Lifeboat Foundation

Most people think of space as a flat sheet: You travel in one direction, and you end up far from your starting point. But a new paper suggests that the universe may in fact be spherical: If you travel far enough in the same direction, you’d end up back where you started.

Based on Einstein’s theory of relativity, space can bend into different shapes, so scientists assume the universe must be either open, flat, or closed. Flat is the easiest shape to understand: it is how we experience space in our everyday lives, as a plane in which a beam of light would extend off into infinity. An open universe would be saddle-shaped, with a beam of light bending across the curvature. And a closed universe would be a sphere, with a beam of light eventually looping back around it to meet its origin.

In order to tell which shape our universe is, scientists can look at a phenomenon called the cosmic microwave background (CMB). This is the electromagnetic radiation which remains from the Big Bang, also called “relic radiation.” It fills all of space and can be detected with a sufficiently powerful radio telescope.

The XENON experiment recently made a breakthrough in their hunt for dark matter, observing the most rare decay process in the Universe that involves neutrinos.

Wielding state-of-the-art technologies and techniques, a team of Clemson University astrophysicists has added a novel approach to quantifying one of the most fundamental laws of the universe.

In a paper published Friday, Nov. 8, in The Astrophysical Journal, Clemson scientists Marco Ajello, Abhishek Desai, Lea Marcotulli and Dieter Hartmann have collaborated with six other scientists around the world to devise a new measurement of the Hubble Constant, the unit of measure used to describe the rate of expansion of the universe.

“Cosmology is about understanding the evolution of our universe—how it evolved in the past, what it is doing now and what will happen in the future,” said Ajello, an associate professor in the College of Science’s department of physics and astronomy. “Our knowledge rests on a number of parameters—including the Hubble Constant—that we strive to measure as precisely as possible. In this paper, our team analyzed data obtained from both orbiting and ground-based telescopes to come up with one of the newest measurements yet of how quickly the universe is expanding.”

A group of Skoltech researchers led by Professor Anatoly Dymarsky studied the emergence of generalized thermal ensembles in quantum systems with additional symmetries. As a result, they found that black holes thermalize the same way ordinary matter does. The results of their study were published in Physical Review Letters.

The physics of black holes remains an elusive chapter of modern physics. It is the sharpest point of tension between quantum mechanics and the theory of general relativity. According to quantum mechanics, black holes should behave like other ordinary quantum systems. Yet, there are many ways in which this is problematic from the point of view of Einstein’s theory of general relativity. Therefore, the question of understanding black holes quantum mechanically remains a constant source of physical paradoxes. The careful resolution of such paradoxes should provide us a clue as to how quantum gravity works. That is why the physics of black holes is the subject of active research in theoretical physics.

One particularly important question is how black holes thermalize. A recent study undertaken by a group of Skoltech researchers found that in this regard black holes are not that different from ordinary matter. Namely, the emergence of equilibrium can be explained in terms of the same mechanism as in the conventional case. An analytical study of black holes became possible due to the rapidly developing theoretical tools of the so-called holographic duality. This duality maps certain types of conventional quantum systems to particular cases of quantum gravity systems. Although additional work is necessary to extend this similarity to thermalization dynamics, this work provides additional support for the paradigm that important aspects of black holes and quantum gravity, in general, can be explained in terms of the collective dynamics of conventional quantum many-body systems.

Astronomers have finally found the last of the missing universe. It’s been hiding since the mid-1990s, when researchers decided to inventory all the “ordinary” matter in the cosmos—stars and planets and gas, anything made out of atomic parts. (This isn’t “dark matter,” which remains a wholly separate enigma.) They had a pretty good idea of how much should be out there, based on theoretical studies of how matter was created during the Big Bang. Studies of the cosmic microwave background (CMB)—the leftover light from the Big Bang—would confirm these initial estimates.

So they added up all the matter they could see—stars and gas clouds and the like, all the so-called baryons. They were able to account for only about 10 percent of what there should be. And when they considered that ordinary matter makes up only 15 percent of all matter in the universe—dark matter makes up the rest—they had only inventoried a mere 1.5 percent of all matter in the universe.

Now, in a series of three recent papers, astronomers have identified the final chunks of all the ordinary matter in the universe. (They are still deeply perplexed as to what makes up dark matter.) And despite the fact that it took so long to identify it all, researchers spotted it right where they had expected it to be all along: in extensive tendrils of hot gas that span the otherwise empty chasms between galaxies, more properly known as the warm-hot intergalactic medium, or WHIM.

Everything we think we know about the shape of the universe could be wrong. Instead of being flat like a bedsheet, our universe may be curved, like a massive, inflated balloon, according to a new study.

That’s the upshot of a new paper published today (Nov. 4) in the journal Nature Astronomy, which looks at data from the cosmic microwave background (CMB), the faint echo of the Big Bang. But not everyone is convinced; the new findings, based on data released in 2018, contradict both years of conventional wisdom and another recent study based on that same CMB data set.

Related: From Big Bang to Present: Snapshots of Our Universe Through Time.

DESI will map millions of galaxies and measure how fast they’re moving. This dataset can tell astronomers how much dark energy exists and how that’s changed.

There are a lot of unsolved mysteries in the Universe, but dark energy is the most confusing. Here’s why.

A trio of researchers with the University of Manchester, Università di Roma ‘La Sapienza’ and Sorbonne Universities has sparked a major debate among cosmologists by claiming that data from the Planck space observatory suggests the universe is a sphere—not flat, as current conventional theory suggests. In their paper published in the journal Nature Astronomy, Eleonora Di Valentino, Alessandro Melchiorri and Joseph Silk outline their arguments and suggest their findings indicate that there exists a cosmological crisis that must be addressed.

Conventional theory, which backs inflation theory, suggests that after the Big Bang, the universe expanded in a way that was flat—two lights shone in parallel would travel forever in parallel. But now, after studying data sent back to Earth from the Planck space observatory (which mapped cosmic microwave background radiation over the years 2009 to 2013) Di Valentino, Melchiorri and Silk have come to disagree with conventional thinking. They claim that there is evidence that the universe is closed—that it is shaped like a sphere. If you shine two lights into the dark of space, they suggest, at some point, the light would come back around to you from behind.

The researchers came to this conclusion after looking at data from the Planck space observatory that showed a discrepancy between the concentration of dark matter and dark energy and outward expansion; there was more gravitational lensing than theory has predicted. Such an imbalance, they claim, would have the universe collapsing in on itself, resulting in a sphere shape. Others who have looked at the same data prior to this new effort have called the data from the observatory a statistical fluke. The research trio note that there are other problems with the flat theory as well, such as scientists’ inability to accurately measure the Hubble constant; each team that tries finds a different answer. There have also been problems with reconciling surveys of dark energy with a flat model.