On 19/5/25 21:05, Timothy Collinson - timothy.collinson at port.ac.uk
(via tml list) wrote:
> <snip>
>
>     1.  As a Kessler cascade is (by _definition_) collisional , shouldn't
>     that be a subpart of 6805.8, as you've got it currently?
>
>
> Yes, I think that would be a 'correct' answer as well.  This may be
> where the whole project becomes more 'art' than 'science', or it may
> just be that I'm wrong.
>
> I plumped for the above because the article seemed to imply that they
> were more distinct than I initially thought.  You could have
> collisions that didn't result in cascades and you could have cascades
> that happened pretty quickly so the whole thing was collapsing before
> there was much time to be stressed about 'mere' collisions.  (Though I
> must admit I got a bit lost in all the author's maths about just how
> quickly.  (Hours? Seems unlikely.  But I had the impression he meant
> days - for some - rather than years, but I may have misunderstood.)
> The other (smaller, easily overridden) reason was that where possible
> I try not to bury things after increasingly obscure decimal points if
> I can help it (but see below).
>
> <snip>

 From what I understand (and, those of you more knowledgeable, chime in
after you manage to stop laughing):

A Kessler cascade (or syndrome) has, at its core, the density of objects
in some orbit, or set thereof, becoming so high that on average, each
collision between such objects results in _more_ objects in orbit than
previously, ultimately proceeding exponentially.

Below such a critical density, orbital objects are removed _faster_ than
they are generated, primarily by atmospheric drag.

IIRC, Dyson structures don't tend to have large scale internal
atmospheres, merely their primary's photosphere.  All else equal, that
would lower the critical object density before things go Kessler.

Again all else equal, something like a laser broom would raise the
critical object density, but at the cost of requiring _more_ active gubbins.

The obvious analog is neutron multiplication in fission reactions - a
system below critical (< 1 neutron out per neutron in) will have the
reaction die out, while a critical system (>1 neutron out per neutron
in) will have the reaction continue.  If that system is critical on
_prompt_ neutrons alone, you have a problem.

I _think_ the density dependence argues for you moving Kessler Cascade
under 6805.8, as both a swarm collision and a Kessler cascade are
collisional, with the latter not only being the former, but at an object
density high enough that the reaction is runaway.  I get what you mean
about not "bury(ing) things after increasingly obscure decimal points",
so if the difference between the two, in your view, is essential, leave
them where they are.

Alex

--