large scale universe


The Huge-LQG (Large Quasar Group)

The Huge-LQG is a possible structure that could be one of the largest in the known universe. Having originally been identified as the largest, the Hercules-Corona Borealis Great Wall is bigger at 10 billion light years.

The Huge-LQG consists of 73 quasars, a quasar being a class of active galactic nuclei is essentially a superheated region of gas and dust that surrounds a supermassive black hole typically being 10-10,000 times the size of the Schwarzschild radius of the black hole. The existence of this structure defies Einstein’s cosmological principal which states that at large scales, the universe is approximately homogenous (meaning that the fluctuation in matter density throughout space can be considered small). It’s around 9 billion light years away from us, has a length of 1.24 gigaparsecs which is 4.0443 billion light years and a solar mass of 6.1 quintillion (that’s 6.1 quintillion times the mass of our sun and our sun is approximately 2 nonillion kg’s)!


Ask Ethan: Is this actually a hole in the Universe?

“What do you do about people and entities who actively harm the amount of knowledge that the general populace has in the world? After all, the opposite of knowledge isn’t ignorance, but rather misinformation posing as knowledge.”

There are plenty of scientific myths that go around, including many that were generated recently by so-called science communicators that actively harm public knowledge. One of them was a now-famous image of a dark nebula silhouetted against a star field, claiming that this was a hole in the Universe a billion light years across with no matter in it. Not only is the image itself a completely different picture – that of a tiny molecular gas cloud just 500 light years away – but the study that led to the conclusion of a “hole in the Universe” has that as only one of many possible interpretations. Far more likely is that we’re simply looking at a large, underdense region that’s well within the range of what’s normal and expected for our Universe.

Go get the full story on this week’s Ask Ethan!


Is Dark Matter Required For Life To Exist?

“Dark matter is the most mysterious, non-interacting substance in the Universe. Its gravitational effects are necessary to explain the rotation of galaxies, the motions of clusters, and the largest scale-structure in the entire Universe. But on smaller scales, it’s too sparse and diffuse to impact the motion of the Solar System, the matter here on Earth, or the origin and evolution of humans in any meaningful way. Yet the gravity that dark matter provides is an absolute necessity for allowing our galaxy to hold onto the raw ingredients that made life like us and planets like Earth possible at all. Without dark matter, the Universe would likely have no signs of life at all.”

Making up some 85% of the mass in our Universe, dark matter is necessary to explain the motions of individual galaxies, the grouping and clustering of assemblies of galaxies, the large-scale structure of the Universe and more. But on a much closer-to-home level, dark matter may be absolutely essential to the origin of life, too! Without dark matter, supernova explosions and starburst events would still create copious amounts of heavy elements, driven outwards by winds and the force of the explosions. But it’s the extra gravity of the dark matter that prevents most of this material from escaping, and allows it to take part in the formation of future generations of stars, to participate in rocky planet formation, and to deliver the ingredients necessary for life.

Go get the whole, detailed story today, and find out why life needs dark matter to exist after all!


The early Universe’s most massive galaxy cluster revealed

“Discovered by Spitzer, it was rediscovered in archival Chandra data, and then reimaged for 28 hours. Also captured by Hubble, this cluster may, by today, be the most massive one in the visible Universe.”

13.8 billion years ago, the Universe as we know it was born with no stars, no clusters and no galaxies. But over time, gravitation has built up all sorts of complex structures, with the largest galaxy cluster today, El Gordo, weighing in at 3 quadrillion Suns. But back when the Universe was just a quarter of its present age, the cluster IDCS J1426.5+3508 already has a mass of 500 trillion Suns, a mass that’s been measured by three different methods. By time we fast-forward to today, this cluster is probably the most massive one contained within our visible Universe.


Throwback Thursday: The Little Bit Of Dark Matter We Know

“While large-scale structure tells us that the vast majority of the dark matter must be either cold or warm, we know that there is a tiny bit of hot dark matter, and that’s in fact what the neutrinos are! So while the large scale structure in the Universe agrees […] with cold dark matter […] we know that there’s a tiny mix — between 0.55% and 1.6% — of Hot Dark Matter, in the form of neutrinos, thrown in there!”

When Fritz Zwicky first calculated what the mass of a galaxy cluster needed to be to keep its galaxies moving at the observed speeds and compared it with the masses due to the starlight he saw, there was a huge discrepancy. The amount of gravity in the Universe, when compared to the amount of visible matter, didn’t match. Adding up all the known sources of normal matter didn’t quite get us there, either: only one-sixth of the matter can be made of protons, neutrons and electrons. The other 83% or so must be some form of dark matter, which is yet undiscovered. Well, except for around 1% of it, which we actually know must be in the form of neutrinos.