The nature of force

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Larry Burford</i>
<br />Thomas, EBTX,
We are still waiting for a *physical* justification for this force field you believe in. Until one is provided, my inclination is to read "magic field" when you write "force field".
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
All fundamental laws in physics imply a kind of magic because by definition they can not be rationally deduced anymore but have to be accepted as first reasons. It is merely required that they are logically self-consistent and consistent with observations.

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www.physicsmyths.org.uk
www.plasmaphysics.org.uk

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Thomas</i>
The definition [is] that a particle changes momentum on encounter with another particle.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">This implies that the momentum change causes the collision. But what about neutrons, photons, and in general entities that have no field? Or what if we have two particles in isolated space that collide inelastically, but we have no means to measure anything except their relative momentum, which does not change? Does that mean they did not really collide?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It is true that not all so called 'collisions' are associated with force fields in the classical sense (e.g. excitation of atomic radiative transitions by electron impact or electron-proton recombination), but this means that in these cases the momentum change can not possibly result in any recoil force (and a force is obviously what you want if you want to explain for instance Gravity through collisions with some hypothetical particles).
In other words, the observed macroscopic force is only consistent with the assumption of an interaction between particles through static force fields. At what level this happens may be an open question, but at some level you certainly have to assume it this way.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I grant that one way bodies can collide is for their fields to interact. But not all physical entities have fields. If two swarms of bees fly through one another, I see three possible outcomes:
(1) No bees interact or change momentum. [By your definition, this means no collision occurred.]
(2) Some bees see the other swarm approaching and choose to randomly change their own flight path. [By your definition, this means a collision did occur because the momentum changed. The "force" acting is will power.]
(3) Some bees run into one another. [Does the fact that no force acts between the bees prior to contact mean that contact is not possible?]<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">For the bees a similar argument applies as for the inelastic atomic 'collisions' I mentioned above: if a bee sees an obstacle and changes its course a result, there is a consequently a momentum change and in this sense you could call it a collision (following my initial definition), but it would not be associated with a force excerted on the obstacle (and a force is what you want to explain). Only if the bee hits the obstacle can there be a resulting force (and this force is then due to the electrostatic interaction of the corresponding atoms).

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">So as I understand it, you maintain that dense particles of comparable size but lacking fields can occupy the same place at the same time without effect?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">All particles should possess some kind of field. Neutrons may not possess an electrostatic field but can be assigned a strong interaction field (and of course also a gravitational field as they have mass). Particles without any field could not interact with any matter at all and would hence be unobservable.

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www.physicsmyths.org.uk
www.plasmaphysics.org.uk

[Thomas] "All fundamental laws in physics imply a kind of magic ... "

&lt;chuckle&gt;

[Thomas] " ... because by definition they can not be rationally deduced anymore but have to be accepted as first reasons."

IOW, " ... there are some things Man was not meant to know."?

[Thomas] "It is merely required that they are logically self-consistent and consistent with observations."

So tell me, in what way does a field made of particles too small to be detected (yet) not agree with observations? The gravitational potential field of MM is an example, with elysons being the particles that are too small to be detected (yet).

As soon as we can detect elysons, the mystery of the gravitational potential field will go away. Along with the mystery of electric and magnetic fields. And the gravitational force field, although not completely explained, will become less mysterious.

Once we are able to detect elysons, of course, one of the very first things we will need to do is explain something about the behavior of elysons that LOOKS LIKE a new kind of force field.

(That new force field will turn out to be built of still smaller particles. Etc.)

LB

NOTE - Real theories, like MM, make specific predictions like these. Predictions that can lead to new machines. Predictions that put the theory at risk, because an observation or experimental result that contradicts one of the predictions makes the theory not work.

Uneducated guesess, like your magic force fields, can only predict that " ... the field is unobservable". No new machines in there.

LB, Either I am not stating this right or you are not reading what I posted. TVF says in a post above the smaller the thing the more dense it is. I am asking why big things are less dense since they are made of small things. I hope this is a bit easier to comprehend. And I am not saying anything I'm asking a question. I'll try in future to keep it simple.

[Jim] "I am asking why big things are less dense since they are made of small things."

Why? That's an interesting question. But first I'd like to know if you have any questions about the observations and experiments that indicate that this (small things are more dense, large things are less dense) is in fact the way the (observable part of the) universe is constructed.