Above the central array of the Atacama Large Millimetre/Submillimetre Array (ALMA), the southern celestial pole…

Whenever you take a look out at the Universe and record what you see, you’re engaging in one of the oldest sciences there is: astronomy. Similarly, whenever you investigate how a physical phenomenon in the Universe works — on quantum, classical, or cosmic scales — including by puzzling out or…

This artist’s illustration depicts how the foamy structure of space-time may appear, showing tiny bubbles quadrillions of times smaller than the nucleus of an atom that are constantly fluctuating and last for only infinitesimal fractions of a second. Rather than being smooth, continuous, and uniform, at the quantum scale, spacetime has fluctuations inherent to it. Although we strongly suspect that gravity is quantum in nature, we can only be sure via experiment. (Credit: NASA/CXC/M. Weiss)

If you were to break down the matter in our Universe to its smallest, most fundamental subatomic constituents, you’d find that everything was made up of individual quanta, each of which possesses both wave and particle properties simultaneously. If you pass one of these quantum particles through a double-slit and…

At any epoch in our cosmic history, any observer will experience a uniform “bath” of…

Whenever we want to understand what’s going to happen to an object when we place it in an environment that’s unfamiliar, there are a few properties we need to know about that environment itself. One of them, unflaggingly, is temperature. Whether something becomes solid, liquid, gas, or plasma depends on…

Apollo 11 brought humans onto the surface of the Moon for the first time in…

In all of human history, only 24 people have ever flown to the vicinity of the Moon, traveling hundreds of thousands of miles from Earth to do so. Twelve of those people, on six independent missions, actually set foot on the lunar surface. We’ve left behind flags, photographs, seismometers, mirrors…

The ‘raisin bread’ model of the expanding Universe, where relative distances increase as the space…

Whenever you have a puzzle, you have every right to expect that any and all correct methods should lead to you to same solution. This applies not only to the puzzles we create for our fellow humans here on Earth, but to even the deepest puzzles that nature itself has…

An event like AT2018cow, now known as either FBOTs or Cow-like events, is thought to…

Every once in a while, a stellar cataclysm occurs in our Universe, bringing the life of a star to an end. The most common type of cataclysm is a core-collapse supernova, where a massive star’s interior implodes, leading to a runaway fusion reaction and a tremendous explosion, where the energy…

This image shows the supernova remnant of SN 1987a in six different wavelengths of light…

Some stars die of natural causes. Others meet a grizzlier fate. As they go through their life cycles, most stars will die on time, right when they’re supposed to, as determined by their initial masses. They’ll burn through their fuel until they can fuse elements no longer, and then…

This image shows a depiction of a solar sail, and in particular of the sail…

For all of human history, embarking upon an interstellar journey has been a seemingly unreachable dream, made practically impossible by the enormous distances separating our Sun from any of our stellar neighbors. Even with the most powerful rocket technology ever developed, it would take tens of thousands of years to…

Ethan Siegel

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

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