On 10/28/2014 6:01 AM, Peter Sas wrote:
Recently I readKant's Metaphysical Foundations of Natural Science (1786) where he tries
to base the basic concepts of physics on the transcendental categories and principles
laid down in his Critique of Pure Reason. One of the most interesting parts, I found,
was the second chapter on 'dynamics' where Kant constructs the concept of matter using
only the concepts of attractive and repulsive forces (presupposing space and time as the
forms of sensory perception). Basically, the impenetrability of matter is explained by a
repulsive force inherent in matter, which needs to be complemented by an attractive
force, since otherwise matter would scatter infinitely throughout space.
Now what caught my attention was Kant's claim that all forces (in modern terms:
interactions) of nature must ultimately be understood as forms of attraction and
repulsion. His argument is very simple: in space, when one object exerts a force on
another, this can ony result either in the objects moving away from each other (so that
the force must be repulsive) or in the objects moving towards each other (so that the
force must be attractive).
Here is what he writes:
"These [repulsion and attraction] are the only two moving forces that can be thought. In
the context of questions about one portion of matter impressing some motion on another,
the two portions must be regarded as points; so any transaction of that kind must be
regarded as happening between two points on a single straight line. Now, there are only
two ways for two points to move relative to one another on a single straight line:
either they approach one another, caused to do so by an attractive force; or they recede
from one another, caused to do so by a repelling force. Consequently, these two kinds of
forces are the only ones we can make sense of; and all the forces of motion in material
Nature must come down to them." (Chapter 2, Explanation 2 to Proposition 1)
I thought this was a real eye opener. Nowadays, of course, we know much more about the
basic interactions than in Kant's time. So I started wondering: First, is it true that
all the basic interactions are forms of attraction and/or repulsion? And if so, then
could it perhaps be possible that all the interactions can ultimately be unified in one
most elementary form of attraction and repulsion? Isn't is the case that when we get
closer to the singularity the interactions become one? But what then are they unified into?
Gravity is clear attractive, though I gather that in inflation gravity can also be
repulsive.
In electromagnetism repulsion and attraction too play an important role, though I am not
sure if this also holds for the weak nuclear force to which the electromagnetic force
appears to be related.
In the strong nuclear force attraction too plays a crucial role.
So how do you think about Kant's suggestion in the light of present day physics? Is
there a chance that all the fundamental interactions are different manifestations of one
single polarity of attraction and repulsion?
In short: matter is defined as filling space and as impenetrable for other pieces of
matter. According to Kant, this concept of matter can be fully contstructed
I think Kant is interesting because he so well exemplifies the limitations of logic and
reason. Rotating bodies pull spacetime around with them so the "force" is not along the
line between them. Photons and electrons have angular momentum and they transmit that in
interactions. Particles have other attributes, generically called charges, which are
conserved just like momentum and so mediate interactions like "forces". So once again
Kant exemplifies a failure of imagination.
Brent
"One cannot guess the real difficulties of a problem before
having solved it."
--- Carl Ludwig Siegel
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
