Dark Matter and Dark Energy

New research has found that the distribution of mass in galaxy clusters can be explained by...
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Looking up at the night sky in Jasper last Summer, I wondered what kept the stars in galaxies together? Was there some other form of energy or matter that made up space or was it just tiny particles. Later on, after stumbling upon some articles about dark matter and dark energy, it rekindled my inquisitive sense about this topic, and I developed a much better understanding of dark matter and dark energy.

Dark Matter
Dark matter makes up the bulk of matter in the universe. The world we experience every day is made of protons, neutrons, and electrons bundled together into atoms as we learn in any high school science class, let’s call it regular matter. In the late 20th century, scientist discovered that the visible regular matter makes up less than 5 percent of the mass of the universe while 25 percent is another type of matter called dark matter. This matter is unusual and it does not interact with the electromagnetic force but instead with a force that scientists are still learning about. In reality, we know very little about dark matter as it does not absorb, reflect or emit light, making it extremely hard to spot.

Phenomena Explained by Dark Matter
Dark matter is what makes it possible for galaxies to exist.  It binds stars close together in the form we know as galaxies. Our knowledge of dark matter comes from the way we observe stars in far off galaxies. Scientists observed that given the amount of visible mass present in a particular area of galaxy its stars are moving faster than expected. The movement is so fast that those galaxies we see should have long since been torn apart. Dark matter can also explain certain optical illusions that astronomers see in the deep universe. For example, pictures of galaxies that include strange rings and arcs of light could be explained if the light from even more distant galaxies is being distorted and magnified by massive, invisible clouds of dark matter in the foreground-a phenomenon known as gravitational lensing.

Dark Energy
Dark energy is even more mysterious than dark matter, and its discovery in the 1990s was a complete shock to scientists. Previously, physicists had assumed that the attractive force of gravity would slow down the expansion of the universe over time. But when two independent teams tried to measure the rate of deceleration, they found that the universe expansion was speeding up. One scientist compared 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. Dark energy makes up approximately 70% of the universe and appears to be associated with the vacuum in space. It is distributed evenly throughout the universe, not only in space but also in time – in other words, its effect is not diluted as the universe expands. The even distribution means that dark energy does not have any local gravitational effects, but rather a global effect on the universe as a whole.

It is clear that the universe and all the aspects related to it are very complex and we are just scratching the surface of its deep mysteries. For centuries humans have wondered about stars in the night sky and have come up with explanations based on their beliefs, and knowledge of at that time. In the last 3 or 4 decades, we have made tremendous progress on our understanding of the universe. However, we are just at the beginning of our journey to explore the universe.

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