I get email press releases from various sources, and a recent one had the subject line "Prediction of Modified Gravity Theory Confirmed". I couldn't help it; I literally snorted a bit. Modified Newtonian Dynamics (or MOND) -- basically, theoretically tweaking the strength of gravity on large scales -- is an attempt to circumvent the need to use dark matter to explain some things going on in the Universe, and in my opinion is interesting but unnecessary.
Well, as those of you who follow me on Twitter know, I just spent 20 out of the past 24 hours traveling from Florida back home to Boulder (next trip I'll just ride my bike to save time) so I'm pretty exhausted. But happily, my fellow
Hive Overmind Discover Magazine blogger Sean Carroll -- who's a real life cosmologist and stuff -- takes this issue head-on and shows why the so-called MOND idea really doesn't work.
Sean goes into lots of detail, but really, for an observer like me, it boils down to two words: "Bullet Cluster" (scroll down to #4 on that page). Until they can explain this, there's no reason to even worry about MOND. That cluster is the 364 kilogram gorilla in the room, since dark matter explains it simply and easily -- Sean covers it in his bullet (haha) list, so go to his post, and find out why so few astronomers seriously doubt the existence of dark matter.