Saturday 19 December 2020

Dark Matter Is Even Stranger Than We Thought

A huge part of the matter in the universe is: dark matter. You can't really "see" it. But, you could see the effects of its gravity. Experts are thinking about how this matter can really behave.

Scientists can see how dark matter is distributed based on how its gravity affects light. However, when astronomers compared recent data from the Hubble Space Telescope and the Very Large Telescope to current models, something didn’t add up.

"Current assumptions" about dark matter physics might not be entirely correct. Watch the video for more explanations.

Dark matter is a form of matter thought to account for approximately 85% of the matter in the universe and about a quarter of its total mass - energy density or about 2.241×10⁻²⁷ kg/m³.

Dark matter can refer to any substance which interacts predominantly via gravity with visible matter (e.g., stars and planets). Hence in principle it need not be composed of a new type of fundamental particle but could, at least in part, be made up of standard baryonic matter, such as protons or neutrons.

Here is the explanation of "dark matter" in simple terms. Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly. We seem to know that dark matter exists because of the effect it has on objects that we can observe directly.

Proving dark matter is a difficult task. Scientists have not yet observed dark matter directly. It doesn't interact with baryonic matter and it's completely invisible to light and other forms of electromagnetic radiation, making dark matter impossible to detect with current instruments.

Some may wrongfully think that there is no dark matter. However, without dark matter, galaxies would lose a large fraction of the gas that forms new stars immediate after the first major star-forming event they experienced.

Dark matter theory is needed to account for the fact that galaxies don't seem to obey the fundamental laws of physics. That led scientists to believe there must be some invisible matter there to create a stronger gravitational pull and faster stellar motion.


  1. Replies
    1. Thanks for enjoying the thoughtful scientific informative blog post.

      "Dark Energy" sure isn't just dark, it is really invisible. Hypothesized by various physicists to drive the accelerating expansion of the so-called universe, dark energy has never been directly observed or measured. Instead, scientists can only make inferences about it from its effects on the space and matter we can truly see.

      Finding measurable hints of so-called "dark energy" effects on certain objects is really a major goal of major NASA missions, such as the upcoming Nancy Grace Roman Space Telescope.

      The Nancy Grace Roman Space Telescope is a NASA infrared space telescope currently under development. Roman was recommended in 2010 by the United States National Research Council Decadal Survey committee as the top priority for the next decade of the science of astronomy.

      In a new paper published September 15 in the journal Physical Review D a group of cosmologists suggests researchers might not need to look deep into the cosmos to make second-hand observations of dark energy (the energy may have been detected right here on Earth).

      In the interesting paper, the researchers claim that hints of dark energy were detected at the Gran Sasso National Laboratory in Italy during an experiment designed to detect dark matter.

      Statistically, there is a 5 percent chance the detection was an anomaly. The detection of the 2012 discovery Higgs Boson, by comparison, was much more certain (there was only a chance in about 3.5 million that detection was anomalous).

      Dark energy repels instead of attracts - meaning it’s what’s expanding the universe.

      It seems that physicists have known the universe is expanding for years, but in the late 1990s, observations made it clear that the universe was not just growing larger but doing so at an accelerating rate.

      "Dark energy" is now believed to be about 68 percent of the mass of the universe, though the ratio grows with the expansion of the universe. Dark energy seems to interact very little with gravity.

      What is "quintessence"? In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of the observation of an accelerating rate of expansion of the universe. The first example of this scenario was proposed by Ratra and Peebles (1988). The concept was expanded to more general types of time-varying dark energy and the term "quintessence" was first introduced in a 1998 paper by Robert R. Caldwell, Rahul Dave and Paul Steinhardt. It has been proposed by some physicists to be a fifth so-called fundamental force. Quintessence differs from the cosmological constant explanation of dark energy in that it is dynamic; that is, it changes over time, unlike the cosmological constant which, by definition, does not change. Quintessence can be either attractive or repulsive depending on the ratio of its kinetic and potential energy. Those working with this postulate believe that quintessence became repulsive about ten billion years ago, about 3.5 billion years after the Big Bang.

      In theory in the future, the universe can expand or become smaller.