Do they have real, observable effects, or are they merely calculational tools?

Is it groupthink? Or is there a deeper reason? In the early half of the 20th century, even after the discovery of the expanding Universe, physicists considered a wide variety of […]

Deniers will never stop misleading others. Here’s the truth. Every so often, advocates of a fringe theory — one that doesn’t fit the evidence as well as the mainstream theory — do what they can […]

We have to use the right definition for the specific question we’re asking. When it comes to the Universe, we frequently characterize objects by examining and reporting on their physical […]

Cosmic rays aren’t just limited by the speed of light. Even among non-scientists, it’s well-understood that there’s an ultimate speed limit to the Universe: the speed of light. If you’re a […]

And which ones are probably examples where we’ve fooled ourselves? Every once in a while — multiple times per year — a new research finding fails to line up with our theoretical expectations. In […]

And, at some point, did the Milky Way lose ours? There are some 400 billion objects flying through the Milky Way galaxy with enough mass that — if they were all made of […]

Complex organisms and living worlds couldn’t exist without these transitions. You couldn’t make the Universe we have today if everything were always the same. Although many philosophically favored the idea […]

We can describe what we see happening, but we don’t understand why. Despite our vast cosmic knowledge, enormous unknowns remain. The quantum fluctuations inherent to space, stretched across the Universe […]

We’ve almost got the entire story. James Webb will put the last piece into place. In all of science, there are really only two ways that something can be “known” to […]

The Big Theoretical Physics Problem At The Center Of The ‘Muon g-2’ Puzzle In early April, 2021, the experimental physics community announced an enormous victory: they had measured the muon’s magnetic […]

And could Earth-based life provide the seeds for biology elsewhere? Today, on Earth, there’s an enormous variety and diversity of life on our planet. Every single surviving lifeform appears, in […]

Even 13.8 billion years after the Big Bang, we can reconstruct the first 3 minutes. About 100 years ago, we began to truly understand the nature of the Universe for the […]

Enough mass in one location will always create a black hole. But not all masses are possible. If you take enough mass and compress it into a small enough volume […]

When you measure not just light, but light’s polarization, you learn so much more. It’s been over 100 years since the first solution for a black hole was discovered in General […]

Something isn’t adding up, but it isn’t a calibration error. It’s been nearly 100 years since we discovered that the Universe was expanding. Ever since, the scientists who study the […]

Both views are equally spectacular, but unequally informative. Every so often, a creative amateur project highlights our professional achievements. This mosaic shows the region between the constellations of Cygnus and […]

Is a proton fundamentally more ‘quarky’ or ‘gluey’ in nature? One question that every curious child winds up asking at some point or other is, “what are things made of?” Every […]

One image can give over 100 times the data we now get from Hubble. NASA’s Hubble Space Telescope, launched in 1990, revealed the previously unseen Universe. The most distant galaxy ever […]

It’s how successful our current theories are. Some 500 years ago, there was one scientific phenomenon that was, without controversy, extremely well-understood: the motion of the celestial objects in the sky. […]

Even before the Big Bang, energetic radiation was always present. When it comes to the physical Universe, the notion of “nothing” may truly be possible only in theory, not in […]

It could have had any curvature at all. So why is it flat? What is the shape of the Universe? If you had come along before the 1800s, it likely never […]

And what might we learn as we collect new, never-before-seen data? If you took one of history’s top scientists from 100 years ago and dropped them into today’s world, what […]

The Universe’s idea of a ‘typical star’ has changed dramatically over time. When you look out at the Universe today, you’re not seeing it exactly as it is at one particular […]

Dark matter was thought to be cold and collisionless. But maybe that’s not the full story. If you look out at the Universe and measure all the matter out there, including […]

If you want to get the Universe we see, a multiverse comes along for the ride. When we look out at the Universe today, it simultaneously tells us two stories about […]

‘Reductio ad absurdum’ won’t help you in an absurd Universe. Throughout history, there have been two main ways humanity has attempted to gain knowledge about the world: top-down, where we […]

By the end of the decade, we may discover one million black holes. A large enough mass in a compact volume inevitably forms a black hole. Both inside and outside the […]

The definitive answer requires better, unbiased data. Despite all the advances that have occurred in human history, one extraordinary puzzle still remains right in our own backyard: we aren’t sure how […]

Are space and time real like atoms are, or is spacetime just a calculational tool? When most of us think about the Universe, we think about the material objects that […]