# What are black holes made of? [duplicate]

I did some research and found that an earth-mass black hole, has theoretical mean density inside the Schwarzschild radius about 4•10^17 kg/m³. This is well within density of neutron stars which are almost entirely made of neutrons. So what kind of matter makes them? Is it the elementary particles or heavier elements?

PS: I found one very complicated answer on Reddit but I'm looking for a more elementary one, if possible at all. Thanks

## marked as duplicate by Kyle Kanos, John Rennie black-holes StackExchange.ready(function() { if (StackExchange.options.isMobile) return; $('.dupe-hammer-message-hover:not(.hover-bound)').each(function() { var$hover = $(this).addClass('hover-bound'),$msg = $hover.siblings('.dupe-hammer-message');$hover.hover( function() { $hover.showInfoMessage('', { messageElement:$msg.clone().show(), transient: false, position: { my: 'bottom left', at: 'top center', offsetTop: -7 }, dismissable: false, relativeToBody: true }); }, function() { StackExchange.helpers.removeMessages(); } ); }); }); Oct 7 at 16:14

• The "density" of a black hole (usually defined as the mass divided by the volume enclosed by the event horizon) is not a constant but depends on it's mass (and gets smaller for more massive holes). You've calculated the density for a particular mass, not a general density. – dmckee Oct 7 at 15:12
• Oh okay, I'll edit it in. – Lagaash Oct 7 at 15:17
• I'm not sure you understood the implication. The supermassive black holes at the centers of large galaxies have a density lower than water at STP. Density doesn't provide any handle to use in probing the internals. – dmckee Oct 7 at 15:21
• I agree, the density just refers to distribution of mass so it can be very low for very large black holes. But I don't have any more actual data to strengthen the question. Most of answers I've read so far talk about stuff I really don't know, so I asked as in relation to density. Thanks for insight dmckee. – Lagaash Oct 7 at 15:26
• Possible duplicate of What kind of matter are black holes made of? – Kyle Kanos Oct 7 at 15:33