Gauge Blocks (Van der Waals forces) - Sixty Symbols

[@fernandopaul1]

manual of instruction, page 1, paragraph 1: Do not drop the blocks.

[@Mrgeoffrow]

And don’t let them rust😂

[@RyuKojiro]

That statement at 5:55 sounds wrong. This might be partially due to the diagram, but his explanation is also vague and misleading. The pits and valleys of rough surfaces don't cause the forces to "not add up right", it simply causes there to be an incredibly low probability of surface area overlap. Since the Van der Waalls force only operates at extremely close distances, this results in a cumulative force too small to hold them together. Consider two equally sized, but differently rough surfaces that have any arbitrary amount of surface area interface when put together. Each side will always have the exact same amount of its own surface area touching the other's.

[@PiercingSight]

They should pin this comment. It's the amount of surface area contact that increases the amount of force, not the bonds being out of wack or something weird.

[@joeblogs8589]

I agree with you. The smoother the surfaces, the better the more molecules are in close contact with each other, giving a greater overall effect. Van der Waal's forces are extremely distance-critical, so with a rough surfaces, most molecules are too far apart to "switch on" the attraction.

[@locktite401]

@@joeblogs8589 There are no molecules. Steel is a metal. Hence a Body Centered Cubic metallic bonded structure.

[@joeblogs8589]

@@locktite401 Yes, but my statement is for surfaces in general looking at V.D. Walls forces in all friction.

[@LReBe7]

This is more a matter of semantics, of course the amount of surface area where the distance is small enough to cause Van der Waals forces will determine the total amount of force. So these VdW forces do have to add up. On the other hand, one could interpret "not add up right" as some forces being repulsive and some attractive, which is definitely not true, all VdW forces are attractive. Btw, the layer of water also acts as a glue through VdW forces, it works through Keesom and Debye forces. The explanation given in this video actually concentrates on the most interesting of the 3 Van der Waals forces: the London dispersion force.

[@Bob_Burton]

Do the technicians know that you dropped the blocks ? They do now !

[@JustinDrentlaw]

That made me cringe so hard when he dropped it. Might as well throw them out and buy a new set now lol. I figure that's why they weren't sticking together too well; cause they've been really beaten up.

[@rockets4kids]

There is a reason they gave the theorist the set covered in rust. You remember how he said the machine shop had multiple sets, right?

[@lifeteen2]

Yup. I've got a high quality set, and they're super easy to wring together, and you could probably hang a 10kg weight from them, they stick so well

[@angrydragonslayer]

@@lifeteen2 i know a guy who owns an original johansson set from 1911 in pristine condition, he actually tested the force and they held a little under 120 kg when wrung together properly.

[@wich1]

@@rockets4kids yup, that is also the reason he’s having difficulty wringing them together, they aren’t all that precise anymore

[@justadamazing]

"Why don't you and I stick together?" Awwww

[@BrokenSofa]

Van Der Waal by Oasis

[@MephLeo]

Today is gonna be the day That they're gonna -throw it back- glue it all to you

[@Quintinohthree]

Broken soffa Someone needs to make this parody. @acapellascience perhaps?

[@iPelaaja1]

Lauri

[@AntiChangeling]

+Leopoldo Aranha But there's no glue... and there's none of that jiggery-pokery either.

[@TheDuckofDoom.]

Every block that drops to the floor I cringe, if the techs see this video they will never loan the professor another tool. Wear is a real concern for standards like these, regular calibration re-certification is needed and many owners actually pay triple the price just to get extra wear resistant ceramic blocks. Even the thermal expansion coefficients are specified by the manufacturers. Then again that may have been their apprentice-grade set.(even at that each block is still $20, higher grades or ceramic and your talking $100 each) (there are about five or six grades depending on the local standards organization, top one or two grades are for controlled environment lab calibration checks of other blocks and measurement devices; middle grades are for a company/shop in house reference; and the bottom two are intended for use out on the production line)

[@BT-uq3qw]

wolfedog99 Evidently Moriarty handles highly precise equations exactly the same as he handles the highly precise equipment. Garbage measurements for input equals garbage solutions for output. He doesn't get it though. He's too busy being impressed with himself.

[@cetyl2626]

wolfedog99 ya, seeing how rusty they were I think he got loaned the junk set, lol.

[@yaisetan]

I doubt he would be dropping them if they were brand new. They're probably old and already worn out

[@meepk633]

You do get it, though. You seem to be fun.

[@00bean00]

+a name a name You sound like you have a problem within yourself

[@BKITU]

Brady Haran: King of "that's a great question!"

[@0dWHOHWb0]

AvE where you at?

[@_winter7745]

0dWHOHWb0 Skookum as frig

[@Samboy_Chips]

Uncle bumblefuck left us at a wee cliff hanger.

[@drapakdave]

Oh come on AvE! He's even wearing a Rush t shart! That makes him an honourary citizen of Canuckistan!

[@SECONDQUEST]

0dWHOHWb0 email him on the gargler

[@arduinoversusevil2025]

I haven't had a chance to watch yet.

[@tubester4567]

If they were my gauge blocks I would be mad at you for dropping them on the floor.

[@OrionFyre]

If they were YOUR gauge blocks, YOU would be the moron for loaning them out to anyone but your doppelganger.

[@JustinDrentlaw]

Yeah, that was super cringey. If I had dropped the gauge blocks at my old job, they probably would have fired me lol.

[@PlasmaHH]

In the last "why do they have to be so smooth" part, I think the piece missing is that otherwise there would just not be enough electrons near to each other because all the surface scratches will lead to only a surprisingly low amount of points where the distance is really small.

[@sjwsbetaskiller6218]

They have to be FLAT. Smoothness is a side effect of lapping them FLAT.

[@ThunderBassistJay]

I really dig the Rush shirt! Thumbs up for the professor!

[@leonardopinhel1219]

@Steve Mould Actually it is quite know why gauge blocks lock on each other. The perfection of the surface is to amazing that the iron atoms from both surface exchange electrons. Well, they always do on each contact, but with the gauges the amount of atoms doing that interaction is astronomical. The resulting adhesion is strong enough to hold its own weight and far more. If you let them REALLY degreased and let it rest for a while, some weeks, once you break the connection you rip out atoms and you kay even damage the surface to a point where no adhesion more is achieved and in worst scenario the precision of the gauge is compromised (I worked with 1 micron gauges in a laboratory long ago, 1,000mm; 1,001mm; 1,002mm.... amazing stuff). In high graded blocks ( metrological calibration ones for instance) even a few days. If you let them for really long time (this one I never did) they begin to exchange atoms and get fused. This is based on the atomic diffusion law, that can predict how long it will take, I do not remember more that deeply this stuff. But it is in the structure of steel, Iron atoms do exchange atoms in a soup of electrons. THAT is the may reason metals are conductors... So hope to have solved the microscopic enigma :o)

[@NomadUniverse]

I've used gauge blocks many times in my career. The act of joining them together is called "wringing" them together. And you do indeed twist them to ring them. It is the best way to push the air out from between them. A very well wrung pair of blocks can be very difficult to get apart. The higher grade ones they use in places like national standards metrology laboratories wring together even better.

[@sjwsbetaskiller6218]

Wringing.

[@mastershooter64]

Wringing.

[@zman97211]

OMG You were dropping STANDARDS on the FLOOR?!?

[@JustinDrentlaw]

Yeah, that made me cringe lol.

[@ChristiaanCorthals]

I experienced this on "air bearings", used for a linear motor system. They are so smooth that you can always demonstrate these forces

[@ralphxu2422]

Like it every time when it fails to stick together he goes "oh f..." hahaha!!!

[@generalralph6291]

A new set of gauge blocks will stick together with the force of a thousand suns.

[@0xyzabcx0]

Cody's Lab has a great video on this.

[@_inabox]

He was testing this but he didn't know why it happens

[@c.james1]

I haven't checked his channel in a little while, but wasn't it Cold Welding he was doing? Not this? It is a similar in the sense that no heat is needed but the reasons they bond are different. But I haven't checked his channel so he may have...

[@FlyingJetpack1]

He did that with gauge blocks as well Chirs, testing in a vacuum chamber if dropping them on each-other would produce the same effect.

[@mickenoss]

Ye, he even went as far as putting them in a vacuum.

[@therealstubot]

Its fun to watch guys first attempt at wringing gauge blocks together. So in my experience, the best way to consistently wring blocks together is to clean them with acetone, then swipe the contact edge along your inside wrist. Then you position them 90 degrees apart and twist them together. Also I've seen it spelled Gage as well as Gauge and I'm not sure. Gauge blocks and a surface plate are the standards in a metrology lab. Also time to recertify those blocks. It looked like they had some rust on them, which destroys their ability to wring as well as their accuracy. Steel blocks should be stored with a coating of light oil. Not sure about ceramic block care.

[@Jellooze]

Whats the point with the acetone if you are gonna rub your skin oil all over the surface anyway?

[@therealstubot]

To get the last guys skin oil off! Well gauge blocks have to be coated with light oil when stored, so the acetone gets that protective coating off. Just to be clear, you can wring gauge blocks together without wiping them on your wrists, it just takes longer. Maybe the wrist wipe pre-charges the blocks... I don't know why it works so well, but I know it does work. Gauge blocks won't wring if there's any kind of oil, dirt, dust... so trying to wring the blocks with the protective oil will result in frustration, and inaccurate measurements.

[@sjwsbetaskiller6218]

They've chosen the low grade ("workshop grade" not laboratory) blocks, rusted and worn out. That's why there is a problem with wringing...

[@xenonram]

SJWs & Betas Killer Even low grade gauge block wring together perfectly fine. The issue was that he's never done it before that day, and they were corroded. And since they were corroded, they were probably not treated well, and may have deep scratches, dings, dents, etc.

[@davidflack6430]

Never run on your skin as your sweat can be acidic and cause corrosion. Use wringing fluid.

[@fahadshafiq7141]

Please have some of Ed Copeland too sometime soon.

[@victos-vertex]

This, so much THIS! I loved Ed Copeland and would like to see him again!

[@papinkelman7695]

Also This

[@Nahvi_PoE2]

Seconded. Love Ed!

[@kirkhamandy]

He dropped a gauge block. Better not let the shop guys down stairs see this video.

[@RobB_VK6ES]

Judging by the reluctance of the blocks to wring together I suspect the machine shop people gave them a worn out shop floor grade set to play with.

[@TheMohawkNinja]

I do believe this works with HDD platters as well. I've noted a similar attractive force when playing around with two of them, and given that they have to be so smooth for operation, I can see this being the case.

[@Binyamin.Tsadik]

smooth means there is more contact surface area that is close enough. Rough surfaces have surfaces that are further away and a few that are close.

[@sjwsbetaskiller6218]

First of all FLAT is what you need. "Shine" is a side effect of lapping blocks flat.

[@RinSenna]

I can tell you, working in metrology, our steel XX grade blocks ring together really well, our tungsten carbide blocks will not ring together at all, or will very weakly. Not sure why that is.

[@AdrianMulligan]

Tungsten is brittle, maybe it is less inclined to be as smooth as steel when polished up...just a guess

[@RinSenna]

The tungsten carbide blocks are polished to a mirror finish for one, and the silicon wafers in this video are also very brittle. Still a mystery.

[@Garganzuul]

Have you been able to measure accumulative error with steel vs. tungsten carbide?

[@meepk633]

It might be because steel is body centered, and tungsten is face centered. Like it might affect where the electronegatives overlap.

[@sjwsbetaskiller6218]

Maybe they're worn out (more than steel ones)?

[@francoislacombe9071]

Van der Waals forces are what let geckos walk on walls and ceilings. Their feet have pads that greatly increase the area of contact with surfaces, maximizing the Van der Waals forces they produce.

[@EebstertheGreat]

If you press together two truly ideal smooth surfaces of the same pure substance in a vacuum, they will simply fuse. Forget about van der waals forces, they will bond on contact in a process called cold welding. As Feynman put it, the atoms in contact at the surface don't "know" they are on different blocks; it is just a continuous lattice of atoms from one block to the next.

[@LReBe7]

I actually have experience with this from my PhD research, this also works for glass slides, just a little cleaning with ethanol is enough.

[@thesphericalguy9018]

More on this please! Very cool.

[@gregt4202]

Dropped?!!! You owe your machinist a new set of Josephson Blocks.

[@MrVenat0r]

Can remember when I was 16 and starting my apprenticeship being shown these and it was like magic.

[@RT710.]

Prof. Moriarty always with the best rock n roll t-shirts

[@ToastyRoland]

I would be pissed if someone dropped any of my gauge blocks. Cheers SS!

[@joeblogs8589]

At that point they've immediately purchased a set of "only dropped once" gage blocks and I'll have a brand new set. Yes, "gage' , cause 'merican.

[@briankosteriva3489]

The effect is really pronounced when the blocks are new. Even fingerprints on the blocks will reduce the effect.

[@RwP223]

We used standard rectangular and cylindrical jo block sets in one tooling position for years, we'd wipe the wd40 off used to preserve them with a clean rag and then to make them stick you would rub both sides with your fingers to get your oils on it (even after brake cleaner), then you push them together making an X, and while pushing you twist to align them. Fingerprints work Brian.

[@wormhole331]

Oil helps them stick with surface tension.

[@Meg_A_Byte]

I finally know! Great to see that. I managed to notice this with two very smooth Tourmalines.

[@Jellooze]

Always thought it was some tiny tiny pit of cold welding that made them stick, with surfaces so smooth, "pushing" out the atmosphere between the steel is semi possible causing the stickyness, guess i was wrong but wow you learn new cool stuff everyday :D

[@MadScientist512]

If you want to try this you can do it with hardrive platters, they're also precision machined.

[@brochan11]

Johnny Ball showed me this phenomena on his tv show back in the '70's. It's nice to know now what the physics is to explain it.

[@Athe1stSc1ence]

My understanding is that it is primarily 'stiction' that does this to gauge blocks? Despite the finish of the block they will both have peaks on the surface and the flatter the average surface is the higher the probability of numerous peaks nano-welding to each other under the force and friction of rubbing them together?

[@stargazer7644]

Stiction doesn't apply when you pull them apart.

[@ProgressiveEconomicsSupporter]

That is a known, undesired effect of metals clean of oxide layer. A problem in space technology, were contacting metall surfaces stick together. There just metall layers fuse coldly together, as if molten

[@jefflucas_life]

No wonder I can not shuffling a deck of cards because the law of van der waals forces.

[@hoarp001]

In the machine shop, we call it 'wringing, its a pretty common word, people talk about wringing two slips together all the time'. And usually we call them slips, rather than gauge blocks. Someone probably already said this...!!

[@davidflack6430]

No one calls them slips any more!

[@stanrogers5613]

That's likely because a "slip" is also a type of sharpening/honing stone meant for concave surfaces, and that name was around for a few centuries before gauge blocks were invented - it avoids confusion. Gauge blocks or "Jo blocks" in the US (for Carl Edvard Johansson, their inventor) are the common shop terms.

[@haydenrogers3486]

So is it basically based on the position of the electrons, a tiny magnetic force on the atomic level?

[@Garganzuul]

Maybe. It could be the Casimir effect too. Odd that this guy didn't mention it.

[@alastairbateman6365]

I always understood that gauge blocks held together due to air pressure as per a collapsing can when the air inside is removed so I am not convinced by your argument. To convince me you need to show that they do indeed still stick together in a vacuum and that the force to separate them is the same in both cases.

[@sjwsbetaskiller6218]

Go and check it yourself.

[@alastairbateman6365]

Whilst I do have a small vacuum bell jar, a water jet pump and ALSO some gauge blocks, they are not suited to carry out the check or I would. Having raised an alternative and I believe widely accepted proposition for the adhesion of the blocks the ball is as far as I'm concerned in Sixty Symbols court to do another video proving me wrong and them right! Not much to ask of a university physics dept. is it?

[@Holobrine]

So I suppose the mono-layer of water on a sufficiently smooth surface can fill in the gaps enough to make the surface almost perfectly flat. Is that right?

[@sjwsbetaskiller6218]

Tiny layer acts as glue and helps flat surface to be more smooth.

[@dansv1]

People who use gage (acceptable alternate spelling) blocks, refer to "wringing" blocks together.

[@MrMartinBigger]

althought van der walls may be the most significant force, isnt there also a suction effect? Since the surfaces are soo smooth there is very little air between it ( and very little area for new air to enter) since they are such stiff objects that when trying to pull them apart it creates a vacuum in the middle of the 2 surfaces.

[@rogerfroud300]

We were told to never leave them stuck together because they would ultimately bond together in places and the surface would be damaged in breaking them apart. Maybe this is really just a precaution against corrosion since it sounds like there's no exchange of electrons going on. I suppose this could be proved by leaving them together for an extended period in a vacuum. the same advice was given about the anvils of a micrometer.

[@davidwilkie9551]

There's a demonstration using Chinese Rubbing Bowls of standing waves, (equivalent to thermal excitation), and it goes with the ejection/evaporation of molecules from the surface tension boundary of a substance (and solids), so the interaction of fields of Van Der Waals forces seems to fit the story. Interesting.

[@Locut0s]

Have you covered a similar sounding topic. Cold welding in space?

[@JayantKumarZ]

does this kind of attraction work even in vacuum chamber? If yes it is the vanderwaal forces. If not it is the air. I am not sure but I have a feeling it is the air pressure that is keeping them together. Like when you glaze them on each other you remove most of the boundary layer and accidentally put some microbumps on the first layer into the microvalleys of the other. So their mating makes a low pressure zone as there's far lesser air molecules between them this means the outside air will keep thek stuck and if we put these things in vaccuum that effect will disappear. If it is indeed vanderwaal thats's the dominating force then vacuum wony affect it so this can be used to distinguish between the two proposed solutions

[@AndreaCalaon73]

At 1 atm pressure if you prevent air from getting in between two surfaces you have slightly more than 1Kg normal force per square cm, which is more than enough for some nice tricks. If you work with precision mechanics you know that very flat and smooth sufficiently large matching surfaces can cause dangerous sudden detachments...

[@stargazer7644]

And yet they still wring together in a vacuum.

[@psychogat3]

will two smooth surfaces made of different materials stick together like this?

[@sjwsbetaskiller6218]

Yes. But you need really flat (gauge block level) surfaces.

[@alexb5275]

Matt indeed. You can do this with a ceramic and a steel block

[@joeblogs8589]

Yes. Buy a brand new aluminium pan with a machined bottom and put it on your ceramic halogen/induction hob. You'll feel the attraction.

[@AwakenConsc]

Question for the scientists: Is gravity actually a long range version of the Wan Der Walls forces with objects that are much more massive than small molecules? or in other words: Is the Wan Der Walls force actually just a short range version of gravity with small molecules? Note: sorry if this question makes you roll your eyes. Please try very hard not to hate on me for asking this.

[@TheLeiZurc]

Despertai Consciências Van de Waals force is electric (or electromagnetic) in nature. Gravity is, well, gravitational. Very different mechanisms. :)

[@AwakenConsc]

@TheLeiZurc Light is also electromagnetic in nature and the mechanisms of gravity interact very closely with what light does. For example, gravitational lensing. It would be kind of nice to discover where electromagnetism and gravity stem from as it would be useful, I think, for a theory of everything.

[@Quintinohthree]

Despertai Consciências No. The gravitational force is very much distinct from the Van der Waals force. The Van der Waals force may be calcuclated to larger at small separations yet smaller at large separations than the gravitational force between the same objects. The medium between the objects is also relevant to the Van der Waals force, whereas it's irrelevant to gravity. To gravity it doesn't matter whether two silica spheres are in water or in air but to the Van der Waals force it can be the difference between attraction and repulsion, besides as much as an order of magnitude difference in the magnitude of the force. There are more evident differences but I think these two should suffice. ADDENDUM: Evidence of the former example is the earth's own gravity. A near constant 9.8 N/kg over several hundred km from the surface well into space. If guage blocks were held together by gravity alone, a pair of them would have to produce at least 9.8 N/kg to overcome earth's gravity yet to not be attracted over longer distances that gravitational field would have to go to 0 in less than a milimeter when Earth's gravitational field requires hundreds of kilometers to even make a dent in the number.

[@AwakenConsc]

Thanks, that's a greatly informative response :)

[@ag135i]

Very well explained, thanks.

[@picobyte]

@sixty Harddrive platters also work very well.Never tried removing the magnetic layer but the degauser should make it nonmagnetic as those gauge blocks.

[@lasse1705]

I was taught that these forces are called London dispersion forces. When atoms are attracted to each other without there being a permanent dipole. Further, I was taught that the van Der Waal's forces also include dipole-dipole attraction from permanent dipoles. This was taught to me in IB chemistry, higher level and that quite recently as I graduated the IB earlier this year. I don't mean to say that he is wrong, As he is correct, but I think it would be more accurate to call it London dispersion forces, which are a sub-category of van Der Waal's forces.

[@Hans-jc1ju]

Really like the new style!

[@edgeeffect]

Smooth?... I just watched a Breaking Taps video of a gauge block under an AFM... they're full of gouges and furrows at nanometer scale. :) I love it when Phil nearly says "f...".

[@MarcusFuchsDD]

I thought the surface has to be so smooth, because otherwise the distance between a major part of the two surfaces - and therefore between the electrons - would to big for this relatively weak interaction which decreases over distance quickly.

[@sjwsbetaskiller6218]

FLAT, not necessarily "smooth" (shine is a side effect of making blocks flat).

[@trespire]

Academia meets blue collar shop floor workers ! Thank you scientist for enlightening us machinist & the mechanically inclined. Fascinating !

[@MonkyPuzel]

Are these specific type of van der waals forces (temporary dipole interactions) not usually called London Dispersion Forces?

[@mikolajwojnicki2169]

I have heard that very clean metals under high pressure can actually stick together using metalic bonding, which can be a big problem for space probes and such. Can anyone confirm?

[@wich1]

Yes, that is cold welding, which is a similar but slightly different process to the wringing together of materials shown and explained in this video

[@steelwarrior105]

You can do that to join pieces of wood, it does require glue because you are joining but you can stick them without

[@alexanderfederowicz]

in short the like charges repel, and the unlike attract, so "Extropic" Charge alignment between opposite charges predominates over time organization occurs over time along the surface.

[@borg286]

Great animations. They fit the feel Phis has.

[@keithglaysher737]

Prof, thanks for that you are a genius! been looking for the reason & you found it in a way I understand it. Cheers Prof.

[@ashkara8652]

Well this is A Level Physics. Finally something I was familiar with beforehand on this channel. At first I thought it was cold welding, but I was wrong apparently.

[@Eastcoast_Rds]

You guys are the best! I was wondering it you could make a video about Maxwell’s demon and the relationship between information and entropy, thank you !!!!

[@leestuurmans2837]

Super fun edit Mr. Haran!

[@pmcpartlan]

Lee Stuurmans That's Dr Heron to you.

[@leestuurmans2837]

Haha, of course, my mistake.

[@slome815]

Just some tiny scratches will make them very hard to stick. With new blocks they stick like crazy. The surface rust on some blocks makes me think that he gave you the bad set, which is the normal thing too do. Cleaning them often with bad paper towels are sometimes enough too make microscopic scratches. Gauge blocks are one of the things that you just don't want to let other people use. Micrometers are another thing that are always returned in bad shaped when one of my collegues borrows them.

[@1TakoyakiStore]

I wonder if this effect happens with glass since one of the molecular definitions of glass is being an amorphous solid, i.e. it's atomic structure has local order but no long-range order is present?

[@juanbautistape]

I would eb}njoy drinking a grand beer with prof and talking about rush and science

[@ashboon1625]

I would like to mention that this is how cold welding works, for engineers out there.

[@fakjbf3129]

Fridge magnets work on the same principle of an overall neutral object using areas of positive and negative magnetic fields to stick to things (though on a massively blown up scale). Fridge magnets have alternating strips of positive and negative facing magnets within them, and held more than an inch or so away the overlapping magnetic fields cancel each other out and no force is felt. But when it get's close enough to a piece of metal the fields aren't overlapping, so the positive facing magnets induce a slight negative field in the metal and vice versa for the negative magnets. Each strip is now held in place, so the entire magnet stays put.

[@ehypersonic]

2:26 Gravity send their regards

[@astron2light]

How to know that it is Van der Waals force or different air pressure? When two glasses of water stack together and can not pull apart, what is the reason behind it?

[@DadSkool]

I made a video about the cabinet makers air gap which i think is the opposite of this phenomenon. Id like to know what other people think. Are these 2 things related?

[@janew2108]

Now this is a great video.

[@Dug6666666]

Wait till the machinist sees this video and how nonchalantly you where handling their precision instruments.

[@sjwsbetaskiller6218]

They gave him the worst (worn out) set, look closely. They knew, he will screw up.

[@WildBillCox13]

Fascinating stuff. Thanks for posting.

[@Merto6]

I dont think the surfaces must be absolutely flat. They just have to fit perfectly so the atoms are as close as possible.

[@Quintinohthree]

Merto6 For Van der Waals bonding you could use surfaces with macroscopic roughness provided they conform well with eachother. However microscopically they have to be exceediingly smooth because any roughness will result in greater separation between the base surfaces. The attraction between approximately spherical irregularities and the surface they touch is pretty much negligible to surface to surface attraction. As the force drops off with the square of the separation (if what applies to sphere-sphere contacts also applies to surface-sphere contacts) A small increase in roughness results in a large decrease in attraction.

[@sjwsbetaskiller6218]

Yes, but it is fairly more practical to make very flat surface, than two custom curves that fit together that accurately as flat ones. So, if you want "wringing" effect, your only practical option is going flat!

[@dhavalbhalara1664]

Will extremely smooth two different materials will stick together?

[@joshcanttakeajoke2853]

I've always wondered how its possible to wring gauge blocks together.

[@mattlewis9364]

Perfectly clean blocks dont wring the best, we always give em a swipe on the wrist so they have a bit of something to actually seal the surfaces.

Is this effect similar to the effect happening during cold welding?

[@wich1]

As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.

[@xtieburn]

Could cold welding be involved with this as well, it seems like the conditions (maximum contact, removing the oxide layer, scraping of the metal together.) for getting it to stick would also apply to cold welding. Though Id then wonder if that would do notably different damage to the surfaces if viewed through a powerful enough microscope.

[@wich1]

As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.

[@trejkaz]

Which is interesting, because up at the macro level, we deliberately make surfaces _rougher_ to make things like glue and paint stick better.

[@Quintinohthree]

trejkaz Paint and glue are not hard surfaces though.

[@trejkaz]

Oh my, I had no idea that paint and glue were not hard. Thanks for pointing out a totally not obvious fact!

[@Psnym]

Nice T-Shirt, Professor!

[@drumnstuff]

Denis Goddard I'm Canadian and I approve this message.

[@tropezando]

I was just going to say the same thing!

[@richardhudson4649]

The Camera Eye caught it!

[@MattH-wg7ou]

I thought it was possibly the Casimir effect. Super interesting!

[@stevendv8487]

then when do you have cold welding?

[@Quintinohthree]

Steven dv Cold welding happens only between oxide-free metal surfaces. Gold in air would do but any metal can do it, provided it's made completely oxide-free at its contact. Cold welding happens when the surfaces physically touch without any gap, the lattices interweave and two objects become one.

[@swapnilmittal8675]

You didn't explain why we need to forcefully slide/rotate the gauge blocks

[@sjwsbetaskiller6218]

To push atoms closer together (regardless of very high level of flatness), and scrape off last tiny bits of dirt. That's general rule in mechanical metrology (try to always slide things together, not just put one on the top of another and expect precise, consistent results, readings).

[@dynamicgecko1213]

Is this what's called "Cold Welding" or are they separate things?

[@explosu]

What did you use for that crumbly sort of bass rumble at 4:20? Was wearing headphones and I thought it was something outside. Could use something like that for my music =3

[@SG1guru]

Does cold welding (in vacuum) operate on the same effect?

[@wich1]

As far as I know they are similar, but not the same. In wringing, also called optical contact bonding, the two bodies are extremely close, but are still separate. All that is keeping them together are the intermolecular forces like the van der waals forces as explained, (disregarding the water effect.) In cold welding greater pressure is applied to force the bodies closer together, so much so that the atomic lattices of the two materials can become one with one another, e.g. in metals usually creating chemical bonds, sharing electrons between neighboring atoms.

[@totodoro]

so, this has nothing to do with cold welding at all?

[@sjwsbetaskiller6218]

Not "at all". Little bit.

[@marksummerfield357]

I've had this happen to me and thought it was a thin layer of oil or something. Now I know. Cool vid

[@MathAndComputers]

How has the drum beat analysis been going, Prof. Moriarty? Any promising results? :)

[@Yupppi]

I watched Cody's Lab try fix the gauge blocks together under vacuum but he never managed to make it work for some reason. Perhaps the fact that he couldn't handle them like you normally could because they were in the tank.

[@Pierrot110194]

If Van der Waals forces are responsible for the formation of a solid and they are nothing but forces which result from a momentary change in dipole moment, how come all crystals have a definite solid structure? Wouldn't the atoms change their relative position to each other all the time, kind of like we imagine a liquid? There obviously is way more to the story and I would love to hear the rest!

[@davidwilkie9551]

Chinese rubbing bowls that are used to demonstrate standing wave effects, are also the indicator of the way water molecules are ejected through the meniscus/surface in evaporation. And observably, it's all about resonance/interference and Quantum Operator Fields Modulation Mechanism of probabilities in potential possibilities for QM-TIMESPACE. Eg Vacuum welding is apparently the norm in orbital technology where crystal bonding is particularly well ordered and monocrystalline, making materials formed there super strong, or so we're told, chip tech is Commercial in Confidence?