Do Atoms Ever Touch?

Professor Philip Moriarty expresses his displeasure with oft-repeated belief that atoms do not physically touch each other.

This project features scientists from The University of Nottingham

Sixty Symbols videos by Brady Haran

----

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.

[Bnio]

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

[fen]

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

[Mrgiveupufail]

'when common sense meets quantum physics'

[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.

[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.

[ahadicow]

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

[bertlowry]

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

[twobyfour]

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

[Cheesepuff]

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

[pairot]

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

[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.

[mcrut]

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. 

[WeeWeeJumbo]

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

[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.

[piccalillipit]

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

[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.

[DANGJOS]

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

[tomasdelatoba]

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

[thishandleistaken]

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

[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.