I understand that, for a stationary black hole without spin (which does not exist), an object that falls into it will freeze, then the image will redshift until it disappears.
I also understand that there is a cosmological (event) horizon, where galaxies freeze, then rapidly redshift in the same way. This happens because these distant objects are accelerated away from us faster than light.
It appears to me that we are seeing black hole event horizons from the outside, and the cosmological event horizon is seen from the inside.
The similarities do give one pause.
The mechanisms are different; one is gravity, and the other is dark energy.
For my Oracle Linux systems, I rely on the vendor ReaR RPM package for the baseline backup. This is similar to the "Ignite" utility that I used in my HP-UX days.
This is two-fold useful, first as it enables boot from backup media for total recovery, second in that it creates a backup.tar.gz that holds everything that was not explitictly ignored in the /etc/rear/local.conf file.
I'm running Oracle databases on these systems (and the local.conf is configured to ignore the datafile directories). I have standby databases (not Dataguard in that I don't have online redolog replication) that allow me to recover them to the primary in a disaster, with some loss of committed transactions.
I finally have rsync configured for some scratch temporary files.
I have dallied with btrfs snapshot replication for home directories (in a loopback mount). My vendor support (via a CSI number) has been on and off, so I don't use btrfs in areas that we need it most.
My replacements do not like the complexity (and I am retiring).
While my karma might get incinerated with this quote, it is incisive on traditional architecture. The author is reviled by many.
“Yes, God damn it, the Parthenon!”
The ruler struck the glass over the picture.
“Look,” said Roark. “The famous flutings on the famous columns—what are they there for? To hide the joints in wood—when columns were made of wood, only these aren’t, they’re marble. The triglyphs, what are they? Wood. Wooden beams, the way they had to be laid when people began to build wooden shacks. Your Greeks took marble and they made copies of their wooden structures out of it, because others had done it that way. Then your masters of the Renaissance came along and made copies in plaster of copies in marble of copies in wood. Now here we are, making copies in steel and concrete of copies in plaster of copies in marble of copies in wood. Why?”
It's amusing to watch the movie version of The Fountainhead and see what are supposed to be Roarke's buildings. He likes the pedestal style, where the first floor is mostly open-work columns around a small lobby. Turns out this is terrible in cold or windy areas. Wind hits the side of the building and is forced down into the area around the lobby. Doors are forced shut by wind pressure. People are knocked off their feet. A strong wind in snow produces a horizontal blizzard.
The Meteorology Building (bldg 54) at MIT was built that way, with all of the above problems. Much embarrassment. Later, much computational fluid dynamics and, in 2019, a rebuild of the plaza level with more walls.
That's enough of an oversimplification as to not really be true.
They developed an issue with explosive decompressions, because at the time we didn't fully understand how cyclic stress caused metal fatigue. It is true that they had square-er windows than modern planes, but they knew that and added reinforcement. The stress concentrations inducing fatigue cracks were around square cutouts for an antenna, not the passenger windows.
Also, the windows didn't pop out of their frames. Large portions of the fuselage ripped open.
And they lived a longer service life after the fuselage was reinforced in the areas that cracks were starting, but had trouble overcoming their bad reputation from the earlier explosive decompressions.
Source: the introduction to the Wikipedia article you linked. Read it.
Not the first place I'd heard that, but I found it ironic that the parent comment's own link refuted their claims in the first couple paragraphs. And Wikipedia tends to be pretty reliable -- in a 2005 Nature analysis, Wikipedia was found to have on average less errors per article than Encyclopedia Britannica: https://en.wikipedia.org/wiki/Wikipedia:Press_releases/Natur...
https://en.wikipedia.org/wiki/Event_horizon
I also understand that there is a cosmological (event) horizon, where galaxies freeze, then rapidly redshift in the same way. This happens because these distant objects are accelerated away from us faster than light.
It appears to me that we are seeing black hole event horizons from the outside, and the cosmological event horizon is seen from the inside.
The similarities do give one pause.
The mechanisms are different; one is gravity, and the other is dark energy.
https://en.wikipedia.org/wiki/Cosmological_horizon
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