Ethan Siegel – Medium

Ethan Siegel

Published in
Starts With A Bang!

How far back in time can we see in space?

We see objects whose light only arrives just now. But we see them as they were in the past: when that now-arriving light was first emitted.

Just now

How far back in time can we see in space?

Just now

Published in
Starts With A Bang!

Ask Ethan: Can a lumpy Universe explain dark energy?

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

3d ago

Ask Ethan: Can a lumpy Universe explain dark energy?

3d ago

Published in
Starts With A Bang!

The quantum reason that explains why the Sun shines

Despite the Sun’s high core temperatures, atomic nuclei repel each other too strongly to fuse together. Good thing for quantum physics!

4d ago

The quantum reason that explains why the Sun shines

4d ago

Published in
Starts With A Bang!

The one-page calendar that changes how you view the year

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.

5d ago

The one-page calendar that changes how you view the year

5d ago

Published in
Starts With A Bang!

Is the universe actually a fractal?

On larger and larger scales, many of the same structures we see at small ones repeat themselves. Do we live in a fractal Universe?

6d ago

$Is the universe actually a fractal?$

$Is the universe actually a fractal?$

6d ago

Published in
Starts With A Bang!

This weird JWST trick lets us “see” dark matter

It’s not only the gravity from galaxies in a cluster that reveal dark matter, but the ejected, intracluster stars actually trace it out.

Jan 6

This weird JWST trick lets us “see” dark matter

Jan 6

Published in
Starts With A Bang!

Ask Ethan: Could SETI detect a “twin” of Earth?

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

Jan 3

Ask Ethan: Could SETI detect a “twin” of Earth?

Jan 3

Published in
Starts With A Bang!

Devouring “the Kraken” led to the modern Milky Way

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

Jan 2

Devouring “the Kraken” led to the modern Milky Way

Jan 2

Published in
Starts With A Bang!

Our Universe has more galaxies than Carl Sagan ever imagined

Forget billions and billions. When it comes to the number of galaxies in the Universe, both theorists’ and observers’ estimates are too…

Jan 1

Our Universe has more galaxies than Carl Sagan ever imagined

Jan 1

Published in
Starts With A Bang!

Most planets in the Universe are orphans without parent stars

Known as orphaned planets, rogue planets, or planets without parent stars, these “outliers” might be the most common type of planet…

Dec 31, 2024

Most planets in the Universe are orphans without parent stars

Dec 31, 2024

Ethan Siegel

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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