Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jeffreyH on 16/02/2019 07:27:49

Title: What field gives rise to the Van Der Waals forces?
Post by: jeffreyH on 16/02/2019 07:27:49

Since forces can be associated with fields I am wondering what this one is.

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: evan_au on 16/02/2019 10:31:11

I understand that Van der Waals forces are due to the electromagnetic field.

There can be quantum fluctuations in the strength of the electromagnetic field around atoms, which induces changes in the fields of nearby atoms, producing a slight attraction.

The Van der Waals force is much weaker than the repulsion between electrons which prevents atoms from passing through each other.

See: https://en.wikipedia.org/wiki/Van_der_Waals_force

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: jeffreyH on 16/02/2019 14:28:57

On the Wikipedia page it states "The van der Waals force has the same origin as the Casimir effect, arising from quantum interactions with the zero-point field." I am not sure how this would relate to the electromagnetic field.

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: jeffreyH on 16/02/2019 14:36:00

Apart from the following on the Wikipedia page on the Casimir effect.
"The Casimir effect can be understood by the idea that the presence of conducting metals and dielectrics alters the vacuum expectation value of the energy of the second quantized electromagnetic field. Since the value of this energy depends on the shapes and positions of the conductors and dielectrics, the Casimir effect manifests itself as a force between such objects."
https://en.m.wikipedia.org/wiki/Casimir_effect
So what is the second quantised electromagnetic field?

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: jeffreyH on 16/02/2019 14:41:41

Is this simply a description of quantum fluctuations in the field? See here https://en.m.wikipedia.org/wiki/Quantization_of_the_electromagnetic_field under second quantisation.

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: yor_on on 16/02/2019 15:14:04

It's a wave definition in where you find a 'imbalance' of 'forces'.  Those create a 'suction' between the plates. 'Zero point 'energy' * And no, it's not the same as negative energy, because that one is.locked to gravity

Title: Re: What field gives rise to the Van Der Waals forces?
Post by: PmbPhy on 17/02/2019 18:41:09

Quote from: jeffreyH on 16/02/2019 07:27:49

Since forces can be associated with fields I am wondering what this one is.

The electric field. Is caused by both intermolecular attraction and electron cloud repulsion. Best to look it up in a chemistry text for a solid description.