Cosmology Archives

January 1, 2025January 1, 2025 by Brian Koberlein

New Study of Supernovae Data Suggests That Dark Energy is an Illusion

The evolution of the Universe as we know it. Credit: NASA

Dark energy is central to our modern understanding of cosmology. In the standard model, dark energy is what drives the expansion of the Universe. In general relativity, it’s described by a cosmological constant, making dark energy part of the structure of space and time. But as we’ve gathered more observational evidence, there are a few problems with our model. For one, the rate of cosmic expansion we observe depends on the observational method we use, known as the Hubble tension problem. For another, while we assume dark energy is uniform throughout the cosmos, there are some hints suggesting that might not be true. Now a new study argues we’ve got the whole thing wrong. Dark energy, the authors argue, doesn’t exist.

December 23, 2024December 17, 2024 by Paul M. Sutter

Is the Universe a Fractal?

formation of complex symmetrical and fractal patterns in snowflakes exemplifies emergence in a physical system.

For decades cosmologists have wondered if the large-scale structure of the universe is a fractal: if it looks the same no matter the scale. And the answer is: no, not really. But in some ways, yes. Look, it’s complicated.

December 18, 2024December 18, 2024 by Evan Gough

The JWST Looked Over the Hubble’s Shoulder and Confirmed that the Universe is Expanding Faster

These 36 galaxies all contain Type 1a supernovae and Cepheid variables. They serve as standard distance markers used to measure how fast the Universe is expanding. Image Credit: NASA, ESA, Adam G. Riess (STScI, JHU)

It’s axiomatic that the Universe is expanding. However, the rate of expansion hasn’t remained the same. It appears that the Universe is expanding more quickly now than it did in the past.

Astronomers have struggled to understand this and have wondered if the apparent acceleration is due to instrument errors. The JWST has put that question to rest.

December 12, 2024December 12, 2024 by Mark Thompson

Another Clue About the Ultra-High Energy Cosmic Rays: Magnetic Turbulence

Artist's illustration of ultra-high energy cosmic rays

Space largely seems quite empty! Yet even in the dark voids of the cosmos, ultra-high-energy cosmic rays are streaming through space. The rays contain 10 million times as much energy as the Large Hadron Collider can produce! The origin of the rays though is still the source of many a scientific debate but they are thought to be coming from some of the most energetic events in the universe. A new paper suggests the rays may be linked to magnetic turbulence, coming from regions where magnetic fields get tangled and twisted up.

December 9, 2024December 9, 2024 by Mark Thompson

Has the Universe Been Designed to Support Life? Now We Have a Way to Test it!

NASA's Hubble Space Telescope provided one of the deepest, most detailed visible views of the universe. The field is a very small sample of the heavens and it is observations like this that raise questions like those posed by the anthropic principle. Credit: R. Williams (STScI), the Hubble Deep Field Team and NASA/ESA

The anthropic principle states that the fundamental parameters of the Universe such as the strength of the fundamental forces, have been finely tuned to support life. Whether this is true or not or whether it is even worthy of scientific investigation has been hotly debated. A new paper proposes some ways that this may now be tested and perhaps brings the topic under scientific scrutiny for the first time.

December 9, 2024December 9, 2024 by Evan Gough

Webb Sees a Supercluster of Galaxies Coming Together

Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers have found new galaxies in the Spiderweb protocluster. Because Webb can see infrared light very well, scientists used it to observe regions of the Spiderweb that were previously hidden to us by cosmic dust, and to find out to what degree this dust obscures them. This image shows the Spiderweb protocluster as seen by Webb’s NIRCam (Near-InfraRed Camera). Image Credit: ESA/Webb, NASA & CSA, H. Dannerbauer

As a species, we’ve come to the awareness that we’re a minuscule part of a vast Universe defined by galaxy superclusters and the large-scale structure of the Universe. Driven by a healthy intellectual curiosity, we’re examining our surroundings and facing the question posed by Nature: how did everything get this way?

We only have incremental answers to that huge, almost infinitely-faceted question. And the incremental answers are unearthed by our better instruments, including space telescopes, which get better and more capable as time passes.

Enter the James Webb Space Telescope.

December 8, 2024December 8, 2024 by Brian Koberlein

Observations by DESI Open the Door to Modified Gravity Models

The relations between various approaches of modified gravity. Credit: J. M. Ezquiaga and M. Zumalacárregui (2018)

The standard theory of cosmology is based upon four things: the structure of space and time, matter, dark matter, and dark energy. Of these, dark energy is the one we currently understand the least. Within the standard model, dark energy is part of the structure of space and time as described by general relativity. It is uniform throughout the cosmos and expressed as a parameter known as the cosmological constant. But initial observations from the Dark Energy Spectroscopic Instrument (DESI) suggest the rate of comic expansion may vary over time. If further observations reinforce this, it could open up cosmological models to alternatives to general relativity known as modified gravity.

December 5, 2024December 5, 2024 by Brian Koberlein

Cosmology is at a Crossroads, But New Instruments are Coming to Help

Illustration of the accelerating expansion of the universe. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

Our understanding of the Universe is profound. Only a century ago, astronomers held a Great Debate to argue over whether our galaxy was an island universe, or whether nebulae such as Andromeda were galaxies in a much larger cosmos. Now we know that the Universe is billions of years old, ever expanding to billions of light-years across, and filled with not just stars and galaxies but with dark energy and cold dark matter. Astronomers summarize this understanding as the LCDM model, which is the standard model of cosmology. While the observational data we have strongly supports this model, it is not without its challenges.

December 3, 2024December 3, 2024 by Evan Gough

Could Primordial Black Holes Be Hiding in Plain Sight?

An artistic take on primordial black holes. Credit: NASA’s Goddard Space Flight Center

Are Primordial Black Holes real? They could’ve formed in the unusual physics that dominated the Universe shortly after the Big Bang. The idea dates back to the 1960s, but so far, the lack of evidence makes them purely hypothetical.

If they do exist, a new paper suggests they may be hiding in places so unlikely that nobody ever thought to look there.

November 29, 2024November 29, 2024 by Evan Gough

A Superfast Supercomputer Creates the Biggest Simulation of the Universe Yet

These images are a small sample from the Frontier supercomputer simulations. They reveal the evolution of the expanding universe in a region containing a massive cluster of galaxies from billions of years ago to present day (left). Red areas show hotter gasses, where temperatures reach 100 million Kelvin or more. The panel on the right is a zoom-in, where star tracer particles track the formation of galaxies and their movement over time. Credit: Argonne National Laboratory, U.S Dept of Energy

Scientists at the Department of Energy’s Argonne National Laboratory have created the largest astrophysical simulation of the Universe ever. They used what was until recently the world’s most powerful supercomputer to simulate the Universe at an unprecedented scale. The simulation’s size corresponds to the largest surveys conducted by powerful telescopes and observatories.