Scientists reported Thursday that the universe apparently contained far more small galaxies a few billion years ago than it does now, a finding that challenges current thinking about how galaxies form.
The central question is: Where did all those dwarf galaxies go?Maybe they merged to form larger ones, or maybe they self-destructed, but in any case there's no easy way to explain their disappearance over such a brief time, scientists said.
The bounty of recent small galaxies "isn't what I expected to find at all. It's quite a shock," said Lennox Cowie of the University of Hawaii.
"I don't think I've truly reconciled myself to the whole thing yet."
The finding "implies that the galaxy population has evolved rapidly and, if true, will require a substantial revision of current ideas about galaxy formation," Cedric Lacey of the Oxford University physics department wrote in the journal Nature.