When was dark matter first discovered

Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot. In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter.

But what is dark matter? One idea is that it could contain "supersymmetric particles" — hypothesized particles that are partners to those already known in the Standard Model. One scientist likened the finding to throwing a set of keys up in the air expecting them to fall back down-only to see them fly straight up toward the ceiling.

Scientists now think that the accelerated expansion of the universe is driven by a kind of repulsive force generated by quantum fluctuations in otherwise "empty" space. What's more, the force seems to be growing stronger as the universe expands. For lack of a better name, scientists call this mysterious force dark energy. Unlike for dark matter, scientists have no plausible explanation for dark energy.

According to one idea, dark energy is a fifth and previously unknown type of fundamental force called quintessence, which fills the universe like a fluid. Many scientists have also pointed out that the known properties of dark energy are consistent with a cosmological constant, a mathematical Band-Aid that Albert Einstein added to his theory of general relativity to make his equations fit with the notion of a static universe.

According to Einstein, the constant would be a repulsive force that counteracts gravity, keeping the universe from collapsing in on itself. Einstein later discarded the idea when astronomical observations revealed that the universe was expanding, calling the cosmological constant his "biggest blunder. Now that we see the expansion of the universe is accelerating, adding in dark energy as a cosmological constant could neatly explain how space-time is being stretched apart.

But that explanation still leaves scientists clueless as to why the strange force exists in the first place. All rights reserved. Unlocking the Mystery Scientists have not yet observed dark matter directly. Expanding Universe Dark energy is even more mysterious, and its discovery in the s was a complete shock to scientists.

Share Tweet Email. Why it's so hard to treat pain in infants. Dark Matter Core Defies Explanation. This image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell The result could present a challenge to basic theories of dark matter.

Abell Pandora's Cluster Revealed. One of the most complicated and dramatic collisions between galaxy clusters ever seen is captured in this new composite image of Abell The blue shows a map of the total mass concentration mostly dark matter. Researchers were surprised when they uncovered galaxy NGC DF2 which is missing most, if not all, of its dark matter. Black Holes.

The Big Bang. Helpful Links Organization and Staff. Astrophysics Fleet Mission Chart. Spacecraft Paper Models. Related Content Dark Energy Multimedia. More About Dark Matter. Even More About Dark Matter. Fermi Dark Matter Video. Recommended Articles. August 19, July 29, July 06, Nancy Grace Roman's Legacy.

We've reached the point where we know most matter in the cosmos is made of matter that interacts weakly with light if at all, but drives much of the gravitational interactions between galaxies. While it's often portrayed as a modern idea added simply to shoehorn observations into the standard model, it actually has a history spanning more than a century, and the theory of dark matter has been refined and improved as we've learned more about our Universe. The origins of dark matter can be traced to the s.

Soon after Isaac Newton presented his theory of universal gravity, some astronomers began to speculate about the existence of objects that might emit little or no light, but could still be known by their gravitational tug on bright objects like stars and planets. This idea was strengthened in the s when Pierre Laplace argued that some objects might be massive enough to trap any light they emit a simplistic idea of a black hole , and by the s Urbain Le Verrier and John Couch Adams used gravitational anomalies in the motion of Uranus to predict the presence of Neptune.

By this point astronomers had demonstrated the presence of dark nebulae , seen only by the light they absorb from bright objects behind them. It was clear that there was more in the Universe than could be seen by visible light. Our modern take on dark matter as a major contributor to galactic mass can be traced to Fritz Zwicky. In he studied the motion of galaxies within the Coma Cluster.

The Coma Cluster is a galactic supercluster containing more than 1, galaxies. Since these galaxies are gravitationally bound, the speed of these galaxies can provide a measure of the cluster's mass. Basically, the more mass the cluster has, the wider the distribution of galactic speeds following a relation known as the virial theorem. A few years earlier Edwin Hubble had estimated that the Coma Cluster contained about galaxies, each containing about a billion stars.

Using the virial theorem Zwicky calculated a cluster mass more than times larger than that of Hubble. Zwicky noted that if his measurements held true "dark matter is present in much greater amount than luminous matter.

Not everyone accepted these results, largely because the virial theorem is a statistical calculation that depends upon certain assumptions.

For example, it assumes the clusters are gravitationally bound. Perhaps the galaxies in these clusters are actually flying away from each other, so that the virial theorem simply doesn't apply.