Can we really touch anything?

[StringJunky]

Sometimes, things are over-analysed...

[swansont]

I think an underlying issue here is that "touch" is a classical, macroscopic concept. At the quantum level one might replace that with "interact".

[Buket]

I think an underlying issue here is that "touch" is a classical, macroscopic concept. At the quantum level one might replace that with "interact".

I agree. And what happens during interaction specifically?

[Strange]

I agree. And what happens during interaction specifically?

 

I was about to say: the electromagnetic fields of the atoms repel each other. But it is more complicated / interesting than that, because these interactions are also what hold atoms together in molecules.

[swansont]

I agree. And what happens during interaction specifically?

 

 

The answer depends on the level of detail you want. The model says that the electromagnetic interaction is an exchange of virtual photons. At the atomic level this repulsion is an exchange interaction from the Pauli exclusion principle, and is the repulsive, r^-12 part of the Lennard-Jones potential https://en.wikipedia.org/wiki/Lennard-Jones_potential

[Buket]

 

Here is a discussion about the topic.

[studiot]

Apart from being rude enough so as not to respond to my comments,

 

What was your point in posting the video in post#31?

[Buket]

Apart from being rude enough so as not to respond to my comments,

 

What was your point in posting the video in post#31?

Oh, I am so sorry.. You had asked a question about me studying this at which level. I don't study it. I am just a curious person..

 

And I posted this video since the guy tells there exist a contact between objects indeed..

[studiot]

Oh, I am so sorry.. You had asked a question about me studying this at which level. I don't study it. I am just a curious person..

 

And I posted this video since the guy tells there exist a contact between objects indeed..

 

Thank you for answering my question.

 

That helps to get what we say at the right level.

 

And yes the person in the video said pretty much what we have been telling you here, although he did not mention the Lennard -Jones force by name, he talked about it.

[Buket]

 

Thank you for answering my question.

 

That helps to get what we say at the right level.

 

And yes the person in the video said pretty much what we have been telling you here, although he did not mention the Lennard -Jones force by name, he talked about it.

Thank you 😄

If what the person in the video (Prof. Moriarty) says is correct then why there are so many people saying that we can not really touch objects? I wonder why..

[Buket]

When the wave function of atoms overlap does the touching process occur?

[swansont]

When the wave function of atoms overlap does the touching process occur?

You can't answer this question. There is no classical "touching" at the quantum level. The concept has no meaning.

[Buket]

You can't answer this question. There is no classical "touching" at the quantum level. The concept has no meaning.

 

Then is there a classical touching in the macro level?

[MigL]

The real question seems to be 'is there anything that can be considered solid at the quantum level ?'.

And the answer would have to be NO.

 

Even elementary particles 'smear' out at the energies needed to approach zero separation.

[swansont]

Then is there a classical touching in the macro level?

Sure. Whenever you stub your toe, or bump into something, or pick something up, that's what we consider touching, classically speaking.

[Buket]

Sure. Whenever you stub your toe, or bump into something, or pick something up, that's what we consider touching, classically speaking.

Then why it is said that we can not touch anything? Is it about the quantum level, like nuclei of atoms never touch but lets say electron clouds contact eachother? Confused..

[swansont]

Then why it is said that we can not touch anything? Is it about the quantum level, like nuclei of atoms never touch but lets say electron clouds contact eachother? Confused..

 

 

Yes. Several classical concepts cease to apply at the quantum level. It's a bit of a carnival trick, really, to phrase a question in classical terms and then cite quantum mechanics in the answer.

[Buket]

Can anyone tell me what the professor exactly say in the video I posted?

[Buket]

You can't answer this question. There is no classical "touching" at the quantum level. The concept has no meaning.

During the interaction of the wavefunction does the touching process (as called in the macro level) occur? Or can we say the contact between two objects occur when 2 forces are in balance?

[swansont]

During the interaction of the wavefunction does the touching process (as called in the macro level) occur? Or can we say the contact between two objects occur when 2 forces are in balance?

 

 

You can't say that because of Newton's 3rd law. Action-reaction force pairs are always in balance.

 

You also shouldn't mention "touching" and "wave function" together, for reasons already discussed: one concept is quantum, the other one is classical.

[Delta1212]

Macroscopic "touching" is the behavior that you get from an aggregate of quantum level interactions, as with pretty much all macroscopic behavior.

 

Imagine a net. You can talk about different properties of the net, and how that net interacts with other objects. Depending on the size of the holes in the net, it will catch some things and let other things pass through. Now take a single string. A single string won't interact with objects in the same way as the net. The net's overall behavior is derived from how that string interacts with those objects as well as with the other strings in the net, but they aren't the same.

 

When you get to talking about individual particles, you're no longer talking about quite the same behaviors as you are when speaking about how the large quantity of particles that comprise macroscopic objects interact.

[Buket]

Macroscopic "touching" is the behavior that you get from an aggregate of quantum level interactions, as with pretty much all macroscopic behavior.

 

Imagine a net. You can talk about different properties of the net, and how that net interacts with other objects. Depending on the size of the holes in the net, it will catch some things and let other things pass through. Now take a single string. A single string won't interact with objects in the same way as the net. The net's overall behavior is derived from how that string interacts with those objects as well as with the other strings in the net, but they aren't the same.

 

When you get to talking about individual particles, you're no longer talking about quite the same behaviors as you are when speaking about how the large quantity of particles that comprise macroscopic objects interact.

So you mean the large quantity of particles can contact with the other object's large quantity of particles?

[Buket]

Do you agree with Moriarty's explanation?

 

https://m.youtube.com/watch?v=P0TNJrTlbBQ

[Buket]

I think what Moriarty says about touching is pretty logical..have any ideas?

[geordief]

He explains what is going on. It doesn't matter what words are used to describe it so long as they are understandable and he is describing the same thing as you are trying to understand.

 

It is good to be clear with language but sometimes it doesn't matter so long as you understand what is happening.

 

Words are also tools.

Edited October 25, 2016 by geordief