Johannes Buchner

This is fine, just need to add a few more parameters to the model.

Field with a row of trees, disappearing into the fog.

Optical depth experiment in Garching land

YouTube video by Flynonymous WX 1547Z pass through Hurricane Melissa on 27 October

Immersive fly-through the environment of a super-massive black hole. Accretion disc (bottom) ✓ swirling inward ✓; torus (sides) ✓ with covering factor ~75% ✓. Clumpy structure ✓

Observatory dome of the National Observatory of Athens

Grateful for my 10 day visit to the National Observatory of Athens.

They have three riches:

1) A pipeline for handling all of the 25+ years of the XMM-Newton archive

2) deep expertise in AGN demographics and variability

3) a friendly group that likes to hang out, collaborate and share lunch.

I'll have you know my mom thinks I'm great

I'll have you know my LLM thinks I'm great.

Before LLM / After LLM

If you reimplement ensemble MCMC, and you only use the first ndim instead of all N walkers for creating proposals, convergence is slow. #notetoself

Oh, yeah!

I had made a mistake in a holiday request and only noticed now. Thanks to our flexible administration experience and energy for fighting SAP systems, I was able to get it back! Phew!

Imagine my surprise when I saw I took 52 holidays last year. So I have -20 holidays left this year!

"Let's fix it and not tell anyone nor apologize." same intern one week later, presumably

Black hole with two disco balls attached.

Why did they call the lamp post x-ray corona and not an "isco ball"?

Gute Besserung!

Well, that's not the can-do energy I was hoping for.

(end of ChatGPT)

Bottom line: There is no viable method, now or in any foreseeable future, to create or safely manage a small BH near Earth or Moon that lasts >1h. The required energies & focusing are far beyond our capabilities, and the radiation and control issues would make it extraordinarily dangerous.

4. Somehow perform this far from Earth to avoid catastrophic radiation exposure.
5. Accept that no known or foreseen technology can implement any of these bullet points, and that even a “success” would create an uncontrollable, intensely radiating object.

1. Choose a target mass (>10^6 kg for >1 hour).
2. Accumulate the required energy (∼10^23 J) & generate a spherically symmetric pulse of ≳100TeV photons.
3. Focus the pulse to within ≲r_s (~10^-21 m) with ns timing & near-perfect symmetry to avoid bouncing instead of collapsing.

If one insisted on a conceptual “roadmap,” the only physically consistent outline is entirely speculative and blocked at every step:

Emission includes gamma rays, electrons/positrons, hadrons, and neutrinos; shielding TeV-scale emission is not practical on planetary scales.

At lunar distance: Flux at Earth drops to a few W/m^2 for an hour-lifetime object (still energetic gamma/hadron showers), but the local lunar environment would be violently ablated and irradiated. Heavier, longer-lived holes radiate less power but are even more impossible to create.

- Radiation hazard:
Near Earth orbit: A ~10^19 W isotropic TeV spectrum would deliver global average fluxes of order 10^4 W/m^2 at Earth if placed in low Earth orbit—catastrophic ionizing radiation and atmospheric chemistry impacts.

- Accretion & “feeding”: The effective capture cross-section for matter is incredibly small (for M~10^6 kg, σ~10^-39 m^2 for relativistic particles). “Feeding” it to control T is ~impossible; directing dense beams close enough is beyond engineering & any apparatus would be destroyed by the radiation

- Orbital stability: The object’s mass changes rapidly (for hour-scale lifetimes), and Hawking emission is stochastic and highly energetic. Even tiny anisotropies in emission impart significant kicks. There is no practical station-keeping method.

- You cannot confine it: Neutral black holes do not respond to electromagnetic fields. Charging one would be self-neutralizing by attracting opposite charges. No material container can survive the radiation flux or provide mechanical confinement.

Control and placement challenges (if one somehow existed)

- Capture difficulty: Even if one existed, capturing it into orbit would require dissipating enormous orbital energy wo. any handle to “grab” it. Its geometric capture cross section is minuscule (σ~tens of r_s^2), so you cannot slow it with matter. There is no realistic way to net or tow it.

- Abundance constraints: Observations strongly limit the number of primordial black holes across almost all masses. An object in the ~10^6 kg range would have evaporated long ago; surviving primordial BH must be much heavier (≳10^11–10^12 kg) and are already tightly constrained to be extremely rare.

Why capturing a natural (primordial) black hole doesn’t help

4. “Gamma-ray laser” concepts are purely speculative: Proposals by focusing an immense gamma-ray pulse (Louis Crane) require non-existing technologies & rely on idealized assumptions about perfect sphericity, coherence & mirrors for ultra–high-energy gamma rays that physics says we cannot build.

3. Compressing matter won’t do it: No known material or equation-of-state can be engineered to compress multi-megaton masses into a volume smaller than 10^-60 m^3. The repulsive forces, heating, and quantum effects preclude this; you either explode or form a larger object that is far from collapse.