Astronomers confirm the existence of a lone black hole

Emotional and Existential Reactions

• Several commenters find the idea of a massive, invisible object drifting through space “creepy” or unsettling.
• Others argue it’s no scarier than space in general: we already live in a hostile, mostly empty environment where many low‑probability cosmic threats exist.
• Some say they’d rather be oblivious if a fatal encounter were inevitable, to avoid societal panic and prolonged dread.

Threats to Earth and the Solar System

• A lone stellar‑mass black hole is not a vacuum cleaner; outside its event horizon its gravity behaves like any other object of the same mass.
• Direct “gobbling” of Earth is considered much less likely than:
  • Distorted orbits, ejection from the Sun’s orbit, or severe orbital chaos.
  • Tidal destruction of planets or moons, or increased asteroid bombardment.
• A pass even at several AU with ~6–7 solar masses (as in the paper) would strongly perturb planetary orbits and could be catastrophic over years to millennia.
• Some discussion explores what happens if a small, fast black hole passes through a planet: accretion heating could in principle exceed the planet’s binding energy and blow it apart, though details are hand‑wavy.

Detection, Frequency, and Risk

• The object was detected via microlensing; commenters stress such detections require rare alignments, so many similar black holes could be invisible to us.
• Still, space is described as “really, really big”: even with millions of such objects, direct encounters with our system are viewed as extraordinarily unlikely.
• People ask how close and massive a black hole could be before routine surveys or orbital deviations would reveal it; upcoming missions like the Roman Space Telescope are mentioned as particularly promising.

Dark Matter and Primordial Black Holes

• Some speculate whether numerous lone black holes could explain dark matter.
• Others note constraints:
  • Too many stellar‑mass black holes would overproduce gravitational lensing.
  • Big Bang nucleosynthesis limits how much “ordinary” (baryonic) dark matter is allowed.
• Primordial black holes of sub‑stellar mass are raised as one possible (but non‑mainstream) dark‑matter candidate; size ranges from “moon‑mass to planet‑mass” are discussed as less constrained.

Early Universe and “Why Not a Giant Black Hole?”

• A lay explanation that uniform density cancels gravity is challenged; GR predicts even a uniform matter distribution tends to contract.
• A more careful explanation: in the early universe, spacetime was already expanding rapidly; high density slowed that expansion but didn’t reverse it into a single black hole.
• This leads into brief discussion of inflation and how current cosmology already relies on speculative physics, making intuitive reasoning about the Big Bang tricky.

Hawking Radiation and Tiny Black Holes

• Commenters discuss evaporation of very small black holes, noting:
  • Black holes below a certain mass would have fully evaporated by now; estimates place that around 10¹² kg.
  • Hawking radiation hasn’t been directly observed; it’s a strong theoretical prediction from quantum field theory in curved spacetime.
• There is back‑and‑forth on how Hawking radiation is generated (virtual particle pairs near the horizon) and clarification that nothing literally escapes from inside the event horizon.
• Some speculate in principle about manufacturing micro black holes with extreme technology, but emphasize this is far beyond current capabilities.