Touching objects

[Saber]

When  two  objects  touch..............   Do  their......toms  and  molecules..........collide ???  @ the   point  of   their  contact ? and  some of them   are exchanged  between the two  objects ?

Or  no the   force  field  around the atoms   dont  let  them  to  even  get  near  each  other ?     *  near   in the atomic  scale 

Edited February 1, 2023 by Saber

[Genady]

Atoms are almost empty. Their nuclei are many degrees of magnitude smaller than atoms and electrons are points with no size. If there were no other forces, atoms would just go through each other. What stops them from passing each other is their electromagnetic fields and a quantum effect called Pauli exclusion principle.

[Saber]

So   does that  mean really  nothing  touches  anything  else  in the world ?  only  approaches  its  limit ?

[studiot]

7 minutes ago, Saber said:

So   does that  mean really  nothing  touches  anything  else  in the world ?  only  approaches  its  limit ?

 

The original theory of touching was put forwrda by Lennard-Jones.

Here is a simple version

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/Atomic_and_Molecular_Properties/Intermolecular_Forces/Specific_Interactions/Lennard-Jones_Potential

 

Wikipedia has a more detailed version with more famous names from the past.

 

https://en.wikipedia.org/wiki/Lennard-Jones_potential

[Eise]

Or Ethan Siegels blog, 'Starts with a bang'.

[Genady]

19 minutes ago, Saber said:

does that  mean really  nothing  touches  anything  else  in the world ?

Yes. There are no surface-to-surface touching points in atomic and subatomic scales.

 

11 minutes ago, studiot said:

only  approaches  its  limit ?

No, it's not a limit, but a distance where the system has smallest potential energy.

[studiot]

7 minutes ago, Eise said:

Or Ethan Siegels blog, 'Starts with a bang'.

Not so sure about this bit from your link. He later contradicts it anyway.

Quote

It might seem counterintuitive, but when you bring your thumb and forefinger close together, then have them touch, then push them together with greater and greater amounts of force, this is precisely what’s happening on an atomic/molecular level. However, there’s an extremely important caveat here: this only works, as far as “touching” goes, because the atoms within your thumb are bound to one another much more strongly and securely than they can be “touched” by the atoms in your forefinger. Similarly, the atoms in your forefinger are bound to one another — in molecules, cell membranes, etc. — more strongly than they get “touched” by your thumb.

 

This is the primary reason why, when you touch two typical objects together, they remain two independent objects, rather than either fusing or merging together. Solid objects, like your finger, have strong atomic bonds — covalent molecular bonds, where the electrons are shared between atoms — that are easy to remain intact and are difficult to destroy. When you push two separate objects together, each object is much more likely to hang onto their own electrons than they are to exchange electrons between them, or to form new covalent bonds from one side to the other.

 

2 minutes ago, Genady said:

19 minutes ago, studiot said:

only  approaches  its  limit ?

No, it's not a limit, but a distance where the system has smallest potential energy.

No me Guv, not guilty.

[Genady]

10 minutes ago, studiot said:

No me Guv, not guilty.

I did it again? Quoted from the wrong place...

I am sorry.

[Saber]

5 minutes ago, Genady said:

Yes. There are no surface-to-surface touching points in atomic and subatomic scales.

 

No, it's not a limit, but a distance where the system has smallest potential energy.

if  im  sitting on a chair   that  means that  im levitating  over it ?
If im holding a cup in my  hand  im  just holding it in he  air with the force of my hands  atoms ?

When im pulling or pushing  objects im  just  moving them with the force of my atoms  and  not even touching them ?

 

[Genady]

4 minutes ago, Saber said:

if  im  sitting on a chair   that  means that  im levitating  over it ?
If im holding a cup in my  hand  im  just holding it in he  air with the force of my hands  atoms ?

When im pulling or pushing  objects im  just  moving them with the force of my atoms  and  not even touching them ?

 

Yes.

[Lorentz Jr]

Atoms repel each other on contact because their electrons are subject to the Pauli exclusion principle (see stability of matter). Whether or not anything "touches" anything else depends on what the electron wave functions represent, and that's still a matter of speculation. One way or another, though, the repulsion is quantum-mechanical in nature (degeneracy pressure), and it occurs when the wave functions begin to overlap.

Edited February 1, 2023 by Lorentz Jr

[studiot]

1 hour ago, Saber said:

if  im  sitting on a chair   that  means that  im levitating  over it ?
If im holding a cup in my  hand  im  just holding it in he  air with the force of my hands  atoms ?

When im pulling or pushing  objects im  just  moving them with the force of my atoms  and  not even touching them ?

 

Sounds good to say to your mates down the cafe.

But don't overthink it.

In particular don't mix-n-match quantum theory and mechanical force theory.

Orbitals and Pauli theory do not lead to expressions of force,
They are energy theories.

[Saber]

Just now, studiot said:

Sounds good to say to your mates down the cafe.

But don't overthink it.

In particular don't mix-n-match quantum theory and mechanical force theory.

Orbitals and Pauli theory do not lead to expressions of force,
They are energy theories.

Does  that mean  that the  world  is  a  completely  different  one  in the  Quantum level ?

[exchemist]

1 hour ago, Saber said:

if  im  sitting on a chair   that  means that  im levitating  over it ?
If im holding a cup in my  hand  im  just holding it in he  air with the force of my hands  atoms ?

When im pulling or pushing  objects im  just  moving them with the force of my atoms  and  not even touching them ?

 

You just need to ask yourself what is meant by "touch". Subatomic so-called "particles" are not like little steel balls. When one says that two object touch, what we mean is that they are close enough for the atoms on their surfaces to repel one another strongly if they are pushed closer together. That is what "touching" means.    

[Lorentz Jr]

1 hour ago, Saber said:

if  im  sitting on a chair   that  means that  im levitating  over it ?

It all depends on what quantum wave functions represent. Ordinary atomic matter is permeated through-and-through by the wave functions of bound electrons, so whether or not the spaces around atomic nuclei are "empty" depends on what electrons "really" are.

Edited February 1, 2023 by Lorentz Jr

[studiot]

2 minutes ago, Saber said:

Does  that mean  that the  world  is  a  completely  different  one  in the  Quantum level ?

Yes and No or not really.

All our theories , including quantum theory, are models which only deal with some aspect or aspects of reality.

These are all fine within their respective realms of application.

Sometimes different models describe the same aspect. In this case we distinguish between when the different models yield the same answer and when they yield different answers.

Objective measurement and observation is the final arbiter.
When the predictions are the same it doesn't matter which we choose so we normally use the easiest, most convenient one.
But when the give different answers, clearly we must operate the  most accurate one.

[Genady]

13 minutes ago, Saber said:

Does  that mean  that the  world  is  a  completely  different  one  in the  Quantum level ?

Yes, in this sense:

13 minutes ago, exchemist said:

Subatomic so-called "particles" are not like little steel balls.

They are unlike anything that we usually visualize as a 'body'.

[Saber]

By the   way  this part

 

 

 

Made  me  think a lot  about  why  when two people are attracted to each other  @ a  certain  level  of sincerity.........i mean  if  those  two  get  closer   to  each  other....past  a certain  level and amount......things  start to  tense & the  situation  between them gets somehow  not that  much .......intimate ......you know what  i mean........

These two things  maybe  dont have anything to do  with  each  other  but i see some similarities  between  them..........iv  lost  many of my  close friends like that  and always  thought  about  it.........that when i get close to a person the attraction must be stopped or @ least regulated or it would ruin the friendship.....
 

[exchemist]

33 minutes ago, Genady said:

Yes, in this sense:

They are unlike anything that we usually visualize as a 'body'.

That's why I put particles in inverted commas. The whole idea of a particle is a rather ridiculous one, when you think about it: a notional ideal object, with no dimensions but nevertheless a host of other properties. 

Edited February 1, 2023 by exchemist

[Lorentz Jr]

22 minutes ago, exchemist said:

The whole idea of a particle is a rather ridiculous one, when you think about it: a notional ideal object, with no dimensions but nevertheless a host of other properties.

Thank you. +1

[Genady]

25 minutes ago, exchemist said:

That's why I put particles in inverted commas. The whole idea of a particle is a rather ridiculous one, when you think about it: a notional ideal object, with no dimensions but nevertheless a host of other properties. 

This reminded me of a Particle Physics course I took once. The professor had started with something like this: There are no particles; end of the class. +1

[joigus]

Very good explanations here, so there isn't much of significance that I can add here. Just another rephrasing of the same idea.

The whole concept of "touching" rests on the assumption that one thing is "here" and the other thing is "there," and that this assumption can be pushed to any scale we want. Quantum mechanics tells us that's an illusion. All the concepts involved must be reviewed: "Here"/"there", "one thing"/"the other thing", and "being".

It's as @Genady says,

1 hour ago, Genady said:

They are unlike anything that we usually visualize as a 'body'.

It's very radical.

[geordief]

6 minutes ago, joigus said:

Very good explanations here, so there isn't much of significance that I can add here. Just another rephrasing of the same idea.

The whole concept of "touching" rests on the assumption that one thing is "here" and the other thing is "there," and that this assumption can be pushed to any scale we want. Quantum mechanics tells us that's an illusion. All the concepts involved must be reviewed: "Here"/"there", "one thing"/"the other thing", and "being".

It's as @Genady says,

It's very radical.

Are all objects modeled as properties  of fields?

If so ,can we say they "touch" when they are entangled?

[joigus]

1 minute ago, geordief said:

Are all objects modeled as properties  of fields?

If so ,can we say they "touch" when they are entangled?

First, we should agree on what the basic "objects" are. Quantum field theory tells us that those are quantum fields. Quantum fields are kind of "instanciation machines" for their quanta. These quanta are discrete jumps in the fields that we recognise in 2 ways:

(1) Mathematically: they carry irreducible representations of the Poincaré group

(2) Experimentally: They show themselves as discrete excitations on experimental equipment consistent with the values of energy/momentum/angular momentum that the theory implies

The second one is more or less clear, I'd say. We never find "half an electron" hitting anywhere. The first one means that these fields factor out in terms that, in turn, cannot be further factored out into parts that mathematically represent translation, rotation, and motion at a speed.

[Genady]

1 hour ago, geordief said:

Are all objects modeled as properties  of fields?

If so ,can we say they "touch" when they are entangled?

I don't think @joigus has replied to the second question. I would reply, no. Because "touching" implies a spacetime relation while entanglement does not.