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Is Dark Energy Real?

Is Dark Energy Real?

This diagram reveals changes in the expansion rate since the universe’s birth 15 billion years ago. The more shallow the curve, the faster the rate of expansion. The curve changes noticeably about 7.5 billion years ago when objects in the universe began flying apart at a quicker pace. Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart. Credit: NASA/STSci/Ann Feild

While we may never observe dark matter or dark energy directly, they adequately explain the motions of stars and galaxies and the universe’s expansion. For decades, astronomers, physicists, and cosmologists have believed that the universe is filled with an unusual element known as “dark matter,” which explains galaxies’ and galaxy clusters’ odd gravitational behavior. Many science-minded individuals believe that the universe is composed of “billions” of galaxies, plus the remainder of the cosmos appears to be composed of a mystery, invisible substance called dark matter (25 percent), and a gravitationally repellant force called dark energy (70 percent). [Sources: 3, 10, 13, 14]

Dark energy is uniformly spread across our universe, not just in terms of space and time; in other words, its influence does not reduce as the universe expands. According to a new model developed by physicists at the University of Copenhagen, 25% of dark matter is linked to unique features that render 70% of the universe’s dark energy. A flat universe with a critical mass/energy density implies that 68.3 percent of the universe’s mass and energy be “dark energy,” a figure estimated from the magnitude and spacing of the CMB’s acoustic peaks. [Sources: 1, 11, 15]

Dark energy has been proposed to explain the observable features of distant Type Ia supernovae, which indicate that the universe is accelerating. The mystery, scientists believe, occurs due to the gravitational impacts of galaxies and galaxy clusters. It has no interaction with baryonic matter and is entirely invisible to light and other kinds of electromagnetic radiation, making detection by present tools impossible. [Sources: 7, 14]

Dark energy is a concept that refers to an unknown force that causes our universe’s expansion to speed up rather than slow down over time. That is the polar opposite of what one might expect from a Big Bang-born cosmos. In the twentieth century, scientists found that the universe is expanding. They reasoned that the expansion might continue eternally or eventually reverse and precipitate a Big Crunch if the cosmos collected sufficient mass and consequently self-gravity. This concept evolved during the early twentieth century’s cosmology. The universe is growing faster now than it did billions of years ago. What could be causing the acceleration of the expansion rate? Astronomers now occasionally refer to it as a repulsive force.

Unsolved mysterious puzzle

In 1997, astronomers stunned themselves and the rest of the world when they discovered that the universe’s expansion is accelerating. They coined the term “dark energy” to describe this accelerated expansion because they were unsure of the source of this strange cosmic phenomenon.

The most straightforward explanation for dark energy is that it is an addition to Einstein’s general relativity theory known as a “cosmological constant.” Physics researchers have attempted to connect this cosmological constant to the quantum vacuum energy that prevalent throughout space-time. Nonetheless, their calculations result in an accelerated expansion intensity that is approximately 120 orders of magnitude too great.

As a result, dark energy may take time to integrate into space-time. Perhaps the cosmos is being influenced by an unknown force, field, or particle — something that the Standard Model of particle physics has never encountered. This entity would account for the faster expansion, although theoretical models encounter difficulties in this area as well.

The issue is that whenever a new force, field, or particle is added to the cosmos’s recipe, that force, field, or particle begins to interact with all of the other forces, fields, and particles known to physics. And, given the absence of evidence for novel physics in any of our high-energy (let alone low energy) physics experiments, this does not appear to be a feasible possibility.

Behind the curtain

However, a recent paper published on the preprint server suggests another possibility: Perhaps dark energy has no direct connection to Standard Model particles but is linked to photons.

The tachocline is a region deep inside the sun where the sun’s magnetic field is powerful. Magnetic fields are carried by photons, so tons of photons are produced in the tachocline. If dark energy somehow connects to photons, then this is where dark energy particles might be produced.

It’s all clear now.

As a result, there may indeed be a mechanism for the sun to spit out dark energy particles. These dark energy particles would then shoot through the remaining mass of the sun, through space, and right now, stream through you.

Numerous experiments spread across the globe are searching for elusive dark matter particles in the hope of witnessing a glimpse of an extremely rare interaction. XENON1T, one of those experiments, recently observed a signal it was unable to explain — the first hint of such a detection fully.

And there is a possibility that the experiment detected dark energy rather than dark matter. It is not a particularly robust detection, and it is far from conclusive evidence for the existence of dark energy. However, a hint is a hint. It has been more than two decades since the discovery of dark energy, and both theory and experiment have made little progress.

Scientists hope that future dark matter detection experiments, such as XENONnT and PandaX-4T will yield additional data and finally provide a glimpse of the dark universe.


Works Cited