25 year update on the “Millennium problems” in physics
25 years ago, physicists created a list of 10 unsolved problems in fundamental physics: the millennium problems.
Now, in 2025, here's the status of all 10.
How far back in time can we see in space?
When we look "away" in space, we're actually looking "back" in time.
How long ago we see for planets, stars, galaxies and more may surprise you.
Can a lumpy Universe explain dark energy?
#AskEthan
Can a lumpy Universe do away with dark energy?
Not if you actually look at the "lumps" (i.e., the structure) in the actual Universe we inhabit.
The quantum reason that explains why the Sun shines
The Sun doesn't shine because protons overcome electrostatic repulsion to fuse together.
They don't.
Good thing for quantum physics.
The one-page calendar that changes how you view the year
Tired of needing to flip through the calendar to match up calendar dates with days-of-the-week?
This one-page calendar for 2025 has you covered, all year, in ways you might never have thought.
Is the universe actually a fractal?
The idea of the Universe as a fractal is fascinating, compelling, and incorrect.
Here's the cosmic reason why.
This weird JWST trick lets us “see” dark matter
By using color inversion plus galaxy/cluster light models, scientists can find "excesses" of light.
Remarkably, they help trace out where the dark matter is.
Could SETI detect a "twin" of Earth?
#AskEthan
With current, 2024-era technology, you might think SETI is more capable than ever.
But could we even detect a "twin" of modern Earth if it were elsewhere in the Milky Way?
Devouring “the Kraken” led to the modern Milky Way
You don't make a modern galaxy without devouring plenty of smaller predecessors.
So, meet the largest "snack" in our Milky Way's history.
Most planets in the Universe are orphans without parent stars
Lots of planets are born around stars, like the ones in our Solar System.
But the ones without parent planets might far outnumber the more familiar ones.
Have we found a galactic “twin” of the Milky Way?
We still aren't sure what our own galaxy looks like.
But somewhere out there is a near-perfect "twin" of our Milky Way, and these galaxies come closest.
Do gravitons need to exist?
#AskEthan
We often assume that gravity is quantum, implying the existence of spin-2 gravitons.
But is that mandatory, and is there any way to test/confirm the idea?
Gold, frankincense, and myrrh: one gift was made in a neutron star
Yes, the gold given to baby Jesus was made in a neutron star collision.
So was somewhere around 94% of all the gold in the Universe... we think.
The 16 stories that shaped physics and astronomy in 2024
Although it might not have seemed that way from most of what you've read, 2024 was a tremendous year of progress for physics and astronomy.
Catch up and see what we've learned.
“Waves in an Impossible Sea”: The 2024 science book of the year
With so many new science books this year, I found @MattStrassler's "Waves in an Impossible Sea" to be far and away my favorite.
Here's my summary, plus a deep Q&A interview with the author!
The most important lesson from JWST’s “baby Milky Way”
JWST found the most detailed "baby Milky Way" ever spotted: from 13.2 billion years ago.
"Cute" isn't exactly the right description.
Instead, it helped the Universe grow up and become visible.
Does quantum computation occur in parallel universes?
#AskEthan
Maybe the real question should be: why do quantum computational stories always need to have insane, untrue claims alongside the actual work that's been done?
-1 for Hartmut Neven.
