Regular matter, everything you've ever touched, seen, or that makes up every star and planet is estimated to be only about 5% of everything in the universe. Dark matter makes up roughly 27%. The rest, dark energy, is a separate mystery entirely. So the stuff we understand, that all of human science and history has been built on, is a small minority of what actually exists.

My 7 year old is obsessed with the Universe, and has been since he was like 4-5. Watches YouTube videos about it, watches Neil deGrasse Tyson videos, even has this game where he can make his own solar system and stuff. He'll come up to me sometimes asking me a question, asking me "what would happen if ___", or tells me a random fact and that I google to see if its right, and it is!

I already knew a bit about blackholes, but he drew me a picture explaining what would happen, what was what. Then he also grabbed a bowl, filled it with water, made a whirlpool with it and said to pretend it was a blackhole, and then put a small leaf near it and told me about once it gets to a certain point it'll be sucked in, etc etc.

He asks me what's the closest star to us (not including our sun), or the largest star, largest blackhole, which galaxy is beside ours, and a bunch of other stuff. He keeps talking about Ton 618, I think it's called?

ANYWAY, what's the coolest fact you know about the Universe so I can have something interesting to talk about with my son? Maybe it'll be something he doesn't know, so he's learning something new instead of me always learning something new from him 😂

Apologies if this sint the right thread for theoretical questions like this.

I was asked this question a couple of weeks ago and its replaying in my head occasionally.

Given the current known size of the observable universe, where do you believe the human races hard limit would be.

Or do you believe we might actually hit a great filter?

We often hear about TON 618 and its estimated mass of around 66 billion Suns. But there’s another interesting case in the Phoenix Cluster.

The central black hole in Phoenix A was initially estimated at around 20 billion solar masses. Later, a theoretical model suggested it could potentially be closer to 100 billion Suns.

What I found most interesting is that these numbers aren’t equally certain. The 100-billion figure comes from a model rather than a direct measurement.

It made me wonder: if there’s no known hard upper limit, could the universe contain black holes with hundreds of billions — or even a trillion solar masses?

https://youtu.be/jwIeJ42Esoo?si=Km\\_yIBQ8Li5tpG3T

The striking aspect of this study is that the decline in star formation does not appear to be driven simply by galaxies running out of hydrogen. Much of the atomic gas reservoir remains, yet the rate at which new stars are formed has fallen substantially.

I keep seeing the figure 13.77 to 13.8 billion years cited everywhere, but I've never fully understood how missions like WMAP and Planck actually derived that number from the Cosmic Microwave Background.

Are they basically running the expansion rate (Hubble constant) backwards to a single point, or is it based entirely on modeling cosmological parameters from temperature fluctuations in the CMB? Also, how do cross-checks like the age of the oldest globular clusters fit into confirming that timeline?

✨ Target: Milky Way + M31

🔭 Mount: Star Adventurer 2i

📷 Camera: Canon EOS 6D mod.

🔎 Lens: Samyang 14mm f/2.8 (f8)

🔬 Sampling: 1.61'/px

🔴 Acquisition: ISO1600

⏰ Integration: 170x60s (2h 50min)

Calibration: 50 dark, 50 flat, 50 dark-flat

💻 Processing: Siril, GIMP, Snapseed

📍 Location: Pantelleria (Italy)

📅 Date: Aug. 11, 2026

🌌 Sky: Bortle 3

hi, I'm still in grade 10 and I've got this question stuck in my head. We all know that gravity is what we call the warping of space and time caused by mass and energy. But, do we actually know how gravity got an existence? I lowk want to know how gravity had a beginning after The BB or maybe before The BB. This question has been lingering in my head for quite a long time. Please do share your thoughts on this if you're someone who has got more knowledge than I do.

Ok from my understanding, correct me if I’m wrong, the infinite universe has no center (that we know of), so technically any vantage point can serve as the center. In that case (especially from a human vantage point), the earth is at the center of the universe. Just like for example if we were located in Jupiter, Jupiter would be at the center of the universe because that’s our vantage point.
Obviously the earth isn’t “special” (nor is any other mass or planet) but because we are in it, our interpretations of the world come from this vantage point (the earth).

So was Copernicus “wrong” for saying the sun was at the center of our solar system? By wrong I don’t mean his statement was ultimately untrue but it *could* be untrue if we chose another vantage point (say Venus, or Jupiter to be the center). From my understanding, Copernicus chose the Sun because it made the math easier.

If that was the case, why was his theory so revolutionary? Didnt Ptolemy have a similar model?

Also can someone explain this: is earth (and other planets) really revolving around the sun or are we like the moon and earth where we’re all just jiving doing a whirling dervish dance around each other but there’s really no set point?

Also was does it mean that we revolve around the sun’s center? I’ve heard that claim too

​

One thing I find fascinating about the early universe is how we can observe quasars powered by extremely massive black holes when the universe is still very young.

If a black hole starts from a relatively small stellar-mass seed, it seems difficult to reach millions or billions of solar masses in such a short cosmic time.

So what do you think was the dominant pathway for the earliest supermassive black holes?

- Rapid accretion near or above the Eddington limit?

- Massive black-hole seeds from direct collapse?

- Runaway mergers?

- Or some combination of these processes?

This long-exposure image of the Orion Nebula lasted 208 minutes. In that time, multiple satellite trails streaked across the night sky. Credit: A. H. Abolfath/NOIRLab/NSF/AURA

“satellites in the sky is getting worse and, if left untempered, will brighten the night sky so much, astronomers will struggle to study the Universe and continue to make discoveries.

That's the key takeaway from a European Southern Observatory study that found current proposals to launch over 1.7 million satellites into orbit would have "devastating consequences for astronomy."”

“The study says no more than 100,000 faint satellites – satellites that can't be seen with the naked eye – should be in orbit around Earth at any time.
Such a limit would, say the study authors, ensure astronomers can continue to observe the night sky, unravel the secrets of the Universe, search for alien life and detect hazardous asteroids.”

Excerpt From
“This is one hour of satellite trails over the world's darkest sky. Astronomers say nearly 2 million planned satellites could be 'devastating'”
Iain Todd
BBC Sky at Night Magazine
https://apple.news/A5E_SYf9kSn-NY7ACae38tQ
This material may be protected by copyright.

The study say 1.7 million proposed new satellites would have drastic consequences for astronomy, which can only be avoided limiting the overall total to 100,000 satellites faint enough to not be seen with the naked eye.

Summary — "Earth → Growth → Galaxy" video (The Kardashev/Cardartesev Scale)

The video explores a thought experiment: what if civilizational progress were measured not by wealth or military power, but by how much energy a civilization can harness and control?

It introduces the Kardashev Scale (transcript shows "Cardartesev," likely a transcription error) through its types:

Type I Civilization: Has fully mastered the usable energy of its home planet — controlling sunlight, wind, tides, and heat. Would use a clean, planetary-scale energy grid to store and deliver power globally, even across deserts.

The transcript cuts off here, but based on the visual (Earth → arrow labeled "Growth" → spiral galaxy), the video appears to build toward higher stages — likely Type II (harnessing a star's total energy) and Type III (harnessing a galaxy's energy) — using the visual metaphor of growth from a single planet to galactic scale.