What's the heaviest thing in the universe?
Define "thing" and define "heavy"
A super cluster of galaxies is probably the heaviest "thing" if you consider such a widely distributed thing a "thing." Otherwise supermassive blackholes are the densest "things" we know, though the may not be the "heaviest"
EDIT: The Universe is the heaviest 'thing'! :D
I also wonder whether black holes are strictly 'in the universe' since they are behind an event horizon.
They definitely are, their gravitational effect can be felt in the universe. So in that sense, they are..
The most massive would be the biggest black hole, unless you want to call a galaxy a "thing."
Hope we can all agree that we really mean to be talking about the most massive, not the heaviest, "thing" -- whatever it is we mean by a thing.
That was my thinking too.
Why stop at a galaxy? How about a cluster of galaxies?
Smaller black holes are even denser, unless you are speculating about the interior distribution of mass in your supermassive hole.
Btw, the OPs question is regarding heaviness (= force on an object due to gravity) and not about mass, so answers should include both an object and a gravitational field.
OK, call it a thing if you like. I'm not going to argue about it, if you don't mind.
(In terms of density) They are not the "heaviest" but Pulsars are very dense as well. What makes them interesting is some pulsars around 20 km in diameter, can have 1.5X the mass of our sun, and have a rotation period of 1.4 milliseconds!! Some can also have a gravitational force 2x10^12 times that of our own earth! Cool!
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