A visual history of the expanding Universe includes the hot, dense state known as the Big Bang and the growth and formation of structure subsequently. The full suite of data, including the observations of the light elements and the cosmic microwave background, leaves only the Big Bang as a valid explanation for all we see. As the Universe expands, it also cools, enabling ions, neutral atoms, and eventually molecules, gas clouds, stars, and finally galaxies to form. Without the Higgs giving mass to the particles in the Universe at a very early, hot stage, none of this would have been possible ..read more

In a hypertorus model of the Universe, motion in a straight line will return you to your original location, even in an uncurved (flat) spacetime. Without access to a higher-dimensional view of what our 3D world appears to be like to us, we cannot know or measure its true extent and shape in space. (Credit: ESO/J. Law)Is the Universe finite or infinite? Does it go on forever or loop back on itself? Here’s what would happen if you traveled forever. The Universe is a vast, wondrous, and strange place. From our perspective within it, we can see out for some 46 billion light-years in all ..read more

Today, the Universe has evolved into the complex, life-friendly place we know it to be because we were able to form neutral atoms early on in the Universe. Yet without just the right quantum properties, the formation of stable, neutral atoms would have been delayed significantly, or might not have even occurred at all. (Credit: agsandrew / Adobe Stock and remotevfx / Adobe Stock)No matter how good our measurement devices get, certain quantum properties always possess an inherent uncertainty. Can we figure out why? Perhaps the most bizarre property we’ve discovered about the Universe ..read more

At left is the iconic view of the Pillars of Creation as seen by Hubble. Beginning in 2022, JWST (at right) has viewed the pillars as well, revealing details such as newly forming stars, faint protostars, and cool gas that are invisible to even Hubble’s impressive capabilities. (Credits: NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI))There are so many problems, all across planet Earth, that harm and threaten humanity. Why invest in researching the Universe? It’s no secret that there is a seemingly endless string of problems to address in ..read more

Axions, one of the leading candidates for dark matter, may be able to be converted to photons (and vice versa) under the right conditions. If we can cause and control their conversion, we might discover our first particle beyond the Standard Model, and possibly solve the dark matter and strong CP problems as well. This would imply that we do live in a Universe with strong CP-violation, but only a tiny amount of it: below the experimental and observational thresholds. (Credit: Sandbox Studio, Chicago, Symmetry Magazine/Fermilab and SLAC)The majority of the matter in our Universe isn’t made ..read more

If you look farther and farther away, you also look farther and farther into the past. If the number of galaxies, the densities and properties of those galaxies, and other cosmic properties like the temperature and expansion rate of the Universe didn’t appear to change, you’d have evidence of a Universe that was constant in time; that is not what we see. (Credit: NASA/ESA/STScI/A. Feild)The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age? According to the theory of the hot Big Bang, the Universe had a beginnin ..read more

This image shows the magnetized galactic center, with various features highlighted, as imaged by the SOFIA/HAWC+ FIREPLACE survey team. The giant bubble at the left of the image is some 30 light-years wide, several times larger than any other supernova-blown bubble ever discovered. (Credit: D. Paré et al., arXiv:2401.05317v2, 2024)Starts With A Bang podcast #104 — The magnetized galactic center The center of the galaxy doesn’t just host stars and a black hole, but an enormous set of rich gassy and dusty features. Find out more! Have you ever wondered what the full story with the gala ..read more

The original “blue Marble” image, from Apollo 17, was actually snapped in the orientation shown here: where south is at the top and north is (invisibly) on the other side of the world. This image is now more than 50 years old, as humanity has transformed our planet in a myriad of ways both leading up to, and since, this image was obtained. (Credit: NASA/Lunar and Planetary Institute)Although human beings arrived on Earth just ~300,000 years ago, we’ve transformed the entire planet completely. Here’s how we did it. When each of us is first born into this world, it might feel like the world ..read more

70,000 years ago, a brown dwarf pair known as Scholz’s Star, right on the precipice of igniting hydrogen fusion in its core, passed through the Solar System’s Oort cloud. Stars, failed stars, and stellar remnants pass through our Solar System multiple times every million years. Both modern humans and Neanderthals were likely around to see this event. Unlike the illustration, however, it’s so intrinsically faint that it still wouldn’t have been visible to human eyes; today, it’s approximately 22 light-years away. (Credit: José A. Peñas/SINC)Despite billions of years of life on Earth, humans fir ..read more

During the Cambrian explosion, some 550–600 million years ago, the first complex, differentiated, macroscopic, multicellular, sexually-reproducing animals came to dominate the oceans. Over the next half a billion years, evolution would take life in many different directions. By the time the asteroid eliminating the dinosaurs arrived, 65 million years ago, mammals had diversified in a number of directions, with the earliest primates splitting off just before that great event. Modern lemurs, shown here, likely bear a strong resemblance to those early primates. (Credit: Bas Czerwinski/AFP/Getty I ..read more