Ethan Siegel

Ethan Siegel

@startswithabang.bsky.social

Cosmologist, science communicator, author, speaker, and longtime writer of Starts With A Bang. Not the next Carl Sagan; the first Ethan Siegel.

5,490 Followers 859 Following 1,420 Posts Joined Sep 2023
1 day ago
Preview
Ask Ethan: How dark will the Universe become? Over billions of years, fewer stars form, galaxies mutually recede, and the Universe becomes ever darker. Here's how fast it all happens.

Ask Ethan: How dark will the Universe become?

Sure, dark energy will empty out the Universe and galaxies will run out of fuel to form new stars.

But that doesn't mean our sky will only get darker.

Look forward to the brightness ahead.

bigthink.com/starts-with-...
#space #astro #stars #physics

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2 days ago

You don't have to be the next Ethan Vishniac to apply!

For all professional astrophysicists looking for a wonderful opportunity to help guide and steward the #AAS journals through the coming years and decades, this is a once-in-a-generation job opening!

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2 days ago
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A quirk of relativity is the closest thing to achieving immortality Nothing lives forever, at least, not in the known Universe. But relativity allows us to get closer than ever: from a physics perspective.

A quirk of relativity is the closest thing to achieving immortality

Even relativity, with all the power of time dilation, won't increase the span of your lived life.

But it can take you far into the future, and even to the ends of the Universe.
bigthink.com/starts-with-...
#space #physics #astro

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3 days ago
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NASA's next X-ray mission, AXIS, has been killed The path to exploring the high-energy Universe was clear and compelling. Here's how 2025's cuts are still causing NASA casualties in 2026.

NASA’s next X-ray mission, AXIS, has been killed

Did you think that the cuts to NASA made in 2025 had all been reversed, and everything is now fine?

Think again.

NASA's AXIS mission, on account of that 2025 bloodbath, is now dead.
bigthink.com/starts-with-...
#space #astro #NASA #AXIS #Xray

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4 days ago

Yeah it's tough: H3N2 doesn't show up on either the flu A or B tests, and also does a great job of evading the immunity you get from this season's flu shot.

Don't assume you're NOT sick just because you test negative! (I think I was sick with it in January.)

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4 days ago

And warning: this will NOT test for the dominant flu strain of the season: H3N2.

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4 days ago

Thank you for that.

Appreciate your take.

Also, when you said "Aha - so you *are* interested in this topic!" I felt like the clown face meme. So well done!

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4 days ago
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The most important quantum advance of the 21st century A century ago, quantum physics overthrew our view of a deterministic Universe. A profound 21st century theorem closes the door even further.

Of course, now I'm curious and you might have a very different take on it, what do you think about the PBR theorem?

I guess, in particular, do you think what I wrote about it recently is correct, or do you think I'm way off base?

bigthink.com/starts-with-...

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4 days ago

That's fair. I mean, I'm only 47, and maybe the "we don't knows" or even the "we can't knows" about QM will someday yield to progress and better interrogation of nature.

As it stands now, there's much work on quantum foundations, a crapton of speculative theory, but very little telling evidence.

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4 days ago

I like what you said about Oreskes; I hadn't heard that history, and I should probably go and learn about it!

That nature article... I mean, there are a LOT of people who are interested in that. I am not one of them, in fact I'm "anti" interested in that.

Philosophy is no substitute for physics.

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4 days ago
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The right way to be a scientific contrarian Not everyone accepts the scientific consensus; some even make careers out of challenging it. But only a select few do it the right way.

The right way to be a scientific contrarian

Contrarians, or those who reject the consensus view, are important to the progression of science.

But there's a right and wrong way to do it.

How does your favorite one stack up?
bigthink.com/starts-with-...
#science #physics #astro #space

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5 days ago

So sorry for your loss Michele.

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5 days ago
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JWST peers inside a dying star's "exposed cranium" Resembling a cosmic brain, the exposed cranium nebula instead shows a dying, massive star, as JWST reveals. Its fate remains uncertain.

JWST peers inside a dying star’s “exposed cranium”

In 2013, NASA's Spitzer observed PMR 1, finding a structure that resembles a human brain.

Today, JWST actually resolves the Exposed Cranium Nebula, revealing what's inside.
bigthink.com/starts-with-...
#space #JWST #astro #nebula

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1 week ago
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Starts With A Bang podcast #127 - Satellites and space pollution What goes up into low-Earth orbit will eventually come down, bringing huge consequences with it. Be informed, not surprised!

Starts With A Bang podcast #127 – Satellites and space pollution

There are many excellent technological uses of satellite technology, but also many harms associated with the pollution of the environment around Earth.

When they clash, must we all lose?
bigthink.com/starts-with-...
#space #astro

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1 week ago
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Ask Ethan: Do signals degrade as they travel through space? In traveling through the expanding Universe, particles slow down while light and gravitational waves redshift. What degrades and what won't?

Ask Ethan: Do signals degrade as they travel through space?

Light and gravitational waves redshift, sure, as they travel through the expanding Universe.

But do those signals degrade and deteriorate, and if so, what do we lose?
bigthink.com/starts-with-...
#space #physics #astro

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1 week ago
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No, particle physics colliders cannot ever destroy the Universe Smashing things together at unprecedented energies sounds dangerous. But it's nothing the Universe hasn't already seen, and survived.

No, particle physics colliders cannot ever destroy the Universe

Every time we push the energy frontier in particle physics, laypersons fear that the world, or even the Universe, will be destroyed.

Here's why we're certain it's all safe... for now.
bigthink.com/starts-with-...
#physics #astro

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1 week ago

Amazing the variety of conclusions one can reach choosing different assumptions in the absence of a single positive signal.

Hence the weak sauce nature of all of our constraints; we can only say "no more than this."

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1 week ago
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Can the Drake equation's final term predict humanity's demise? No civilization, no matter how successful, can last forever. What does the non-detection of intelligent aliens mean for our own longevity?

Can the Drake equation’s final term predict humanity’s demise?

Here in 2026, we still have not found the existence of any life beyond Earth.

What does that mean for the Drake equation, the longevity of intelligent civilizations, and humanity's future?

bigthink.com/starts-with-...
#space #astro

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1 week ago
YouTube
My first science video in 3 years! YouTube video by Physics Girl

If you haven't been aware, Physics Girl (Dianna Cowern), @thephysicsgirl.bsky.social here on BlueSky, has been sick with long COVID, and specifically COVID-induced ME/CFS, since 2022.

Here is her first science video in 3+ years.

Here's how solar neutrinos work!

www.youtube.com/watch?v=B3m3...

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1 week ago

This is a good point: why put your energy into ragebait when there are actually things we want to do?

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1 week ago

You must've missed his rage-inducing interview in NYTopinion about 8 months ago with Peter Thiel, where he normalized Thiel's advocating for the extinction of the human race and to have it replaced with a Borg-like transhumanist collective.

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1 week ago
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Did Hubble's new "dark galaxy" kill modified gravity? The discovery of CDG-2, a galaxy that's more than 99.9% dark matter, could reveal a new population of ultra-faint galaxies. But is it real?

Did Hubble’s new “dark galaxy” kill modified gravity?

Hundreds of millions of light-years away, a collection of four globular clusters was found orbiting... nothing.

Is there a "dark galaxy" there, and if so, is modified gravity now dead?
bigthink.com/starts-with-...
#space #astro #gravity

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1 week ago

One of the things that bothered me very much about public school, and it was Mr. Massi (remember!) who taught us this, is that the job of public education is not to teach us what America is, but to instill the mythos of "America, and it's working" in us.

We get fed a lot of that by pundits, too.

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1 week ago

A shifting Overton window will do that.

Eisenhower would practically be a socialist today.

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1 week ago

And yet he and David Brooks and Bret Stephens continue to make careers out of saying the most Archie Bunker-esque things, but with a veneer of Christopher Rufo over it.

I can't even tell which of them is the worst tbh. Maybe you know?

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1 week ago

It's hard because there is good journalism in there.

And there are quality opinions that are published there.

But it also fails the Voltaire paradox of intolerance real hard.

They aren't just tolerant of it; they seek the traffic that ragebait brings them. And there is so much that's enraging.

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1 week ago

No. This was a condemnation of every one of those opinion columnists you asserted was superb.

As opinion columnists, none of them are or were superb in any way. All of them are, as I said earlier, choices that the editorial board made with every piece.

I'll stand by that one.

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1 week ago

That's fine. I got excited and got hyperbolic here.

There are plenty of sane people saying sane things separate from, just alongside, the inhumane murder justifiers, grifters, and advocates of revoking human rights for some.

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1 week ago

I don't buy this argument. You can't look at the best thing someone's ever done and have it absolve them of the horrors they inflicted on society with the worst of their advocacy.

But I have all sorts of issues with how journalism is practiced, and with all major newspaper editorial boards today.

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1 week ago

I mean I even gave kudos to Kristof and I love nearly all of what Bouie writes, so yes, maybe I got a little hyperbolic.

Still, the point of "we platformed 5 good people and X Nazi sympathizers, and that's good editorial boarding" is not really acceptable to me when X is ever so much more than 0.

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