alluded to with astronomical energy levels

[@cassiopeia9701]

well how did i go on my comment is a year old... but yeah you seem to have missed the point too. The whole argument is there is no "common mans" way of defining touching

[@cidfacetious3722]

@@cassiopeia9701 no it is you missing my point not only did I get your point and agree with it what I was saying is the question that was asked as it was being asked by the Common Man was not understood by the physicist who heard it as a physicist the common man doesn't understand the waves and all the weirdness of quantum mechanics what to repeat myself the answer to the common man's question as it was asked is no they do not ever "touch" if a physics student asked the question then the answer in the video would be what we were looking for the whole video was literally a giant misunderstanding between the question and the answer

[@mcrut111]

people need to realize that you can have a great heated discussion like this one between brady and mariarty, and still walk away and be good friends or colleagues. just because you disagree doesn't mean you get to hate that person, that is an immature reaction.

[@twobyfour]

Almost 8 years on and this is still one of my favourite episodes.

[@thishandleistaken1011]

This is fucking comedy. 9:36 is one of my favorite parts, Phil's reaction to brady's "true contact" is perfect.

[@noob94884]

people seem to be forgetting that the 'electron shell' represented by the skin of the football is **NOT SOLID** !! It is a spinning electron!! (VERY SIMPLE DESCRIPTION!!)

[@jja77a]

actually electrons dont even "spin" around the nucleus

[@noob94884]

jja77a so WHAT does an 'electron round a nucleus' DO??????

[@jja77a]

it is best described as a probabilistic "wave function"

[@gressorialNanites]

well, EVERYTHING is ultimately best described as a probabilistic wave function...

[@DANGJOS]

NO! There aren't any other videos on Sixty Symbols on the Pauli Exclusion Principle please do one

[@00BillyTorontoBill]

do the search then look at the video descriptions...you're right its not stated in a title...but it does appear in descriptions.

[@vitorfernandes2406]

I didn't find those videos. Please make more of them and please include some math

[@DANGJOS]

@@00BillyTorontoBill Wow I am so insanely late to this comment, but can you point me to which videos that is?

[@TheRealBanana]

I think the video he was referring to was entitled "Was Brian Cox wrong?" .

[@DANGJOS]

@@TheRealBanana Ah that makes sense. Yes, that one is about the Exclusion principle. They should go into more detail though

[@occamschainsaw3450]

But what did this people expect, for nuclear fusion to happen every time we clap our hands or something?

[@niko_hand589]

That explains why my house is blown up

[@hewhoisknownastaco]

Ha, that's a great name, Occams Chainsaw.

[@Carcaroff87]

i dieded.

[@xenoblad]

Just say they don't touch, so we use a different definition for touch since touch as a word is useful.

[@aussiebloke609]

+xenoblad That's probably the most accurate and enlightened idea so far. Simply explain that the scientific definition of touch is different to the common, everyday definition we generally use. People will still often get it wrong, though...rather like the difference between hypothesis, theory and law (which even some scientists still get wrong.)

[@hewhoisknownastaco]

I think his explanation of the footballs touching was perfect. He asked if they where in contact and then he pushed down and got them, or at least their centroids, even closer to each other.

[@BrokenSofa]

What Brady needs to understand is that nothing is solid. There is no touching between anything, it's just a question of attracting and repelling. Imagine this, if you smack your hand on the table, would you say that the hand and table are touching? If your answer is yes, zoom in the molecule level. Would you say that the molecules are touching? As touching is being defined by their edges being indistinguishable as two seperate objects. Now zoom in to the atomic level, would you say that the electrons are touching? Considering that the electrons are just floating in a magnetic field around the core of the atom. If you don't define contact as the electrons touching, then what about the nucleus? Do the nucleus of each atom have to touch before you call it 'contact'? Because if the nucleus' are touching on each atom, you've put the atoms in a state of fusion, not contact. I don't think that Brady understands a tad bit of what he is talking about, Moriarty on the other hand is a professor in this subject, if I didn't understand any of this I'd probably put my money on him either way.

[@sixtysymbols]

Broken soffa just so I am clear, this comment is in support of Phil's view, right? You wrote "There is no touching between anything" - that seems to be the WHOLE position Phil is arguing against!?

[@Relbl]

Sixty Symbols The title of the video is 'Do Atoms Ever Touch', and the electron orbit/shell/potential is part of the atom, and these orbits/shells/potentials absolutely interact and 'touch' - the whole of Chemistry is based on this being fact! You come off as fairly petulant when you essentially say 'yea, well, the nucleii never touch so na na na na na na'... come on, that's just silly. Maybe you mean to ask 'do nucleii ever touch?', 'or do quarks ever touch?', etc, instead of 'do atoms ever touch'...

[@BrokenSofa]

Relbl That's exactly my point, no one knows what touching really means. and that's the point that the irish guy is trying to get across.

[@Relbl]

Broken soffa but the question is stated one way and answered that way by the PhD, whereas the director tries to change the question after asking it

[@BrokenSofa]

Sixty Symbols Contact is still undefined but seems to mean that contact means that something is touching on the cellular level and you can't get any object between these 2 or more objects that are in contact, right? In that case, if you zoom in to the level of molecules, none of theese objects are touching because you can not tell where one object starts and another begins. There is no clear line of what touching really means. A language has to have the same meanings for the same words, otherwise there is no point in debating when we don't understand each other. That's why we have to figure out the meaning of the word 'contact' and the word 'touching' before we start arguing about something in two different languages.

[@_varden]

Great video. Moriarty's analogy with footballs moving closer than the point of contact (squeezed together) repelling from each other was really good.

[@sixtysymbols]

***** I agree that was useful

[@GabrielKnightz]

The best ones are when these two argue, it's hilarious on top of being informative.

[@StreuB1]

This has got to be one of my favorite Sixty Symbols video ever. Professor Moriartys fire and passion and such a high level discussion really gets you turned up and into it as well. Such a great discussion! REALLY makes you think!! My real question is.......if the repulsive and attractive forces are pushed beyond equilibrium, does the repulsive force approach infinity the closer two elementary particles come? I would assume not because if the repulsive force was infinitely great, fusion could never happen and we could never have collisions. Though.....would the point where we add enough energy to the system to get (in theory) two elementary particles so close that their distance from center to center equals the sum of their radii?? Or is that one of the problems....elementary particles can't be thought of as round balls? Thank you Brady and Professor Moriarty!!

[@BobSmith-dt6xs]

+Brian Streufert In fusion they don't have to physically touch each other because even protons aren't point-like; they don't have a precise position. You just have to get them close enough so that they bind.

[@FlyingJetpack1]

+Brian Streufert It infact DO go to infinity, you will need infinite energy to get the "center" of a partical to the other's "center" [cough cough with quotation marks]. Getting two particals in the same position is fundamentally impossible, and the closer you are to achiving it, the more energy you will need to put in. As for infusion, as long as they can get close enough + some other criterias, a bond can happen, created by the strong force. I'm no expert on that subject so you'd be better off looking it up yourself.

[@alyasgrey9370]

+FlyingJetpack1 No... just no.

[@AdasiekkkTrzeci]

+Brian Streufert There isn't just one "attractive force" and one "repulsive force". If you were to plot a graph of force vs distance, you'd find that there is more than one local minimum (ie. more than one point at which the forces balance). This is possible because the different forces will be effective at various distances, some are short-range while others are long-range. In fusion, there comes a point in which the strong nuclear force starts playing a significant role and in effect you create a new minimum point. But there is a barrier that needs to be overcome to get there in the first place.

[@jacobscrackers98]

I personally found it intimidating and unneccesarily aggressive. You don't need fiery words to make a point, you just need truth and logic on your side.

[@AlphasysNl]

This video, with your "layman" questions and ideas vs. the "expert" definitions, was riveting to watch, Brady. I would even go so far as calling it the best Sixty Symbols video to date! Even though it never mentioned a symbol...

[@Paul_9320]

This is brilliant. My favourite vid on KZbin. Watching the passion that both are genially arguing with and the wider discussions this brings about science communication was mindblowing. More like this please. Passionate, educated people arguing in a fact based way.

[@squidcaps4308]

Easily one of the alltime best videos from Sixty Symbols, i could watch these two debate for an hour (i could debate for days, i like the swoosh sound that it makes in my brain, everything lights up like fireworks, coffee and debate, what a rush and oh my god, how nerd am i really?.). The debate is true and shows exactly what people who are getting so deep in their fields of study that the semantics are not working on same worlds anymore. This is just the same concept of how matter is mostly just empty space but that is not how we experience it when you get hit by a truck. I get why he gets so worked up about it, when you have an insight how something works and you know you can explain it quickly inaccurately but enough for applications to use it or you can explain it right.. Sometimes the right explanation is worse than what is needed, ie "quick&inaccurate but it works". But for everyday life, things touch. For philosophical aspect, nothing ever touches and the real scientific fact is that the definition of touch is different and it combines the other two (and gives nice philospohical twist: we touch everything since touch is just interaction between forces anyway..)

[@L00NGB00W]

Brady. Don't piss off Professor Moriarty.

[@argentvixen]

I absolutely love how passionate he is about this. And I agree, it is a wonderful opportunity to help people redefine their understanding of "touch". I feel that is what the masses are trying to work out with all the chatter but I also agree that it is necessary for smart and passionate people who study this stuff for a living, to patiently but consistently help keep the flow of understanding on the right track.

[@RazzorG]

I love when Prof. Moriarty gets really passionate about the arguments.

[@RinoaL]

i love how there is a bit of debating in this video :D a lot of the issues people have with this is due to people thinking of atoms as a hard sphere when really its a collection of objects that might as well be 0-dimensional points in space. but those points are like little force field generators that create a spherical field around it that will influence other objects. so the atom's outer edges are very fuzzy.

[@FranklinNewhart]

This who damn discussion is very Fuzzy.

[@daffidavit]

Don't tell that to Brian Greene. He'll get all tangled up in his strings.

[@000Mazno000]

When i watched this when it came out, I was on Brady's side, but now I totally understand Moriarty's frustration.

[@piccalillipit9211]

*THE GUY ASKING THE QUESTIONS* is actually brilliant at asking the obvious question most people would be embarrassed to.

[@elfutbolphenom]

I liked how Professor Moriarty kept saying "the analogy breaks down" and Brady kept refusing to accept that, because that is what my students do as well. I think one of the primary issues causing the disconnect between the two sides of these arguments is the misconception of atoms and molecules as objects which are essentially solid in the same way that macroscopic objects are solid is so deep-seated that most "normal people" (oh Brady) have real trouble navigating a more quantum, probabilistic reality. But... the analogy really does break down!

[@sixtysymbols]

elfutbolphenom time for a better analogy then! :)

[@PelegTsadok]

This concept, that reality isn't as solid as we think or hope it is, is extremely hard to understand. I understand that it is, I just don't get how it can be so abstract(if that's the right word). For an example, I understand objects with mass curve space-time, I just don't get what this "space-time" is and how we can observe it.

[@ScourgeNagash]

Sixty Symbols How about use a planet and a ball as the objects. If the ball is falling toward the earth there will come a point where the forces attracting the earth and the ball(gravity in this case) are balanced against the force of the earth and the ball pushing away from each other. The ball is resting on the ground and you can say both are in contact. With more force you can push the ball into the ground, but that does not mean a ball resting on the ground is not in contact with the ground.

[@sandropollastrini2707]

I liked the discussion: in my opinion it highlighted the difficulty of the scientist to find a common metaphorical ground to speak to the layman, and for the layman the difficulty to digest the radical change of point of view needed to understand the quantum world. Furthermore the topic is simply fun.

[@NZAnimeManga]

This was brilliant; reminds me of my interview with Prof. Moriarti last year. Mainly about the Pauli exclusion principle in terms in white dwarf's eletron degeneracy pressure.

[@TCBYEAHCUZ]

brady's wrong, the best analogue to moriaty's explanation is to have the two bouncy balls touch, Say that the ball has reached a point where it's at equilibrium of the two forces, you can squeeze the two balls together but they will revert back to this equilibrium. That is contact, Then say the balls are spherical clouds with no hard surface.

[@salottin]

The part where he pressed them together explained that beautifully. This video ANGERS me

[@CitrusTsunami]

Yeah i just kept thinking the words influence and equilibrium could have helped dissolve the incompatibilities of their arguments. There's physical contact, with the nuclear cores touching physically, but that's not the definition of contact as used in his papers and as he says, there would be no real point to defining it that way, no way to apply the definition to a real atomic situation. There is the positive attraction that is the result of the partial charges, then the zero point equilibrium which he's saying is the definition of contact, where the repulsive force (if you bring them further together) will be in equilibrium with that attractive force! Sad to watch it go on that long with so much argument because of a misunderstanding on the cameraman's part lol

[@hanskloss7726]

How is he , personally wrong? How do you even know? Do you know the guy personally? I think whatever he knows or does not know he played the role of advocatus diaboli perfectly. He managed to stir quite some tension by the Professor and by the public here. I'd say perfect success for the devil :)

[@gileee]

So things are in contact if they're so close that you cannot make them get closer without applying a force, because that means you're making them deform or overlap or whatever (depends on what the things are) and that's beyond simple contact. If I'm about right that might have been better explained by trying to push the same pole of two magnets together and feeling the point at which the magnetic fields touch and start repelling each other.

[@obiwansaysbuybuybuy7041]

@Chaim Goldbaum you got it right. Atoms are not footballs, they are not solid particles, and do not have a surface to be in contact with another atom in the same way as things in the macro scale.

[@s0c1al1z3dm3d1c1ne]

Phil is by far the most punk rock physicist of all time. I love this guy.

[@SardiPax]

I loved seeing a scientist/professor getting so excited about his topic. Wonderful. Well done Brady, now see if you can get Professor Poliakov as animated :)

[@gara911ultra]

I fully agree with Moriarty's definition of contact. If we were to compare an atom to a soccer ball, where the nuclei of the atoms are comparable to the center of the soccer balls. As soon as the atomic forces are balanced between two atoms, it is similar to a soccer ball resting on another. At this point, this is contact. If you push the soccer balls closer together, and do the same with the atoms, this is also contact but there is just more force in the system. The center of the soccer balls are closer together, and the nuclei of the atoms are closer together, all of this is still be considered touching. There is also a limit of how close you can push the atoms and the soccer balls together. At some point the soccer balls will rupture, and the atoms will fuse. Once the soccer balls blow out there will be no clear center to them, the same will happen once the atoms fuse. After this point there is no longer contact between the atoms, but a fusion of two atoms. P.S. This is just my view on this discussion. I am by no means a physicist, but i still believe that this is a good definition of contact.

[@VV66613]

Professor Moriarty has a lot patience....

[@nosuchthing8]

so when the moon orbits the earth, and the outward force from the velocity matches the inward force from gravity, the system is in equilibrium. But according to you the earth also touches the moon, even though it is many hundreds of thousands of miles or kilometers away?

[@roxydzey]

*of patience. lietuvį visur sutiksi :D

[@abdalhadifitouri131]

Some people enjoy debate. I do very much

[@MKWiiLuke4TW]

this is two years late I realize but like that's not right, there is no outward force exerted on the moon, that force is fictitious and only created by the function of the moons perpendicular velocity to it's orbit and it's free fall acceleration being in equilibrium, you have no true repulsion force between the two, if the moon wasn't in motion it would come towards the earth, and push through it until the gravitational force equalled the force exerted outward by the earth, you can only define contact when comparing "real" forces

[@NuncNuncNuncNunc]

Patient, smart, and dangerous.

[@Slithy]

Seriously, "contact" and "touch" are totally different things. When you have eye contact with a person, for example, it doesn't mean that your eyeballs are touching. So you can have contact without touching, or you can have both, or you can even have touching without contact, it all just boils down to the definition. And if a group of scientists come up with a perfectly reasonable and usable definition of contact, i don't feel like i'm in a position to argue about it. But what prof. Moriarty described is a contact without touching. If, on a quantum level, you want to make 2 things touch - you should call CERN.

[@z-beeblebrox]

Well, you have to be careful, because it's not like the footballs touching, where you have two discrete particles. It's more like if you have little objects under a blanket and all you can measure is the ripples they make (except not this at all because the objects under the blanket literally wouldn't exist) - you can't really say the ripples touch any more than you can say they don't touch. Either they make a sort of contact/interaction, or they sort of merge. What Moriarty eventually ends up trying to say is that the whole concept of "touch" as we know it is basically irrelevant in the quantum world, because there aren't any solid objects capable of doing it (or not doing it)

[@joeymacguffin]

It's more that "touch" simply doesn't make sense at the atomic level, where there's no such thing as physical objects with defined shape and size. The definition of "touch" relies on clear boundaries between object and environment that aren't applicable on a molecular scale.

[@LivingChords]

You have to distinguish between physical contact and something like eye contact.

[@SenneChristiaens]

"When you have eye contact with a person, for example, it doesn't mean that your eyeballs are touching" That image is hilarious, thanks for that statement.

[@SangoProductions213]

such a touching speech. No? Nothing? I'll sit in my corner now.

[@pepe6666]

thats an interesting video. i think the shortest way to explain what the professor is saying is that on the quantum scale, electrons arent discrete particles. they dont have a specific location, so atoms dont have a specific border. so when you bring atoms close together, you only have a probability of them touching. given that, you cant specifically say 'the distance between the atoms is zero' - because that would be precise knowledge of the atoms position. er i think. the idea of discrete location breaks down at the quantum level

[@zephyrandboreas]

Just came across this video. Really loved it. Not just by the energy of the discussion but because, as a scientist I do understand the limitations of the analogies that we create to explain scientific concepts. It is always the case that analogies breakdown at some point because we use common language to help visualize in a simplified manner phenomena that require a very specific set of rigid criteria to be accurately described. This would be an excellent topic for a video on its own. Analogies are powerful to help visualize a concept without all the intricacies and level of detail that would likely make the average viewer's eyes glaze over. But at the same time there is very much the danger of a person to make extrapolations based on the perceived reality of the analogies when this is not correct because of their inherent limitation. I always believe that it is important to be very clear on this. It is the same as when as scientists draw conclusions from their experiments without taking into proper consideration the limitations of the methods used, and which precisely establish the limits of the claims made.

[@chalked9815]

Amazing breakdown of the video. Hope you're doing well!

[@Teth47]

I think what Prof. Moriarty is trying to say is that the boundary at which we can say, from a macroscopic perspective, that two objects are in contact, is too fuzzy to define it that way. There is no edge to a proton, for instance, and even less so for an atom or molecule. The boundary at which the attractive and repulsive forces balance *is* the point at which two objects interact in a way analogous to what one might think of as "contact". If you push then closer together, all that happens is that it deforms to maintain that space, just like the two footballs when he pushed them together, or they overlap in the same way you would expect if you pressed two curled up slinkies together, the individual pieces diffract into what would be considered the interior of the object, because there is no barrier there physically preventing the electrons from moving past one another. In both cases, they are in a state that could reasonably be defined as touching. No more space can be removed from between the two objects, because probabilistically, there is no more space there.

[@TheFounderUtopia]

In summary, I think Brian nicely demonstrated that when people say "atoms never touch" they actually ARE making an accurate statement, because as Phil said, you can't extend that macroscopic concept of touch down to the atomic level. But it seems what he takes issue with is more the way people go about justifying this using science they don't fully understand, creating a misleading impression of how these things work.

[@EmceeJoseph]

A bit late to the party but I'm guessing the idea is that basically whenever macroscopic touch happens, at least a few nuclei are at this equilibrium boundary if not all on the surface (due to roughness), and the stronger you press things together once they're past that point the more nuclei get to that point and you keep going until all the surface nuclei are at that point (well beyond macroscopic touching and beyond perhaps the material's capacity to withstand the pressure) and after that you hit fusion/fission or whatever.

[@hanumanvaya]

"Long before you get to the repulsive side, you have an attractive force..." Pretty much sums up my marriage.

[@Aphetorusbull]

I'm perfectly happy in saying that an atom is touching another one when the two forces are equal. What's wrong with that. If you understand that we have no macro equivalence to an atom why are we trying to draw analogies? Using analogous thinking is not of any real value when you have nothing that is analogous! great video by the way.

[@Aphetorusbull]

As a follow up, how do you define the edge of something that doesn't really have an edge?

[@Aphetorusbull]

Hi Mark as best I can tell "touching" is a macro concept and not really applicable at the atomic level. So Eye contact and balloons and balls are all analogies that are not really useful. If you insist on trying to draw analogies lets use some fictional star-trek language. Each atom has its own integral glowing blue force-field. Atoms attract each other but when the atoms get close enough to touch force-fields the attraction ends. If you try to compress them closer the force-field turns red and starts to crackle and hiss and begin to push away from the contact. Now in that mental image are the force fields touching?

[@AmxCsifier]

I agree, our macro perceptions are holding us back I also think that the Professor using balls as analogy to atoms is a significant compromise

[@WorthlessWinner]

Intuitive language and metaphor just lead to confusion a lot of the time.

[@iamhaute69]

Aphetorusbull exactly! looking at an edge on microscopic or even deeper level would move things to fractal geometry!! A circle is never round on fractal level!! its all polygons!!

[@MrBanzoid]

Ohhhh, I love a heated discussion! To he honest, as an astronomer I never really gave this subject a lot of thought. Thanks to Prof Moriarty for explaining it so well.

[@m2langberg]

This is your best video EVER! I love the intense discussion! More like this!!

[@sixtysymbols]

Mike Langberg cheers

[@whopperlover1772]

In the end, I don't know if my hands are touching and now I have a headache...

[@LeviCarlton]

+Fester Blats They do touch

[@DamienZshadow]

+ByteMe Don't listen to them, the real answer is another question. "What IS touching?"

[@oneshotki11]

They both touch and dont touch. Schrodinger hands.

[@kenwalter3892]

ByteMe Touching yes, in contact no.

[@jukechuu]

@@DamienZshadow "hey vsauce michael here"

[@TheReligiousAtheists]

I'd say that the fault in Brady's arguement is that he says that he says that 'contact' is when you can't bring those footballs any closer, and he also says that if you keep one on top of the other, condition is satisfied. But anyone can tell you that you CAN move them closer if you squeeze them, which means that they don't satisfy the condition of you just keep them on top of each other. So you might think "Then let's define 'contact' to mean the point where to bring the 2 objects closer, you'd have to apply forces on them and 'squeeze' them to bring them closer". Well, that's exactly what Professor Moriarty defined contact to be! The reason I like this expression is that you can explain it to a layman without saying "It's quantum mechanics, it's just like this", which, needless to mention, is a very dissatisfactory answer.

[@thesnowedone]

I actually liked Brady's definition of a "layperson" concept of touch being zero plank length distance between two particles. This is what I would have thought would be the case. That said Professor Philip Moriarty does argue (and rightly so) that this sort of point of contact would not one you would naturally occurring (exceptions being nuclear fusion). I would actually like to see is a list of all possible definitions of contact, both from a physics and chemistry point of view. Perhaps by examining all the definitions of touch that can be derived from via scientific method we can perhaps tease out an acceptable set of criteria that would satisfy everyone.

[@JaxsonGalaxy]

I find in scenarios like this where people often try to take a macro-scale concept and apply it to quantum-scale physics, it's more useful to go the other way and take the quantum-scale physics up into the macro-scale, just to give a perspective on how different the two are. In this case if we scale up the quantum particles and turn them into apples or whatever when we bring them closer and closer together, they have a Vanderwaals attraction similar looking to a magnetic attraction, then they come to a point where the both float a distance from each other, if they are pushed past that point, they begin to repel, again similar to magnets. IF there were a force strong enough to push the two apples together close enough that we couldn't slide a piece of paper between them, a massive release of energy something similar to a nuclear explosion would occur and in the end we would cease to have two apples, but instead we'd have one new, different thing, for this case lets say a bar of gold. This is just a figurative visual explanation, but it is in actuality what happens on a quantum scale, and that's the part that people can't wrap their heads around. 2 Apples that "touch" = 1 explosion + 1 bar of gold. 2 Hydrogen atoms that "touch" = 1 Star + 1 Helium atom. Of course this definition doesn't really help us find an answer to the question "what is touching" but it does at least give us the concept of why that is the wrong question to ask in the first place. The question is fundamentally wrong, so any answer, no matter how valid or accurate, will ultimately be unsatisfactory.

[@calsta619]

Nicely put in simple Chinglish.

[@Haitchpeasauce]

Fantastic discussion. Heated, but respectful and edifying. It's great to see conceptions and assumptions being tested, and how the physical realities always challenge the way we use language to express them. So the take away points I got were: electrons cannot collide as a fundamental of quantum mechanics, that nuclei touching is basically fusion, that the energy required for nuclei to fuse is (thankfully) many orders of magnitude greater than what can be produced by mechanical means, so contact is understood as a natural equilibrium state of attractive/repulsive forces at the atomic scale. Even in chemical bonds the nuclei don't come into contact with each other, so it's hard to make a case that contact is by definition two nuclei touching.

[@Saki630]

This guy is tough Brady, I was intimidated from all the way over here in my bunker.

[@sixtysymbols]

Saki630 he's a sweetie really

[@Saki630]

Sixty Symbols You are correct because I just watched some more videos and saw how he talks about other things that he loves to do. I am envious of you and your colleagues. To me it seems you have the best job/hobby because you get to talk with some of the greatest minds of science and successfully bring condensed simple explanations to people all over the world. Some of which may have never had a chance to go to school in the first place, and are learning using your videos.

[@johnwaters97]

Sixty Symbols Can you do an other video where you discuss what happens when two particles (that you both agree have the necessary qualities for the analogy, unlike electrons) have zero plank lengths between them?

[@TNTEQUALSFUN]

Saki630 just a prof getting really passionate about his work :D

[@randy109]

+Kazza FDM Exactly! Without a very small fraction of people Passionate about obscure topics Mankind would still be in the dark ages. Thanks!

[@WildBillCox13]

Very, very, interesting. Makes me want to audit your lectures, Doctor Moriarty. An observation: The more we try to pin down a single, discrete, definition, the more nebulous its addenda become. Heisenberg vindicated? And a conceit: Pardon me for weighing in, but this is so darn interesting I feel compelled to to do so: It seems like what we have here is a discussion as to what any given physicist thinks of as contact. I appreciate Professor Moriarty's conviction and the sharp questions of the interviewer, but argue that it's a point of perspective and nothing else. To define contact we must first agree on what scale we're on. At the atomic or molecular scale, as soon as your electron cloud interactions reach a certain resonance you have, in essence, contact. In Fusion Mechanics, you're in contact when two particles fuse (or a number of particles interact so as to leave a heavier nucleus and liberate the excess binding energies as photons and what have you) in what is essentially the same region. In Neutron Condensates (Neutron Stars, degenerate matter, "cold plasma", and whatnot) the contact is more intimate, though less rigid, by current theory. At the macroscopic level, contact occurs when my nerves tell me so. The feel of a rose petal against my cheek, the soft touch of a lover's lips to the back of your neck . . . And, finally, from the cosmic perspective, Galaxies collide without ever one star ever touching another.

[@facilis]

I return to this video a few times a year. Absolute classic example of passion

[@jorgerangel2390]

I love it! nothing like a little controversy.

[@justagenosfan]

professor: explains camera man: yes but i think ur answer is wrong

[@jadissa3841]

Wonderful video! I think a somewhat helpful explanation to someone fairly initiated is that the position of particles in quantum mechanics is not defined by a vector (three numbers -- coodrinates) but rather by a wavefunction. And if you imagine a wavefunction with a peak at a certain point representing a particle (say an electron) and another one representing the other particle (another electron in this case) with a peak at another point. Getting the electrons closer together means that the wave functions get closer and closer, but there's really no point where we can say that there is no "space" between them or that they are touching. The only point where we can say that they "touch" is where the peaks of the two wavefunctions overlap, and that's obviously not possible because of Pauli's exclusion principle. I think that is what the professor meant when he said that it's impossible to have no space between the electrons because of the Pauli exclusion principle. Also -- if I'm right -- because of the Pauli exclusion principle there should be no place where the wave functions overlap in any way, so that means that as you get the electrons closer together their wavefunctions will get narrower and narrower forever. Also, on a side note, their momentum gets more and more uncertain because of the Heisenberg uncertainty principle. Please correct me if I'm wrong.

[@kasuha]

Honestly, I think it would be better if you had this conversation before you made the video, then made a way less heated video which just explains the point while taking all these arguments into account.

[@sixtysymbols]

kasuha ha - that is what we did many times over the course of a year - then we decided it would be fun to let people see how that played out for a change. Not everyone's cup of tea I realise. But others really liked "seeing how the sausage is made".

[@Orphen88th]

Sixty Symbols I have a feeling after seeing this video, that the negative temperature video was probably hashed out before hand too.

[@danilooliveira6580]

that was actually one of the most entertaining videos from you guys, but I feel that it needed to be longer

[@ObserverZero]

"The analogies can't be extended to the definition" is exactly what people mean when they say "they aren't in contact". Our idea of contact doesn't exist.

[@ObserverZero]

Sure, there is a difference in colloquial "touch" and scientific "contact".

[@RFC3514]

Maybe _your_ idea of contact doesn't exist. Mine certainly does. Contact is when things bump into each other (instead of going through each other). For all I know, microscopic particles called "contactons" might be generated for a fraction of a second, or _some_ atoms might be going through each other like ghosts and then disintegrating into small black holes that feed the great god Contacthulhu (praised be his mighty footballs). Either way, the practical result is the same: one thing bumped into another. Professor Moriarty is just explaining that what we perceive as an object bumping into another is not the moment where the nuclei of their atoms "touch" and fuse together (which would have rather more spectacular results), it's the point where two specific forces are in equilibrium. Or are you still stuck in the 19th mentality of atoms as little balls of indivisible and incompressible matter, with a perfectly-defined "surface" ? The closest thing to a "surface" is precisely that point of contact (i.e., equilibrium), but even that is flexible, and depends on the energy you apply.

[@ObserverZero]

Right. Most people with skin, and a sense of touch have a 19th mentality and think things have a perfectly defined surface, but recognise that it is wrong, because as you say, contact is not what I (most people) think it is. I think we all agree.

[@RFC3514]

Harald Veland Having skin and a sense of touch doesn't make you aware of the existence of atoms, let alone their structure, so that's really a non sequitur. All you know from having skin (and macroscopic observations in general) is that things generally don't go though other things, and that you can feel a force pushing back when you push against something. In fact, skin (and flesh) gives you a good indication that things can be compressed, and that "contact" is a fluid thing (it can be so light you don't feel anything, or so strong that it crushes). What this really has to do with is the nature of _atoms_. The ancient Greeks picked the word "atom" (meaning "indivisible") because they thought it was, but anyone alive today should have learned otherwise in school. If an atom is made up of several particles (even if we ignore the fuzzy wavelike nature of those particles), then the concept of a single hard "surface" immediately stops making sense. There are plenty of macroscopic parallels to this, too. For example (*), assuming your head is covered in hair, if you lean back against a wall you'll say that you are "in contact" with the wall when the force pushing you against the wall is more or less in equilibrium with the springiness of your hair (which is keeping your scalp at some distance from the wall - maybe 0.5 mm, maybe 2 cm, depending on how thick your hair is). You won't say that you are "in contact" as soon as one hair interacts with the wall (you probably won't even feel it), nor will you need to wait for all your hair to be crushed into a sub-atomic membrane, letting the atoms that make up your scalp interact directly with the ones that make up the wall. Contact is a fuzzy, practical thing, even at a macroscopic level. This notion of equilibrium (where something pushes back strongly enough to counter the thing trying to get closer) is perfectly compatible with our (or, at least, with _my_) idea of contact. (*) This example probably falls into the "Feynman's hairy balls" category.

[@ObserverZero]

Man, I saw the video, but hanks for the transcript. Why are you still arguing? "If an atom is made up of several particles (even if we ignore the fuzzy wavelike nature of those particles), then the concept of a single hard "surface" immediately stops making sense." -That's what I'm saying. And Brady. We assume that things "touch" at the atomic and subatomic level purely by intuition. That doesn't actually happen. We agree. :)

[@d.w.5144]

Hello Prof Moriaty. I am some of this normal people who are whatching these wonderfull Sixty Symbols videos . I am from Germany and my english isn´t so good to understand everything. Hopefully I am waiting for such a blog in German, but I am in "touch" with your explanation of touch. Your try to explain it with 100% of your heart and soul. Its a pleasure to watch these stuff. Our world is wonderfull and full of secrets. Your guys bring light in it. I whish I was young again and try to study physics. Thanks a lot

[@chap666ish]

"Jeez, if we could have nuclear fusion by just doing that... it would be wonderful" Er... no. That would be reallly, really bad :-)

[@Lavabug]

***** High five! Uh oh...

[@dabzdavid2378]

6:24 He said "exactly" without hearing Brady. LOL

[@akshatsaxena1431]

Omg that's really funny

[@seijirou302]

What a gift it would be to have a conversation with Moriarty.

[@HelciusCabral]

You almost made your point across at 10:00 when you questioned about fitting a piece of paper between the touching footballs, but you two wandered off in another direction.

[@kunalgub]

Like he said, the analogy breaks down. Since electrons are not particles at a fixed point (they aren't even particles in some ways), in order to define contact, we need a definition based on forces rather than space between them.

[@sirmetaladon]

This is the best kind of arguing. I love it.

[@5om3kid77]

The best bit is when the Professor is about to drink his tea without realising it.

[@ShinDMitsuki]

This is really just some big argument about semantics, so there's a lot you can say about it. If you look at the definition of contact, it will tell you to come into a state of "touching" the object. If you look up the definition of touch, it will say going close enough as to be in a state of contact with an object. In other words, what the professor is saying things DO touch each other, because that touch is defined by the physical property of when a certain influence is exerted over the object. The definition you present at the end is saying objects are only "touching" when they occupy an area of infinite density, because there is no space between them and the next object. My question to you then is though assume they were some type of weakly reacting particles that could pass through each other. Even if they occupied the space right next to each other, are they "touching" if they do not exert any influence over each other? What I took from the video is that the professor has a problem with people fundamentally misunderstanding what contact is in the first place, so it's erroneous to say things don't "truly" come into contact, because things DO truly come into contact, and the definition of said contact that we observe on a macroscopic scale is X on a microscopic scale.

[@ShinDMitsuki]

Sorry for blabbing on more about this, but I think the point is really driven home when he puts one ball on top of the other then pushes down harder, causing a collision that changes the shape of the ball. On a macroscopic scale, we think of contact as when you put something on the surface of an object. You then said "Well the collision is when I can't put a piece of paper through that" or something to that effect. What you ignored, however, is the fact that the reason you can't just leisurely put the paper through the ball is BECAUSE of the forces spoken about. On a macroscopic scale, what we call contact is described by the professors definition on the Microscopic scale, therefore it IS collision. It's wrong to say because it "looks" different it is fundamentally different and something fundamentally can't happen. It also should be said that we usually say things can be in contact with other things but at different levels. If we grab somebodies arm, and then grab it again and squeeze harder, we consider both contact and we don't say the first isn't because it's further from the atoms contained in the persons arm. Also, the macroscopic implications of what you spoke about (the plank length based definition) would cause something macroscopically that I doubt few people would consider plain old "contact."

[@vedranjosipovic7673]

Brady is just an amazing interviewer, I love him!

[@MWash-ix6fu]

I love the Professor's Passion in this video. I come back to it every so often. It has re-watchability!

[@2bsirius]

This video touched me.

[@conelrad1447]

This reminds me so much of me arguing with my dad

[@sankha6920]

I can literally understand what you mean 😂

[@2serveand2protect]

WOOWW! This channel is AWESOME! for the first time on YT I see something TRULY WORTH WATCHING!! BIG THANKS, FELLAS!

[@NemosChannel]

Look, it's very simple. If there's no contact on the atomic level, then there's no contact at all. For the word contact to even mean anything, there has to be contact at the atomic level. The only question is what that contact is, and that's what he says they measured: the point where the repulsive force cancels out the attractive force.

[@NemosChannel]

This was a great discussion btw.

[@brandynkelly9319]

This comment is the best summary of the video without a doubt!

[@WorthlessWinner]

Sadly it looks like things are adjacent in space on the macro scale (to the resolution our eyes detect) when the repulsive force outweighs the attractive force, so people think things have to be adjacent to touch. Even though that's not what really happens at any level.

[@hectordng]

great video, one of my favorites. love his passion and the way he trolls him

[@what_resists_persists6060]

I just love the guy behind the camera. He is the voice of all of us

[@AgglomeratiProduzioni]

What was wrong with the cup of tea at 0:50?

[@Daniel-wq2qw]

+Ruben The fact that Moriarty is an energetic person and would throw tea everywhere if he kept holding it :P

[@AgglomeratiProduzioni]

Ahahah

[@qCJLbggG4IWAY9nTH6o]

+Ruben It's not TOUCHING.

[@lolerskates876]

Maybe it's not Metal enough

[@cortster12]

I feel for the guy. Explaining that subatomic particles are not in fact physical to people who don't understand this is frustrating.

[@WayneJohnsonZastil]

I understand what your saying, but why use the word contact then to confuse us, why not use contact limit or contact. +

[@smedleybelkin19]

Wayne Johnson Nobody uses these words to '...confuse... you'.

[@garydagget7738]

This was a thoroughly enjoyable watch, made even more fun by Brady's notes in the description. This is proper, heated debate between two people who share mutual respect, but who are passionate about their own viewpoints. There is a difference between how most people argue and how people who respect each other argue. The world needs more respect, because it looks like you guys LOVE to argue about this particular topic. You listen to each other while you debate, and give ground where it's due, while most people won't concede the floor once they've started making a noise, whether their point is made or not. Note: More often than not, I fall into the "most people" category when things start to get heated...I AM just some random guy off the internet, after all :-)

[@lumburgapalooza]

10:35 WRONG!His definition of atomic contact is absolutely that of the functional definition that most of us walk around with. When I see a hand make contact with a face, the equilibrium of attractive and repulsive forces IS what I'm observing whether I know it or not. The problem is that the average person has no concept of what is happening to the objects at the quantum level. It would be like saying the average caveman's definition of fire is different from ours. We can all identify and describe fire at the level of sensory experience. Our understanding of combustion doesn't invalidate the functional definition based on sensory information, it amends it.

[@NighteeeeeY]

Im totally with Brady. The "answer" made me feel uncomfortable for some reason. Well as he said, as we know from the Pauli principle 2 electrons can never be in the same space OR they will never even >>touch

[@mazehazeglaze]

***** I think it would be more accurate to say they occupy the same "quantum state" rather than "space"...

[@RedTriangle53]

The point here is that you can define "touching" as when two electrons occupy the same space, both move at absolute 0 velocity relative to the observer, and through perfect measurements can be pinpointed as perfectly as the uncertainty principle allows. But that just isn't how contact works. When the balls "touch", and you see how it works on a microscopic level, it's because of this "locking" into place of the forces, not because of near-impossible oddities in quantum physics. You'll have to choose one: If your picky definition of touch is correct, then nothing ever touches, and if things touch, then that picky definition can't be correct. It's a law of physics that all laws of physics need to be present, in one form or another, at all scales(and velocities/accelerations), thus the two scales of "contact" need to be due to exactly the same effect. You are ultimately discussing physics using your own definitions instead of facts. I think a good analogy(if you're reading this, Moriarty) would be if you immediately defined the surface of the ball as the point of this equilibrium. I think Brady(and some confused viewers) like grabbing hold of the fact that they didn't see macroscopic contact, and use it to validate their own preexisting views. And stressing that the pauli exclusion principle is the microscopic manifestation of the contact force would be a better rhetoric for the purpose of explaining it to the viewers. There are only so many points you can make in a heated discussion, I guess. I'd like to see a more tutorial-style video on this.

[@RedTriangle53]

***** thanks alot!

[@CharlieUlivarri]

If the electrons aren't in a stable position, then the concept of no space between them breaks down at the atomic level. If the definition that Brady used were the definition of contact, then it might well work at some times but break down when, say, the electrons are on opposing sides of the nucleus; where contact would be defined at that instant as the nuclei overlapping or fusing with each other.

[@RedTriangle53]

Connor Hill I'm not batman?

[@LouieGrind]

I interpret the question like this. If a molecule has an outer border of mass (which I don't know if they have) where you would have to break the molecules border of mass in order to get closer to the center of the molecule. If two of these borders approach each other until the point where if you add an infinite small amount of distance closer, between these two borders, it would break one of the borders of mass on one of the molecules. Then, and only then, they would be in "true" contact. The problem here is that you assume that a particles mass occupies a defined space and doesn't change this defined space no matter what. Also, no one really definitely knows if particles actually occupies space with actual mass or if everything is just energy repelling each other.

[@SteveFrenchWoodNStuff]

So basically, he explains that atoms DO make contact by demonstrating that they do NOT. Hmmm.

[@TheFlyersFan88]

The atoms do make contact. When the forces between the atoms are equal, the atoms are in contact. The analogy with the soccer balls is great, when the balls are touched together, they are in contact. Yes, they can be forced together more, but they are not any "more" in contact with each other just like the atoms are not "more" in contact after they are forced passed the equilibrium point.

[@CalvinHikes]

A case of a brilliant scientist who can't quite understand what the question is.

[@vasilivanich3842]

A not too uncommon case of an incompetent asker not understanding what he asks. Quite analogously to the question "do imaginary numbers exist?" and the lack of the definition of existence.

[@VeniVidiVelcro]

I think what he's trying to say is that we can define "contact" as the distance between two objects at which the distance between the objects is the same (or at the same scale) as the intermolecular distances between molecules inside the objects themselves (being through Van Der Waals interactions or hydrogen bonds). So the point of contact is the point at which you can no longer distinguish whether the adjacent molecules belong to the same object, or to the other object.

[@mmaman6931]

Loooooool

[@Punditube]

Please make a video where Professor Philip Moriarty visits the westboro baptist church. Would love it. Thank you.

[@eddotron1224]

It'd just be like that scene in Kingsman

[@2serveand2protect]

We are INSTINCTIVELY drawn to consider "touch" as just the a FEELING (i.e. - a AN ELECTRICAL IMPULSE TO THE BRAIN) that gives us the SENSATION of "TOUCH" ...PLUS...the "visual recognition" of it (for example) >>> two fingers of my hand that "TOUCH" each other gives me the SENSATION of "touch" PLUS the VISION of it when I see them "touching" but fundamentally in physics that is isn't true "surface contact". On "atom-scale" we cannot truly see like matter behaves and furthermore...that was the BEST definition of "touch" I've ever heard! :)

[@jakedowman-french3205]

Contact may not necessarily construe touch, but interaction.

[@jakedowman-french3205]

Also, I loved the debate aspect of this video. Nice to see people so passionate about their fields.

[@d3line]

Everything is interacting. Electro-magnetic and gravitational forces inversely proportional to the square of distance between bodes, so that forces never actually zero. Right now electrons on your skin are busy interacting with electrons of alpha-centauri. Just weakly, but they do.

[@noswonky]

Perhaps the thing defined as 'contact' at the quantum level should be given a different name.

[@EmdrGreg]

Or, people who are working in the field could have their specialized vocabularies and it shouldn't bother us.

[@TheRealSkeletor]

Quantum contact? Quantact?

[@higharcangle]

In the macroscopic world, if we have an object sitting on a table, we can say that's contact. The object on the table has the repulsive force of the table and the attractive force of gravity canceling out. Hence, "contact".

[@joaomelo7538]

The thing is most people think contact is a point in space. It is not. It is a fenomenon. You see the fenomenon and try to explain what is happening, you see contact therefore contact ir real. But what happens and the microscopical scale? The forces balance out. When people say that there is actually no contact what they mean (or should mean) is that their definition of contact does not work and does not describe the fenomenon. We haven't defined contact, we discovered what really happens.

[@heynando]

yep, i can easily see this discussion reaching the language barrier, but it seems that they have not figured this out yet which is weird and not expected. Once they both realize such obstacle and overcome it they will actually agree regarding the same subject.

[@Vulporium]

I really enjoyed this, usually i'm uncomfortable with such a high energy conversation. But the subject matter was expressed passionately and with knowledge and understanding. Great questions were asked, and great reasoning was given.

[@bikerchrisukk]

I trust the guy who has a microwave oven next to his desk - that's dedication :-)

[@Jontman42]

The point ultimately is that in reality _nothing_ has a rigid surface like you'd think a macroscopic ball has for example, hence nothing is truly in "contact" or "touching" anything in the layman terms. The scientific view here is that all those definitions of "contact" are useless, so the definition is what Moriarty is saying. The question otherwise seems nonsensical and/or pointless.

[@kurtilein3]

the scientific definition does match the everyday definition quite nicely. as in, when you put a book on a table, our everyday definitions say the book and the ta ble are in contact. and science says: the book pushes against the table and the table pushes against the book, so there is a repulsive force, so they are in contact. and as you walk, your feet are in contact with the ground when the ground is pushing against your feet.

[@velikiradojica]

kurtilein3 Contact, as defined by Moriarty: (1) van der Waals Force + Electric Repulsion Force = 0 Book on table: van der Waals Force + Electric repulsion force + Force of Gravity= 0 Assuming the book and table are perfectly rigid, since the FoG is "adding" to the vdWF, ERP and vdWF will not fulfill the definition (1) of contact. So, gravity pushes the two objects past the point of contact.

[@beaudesting]

velikiradojica If you assume the two bodies to be perfectly rigid then you can also safely assume the FoG to be zero and the equation for "book on table" is balanced. The relative strength of electromagnetism and gravitation is 10^36 which means the effect of gravitation in that equation is much, much smaller than whatever forces (deformation) you're ignoring by assuming rigid bodies.

[@velikiradojica]

beaudesting I'm assuming rigid bodies for easier understanding.

[@billd01rfc]

This might be the best ever KZbin video I've ever seen . . . the passion is unbelievable . . . but totally controlled . . . and footballs!

[@D3w10n]

@ 9:15 "normal person..." XD Best moment in whole video

[@dylanlong8744]

"im not touching you. im not touching you."

[@DanG249]

still one of my favorite videos -- I've come back to this so many times

[@fupz]

I felt a bit uncomfortable watching this video because of the argument... I agree with Professor Moriaty though

[@fupz]

I guess you're right - Hope you and Brady made up afterwards! :-)