Scientists have proposed an intriguing theory on our universe’s rapid expansion.
For years, scientists have grappled with the enigma of the universe expanding rapidly.
Observations like the redshift of galaxies and the cosmic microwave background hint at this cosmic phenomenon, but a complete explanation remains elusive.
A theoretical study has now provided an intriguing explanation: our universe’s expansion may be driven by the collisions and mergers with other universes, colloquially referred to as “baby” parallel universes.
Theoretical predictions have been confirmed with the discovery of an outflow of molecular gas from a quasar when the Universe was less than a billion years old.
A quasar is a compact region powered by a supermassive black hole located in the center of a massive galaxy.
They are extremely luminous, with a point-like appearance similar to stars, and are extremely distant from Earth.
Ever since the James Webb Space Telescope (JWST) captured its first glimpse of the early universe, astronomers have been surprised by the presence of what appear to be more “ultramassive” galaxies than expected. Based on the most widely accepted cosmological model, they should not have been able to evolve until much later in the history of the universe, spurring claims that the model needs to be changed.
This would upend decades of established science.
“The development of objects in the universe is hierarchical. You start small and get bigger and bigger,” said Julian Muñoz, an assistant professor of astronomy at The University of Texas at Austin and co-author of a recent paper published in Physical Review Letters that tests changes to the cosmological model. The study concludes that revising the standard cosmological model is not necessary. However, astronomers may have to revisit what they understand about how the first galaxies formed and evolved.
Last year, the Keck Cosmic Web Imager, also atop Maunakea, caught the first direct light emanating from wispy web filaments that cross one another and stretch across the darkest corners of space. These are filaments that sit isolated between galaxies, in the largest and most hidden portions of the cosmic web.
“Seeing” the location of dark matter around these cosmic web strands is a completely different story, however.
That’s because, despite making up an estimated 85% of all the matter in the universe, dark matter is invisible because it doesn’t interact with light like everyday matter that comprises stars and dust does.
ESA’s Euclid mission was launched in July 2023 and has already sent home test images showing that its instruments are ready to go. Now, the space telescope begins mapping huge swaths of the sky, focusing on an area for 70 minutes at a time. Throughout its 6-year mission, it will complete 40,000 of these ‘pointings’, eventually observing 1.5 billion galaxies in the sky. Astronomers will use this map to measure how dark matter and dark energy have changed over time.
The interior of black holes remains a conundrum for science. In 1916, German physicist Karl Schwarzschild outlined a solution to Albert Einstein’s equations of general relativity, in which the center of a black hole consists of a so-called singularity, a point at which space and time no longer exist. Here, the theory goes, all physical laws, including Einstein’s general theory of relativity, no longer apply; the principle of causality is suspended.
This constitutes a great nuisance for science—after all, it means that no information can escape from a black hole beyond the so-called event horizon. This could be a reason why Schwarzschild’s solution did not attract much attention outside the theoretical realm—that is, until the first candidate for a black hole was discovered in 1971, followed by the discovery of the black hole in the center of our Milky Way in the 2000s, and finally the first image of a black hole, captured by the Event Horizon Telescope Collaboration in 2019.
In 2001, Pawel Mazur and Emil Mottola proposed a different solution to Einstein’s field equations that led to objects that they called gravitational condensate stars, or gravastars. Contrary to black holes, gravastars have several advantages from a theoretical astrophysics perspective.