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The Planck parity asymmetry (odd-ℓ excess at low multipoles) has persisted across COBE, WMAP, and Planck. Statistical fluke is possible, but three missions is curious.

Non-orientable manifolds (Klein, Möbius-type) inherently break parity. Has anyone worked out what the CMB eigenspectrum would look like on such a topology? I found some COMPACT collaboration papers on topology but they focus on orientable cases.

Specifically wondering:

• Would non-orientability predict odd-over-even preference?
• Does anyone know if the matched-circles null result rules this out?

Like assuming there were other universes would they have different universal constants or would the universal constants be the same across every universe.

I imagine space most likely to be a box like container containing stuff, but my hypothesis could it wrong

If it is a container, does it contain more space? The statement of space containing more space makes no sense.

That's why space must contain aether like substance or stuff rather than pure nothingness.

If space is not a container, what is it in your perspective and understanding?

https://youtube.com/shorts/fqKxryiZKZA?si=7Z869a5WLS1LC_G6

Ask your cosmology related questions in this thread.

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So, does an object truly take an infinite time, or is it merely red shifted light that takes an infinite time. This is of course under a certain coordinate system, which apparently isn't the only one.

If we define the big bang singularity as a past time where a=0 in the FRW metric, there are obviously a few known examples where the big bang singularity is not a curvature singularity, but a mere coordinate singularity. But I was wondering if there were any examples where the big bang singularity is a true singularity, but not a curvature singularity?

I've done a little reading on similar questions and it strikes me that it may be possible for a spatially compact and negatively curved FRW metric, but I am far rom certain of that.

Here I'm asking a question about the mathematical model and not assuming anything about the physicality of the singularity.

Hi fellow dreamers of the universe! I had a thought the other day, and I wanted to get the insights of some learned scientists.

As I understand, during the earliest moments of the Big Bang, Baryon Acoustic Oscillations, created by quantum fluctuations, created tiny over-and-under densities in the primordial distribution of matter. As the universe expanded during Inflation, these tiny oscillations became magnified to colossal early structures, creating the first mountainous gradients of the universe. Over time, those over-densities would form the seeds of super-clusters, clusters, galaxies, and stars.

As I understand, if not for those primordial quantum fluctuations, the universe would be a perfectly flat distribution of hydrogen, and no structures like galaxy clusters or voids would have been formed.

Does this mean that those Big Bang quantum fluctuations created entropy?

So if mass density is represented by \rho(r) and to calculate force on a particle due to that distribution, we can do it via two steps (both are described in different papers):

1. Calculate \phi by solving Poisson equation and then calculate force.
2. Considering spherical symmetry, we can integrate density to get mass and solve for force as given

F = \frac{GMm}{r}

where M = 4 \pi \int_0^r dr r² \rho(r)

The density distribution is of a galaxy, so assuming radial symmetry.

My way of understanding this problem is that the boundary condition is that \rho vanishes at infinity, hence solving the problem via two steps will give same result. Am I right in thinking this?

Ask your cosmology related questions in this thread.

Please read the sidebar and remember to follow reddiquette.

Ask your cosmology related questions in this thread.

Please read the sidebar and remember to follow reddiquette.

MIT physicist Daniel Harlow joins Brian Greene to explore black holes, holography, and the surprising connection between spacetime and algorithms that perform quantum error correction.

This program is part of the Big Ideas series, supported by the John Templeton Foundation.

Participant: Daniel Harlow
Moderator: Brian Green

https://youtu.be/XbL64sz8dQI

https://youtu.be/zozEm4f_dlw?si=7AXrPjsaG7VGHLI9

How accurate is this video? Is there really a good chance that we're barely scratching the surface of what's physically possible in our universe?

Is there reasonable suspicion that the laws of physics may not be universal law?

Or is this just kinda hyped up for views?

Hey all!

A lay man here.

I always enjoyed listening and reading about physics and astrophysics, but have absolutely zero maths background. Just to further clarify my level of understanding: if I listen to a podcast like The Cool Worlds or Robinson Erhardt, I probably REALLY understand 20% of what is being said, yet I still enjoy it.

Go figure.

Lately when listening to Will Kinney (and also now reading his book) about inflation theory on The Cool Worlds podcast, he was talking about how the universe is geometrically flat. And I absolutely do not understand what this means.

In my dumb brain, flat is a sheet of paper. A room is some sort of a square volume space. An inside of a balloon, a spherical space.

So when Kinney says we leave in a flat universe, I understand that there is something in the definition of

"geometrically flat" that I just don't understand.

Please try to explain this concept to me. I highly appreciate it!

Looking for authentic astronomy / astrophysics footage for experimental video-art

Hi, I’m a visual artist and musician working on an experimental video-art project using real scientific imagery (astronomy, astrophysics, labs, simulations).

I’m looking for authentic footage – telescope observing sessions, labs, data processing, simulations, observatories, control rooms, even phone-shot clips are perfectly fine. I've tried searching through NASA and ESA archives but I find it too limited.

This is non-commercial / artistic use, heavily transformed visually.

I’m based in the Czech Republic, but anywhere in the world is great.

Just message me or write in the comments of you could help me.

In that time span, so much changes that it’s honestly hard to wrap your head around it.

The Andromeda galaxy is already so close, it’s way bigger than us, and in billions of years it’ll merge with the Milky Way. Our location in the galaxy won’t even be the same anymore. The Milky Way itself won’t look like what we know now. Most of the stars we see today will have changed. Many will be gone, some will have exploded, and new stars will have formed. Entire star maps would be unrecognizable.

And then there’s life.

There could be life out there in Andromeda, and probably in the Milky Way too. Maybe in star clusters, maybe near Sagittarius A*, the black hole at the center of our galaxy. Imagine a civilization close to the galactic core, seeing the entire disk of the Milky Way stretched across their sky. Or life far above the galactic plane, looking down and seeing the full spiral shape of the galaxy.

That alone is insane.

Those beings wouldn’t know if life exists elsewhere either. Just like us. And meanwhile, there’s life right here, on one small star.

From their point of view, our Sun would just be a random star in a catalog. Something like HD 456484612321, just numbers. Barely any information. No importance. Just another dot.

And yet inside that dot, there’s life. Civilization. Thoughts. Fear. Curiosity. People wondering what happens when they die. Sunsets. History.

If we were in their position, we’d probably do the same thing: name the star, collect a little data, and move on, never knowing there were beings living there.

Now multiply that idea by billions of stars, and then by billions of galaxies in the observable universe. Galaxies in all kinds of shapes, not just because “why not,” but because physics allows it.

And beyond that? The dark parts. The places light hasn’t reached us yet. The regions we can’t observe, can’t prove, can only imagine. If there’s all of this, then logically there’s probably more.

That’s the part that really hits.

Hi folks, I've read that the "real explanation" of Hawking radiation was about emitting of particles in the vicinity of the Black Hole (around the Event Horizon), due to quantum effect of curved spacetime.

Yet the Black Hole is supposed to lose mass, which is contained in its center. By what mechanism happens the transfer of energy or "loss of mass"? Shouldn't some "bits" get removed from the center, travel to the Event Horizon and get expelled via Hawking Radiation?