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Ask Ethan: Does Mars’s gravity prohibit human colonization?

Human bodies decay in the microgravity environment of interplanetary space, but recover on planet Earth.

The low gravity of Mars will be a challenge, but maybe not a dealbreaker.

Mars is very different than Earth: smaller, drier, colder, etc. But the biggest long-term challenge, for human colonies, is its low gravity.

The physical Universe isn’t made of pure mathematics alone

Mathematics is great, as a tool, for describing the Universe.

But our Universe isn't made of pure mathematics alone.

To transform it into physics, something more is required.

Mathematics is our language for quantitatively describing reality, but it can also take us to worlds that never were. Physics needs more.

The big reason Einstein would never have used AI

The point of school is to grow your mind; the point of science is to discover truths about reality.

We know that Einstein never would've used AI.

Here are the dangers if you do.

Many think that intelligence can be outsourced to AI. Einstein wouldn't have used it. If he had, he never would have become Einstein.

99% of a core-collapse supernova’s energy is invisible

Despite how luminous core-collapse supernovae are, 99% of the energy they carry away is invisible: in the form of neutrinos.

Here's why that must be the case.

Despite the brilliance of these cosmic beacons, only 1% of a core-collapse supernova's energy is observable. The other 99% is in neutrinos.

Big evidence for “second generation” black hole mergers

With 390 gravitational wave events under our belts, we can actually see a difference between spin-orbit aligned and non-aligned mergers.

The switch is at 40-45 solar masses.

With nearly 400 black hole events from gravitational waves, we can begin to infer their origins. At least two different populations emerge.

Starts With A Bang podcast #131 – The baryon life cycle

The Universe was born with just hydrogen and helium for atoms: insufficient for making complex molecules, rocky planets, and life.

So how did we get from there to here?

The history of atoms in the Universe is our own history: without them, there would be no us. So how do we piece their cosmic story together?

Ask Ethan: What sets the size of the observable Universe?

We know how big the observable Universe is, was, and will be: not just today, but far into the past and future as well.

Here's what sets the "actual size" of our cosmos.

For all we know, the cosmos could truly be infinite in scale. But the observable part of our Universe? It's finite, and its size is known.

America pioneered gravitational wave research. Now it may leave it behind.

The USA has led the way in detecting gravitational waves here in the 21st century.

The ongoing threat is that we'll abandon it, as we've done with so much science already.

The LIGO facilities in the U.S. are the most sensitive gravitational wave detectors in the world. Their future remains uncertain.

Forget seeing the Universe’s beginning. It’s already been erased

The Big Bang gave us our cosmic origin story, and inflation took us back even before that, to an earlier stage.

So where did inflation come from?

That information's all been erased!

We used to think the Big Bang started it all. Then we realized that something else came before it, erasing everything that existed prior.

Why the “smallest” giant telescope may be the world’s best

At only 25 meters across, the GMT pales in size next to the 39 meter ELT for next-gen flagship telescopes.

Yet due to some brilliant decisions, GMT science, overall, looks better.

Get on board!

At "only" 25 meters in diameter, the Giant Magellan Telescope is the smallest of three current projects. That might make all the difference.

Famous study in error: the Universe isn’t anisotropic

Just two weeks ago, a bold claim was made: that DESI data reveals an anisotropic Universe, on larger scales than should be possible.

It's not possible; these errors explain why.

Using the newest large-scale structure data, a team of researchers announced an unexpected anisotropy on cosmic scales. Too bad it's wrong.

What has more power: Earth’s aurorae or fireworks shows?

Sure, the USA may have broken the record for most fireworks at a single fireworks show.

But can the power in all of our fireworks compete with the power in Earth's aurorae?

Over 800,000 fireworks explode in under and hour in the world's largest fireworks shows. How do natural auroral displays compare in energy?

Ask Ethan: Could we spot an extinction-level asteroid?

The last extinction-level impact happened here on Earth 65 million years ago.

If humans had been around back then, how much warning would we have had before our demise?

65 million years ago, a massive asteroid struck Earth, causing a mass extinction. Without advance warning, could anyone have spotted it?

How to not overestimate the number of stars in the Universe

Yes, we know how many stars are within the observable Universe: just over 2 sextillion.

But we see far fewer than that, and mustn't overestimate the true number.

Be careful.

With ~400 billion stars in the Milky Way and 6-20 trillion galaxies overall, that makes for a lot of stars. But not as many as you'd think.

Is it finally time to take dark matter-free galaxies seriously?

NGC 1052-DF9 has just been identified as the fourth galaxy appearing to be dark matter-free.

Are they truly what they seem, or might they have dark matter after all?

The first one, NGC 1052-DF2, was mired in controversy. With four examples now, there only remains one possible escape. What does nature say?

The most distant lensing cluster reveals a dark matter surprise

XLSSC 122: the most massive galaxy cluster for its time, the most distant gravitational lens, and the cuspiest dark matter profile of all.

More examples like these, please!

Over 10 billion years in the past, an ultra-massive galaxy cluster lenses objects behind it. That has big implications for dark matter.

Could nearby relic galaxy NGC 1277 lead to the first stars?

Galaxy NGC 1277 hasn't formed stars in over 10 billion years.

The strongest-ever silicon signal that's inside of it could indicate the remains of the first stars of all.

At 240 million light-years away, galaxy NGC 1277 hasn't formed new stars in over 10 billion years. Could it contain the first stars' ashes?

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