Ethan Siegel

Cosmologist, science communicator, author, speaker, and longtime writer of Starts With A Bang.

Not the next Carl Sagan; the first Ethan Siegel.

🌉 [bridged](https://fed.brid.gy/bsky/startswithabang.bsky.social ) from 🦋 [startswithabang.bsky.social](https://bsky.app/profile/startswithabang.bsky.social ), follow Bridgy Fed for Bluesky (npub1pqr…2sck) to interact

Web site: https://bsky.app/profile/startswithabang.bsky.social

Last Notes

2026-07-30 15:23:58 GMT

Johannes Kepler, not Newton or Einstein, is science’s best role model
People often look to Einstein or Newton as a scientist's best role model.
But Kepler did something more important: he changed his mind when the evidence demanded it.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/johannes-kepler-role-model/ )
#space #astro #kepler #science
[Johannes Kepler, not Newton or...](https://bigthink.com/starts-with-a-bang/johannes-kepler-role-model/ )

2026-06-06 07:18:14 GMT

Starts With A Bang podcast #130 – the initial mass function of stars
Give the Universe a massive enough cold cloud of gas, and it'll give you a spectrum of stars of all different masses.
But that spectrum isn't universal, and we finally understand why.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/starts-with-a-bang-podcast-130-the-initial-mass-function-of-stars/ )
#space #astro
[Starts With A Bang podcast #13...](https://bigthink.com/starts-with-a-bang/starts-with-a-bang-podcast-130-the-initial-mass-function-of-stars/ )

2026-03-05 17:27:59 GMT

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-...](https://bigthink.com/starts-with-a-bang/particle-physics-destroy-universe/ )
#physics #astro
[No, particle physics colliders...](https://bigthink.com/starts-with-a-bang/particle-physics-destroy-universe/ )

2026-01-13 21:00:54 GMT

This is your chance to tell the NSF how to fix itself.
Say no to the grift of AI datacenters. Say no to putting "quantum" where it has no business. Say no to false metrics. Say no to biotech scams.
Say yes to sustained investments. To fundamental science. To flagship facilities. To STEM education.
RE: https://bsky.app/profile/did:plc:yhsjztvyfpnvs6k75aevzmkt/post/3mcdclk55f22i

2025-10-22 16:27:32 GMT

We still don’t know how “hot” the hot Big Bang was
The earliest stages of the hot Big Bang were far hotter than any conditions that exist in the Universe today.
But things weren't arbitrarily hot; here's what we do (and don't) know today.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/how-hot-big-bang/ )
#space #astro #physics
[We still don't know how "hot" ...](https://bigthink.com/starts-with-a-bang/how-hot-big-bang/ )

2025-10-15 23:20:49 GMT

If you haven't ever heard this Sam Cooke classic, it's just as relevant as ever.
A change IS gonna come.
[www.youtube.com/watch?v=wEBl...](https://www.youtube.com/watch?v=wEBlaMOmKV4 )
[Sam Cooke - A Change Is Gonna ...](https://www.youtube.com/watch?v=wEBlaMOmKV4 )

2025-10-15 15:28:07 GMT

The true cost of “solar power at night” with Reflect Orbital
If you played SimCity 2000, you might've loved the idea of "beaming power from space" down to Earth.
Reflect Orbital took that idea, tech-bro'd it, and now could end "night" as we know it.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/true-cost-solar-power-night-reflect-orbital/ )
#space #astro
[The true cost of "solar power ...](https://bigthink.com/starts-with-a-bang/true-cost-solar-power-night-reflect-orbital/ )

2025-08-12 16:21:43 GMT

At 36 billion solar masses, is the heaviest black hole too massive?
Yes, gravitational lensing has helped us find a 36 billion solar mass black hole an impressive ~5 billion light-years away.
It's *almost* too massive, and that means something profound.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/36-billion-solar-masses-heaviest-black-hole/ )
#space #astro
[At 36 billion solar masses, is...](https://bigthink.com/starts-with-a-bang/36-billion-solar-masses-heaviest-black-hole/ )

2025-08-08 15:21:22 GMT

Are parallel universes and the multiverse real?
#AskEthan
Parallel universes and the multiverse are fun, but highly speculative, ideas.
Can anything we do ever "prove" that they're actually real?
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/parallel-universes-multiverse-real/ )
#space #astro #physics #science
[Ask Ethan: Are parallel univer...](https://bigthink.com/starts-with-a-bang/parallel-universes-multiverse-real/ )

2025-06-08 00:37:06 GMT

Holy crap.
Viewing the updated block schedule for the upcoming #AAS246 meeting, and so many town halls, where we get updates from NASA and NSF admins, plus updates on specific missions and observatories, have been outright cancelled.
Likely means tons of things are going away, with no information.

2025-04-15 15:49:29 GMT

Science’s best answer to “where did the Universe come from?”
For hundreds of thousands of years, humans have wondered what our Universe is and where it came from.
Only now, in the 20th and 21st century, has science delivered the answers.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/science-answer-where-universe-come-from/ )
#space #science #physics
[Science's best answer to "wher...](https://bigthink.com/starts-with-a-bang/science-answer-where-universe-come-from/ )

2025-04-01 14:23:27 GMT

10 reality-bending facts about the scientific Multiverse
Love the multiverse?
Hate it?
Don't believe it's real or relevant for our existence?
These 10 facts about it, like it or not, are firmly rooted in science.
[bigthink.com/starts-with-...](https://bigthink.com/starts-with-a-bang/10-facts-scientific-multiverse/ )
#space #physics #science
[10 reality-bending facts about...](https://bigthink.com/starts-with-a-bang/10-facts-scientific-multiverse/ )