Viewing profile — ldunn

The diagram on the Wikipedia page for Kruskal-Szekeres coordinates[1] does the job. There you see the trajectory of some infalling observer along with some future light cones[2] of…

It doesn't have to move in such a direction! Look at a spacetime diagram and think about the trajectory of your head and feet! Read a book on GR! Do literally anything except have …

I agree that if you are freely falling and then you are suddenly not freely falling because you hit the surface of a planet and experienced a huge acceleration, you will notice. Th…

It is absolutely untrue that GR predicts that you would be knocked unconscious crossing the horizon. In fact one of the most fundamental aspects of GR (equivalence) predicts the ex…

Why wouldn't you be able to see your feet? Your head is also falling through the horizon (hopefully - otherwise you are going to be very unhappy), so the light from your feet doesn…

Er, again, fine, but this has nothing to do with the question of "how can something so hard to detect be so abundant". The question isn't "should the non-detection of dark matter d…

This tells you that the chance of detecting dark matter is higher than it would be if it were only, say, 0.1% of the energy content of the Universe. Which is true, but so what? May…

Why do you think that how hard it is to detect should have anything to do with how much of it there is?

It bears mentioning that the situation is even more constraining than this, because you're not just looking at galactic dynamics - you're looking at galaxy _cluster_ dynamics, and …

Strain drops off as 1/r, not 1/r^2

I've done some very preliminary (and bumbling) work with that at https://github.com/ldunn/kern/ It's rudimentary, but it does compile and it does run, and I'm not aware of any part…