Cosmology Archives

January 23, 2021January 23, 2021 by Brian Koberlein

In Theory, Supermassive Black Holes Could get Even More Supermassive

Artist view of a stupendously large black hole. Credit: NASA, ESA, and D. Coe, J. Anders

Our universe contains some enormous black holes. The supermassive black hole in the center of our galaxy has a mass of 4 million Suns, but it’s rather small as galactic black holes go. Many galactic black holes have a billion solar masses, and the most massive known black hole is estimated to have a mass of nearly 70 billion Suns. But just how big can a black hole get?

January 10, 2021January 15, 2021 by Brian Koberlein

There's no way to Measure the Speed of Light in a Single Direction

Special relativity is one of the most strongly validated theories humanity has ever devised. It is central to everything from space travel and GPS to our electrical power grid. Central to relativity is the fact that the speed of light in a vacuum is an absolute constant. The problem is, that fact has never been proven.

December 28, 2020December 28, 2020 by Brian Koberlein

New Data Supports the Modified Gravity Explanation for Dark Matter, Much to the Surprise of the Researchers

A falling apple. Credit: Bithin raj / Unsplash

Dark matter is an extremely good theory. It’s supported by a wealth of observational and computational data, which is why it’s part of the standard model of cosmology. But dark matter hasn’t been directly observed, so sometimes even strong supporters of dark matter are motivated to look at the alternatives.

December 18, 2020December 18, 2020 by Brian Koberlein

A new Type of Atomic Clock Uses Entangled Atoms. At Most, it Would be off by 100 Milliseconds Since the Beginning of the Universe

Lasers are used to squeeze atoms and entangle them. Credit: MIT

Measuring time is about counting steps. Whether it’s the drip-drip of a water clock, the tic-toc of a mechanical clock, or the oscillating crystal of a quartz watch. Any accurate timepiece is built around counting the steps of something regular and periodic. Nothing is perfectly regular, so no clock keeps perfect time, but our timepieces are getting very, very accurate.

December 2, 2020December 2, 2020 by Brian Koberlein

Neutrinos Have Played a Huge Role in the Evolution of the Universe

Computer simuations show how neutrinos can form cosmic clumpiness. Credit: Yoshikawa, Kohji, et al

It’s often said that we haven’t yet detected dark matter particles. That isn’t quite true. We haven’t detected the particles that comprise cold dark matter, but we have detected neutrinos. Neutrinos have mass and don’t interact strongly with light, so they are a form of dark matter. While they don’t solve the mystery of dark matter, they do play a role in the shape and evolution of our universe.

November 28, 2020November 29, 2020 by Matthew Cimone

One of These Pictures Is the Brain, the Other is the Universe. Can You Tell Which is Which?

Left: section of cerebellum, with magnification factor 40x, obtained with electron microscopy (Dr. E. Zunarelli, University Hospital of Modena); right: section of a cosmological simulation, with an extension of 300 million light-years on each side (Vazza et al. 2019 A&A).

“Science is not only compatible with spirituality; it is a profound source of spirituality. When we recognize our place in an immensity of light years and in the passage of ages, when we grasp the intricacy, beauty and subtlety of life, then that soaring feeling, that sense of elation and humility combined, is surely spiritual.” – Carl Sagan “The Demon-Haunted World.”

Learning about the Universe, I’ve felt spiritual moments, as Sagan describes them, as I better understand my connection to the wider everything. Like when I first learned that I was literally made of the ashes of the stars – the atoms in my body spread into the eternal ether by supernovae. Another spiritual moment was seeing this image for the first time:

Hippocampal mouse neuron studded with synaptic connections (yellow), courtesy Lisa Boulanger, from https://www.eurekalert.org/multimedia/pub/81261.php. The green central cell body is ? 10µm in diameter. B. Cosmic web (Springel et al., 2005). Scale bar = 31.25 Mpc/h, or 1.4 × 1024 m. Juxtaposition inspired by Lima (2009).

November 23, 2020November 23, 2020 by Brian Koberlein

Gravitational lenses could be the key to measuring the expansion rate of the Universe

Illustration of gravity waves from a neutron star merger. Credit: NRAO/AUI/NSF

One of the tenets of our cosmological model is that the universe is expanding. For reasons we still don’t fully understand, space itself is stretching over time. It’s a strange idea to wrap your head around, but the evidence for it is conclusive. It is not simply that galaxies appear to be moving away from us, as seen by their redshift. Distant galaxies also appear larger than they should due to cosmic expansion. They are also distributed in superclusters separated by large voids. Then there is the cosmic microwave background, where even its small fluctuations in temperature confirm cosmic expansion.

October 9, 2020October 9, 2020 by Paul M. Sutter

Matter makes up exactly 31.5±1.3% of the Universe

dark matter shown in blue — This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J0416. This is one of six clusters that was studied by the Hubble Frontier Fields programme, which yielded the deepest images of gravitational lensing ever made. Scientists used intracluster light (visible in blue) to study the distribution of dark matter within the cluster.

Weighing the universe is a tricky task, but a team of astronomers have used a clever technique to measure how many galaxy clusters are in the cosmos, and from there come up with a total amount of matter. The answer: 31.5±1.3% of all the energy in the universe.

October 8, 2020October 8, 2020 by Brian Koberlein

Gravitational-Wave Lensing is Possible, but it’s Going to be Incredibly Difficult to Detect

This diagram shows how Hubble is able to observe a quasar, a glowing disc of matter around a distant black hole, even though the black hole would ordinarily be too far away to see clearly. Credit: NASA and ESA

Gravity is a strange thing. In our everyday lives, we think of it as a force. It pulls us to the Earth and holds planets in orbits around their stars. But gravity isn’t a force. It is a warping of space and time that bends the trajectory of objects. Throw a ball in deep space, and it moves in a straight line following Newton’s First Law of Motion. Throw the same ball near the Earth’s surface, and it follows a parabolic trajectory caused by Earth’s warping of spacetime around it.

September 17, 2020September 17, 2020 by Brian Koberlein

Colliding Neutron Stars Don’t Make Enough Gold to Explain What We See in the Universe

gamma-ray burst from neutron star merger — Artist rendering of colliding neutron stars. Credit: Robin Dienel/Carnegie Institution for Science

In the beginning, the universe created three elements: hydrogen, helium, and lithium. There isn’t much you can do with these simple elements, other than to let gravity collapse them into stars, galaxies, and black holes. But stars have the power of alchemy. Within their hearts, they can fuse these elements into new ones. Carbon, nitrogen, oxygen, and others, all up to the heavy element of iron. When these first stars exploded, they scattered the new elements across the cosmos, creating planets, new stars, and even us.