Is it true that you are never actually touching something?

[sokrates]

Hello,

I am not a physicist. I am an electronic engineer. I found out that people cannot actually touch anything from this link http://www.worsleyschool.net/science/files/touch/touch.html. There is just an electromagnetic repulsive force when we touch a subject. But I need more "scientific" paper to read about this topic. Did you any document explain this phenomenon?

Thanks
Suad

It depends on how you define "touching" at the molecular level.

So this is really a ridiculous question.

What's touching?

Nothing touches nothing in universe if you take the question from a daily; practical perspective.

 

[adba]

It depends on how you define "touching" at the molecular level.

So this is really a ridiculous question.

What's touching?

Nothing touches nothing in universe if you take the question from a daily; practical perspective.

There is no ridiculous question but there are ridiculous answers. Because the person who asks a question doesn't naturally know what it is.

Touching involves the contact meaning in my question. If you glance at the link which I wrote in the question text, you will see.

If an atom has a border which the outer electrons constitute (I am not sure that). When an everyday life touch (or contact) occurs, the atoms repel each others without exceeding the border of others.

If this case is true, I just need another a bit serious document about it.

 

[ZapperZ]

There is no ridiculous question but there are ridiculous answers. Because the person who asks a question doesn't naturally know what it is.

Touching involves the contact meaning in my question. If you glance at the link which I wrote in the question text, you will see.

If an atom has a border which the outer electrons constitute (I am not sure that). When an everyday life touch (or contact) occurs, the atoms repel each others without exceeding the border of others.

But this isn't that well-defined either. In many instances, one forms "bonds", and this can easily be beyond the "diameter" of the outer orbital. Now, do you consider this to be "touching"?

Things may look easy when viewed from a naive perspective. It isn't that trivial if you dig a little bit more into it. The fact that definite spatial boundary of something at the quantum level isn't something that can be clearly specified requires that anyone asking such a question makes a clear definition what these criteria such as "touch" mean.

Zz.

 

[Vanadium 50]

But this will end up being an argument about semantics, not science.

Did I call it or what?

 

[adba]

But this isn't that well-defined either. In many instances, one forms "bonds", and this can easily be beyond the "diameter" of the outer orbital. Now, do you consider this to be "touching"?

Things may look easy when viewed from a naive perspective. It isn't that trivial if you dig a little bit more into it. The fact that definite spatial boundary of something at the quantum level isn't something that can be clearly specified requires that anyone asking such a question makes a clear definition what these criteria such as "touch" mean.

Zz.

Ok. I understand (from a naive perspective) that I cannot get an answer because I could not explain "touch" meaning. Actually you are right I have to ask well-defined questions. I gave up.

Thanks

 

[adba]

I found it

I found the question. It is a good starting point for me. Because I have not been able to ask the right question up to now. so I could not get the answer. But now, I found it.

I am asking my question.

Assume two matters (matter A and matter B) have a distance between each other.

First Case: When the distance is one meter. The electrons of matter A repels the electrons of matter B and vice versa, even tough we cannot sense or measure this repellency.

Second Case: When the distance is so close as two matter contact each other (Let's say that matter A pushes matter B for any reason). The electrons of matter A repels the electrons of matter B and vice versa, we can sense and measure this repellency.

The question is this: Is there any difference between two "repellency" force except their quantities?

 

[A. Neumaier]

First Case: When the distance is one meter. The electrons of matter A repels the electrons of matter B and vice versa, even tough we cannot sense or measure this repellency.

Second Case: When the distance is so close as two matter contact each other (Let's say that matter A pushes matter B for any reason). The electrons of matter A repels the electrons of matter B and vice versa, we can sense and measure this repellency.

The question is this: Is there any difference between two "repellency" force except their quantities?

The residual force between electrons bound in two different atoms or molecules consists of two terms:
(i) the attractive van der Waals force, which decays with distance like 1/r^7, hence is immeasurable at the distance of 1m but noticeable as friction at close to contact distance. (It is attractive although the electrons carry the same negative charge since it also contains the effects of the positive charge of the nucleus.)
(ii) the repulsive (approximate hard core) force, which decays with distance like 1/r^11 (or so), hence is immeasurable already at distances just beyond contact but gets very strong at contact distance, and ensures that solid matter cannot penetrate other solid matter.
(The same holds for fluid matter - liquids and gas, but there the molecules are so weakly held together that the matter simply gives way to the contact motion.)

 

[zketrouble]

But there is also the fact that chemical bonds form between the two objects touching. If they are connected, how can one say they are not touching? And we're right back arguing about semantics.

Yes, it is highly semantic. However, it also depends on how you visualize an atomic bond. It's not quite like the molecular model kits you buy at the campus store, where a plastic stick connects and "touches" the two plastic atom models together. They are attracted to get close together, but never too close, as the protons in their nuclei repel each other. The electron doesn't touch the proton of its own atom nor of other atoms, and why this is the case is not quite understood (as far as I know anyway). We could get really semantic with the word "connected," in that they are connected but not touching, It's not like there's a rope tying the two together. They are simply atoms floating around surrounded by empty space, moving closer to but never touching other atoms, no matter how attracted they are (except perhaps at the CERN particle smasher or something).


So to draw a simple diagram answering the touchy* question:

||

Let the distance between those two lines equal say, a billionth of an inch (choosing a random but tiny distance here). Let that be the hypothetical closest distance ones hand can make it to, say, the keyboard I type on. How am I pressing the keys If I'm still that far away from them? Surely I would have to actually REACH the keys in order to press them, some may say. Theres another way of looking at it though. My hands are both on the keyboard now. As I push to move closer, the key moves away to enter sentences at my command.

How do I feel the keys, or any other object for that matter? Well, objects have different characteristics at the chemical level, such as temperature for instance. Energy from this the cup of coffee a billionth of an inch away from my hand is transferring heat to the atoms of my hand, which stimulate the nerves that tell me my hand is warm. With texture, some atoms may be a billionth of an inch away and others perhaps only a millionth of an inch, and our bodies pick up on these differences. Static electricity is also picked up by our senses.

Even when you push REALLY hard, say I squeeze my coffee cup to the point where it breaks and spills hot coffee all over me. Thats me getting closer and closer to the molecules making up the cup, with my hand losing a bit of strength from all the effort it takes to get closer, until the molecules in the cup finally put enough of their energy into repelling away from the molecules in my hand and the glass cracks and breaks away from my hand. Hot coffee spills all over my hand, and there's so much heat that the energy transfer excites the proteins in the dermis and epidermis of my skin to burn me.

Don't want to go too deep into it but that's the way I look at it.

 

[A. Neumaier]

Yes, it is highly semantic. However, it also depends on how you visualize an atomic bond. It's not quite like the molecular model kits you buy at the campus store, where a plastic stick connects and "touches" the two plastic atom models together. They are attracted to get close together, but never too close, as the protons in their nuclei repel each other. The electron doesn't touch the proton of its own atom nor of other atoms, and why this is the case is not quite understood (as far as I know anyway).

One cannot view the electrons as little balls moving inside a molecule and somehow avoiding falling into a nucleus - the nuclei would attract little charged balls until they fall into them. The electrons are rather like a fluid surrounding the nuclei and making up the spatial extent of the atom. Chemists draw the shape of these fluid clouds (more precisely, the electron density) as orbitals. Electrons show up as particles only under particular circumstances; e.g., in detectors such as Geiger counters.

 

[zketrouble]

One cannot view the electrons as little balls moving inside a molecule and somehow avoiding falling into a nucleus - the nuclei would attract little charged balls until they fall into them. The electrons are rather like a fluid surrounding the nuclei and making up the spatial extent of the atom. Chemists draw the shape of these fluid clouds (more precisely, the electron density) as orbitals. Electrons show up as particles only under particular circumstances; e.g., in detectors such as Geiger counters.

I understand this. But if the electrons keep moving closer and closer to the nucleus due to the attraction between positive proton and negative electron, the atom would be unstable and would simply collapse. Why this doesn't happen is not known as far as I know (though there may be a proven reason or highly accepted theories that I'm unaware of).

Now this gets into further semantics. Only a tiny portion of an atom is actually MATTER, most of it is empty space between these electron orbitals and the proton/neutron nucleus. If a valence electron is orbiting in a covalent bond between, say, O₂, it's moving around the empty space portion of the atom. Is this considering "touching" ? ? ? I don't consider it to be. But, it all depends on how we want to define the terms we use in English. Yes it is part of the atom that the electron his traveling through, but it is not touching anything but empty space within at atom. Quite the paradox, but it's not touching anything in general.

Of course, photons have bounced into electrons causing both the photon and the electron to sharply change its direction. This leads to the debate of whether a photon is a particle or a wave, but let's just assume that wave-particle duality is true based on the wave-like and particle-like nature of the photon. Thus it isn't to say that it is not POSSIBLE for two pieces of matter to touch each other, for the photon did touch the electron (unless perhaps there's some sort of undiscovered particle of a particle, smaller than quarks and fermions and all the other pieces at the quantum level that is having an effect on whether or not the electron and photon actually "touched"). It is possible for two pieces of matter to touch, but in general, they don't. So I think it is safe to say that we never touch something, even if "never" means we only touch the amount of matter equivalent to three electrons within a lifetime. Shoot, more semantics, now we have to define "never." Even if "never" isn't an acceptable word choice, the idea around this is that in general, we are not touching what we feel.

 

[ZapperZ]

I understand this. But if the electrons keep moving closer and closer to the nucleus due to the attraction between positive proton and negative electron, the atom would be unstable and would simply collapse. Why this doesn't happen is not known as far as I know (though there may be a proven reason or highly accepted theories that I'm unaware of).

What is wrong with "Quantum Mechanics"? I'm guessing that you've solved for, say, the hydrogen atom's wavefunction for you to not be ignorant of its existence. So what is the problem with the "explanation" given in such a description, and what we have already described in our FAQ thread?

You also need to consider that in all of this, you never offered a definition of the word "touch", and to consider that such a pedestrian usage of the word may not mean anything in this case.

Zz.

 

[A. Neumaier]

I understand this. But if the electrons keep moving closer and closer to the nucleus due to the attraction between positive proton and negative electron, the atom would be unstable and would simply collapse. Why this doesn't happen is not known as far as I know (though there may be a proven reason or highly accepted theories that I'm unaware of).

There are no electron _particles_ moving around an atom - this is the old, insufficient Bohr model, so nothing that would collapse. It is very well understood why atoms are stable - the ground state is a stationary state that can live indefinitely (unless the nucleus decays).

Only a tiny portion of an atom is actually MATTER, most of it is empty space between these electron orbitals and the proton/neutron nucleus. If a valence electron is orbiting in a covalent bond between, say, O₂, it's moving around the empty space portion of the atom. Is this considering "touching" ? ? ? I don't consider it to be.

There is no empty space around a nucleus, as in Bohr's superseded model. According to quantum electrodynamics, the space is filled by an electron _field_ around the nucleus which neutralizes its charge and fills the space defining the atom size. What is displayed by a field ion microscope http://en.wikipedia.org/wiki/Field_ion_microscope is the boundary of this field. But this boundary is not perfectly defined but a bit fuzzy, more like the surface of a piece of fur or of a cloud.

If two atoms or molecules touch, the volumes occupied by their electron fields touch, and repel each other, while at a slightly (but not much) larger distance there is a slight attraction, the van der Waals attraction, responsible for the formation of liquids.

Thus touching is real. The nuclei don't touch each other but the atoms and molecules do.

So I think it is safe to say that we never touch something [...] we are not touching what we feel.

Your conclusion is quite unsafe, since your intuition is based on the superseded atomic model of Bohr rather than on modern quantum field theory.

 

[DarioC]

Yep Van.50, you called it right on.
DC

 

[zketrouble]

There are no electron _particles_ moving around an atom - this is the old, insufficient Bohr model, so nothing that would collapse. It is very well understood why atoms are stable - the ground state is a stationary state that can live indefinitely (unless the nucleus decays).



There is no empty space around a nucleus, as in Bohr's superseded model. According to quantum electrodynamics, the space is filled by an electron _field_ around the nucleus which neutralizes its charge and fills the space defining the atom size. What is displayed by a field ion microscope http://en.wikipedia.org/wiki/Field_ion_microscope is the boundary of this field. But this boundary is not perfectly defined but a bit fuzzy, more like the surface of a piece of fur or of a cloud.

If two atoms or molecules touch, the volumes occupied by their electron fields touch, and repel each other, while at a slightly (but not much) larger distance there is a slight attraction, the van der Waals attraction, responsible for the formation of liquids.

Thus touching is real. The nuclei don't touch each other but the atoms and molecules do.



Your conclusion is quite unsafe, since your intuition is based on the superseded atomic model of Bohr rather than on modern quantum field theory.

I can't say too much about quantum field theory and quantum mechanics because I just recently got interested in the subject. But these electron clouds are not really "clouds," they are just the space which an electron may or may not occupy at any given time. The electron itself can only be in one place at one time. I'm aware it doesn't revolve around the nucleus like the planetary model but in fact in a quantum, wavelike fashion as suggested by de Broglie. The matter of the electron can only be in one place at a time, and it moves around as waves. However, look at the mass/size of the protons, neutrons, and electrons and compare that to the atom. The electrons aren't filling all the space around the nucleus, they are moving around there.

As for the volumes of the electron fields touching, most of this is empty space, and two electrons won't touch each other because they repel each other. They are traveling all around each other, in each others electron clouds, but are any two pieces of matter ever coming into full contact?

The nucleus of an atom makes up only a tiny fraction of the entire atom. The electrons make up an even smaller portion. How is it possible that there is no empty space within the atom? If the nucleus makes up 1/(insert large number) of the atom, and the electrons make up another 1/(insert larger number) of the atoms mass, how is it possible for these fractions to add up to equal 1? There is a large field where the electron(s) of an atom may be at any given time, but that doesn't mean that they are there nor that they are making full "touching" contact with other nearby electrons.

If I'm totally missing something here please do fill me in.

 

[zketrouble]

Did I call it or what?

Yep, you called it. I smelled it coming also, and despite efforts to avoid it I've been entangled with it.

 

[ZapperZ]

I can't say too much about quantum field theory and quantum mechanics because I just recently got interested in the subject. But these electron clouds are not really "clouds," they are just the space which an electron may or may not occupy at any given time. The electron itself can only be in one place at one time.

That is totally incorrect. It is at a particular location when you make a position measurement of it, but before that, it is really spread out. That's the whole point of the principle of superposition that resulted in the Schrodinger Cat scenario! Things CAN be in many places at once! If it is only at one particular location at a particular time, you will not have bonding/antibonding states, etc. in molecules.

This is a clear example where one cannot simply learn about physics in bits and pieces, because a lot of things are involved in many of these phenomena.

Zz.

 

[ThomasT]

It is at a particular location when you make a position measurement of it, but before that, it is really spread out.

Of course the question then is "what is really spread out, and exactly how do we know that?".

That's the whole point of the principle of superposition that resulted in the Schrodinger Cat scenario! Things CAN be in many places at once!

But this is only the case when we don't know (ie., haven't made a measurement). Because when a measurement is made, then the possibilities of the superposition are localized/collapsed to a specific position/outcome.

If it is only at one particular location at a particular time, you will not have bonding/antibonding states, etc. in molecules.

Ok, so it isn't at a particular location at a particular time, but you said above that "it is at a particular location when you make a position measurement of it".

Please clarify.

 

[A. Neumaier]

Of course the question then is "what is really spread out, and exactly how do we know that?".

The electron _field_ is spread out, and we know it since quantum electrodynamics (from which everything is derived, with very high accuracy in some cases) is primarily a field theory. Electrons behaving as particles (in the sense of being localized at approximately one place) only exist if you consider the field theory in the limit of geometric optics - which is an essentially macroscopic view not applicable inside atoms or small molecules.

But this is only the case when we don't know (ie., haven't made a measurement). Because when a measurement is made, then the possibilities of the superposition are localized/collapsed to a specific position/outcome.

It is impossible to make a measurement of an electron bound in a molecule. What one can measure there is only the charge distribution. To measure the position of a single electron, you need to make it reach a localized detector such as a Geiger counter.

Ok, so it isn't at a particular location at a particular time, but you said above that "it is at a particular location when you make a position measurement of it".

Namely when the Geiger counter clicks. But it doesn't measure of the many bound electrons in its material but only clicks when essentially free electrons reach it.

 

[ZapperZ]

Of course the question then is "what is really spread out, and exactly how do we know that?".

But this is only the case when we don't know (ie., haven't made a measurement). Because when a measurement is made, then the possibilities of the superposition are localized/collapsed to a specific position/outcome.

Ok, so it isn't at a particular location at a particular time, but you said above that "it is at a particular location when you make a position measurement of it".

Please clarify.

I don't have to make a position measurement to detect such superposition. You are forgetting that I can detect such a thing by measuring either a non-commuting observable, or a non-contextual observable.

For example, if A and B do not commute, then measurement of A does not collapses the observable for B. Similar things can be done in trying to detect such superposition. This is what has been done in the Delft/Stony Brook SQUID experiments in detecting the coherence gap. The coherence gap exists because of the superposition of the supercurrent in BOTH directions at the same time!

Zz.

 

[ThomasT]

Ok, thanks ZapperZ and A. Neumaier.

 

[A. Neumaier]

The nucleus of an atom makes up only a tiny fraction of the entire atom. The electrons make up an even smaller portion. How is it possible that there is no empty space within the atom? If the nucleus makes up 1/(insert large number) of the atom, and the electrons make up another 1/(insert larger number) of the atoms mass, how is it possible for these fractions to add up to equal 1? There is a large field where the electron(s) of an atom may be at any given time, but that doesn't mean that they are there nor that they are making full "touching" contact with other nearby electrons.

The electrons make up a tiny proportion of the mass of an atom, while the nucleus makes up the rest. These proportions add up to 100%.

The nucleus makes up a tiny proportion of the space occupied by an atom, while the electrons make up the rest. Again things add up to 100%.

The picture of an atom being mostly empty stems from the childhood of atomic structure analysis, where most of the atom's extension was found to be transparent for alpha rays,
and the early models explained that by pointlike nuclei and electrons. http://en.wikipedia.org/wiki/Rutherford_model

But we don't think glass doesn't occupy space because it is transparent for light, or that only the bones of our bodies occupy space because the remainder is transparent for X-rays. So why should we think of the electronic fluid surrounding nuclei not to occupy space simply because it is transparent to alpha rays?

 

[Carlov]

I really apologize for bumping an old topic, but I have a pretty significant question:

Thus touching is real. The nuclei don't touch each other but the atoms and molecules do.

How often does this happen? When my skin touches the surface of a desk, or my wife's skin, are the atoms (or the electron fields of the atoms) touching then? Or does this happen only under specific circumstances?

 

[K^2]

How often does this happen? When my skin touches the surface of a desk, or my wife's skin, are the atoms (or the electron fields of the atoms) touching then? Or does this happen only under specific circumstances?

Electrical conduction will require some overlap of the electron clouds, and you can get conduction with a rather light touch. So I would say you are pretty much guaranteed to have some significant overlap whenever you are touching something.

At how many points that actually happens is a different question, and it will depend greatly on the surface in question.

 

[A. Neumaier]

I really apologize for bumping an old topic, but I have a pretty significant question:



How often does this happen? When my skin touches the surface of a desk, or my wife's skin, are the atoms (or the electron fields of the atoms) touching then? Or does this happen only under specific circumstances?

It always occurs. Whatever we feel is ultimately just the electron field.

Think of the electron field as a kind of glue. If two surfaces with glue on them touch, the glue merges, until the surfaces separate again. The change in the glue field is ''noticeable'' by both surfaces.

In the same way, when we touch something, the electron fields merge, and are changed by that enough that the nerves register contact.

 

[DiracPool]

is it true that you are never actually touching something? i keep hearing that this is true but why is it that we can feel the texture of things?

In all serious, this is not a difficult question to answer, even philosophically. The way it is presented immediately defines it as a psychophysical question. It is every bit the same as the question: "If a tree falls in the woods and no one is around to hear it, does it make a sound." The answer to that question is obviously NO. Why? because "sound" is defined as the vibration of molecules in a medium (usually air) purturbing a human's basilar membrane which sends a signal to the brain causing the conscious perception of the vibrating medium. No basilar membrane around? No sound.

It is exactly the same with the idea of "touching." The OP said, "you" are never actually touching something. When we think of what it means to know we are touching something, it means that we have a conscious perception of our bodies making contact with another object. It is that experiential sense that the sense organ gives our awareness of a tactile sensation that defines "touching." It actually has little or nothing to do with whether two objects actually make physical contact with one another, and from a QM perspective, you can't even prove that ever happens. But that wasn't even the question, it wasn't about "contact," it was about "you touching" something. In short, whether or not you are actually making contact with an object, if you feel its texture or feel like you are touching it at all, then YES, Millie! You are actually touching it. That's the real deal.

 

[K^2]

It always occurs. Whatever we feel is ultimately just the electron field.

E-field can significantly extend past the electron density, though. Yes, I know the actual interactions are going to be much shorter range due to charges almost completely balancing, Van der Waals, etc., but the above seems like an over generalization.

 

[A. Neumaier]

E-field can significantly extend past the electron density, though. Yes, I know the actual interactions are going to be much shorter range due to charges almost completely balancing, Van der Waals, etc., but the above seems like an over generalization.

We have no sensors for the e/m field (except for vision), thus its longer range does not count.
All touching is based on contact, which is governed by the electron field.

 

[K^2]

Our touch receptors are sensitive enough to pick up minute movements caused by an E-field from charged object. It's much better picked up by hairs, but if you move your hand past a charged object, you should still be able to feel it.

But more importantly, the actual interaction of "touch" is an electrostatic interaction. You are still responding to an E field. Not to electron densities. Not directly.

 

[DiracPool]

But more importantly, the actual interaction of "touch" is an electrostatic interaction.

All this talk about electrostatic interactions involved in our sense perception I don't think advances an understanding of the OP's question. Why not just make the statement,"it all has to do with atoms." ALL sensory perception relates to electrostatic interactions. I don't think all of this discussion about electric fields, van der waal forces, etc. is advancing any insight into the psychophysiology of touch.

Touch receptors are mechanoreceptors in the deeper layers of the integument. They produce action potentials that travel toward the brain when they are "bent" or mechanically altered by a pressure on the superficial layers of skin. There can be a pressure there that is subliminal to conscious perception even though the mechanoreceptors are issuing pulses. Similarly, there can be pressure or contact on the skin that is insufficient to generate action potentials because the pressure is not great enough to deform the receptor in such a manner as to trigger action potentials.

That triggering is accomplished via the bending of the receptor allowing the transfer of Na+ and K+ ions to traverse the neuronal membrane triggering the potential. Yes, it is electrostratic, but then again, so is everything in human physiology.

 

[DiracPool]

I guess my point is that it seems to me the OP's question has already been answered--if you feel like you're touching something, then yes you are touching it. That could be a baseball you grip in your hand, a raindrop on your forearm, a laser beam pointed at your forehead, or a resistive magnetic force on a metal plate in your head when you're taking an MRI.

It seems to me that this discussion of the physics of overlapping electron clouds, etc., is now off-topic for this discussion. I just don't see the relevance. Maybe that conversation should be taken up in a new thread.

 

[Carlov]

No, it is entirely relevant. We're not discussing the sensation of touch per se (that would be more off-topic, if anything), we're discussing the physical definition - i.e. if we clasp two sponges together, are those sponges touching? Is there merely empty space between the atoms of those sponges? OP's question was probably raised in response to the popular notion brought up by certain physicists like Michio Kaku that say we're actually hovering over our chairs when we sit on them. Fortunately, the question in that context has been answered in this thread.

 

[DiracPool]

i.e. if we clasp two sponges together, are those sponges touching? Is there merely empty space between the atoms of those sponges?

Doesn't this get down to an epistemological question, though, at its foundation? I mean, if we continue to look deeper and deeper into the problem, don't we just come up with superpositions of states and wave functions? If these wave functions, as many do, extend out to infinity, albeit at negligible values for large radius's, how can we say where "contact" ends and inter-particle space begins? I think analysis at this level is qualitatively distinct from the psychophysics of sentient experience that seemed to be the OP's central concern.

 

[A. Neumaier]

All this talk about electrostatic interactions involved in our sense perception I don't think advances an understanding of the OP's question. Why not just make the statement,"it all has to do with atoms." ALL sensory perception relates to electrostatic interactions. I don't think all of this discussion about electric fields, van der waal forces, etc. is advancing any insight into the psychophysiology of touch.

Touch receptors are mechanoreceptors in the deeper layers of the integument.

It is this level that is addressed in question and answer. The question was not about how the receptors and the transmission work, but what causes the receptors to signal.

The signal is caused by a mechanical force on the skin, not by an electromagnetic one, since our skin is comnpletely insensitive to small electromagnetic fields unless these casue some mechanical or thermal effect first.

And the mechanical effect is a force caused by touching. Touching is the contact of electron clouds to an extent significant enough to change the macroscopic force field.