Category: SCIENCE

Scientists just viewed one of the tiniest, most isolated, lowest-mass galaxies ever found with JWST. Despite all odds, it’s still growing.

Here in our cosmic neighborhood, galaxies come in all sorts of sizes, masses, and shapes. The largest, most massive galaxies in the Local Group are the Milky Way and our big sister, Andromeda: two galaxies representative of modern large spirals. While galaxies like our own are easy to find all throughout the Universe, they’re not the most common type of galaxy at all. Instead, it’s smaller, lower-mass galaxies that are far and away the most common, with an estimated 30-to-100 tiny dwarf galaxies found throughout the Universe for every one Milky Way-like galaxy out there. While the largest, brightest, most massive galaxies are the easiest ones to spot, it’s actually the smaller, more common, lower-mass galaxies that are primarily responsible for blowing away the intergalactic neutral gas and making the cosmos visible.

Some of the small galaxies that we find have large reservoirs of gas within them, where they continue to form stars throughout their lives, while others are virtually gas-free, having formed all of their stars in just one major burst that occurred long ago. However, the small galaxies that…

Since mid-2022, JWST has been showing us how the Universe grows up, from planets to galaxies and more. So, what’s its biggest find of all?

It’s now been more than a full three years since the James Webb Space Telescope (JWST) — humanity’s newest flagship space observatory — was launched into space. Just as the Hubble Space Telescope revolutionized our view of the Universe with its unprecedented capabilities, which it primarily did by showing us what the Universe looked like, JWST is uncovering never-before-seen features and properties of objects throughout the Universe: features and properties that no other observatory, not even Hubble, has ever been capable of. After a little more than six months of pre-science operations, including deployment, alignment, commissioning, and calibration, science operations began in July of 2022.

In the 2.5 years that have passed since, we’ve learned an enormous set of new lessons: about exoplanets and their atmospheres, stars, galaxies, star-and-planet formation, cataclysmic events, and much more. And yet, even the people who work professionally (and prolifically) with JWST data can’t keep up with it all. At the 245th meeting of the American Astronomical Society, I was asked a deceptively…

A proton is the only stable example of a particle composed of three quarks. But inside the proton, gluons, not quarks, dominate.

One question that every curious child winds up asking at some point or other is, “what are things made of?” Every ingredient, it seems, is made up of other, more fundamental ingredients at a smaller and smaller scale. Humans are made of up organs, which are made of cells, which are made of organelles, which are made of molecules, which are made of atoms. For some time, we thought that atoms were fundamental — after all, the Greek word that they’re named for, ἄτομος, literally means “uncuttable” — since each species (or element) of atom has its own unique physical and chemical properties.

But experiments taught us that atoms weren’t fundamental, but were made of nuclei and electrons. Moreover, although the electron couldn’t be split apart, those nuclei were further divisible: into protons and neutrons. Finally, the advent of modern experimental high-energy physics taught us that even the proton and neutron have smaller particles inside of them: quarks and gluons. You often hear that each nucleon, like a proton or neutron, has three quarks inside of it, and that the quarks exchange gluons, keeping them bound together. But that isn’t…

Here in our Universe, stars shine brightly, providing light and heat to planets, moons, and more. But some objects get even hotter, by far.

Stars are what illuminate the depths of space.

Nearly all luminous radiation is starlight: emitted from plasma-rich stellar photospheres.

Stars’ typical surface temperatures are no lower than ~2700 K.

The most massive main-sequence stars cap out with exterior temperatures of ~50,000 K.

The electromagnetic force can be attractive, repulsive, or “bendy,” but is always mediated by the photon. How does one particle do it all?

In our Universe, photons are one of the essential ingredients to matter — and life — as we know it. Light of all types (visible, infrared, ultraviolet, etc.) is made up of photons, and photons can be absorbed or emitted by charged particles, including within atoms, allowing for all sorts of vital processes and phenomena like photosynthesis, radiation, and even what we perceive as “color.” But photons serve another function that’s more fundamental: they themselves are the particles that mediate the electromagnetic force. When charged particles attract, repel, or are bent in a magnetic field, it’s the photon that does the heavy lifting, as it’s the underlying cause behind all of these interactions.

So how is it, then, that this one species of particle, which happens to be both massless and electrically neutral, is responsible for all of these phenomena? How can “exchanged photons” do it all: cause attraction, repulsion, or a perpendicular bending force? That’s what Jon Joseph wants to know, writing in to ask:

“The electromagnetic force is mediated by photons…

In the year 2000, physicists created a list of the ten most important unsolved problems in their field. 25 years later, here’s where we are.

Back in the year 2000, physicists gathered with an unusual purpose: to choose the 10 greatest unsolved problems in fundamental physics for the new millennium. At that time, we had:

• discovered most of the particles of the Standard Model, but not yet the Higgs boson,
• a strong idea that gravitational waves existed and carried energy, but no direct detection of their existence,
• robust evidence for the existence of dark matter and strongly suggestive evidence for the existence of dark energy, but no direct detection of either,
• and it was also a time where physicists placed a lot of hope in speculative ideas — such as supersymmetry, grand unification, extra dimensions, and string theory — for driving physics forward.

The limitations were that, in order to be considered, the problem must be deemed important, well-defined, and articulated in a clear way, that each participant could only submit one and only one question, and that duplicate entries would be rolled together into one. At the end of the…

Our Universe isn’t just expanding, the expansion is accelerating. Instead of dark energy, could a “lumpy” Universe be at fault?

It’s now been more than 25 years since astronomers discovered “most of the Universe” in an incredibly surprising way. In terms of energy, the most dominant species in our Universe isn’t light, it isn’t normal matter, it isn’t neutrinos, and it isn’t even dark matter. Instead, a mysterious form of energy — dark energy — makes up about ⅔ of the total cosmic energy budget. As revealed by supernovae, baryon acoustic oscillations, the cosmic microwave background, and other key probes of the Universe, dark energy dominates the Universe and has for around ~6 billion years, causing our Universe to not only expand, but for that expansion to accelerate, causing distant galaxies to recede from us with greater and greater speeds as time goes on.

But could all of this be based on an erroneous assumption? Could dark energy not exist at all, and could a lumpy, highly inhomogeneous Universe be the culprit, as one recent study has claimed? That’s what many of you, including Dirk Van Tatenhove, Michael Wigner, and Patreon supporter RicL want to know, inquiring things such as:

“Is the timescape model of cosmic…

It’s simpler, more compact, and reusable from year-to-year in a way that no other calendar is. Here’s both how it works and how to use it.

Each year, most of us throw out our old calendar and replace it with a new one. Each month, we flip our calendar forward another page, and if we ever need to know which day-of-the-week corresponds to a particular day/month combination, we have to either calculate it ourselves or flip forward/backward to the relevant month. Simple but curious questions, such as:

• What date will American Thanksgiving fall on this year?
• Which months have a “Friday, the 13th” in them?
• What day of the week does July 4th fall on?
• Or which day of the week is Christmas Day?

aren’t so easy to figure out unless you actually flip to the needed month (or look up all of the months) to figure out what the proper answer is.

But it turns out that, mathematically, the answer to these questions — or any question where you want to match up the day of the week with the day/month combination in a year — are extremely predictable, straightforward, and simple to figure out. If, that is, you don’t restrict…

Earth is actively broadcasting and actively searching for intelligent civilizations. But could our technology even detect ourselves?

Someday, if nature is kind to us, we’ll make the grandest discovery of all: that we aren’t alone in the Universe. While various observatories and space missions might someday soon find life on other worlds, our ultimate ambition is even grander: to find another intelligent, technologically advanced civilization out there, to receive and listen to their signals, to send our own human-generated signals their way, and to establish two-way communication. If there’s anyone else out there within a reasonable distance to make contact with, it’s only a matter of time, technology, investment, and luck before our searches pay off.

But how far along on the path toward finding extraterrestrial intelligence are we, really? Could we even detect another civilization that’s operating and broadcast at the level that humans are currently at here on Earth? That’s the question of David Dempster, who asks:

“[What is the] distance at which we could detect ourselves? I would love it if you would consider this as a topic for an article.”

Did the Milky Way form by slowly accreting matter or by devouring its neighboring galaxies? At last, we’re uncovering our own history.

When it comes to any aspect of the Universe, there are two questions we always attempt to answer: “What is it like today?” and “how did it become the way it is?” From atoms to planets to stars to galaxies, we seek to both understand what things are like today and to gain an understanding of how they evolved from their precursor ingredients into their present state. It’s tremendously difficult. However, in astronomy, we cannot perform experiments at will: We only have the Universe as it exists today — a momentary snapshot of the cosmos — to observe. At this moment, all that remain are the survivors of a cosmically violent past.

But just as a good detective can use the scant evidence that exists to reconstruct what occurred at a crime scene, astronomers can use the various pieces of evidence that remain in the Universe, along with the known laws of physics that govern all objects, to reconstruct as much of our cosmic history as possible. Our Milky Way galaxy, most assuredly, wasn’t always the way it is today: large, massive, and filled with hundreds of billions of stars. Instead, we grew up via a combination of…