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Henry Martin and Rishil Saxena
Credit: Volker Springel, National Geographic
Only about five percent of the known universe is made up of atoms and light--things that we can observe and that make up everything we see around us. In that case, what makes up the other 95%? Is it just empty space? For a while, that’s what scientists believed. It wasn’t a satisfying solution, however, since this model would not allow the universe to remain stable, so something else has to be holding it together. From this, the theory of dark matter was created, which hypothesizes that there is some other substance in addition to normal, visible matter that we cannot see. In the theory, dark matter is what provides our universe with enough mass and gravitational force to keep the universe intact and prevent everything from flying apart. Still, dark matter is almost impossible to detect, because it does not interact with any form of light, so all data about dark matter so far have come from observations of its gravitational force. The first clear evidence of dark matter came in 1933, when Fritz Zwicky found that the mass of an observed galaxy cluster was too small to be holding the cluster together on its own. Based on similar observations gathered over time, scientists have hypothesized that dark matter makes up 27% of the known universe.
If this is the case, normal and dark matter still only make up 32% of the total space in the universe, leaving 78% unaccounted for. What makes up the other 78%? In the early 1900s, scientists made an unexpected discovery: the universe is not only expanding, but it’s expanding at an ever-increasing rate. To help understand this phenomenon, scientists created the idea of dark energy, which they cited as the force driving the expansion of the universe. Like dark matter, it’s almost impossible to detect directly; instead, scientists measure its effects to get a better idea of how it works. Through observations of far-away celestial objects and measuring things like redshift, they were able to confirm the existence of dark energy and determine an estimate of how much of it exists in our universe. Based on their calculations, they determined that dark energy makes up the remaining 78%, completing the modern model of dark matter and energy.
Credit: CERN
It is well agreed upon today that dark matter and energy exist. But what are they really? No one knows for sure, and there are many different theories. Some scientists hypothesize that they are made up of particles that are “partners” of the ones that currently exist in the Standard Model. Other theories guess that dark matter exists in other dimensions and use physics outside of the Standard Model. Either way, our technology isn’t capable of directly measuring dark matter, especially since we haven’t figured out exactly where to look.
Recently, however, breakthroughs have been made that may eventually lead to the direct detection of dark matter or energy. In an experiment led by Fermilab and the University of Chicago, a detector scans a wide broadband of frequencies for the presence of dark matter. Although they were not able to find any dark matter with the tests they ran, they were able to narrow their constraints as to where it may be. The scientists working on the project are constantly tuning the sensitivity to certain frequencies to try and find the optimal range for detecting dark matter.
Credit: University of Chicago
The effects of properly understanding dark matter and energy could potentially change human civilization forever. Dark matter is theorized to have six times the density of normal matter–just imagine if we could find a way to harness this extraordinary capability. The power and force that dark energy has, if used correctly, could potentially be used to revolutionize technology.
Henry Martin
Henry Martin
class of 2025
Rishil Saxena
Rishil Saxena
class of 2025
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