| bottom-up scenario | has definition A galaxy-formation scenario in which small galaxies form first. Larger and larger structures are then formed in due course. |  |
| has definition The idea that small structures, perhaps galaxies or even smaller substructures, form first in the universe, followed later by larger structures. |  |
| is a kind of galaxy theory |  |
| galaxy theory | has domain extragalactic astronomy |  |
| theory | has validity correct or incorrect with caveats |  |
| has author or reasearch group |  |
| has date or a range of dates for which the theory was active |  |