Astronomers estimate that roughly 85% of all the matter in the universe is dark matter, meaning only 15% of all matter is normal matter. Accounting for dark energy, the name astronomers give to the accelerated expansion of the universe, dark matter makes up roughly 27% of all the mass energy in the cosmos, according to CERN (opens in new tab) (the European Organization for Nuclear Research).
Astronomers have a variety of tools to measure the total amount of matter in the universe and compare that to the amount of “normal” (also called “baryonic”) matter. The simplest technique is to compare two measurements.
The first measurement is the total amount of light emitted by a large structure, like a galaxy, which astronomers can use to infer that object’s mass. The second measurement is the estimated amount of gravity needed to hold the large structure together. When astronomers compare these measurements on galaxies and clusters throughout the universe, they get the same result: There simply isn’t enough normal, light-emitting matter to account for the amount of gravitational force needed to hold those objects together.
“Writer Fuel” is a series of cool real-world stories that might inspire your little writer heart. Check out our Writer Fuel page on the LimFic blog for more inspiration.
