array9

It is difficult to see how you clump dark matter together, as it is not sticky.

But you might be lucky with a black hole which is its own stickiness.

Indeed black holes might be the only way to stop dark matter just oscillating back and forth under gravity.

But it seems much more likely that matter gets taken into a black hole rather than dark matter.  You cannot make a solar system out of dark matter, and so it must be very difficult to construct a black hole.

martin

You might have thought that the random action of waves on a beach would have produced spherical pebbles.  But this is not the case, indeed almost all are distinctly not spherical.

Probably the best way of thinking about it is in terms of potential energy and packing efficiency.  If you take a box of squashy balls, you can squish down on them and lower the centre of gravity.  You get them to pack just slightly better.  That’s what nature likes.

Now this does not explain the shape that they actually adopt, as squashing would produce some foam bubble shape.

Maybe they don't start off being highly symmetric, but have certain long and short axes.  And the erosion is likely to be mostly around the short axes, and these will roll more readily.  So you might get the long axes remaining, with the short axes having higher wear rates.  This produces better packing than spheres.  The more dimensions the worse the packing, I guess.  Packing balls is worse than packing rolls.

martin

I am assuming that dark matter interacts with gravity only.

It is difficult to see how you capture dark matter, as you cannot contain it.  You would have to slow it down with use of gravity, and then get it to oscillate around some strong gravitational source.

It is difficult to see it happening without some non-gravitational clumping of ordinary matter happening at the same time.

Indeed it is difficult to see how two bits of ordinary matter can clump by gravity alone, and it probably takes the randomness of 3+ body problems to achieve.

Martin

How on earth would you find out?

My guess is that if you want to call a halt to the cascade of smaller and smaller particles, then you need at some point to have something which really cannot interact with itself, other than through gravity.  Clearly photons don't.  And so I vote that neutrinos don't.

If you see neutrino's as being the spacial granularity or quantum, then I think you want them to only ever be able to hit absolutely head on, and not scatter.  So you might get reflection.  But I prefer the thought that this does not happen.

You could only tell if you could tell the difference between the neutrinos, colour or whatever.

I feel it is nicer to assume that you can never see a collision, and see what the consequences might be.

Martin

The 'good guy' wins?  This may possibly be true over the very very long term.

But it is not so obvious.

Consider grasses and trees.  Trees do not have to be that efficient to wipe out grasses, even if grasses are very efficient with resources.  They only have to be able to get above the level of grasses and cut out the sun light.

Indeed one might think that the specialisation of coping with height, might hinder their efficiency.  Smaller percentage of material devoted to photosynthesis?

The fact is that the technology of the plant, may be more competitive than its resource efficiency.  The trees deny resources to the grasses, which in turn may make the grasses even more efficient.  But I doubt if it helps.

Maybe cold blooded animals are more efficient than warm blooded animals, but it won't help them much either.

The trees are the large dinosaurs of the plant world.  The grasses have to find some way of fighting back perhaps.  I guess we call it agriculture.  Make yourself indispensable to man.

It seems funny that so many people think of trees as the way to de-carbonise the earth's climate, whereas I am thinking that it would be better to look at those other plants that the trees bullied.  And remember that the grasses probably bullied lots of even smaller things.  Trees may be the last thing one should champion.

Martin

If you are contemplating a granular universe with a minimum quanta of distance or volume, then it may make sense to assume that there exists something of that precise size.  Otherwise one is wasting energy surely overengineering it.

So maybe one should be thinking that a neutrino is precisely that minimum physical size.

Not sure how everything would fit together.  Clearly you cannot have spaces inbetween things smaller than a neutrino, and so a clump of neutrinos would have to be really perfectly fitting together with no gaps, whatever that would mean.  Bang goes euclidean geometry with rather few ways of filling space with regular bodies.  Neutrinos are not cubes!

Probably time to set up a new set of axioms for a new geometry, neutridean geometry

- the Universe is the set of all quanta
- quanta a and b are contiguous if the set of a and b is the only straight line between them
- a set of quanta are contiguous if there are subsets for every pair of quanta, which are lines between them
- a line between two quanta a and b is a set of quanta that is contiguous and includes a and b, and from which no quanta can be removed without breaking the contiguity
- a straight line between a and b is a line with the minimum integer number of quanta
- there may be more than one straight line between a and b
- there is at least one straight line between a and b in the universe
- there are lines between any two quanta a and b in the universe

You can prove at least a few things, which I leave as exercises:

* If c is a quanta on a straight line between a and b, then there is a straight line between a and c and one between c and b, and the union of these two lines is a straight line between a and b.
* the Universe need not be finite or countable
* if a and b, and b and c, are contiguous, there is a line between a and c, but if need not be a straight line.
* if a,b and c are a straight line between a and c, then a and c are not contiguous

martin