Dark Matter vs. Dark Energy: What's the Difference?

Dark matter and dark energy are important for understanding the universe. Despite being invisible to humans, dark matter and dark energy comprise 27% and 68% of the universe's mass and energy, respectively. In contrast, all visible matter accounts for only 5%.

The concepts of dark matter and energy can be difficult to grasp because they deal with unseen elements and the expansion of far-off galaxies.

Dark matter does not give off or reflect light, so it is invisible. Scientists can detect it because it has a gravitational effect on visible matter. Though scientists can see these effects, they cannot fully define dark matter.

Meanwhile, dark energy is a little-known force that acts on galaxies. Like dark matter, it is evident because of the measurable expansion of the universe, which is pushing galaxies further away from one another.

Here is a closer look at what we know about dark matter and dark energy and the hypotheses scientists are developing related to them.

What Are Dark Matter and Dark Energy?

Dark matter and dark energy are enigmatic substances, but they both play a pivotal role in shaping the cosmos. Here is a closer look at the impacts each of these elements has on the universe.

Dark Matter

Dark matter is impossible to see and difficult to detect because it doesn’t interact with electromagnetic forces. It was first discovered in the 1930s by Swiss astronomer Fritz Zwicky, who observed a far-away galaxy and calculated that the visible mass was not large enough to exert the gravitational force needed to hold it together.

In the 1970s, American astronomer Vera Rubin explored this idea further. She noticed that the outer regions of galaxies were rotating faster than expected. This would only happen if there was an unseen element that added to the overall mass galaxy.

These discoveries indicate that dark matter helps shape the structure of space. In other words, its gravitational pull creates a framework that supports galaxies and keeps them from breaking apart. It also helps distribute galaxy clusters, ensuring they do not collide or drift apart.

Dark Energy

Dark energy is a mysterious energy source found throughout space. Scientists think it is responsible for the accelerated expansion of the universe. Teams of astronomers from Australia and the U.S. actually made similar discoveries in the 1990s because supernovae (exploding stars) were not as bright as expected. They hypothesized that the dimness was due to the accelerating expansion of the universe.

The discovery meant that an unseeable force, which became known as dark energy, makes up a large portion of the universe's total energy density.

The nature of dark energy remains unclear, but it supports a uniform but accelerating expansion. Ultimately, dark energy will dictate whether the universe continues to expand or whether it will reach its limit and collapse.

Difference Between Dark Matter and Dark Energy

Dark matter and dark energy are fundamental to the cosmos. Both exert forces on visible matter and provide structure to galaxies and the wider universe. However, there are a few important differences.

Here is a look at three of the ways dark energy and matter are different from one another.

Interactions With Regular Matter

Dark matter and dark energy interact with visible matter in very different ways.

Dark matter interacts with regular matter by exerting gravitational pressure on it. This gravitational pull influences the shape and motion within galaxies and galaxy clusters. In contrast, dark energy has a repulsive force that is the opposite of gravity. This force causes the universe as a whole to expand, with galaxies traveling further and further away.

Detection Methods

Detection methods for dark matter and dark energy are also very different.

Dark matter is studied through gravitational lensing, which involves measuring gravitational influence by how much it bends light from distant objects. Scientists can also detect dark matter through the analysis of galaxy rotation curves. Both these methods allow scientists to see the influence of the invisible force on visible matter.

Dark energy, on the other hand, is detected by watching type Ia supernovae. They measure the distance it’s moving away from Earth to help gauge the speed at which the universe is expanding.

Also, cosmic microwave background (CMB) radiation, which is an observable remnant of the Big Bang, can help offer insights into the influence of dark energy and the speed at which the universe is expanding.

Exact Nature

The exact nature of dark matter and dark energy remains a mystery. There have been

studies and experiments, but neither force acts like any known particles or substances. Because of this, scientists have yet to determine the composition of dark matter or the mechanism that gives dark energy its expanding force.

Hypotheses range from calling dark matter an invisible grid or web to saying that it’s either Weakly Interacting Massive Particles or very small particles that don’t interact with light and therefore remain unseeable.

Research continues to focus on how these forces interact with visible matter in the hopes of gaining insights into their natures.

Current Research and Future Implications for Dark Matter and Energy

Research into dark matter and dark energy is pivotal for helping us understand the universe. Experiments like those conducted at the Large Hadron Collider (LHC) look for answers. Scientists are trying to discover dark matter particles by essentially recreating the environment that led to the Big Bang at the start of the universe.

Other efforts, like the Euclid mission, focus on mapping the distribution of dark matter and dark energy to learn more about their effects.

By finding the elements that make up dark matter, scientists hope to unlock new aspects of particle physics and cosmology. Their research could lead to a new understanding of the makeup of the universe. New telescopes and computer-aided analysis may help advance these studies.

Also, this science could have potential practical applications, such as new ideas for propulsion and navigation for space exploration.

Though scientists have an understanding of the effects of dark matter and energy, these forces remain largely mysterious. However, ongoing studies continue to shed light on the way the universe and faraway galaxies function.