2023-12-26 19:44:29
The James Webb Space Telescope succeeded in discovering a new fact with amazing accuracy that deepens the mystery regarding the expansion of the universe, and destroys many theories in cosmology.
Nearly a century ago, astronomer Edwin Hubble discovered the balloon-like inflation of the universe and the accelerating push of all the galaxies away from each other. Scientists saw that following this expansion back in time led to our current best understanding of how it all started: the Big Bang. . But over the past decade, a troubling gap in this picture has emerged: Depending on where astronomers look, the expansion rate of the universe varies greatly.
On the second anniversary of its launch, the James Webb Space Telescope has reinforced this paradox with stunningly accurate new observations that threaten to turn the standard model of cosmology upside down.
Dark energy
“It’s a controversy that should make us question whether we really understand the formation of the universe and the physics of the universe,” says Adam Ries, a professor of astronomy at Johns Hopkins University and leader of the team that made the new James Webb Space Telescope measurements. Discovered in 1998, it is the mysterious force behind the accelerating expansion of the universe.
Scientists agree that the beginning of the universe was with a bang or a big noise, and then in an instant, the young universe was formed.
Most scientists believe that as the universe inflated like a balloon, ordinary matter (which interacts with light) gathered around clumps of invisible dark matter to form the first galaxies, connected to each other through a vast cosmic network.
At first, as the contents of the universe spread out, the energy density and thus the expansion rate of the universe decreased, but then regarding 5 billion years ago, galaxies began to recede once more at a faster rate than ever before. The reason, according to the images that scientists are analyzing, is another invisible and mysterious entity. It is known as dark energy.
The simplest and most common explanation for dark energy is that it is a cosmological constant, an inflationary energy everywhere and at every moment, woven into the fabric of extended space-time, and Einstein called it lambda in his theory of general relativity.
Expansion of the universe
Measuring the expansion of the universe requires a little more than just using radar, and scientists have used two methods to measure the growth of the universe. The first is to look at what is called the cosmic microwave background (CMB), which is a remnant of the universe’s first light that was produced only 380,000 years following the explosion. They track through images the hottest and coldest spots where matter is more or less dense, and by combining the energy densities of ordinary matter, dark matter, dark energy, and energy from light, they determine the maximum speed of the universe’s expansion.
As for the second method to find the rate of expansion, scientists use pulsars called Cepheid variables, which are dead stars with outer layers of helium gas that grow and contract as they absorb and emit the star’s radiation, causing them to flash periodically like distant signal lights.
In 1912, astronomer Henrietta Swan Leavitt found that the brighter the Cepheid star, the slower it flashed, enabling astronomers to measure the star’s absolute brightness and thus its distance.
Cosmology is in danger
A group of astronomers now argue that the tension, combined with the observation that the Milky Way lies within a low-density supervacuum, means that Lambda-CDM and dark matter theory should be ditched altogether.
Pavel Krupa, professor of astrophysics at the University of Bonn, says that what he is seeing now is a collapse of cosmology, and that a theory called Modified Newtonian Dynamics (MOND) must replace the theory of Lambda-CDM and dark matter, because the presence of our Milky Way galaxy in the new images is near the center of galaxies with… The broad density of 2 billion light-years skews our measurements of the Hubble Constant, while other astronomers say their own calculations don’t agree with MOND’s claims.
On the other hand, scientists seek to make a modification to the Lambda-CDM model, which assumes that dark energy (lambda) is not constant but instead evolves over the life of the universe according to unknown physics.
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