The kitchen where stars are baked works on a simple recipe: as much flour as you have, that's how many pies you get. For a long time, astronomers saw a strict relation between a galaxy's mass and how fast it forms stars, and they considered it a standalone rule. But a new study of 24,954 nearby galaxies shows that this relation is just a shadow of two more fundamental laws.
The first law links the amount of molecular gas (the main raw material for stars) to the mass of already existing stars. The second links the amount of gas to the star formation rate. Both relations turned out to be tighter and more reliable than the original 'stellar mass – star formation rate' relation. Statistical analysis confirmed: once you account for gas, the direct correlation between stellar mass and star formation disappears. Gas is the true mediator.
The practical takeaway: to understand how many stars will ignite in a galaxy tomorrow, look not at its mass but at its cold gas reserves. It's like predicting a harvest by the number of seeds, not by the size of the barn. The main sequence of star formation turned out to be not a law of nature but a convenient consequence – much like how the queue at a bakery depends on the availability of flour, not on the number of already baked loaves.
In a sample of nearly 25,000 galaxies, the relation between gas and stars turned out to be so tight that its scatter is smaller than that of the famous 'mass – star formation rate' relation that has been studied for decades.
In the novel 'The Three-Body Problem', a civilization uses stars as fuel – but even there, gas is indispensable: interstellar matter becomes the raw material for new stars.