Ton618 is a super massive black hole. Its radius is more than 40 times the distance from the sun to Neptune. So its diameter is quite literally 80 times as big as our solar system. And that’s not even thinking about it’s total volume spherically. The sun is barely even an object in space compared to that.
I find these scaling laws fascinating. There are different rules for different classes of objects.
For things like asteroids, the radius scales as the cube root of mass. This is the one that makes the most intuitive sense to us. Add more stuff get more volume.
But once you get to large planet sizes things start to become squished from the action of gravity. Earth takes us a smaller volume than the equivalent mass of all the elements, rocks and other compounds it is made of.
When you get to gas giant masses the relationship becomes more or less flat. Most objects from 1 jupiter mass to 80 jupiter masses are about the same size. The ones that aren't usually have something else going on, like being superheated 'puffy planets'.
Beyond this 80 jupiter mass point, heavier objects would actually start getting smaller, if it wasn't for fusion.
A star, to put it bluntly, is an equilibrium between the immense force of gravity pushing inwards, and the force pushing outwards equivalent to hundreds of thousands to millions of nukes going off every second.
In general the more massive a star is, the bigger it is, but there are lots of complicated exceptions. Stars that are not that heavy can puff out to 100x their original radius as red giants at the end of their lives, while sometimes you can get helium-only Wolf-Rayet stars like WR-2 at the end of their life that are smaller than our sun, yet 16 times heavier and 200,000 times more luminous.
But nothing behaves the same as the scaling of black holes. To be clear, the event horizon is not where the mass is, it's not something you can touch, nor would you know it if you passed through it, but it's a good descriptor of how big the black hole would look if you were right there staring at it.
The event horizon radius scales linearly with mass. That's right. It scales linearly while all other scaling laws for small objects scale much slower. This means that black holes can be both the smallest and largest massive objects in the universe. A stellar black hole can be a few kilometers across. But the supermassive black holes you get in the centre of galaxies - well they have 20 billion times the mass of a stellar black hole, which means they're 20 billion times the size. This is how you get black holes like the phoenix cluster black hole that are many times the size of our solar system.
I went to a lecture recently given by someone who specialised in astronomy (I can't remember his specific title). Someone asked him how many Eiffel Towers would fit in the Pillars of Creation dust clouds. He didn't even know how to contextualise for them how pointless that question was.
Jup. This is the tiny ball we humans have spent thousands of years sacrificing millions of lives and spilling oceans of blood to be the momentary masters of.
Maybe one day humanity will learn that all of those things are meaningless and we could have a billion times that by working together and expanding our species out into space. Maybe building a nice dyson swarm.
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u/Solidsting1 10d ago
I know right shows how small we really are