Red Baron Farms
Philosopher
I am very familiar with that thought experiment yes. Anyway it seems tlp has also abandoned Mill's claim this is dark matter too, because it is unsupportable. So they all believe dark matter doesn't exist at all, it's all hydrinos.I'd rather you didn't (defer to my expertise).
You're familiar with the thought experiment - originally due to Newton IIRC - firing a cannon horizontally from a tower on the surface of an airless world? To a first approximation, the trajectory of the cannon ball is a parabola; in more detail, it's part of an ellipse, with the center of the Earth as a focus.
Up the speed and the cannon ball will go into orbit, returning to strike the cannon after one orbit (so you need to lower it!).
A DM particle is like the cannon ball. If launched at a different angle, the (partial) ellipse will be different. And unless it's launched either "straight up" or "straight down", it won't go through the center of the Earth.
On a planet that's not rotating (or the cannon not at either pole of a rotating one).
The (or rather a) complication comes from the shell theorem (remarkable, eh?).
As a DM particle falls through the Earth, the mass it's "feeling" is that within a sphere at its location (to first order; there are many second, third, ... order effects I'm ignoring). Which, obviously, decreases as it gets closer to the center of the Earth. This means its orbit will not be elliptical (special cases aside).
Rotation matters: even if a DM particle is created with zero velocity, wrt the device which created it, fixed firmly on the surface of the Earth, its velocity is not zero wrt the center of the Earth (special cases aside). How come? Well, think of why sites which launch satellites tend to be closer to the equator than the poles, and why the launch direction is almost always east-ish (Israel's success came with a heavy cost in terms of satellite mass and rocket fuel expended; Russia would love to have a launch site closer to the equator).
Indeed.
But, come February - per markie'spromisehintwhatever - we will know for sure that hydrinos exist ... when the five (or more) working prototype hydrino-based generators are delivered to truly independent testing facilities.![]()
That means my work on that part of this is done. Hydrinos can't be considered dark matter period. Mills proven wrong.
The next step then is to get some characteristics for this dihydrno gas, that is so common that 95% of the whole universe is Hydrino.
Oh but oops, magically it is undetectable once created.

The not dark matter that magically goes dark when we try to measure it?
Its quantum madness?