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[Starver]

Depending on what you define as the black hole (with or without accretion disc, outside or inside the event horizon), it may not be possible to see the hole, by definition of what one is, but the shadow/silhouette or something similar is visible against its immediate hole-created surrounds.  Looking directly at the centre you'd see not much light from the matter yet to sufficiently fall inwards (and none from that which has) but as you view towards the sides you get an edge-on view of a wide swathe of that (actually, over the horizon, due to the gravitationally bent light-paths) so effectively you see "what it blots out", or its self-imposing shadow, of the especially 'glowing' material in its immediate vicinity.

Depends on how you want to describe it. It's a bit beyond everyday naked-eye observation, so it's not exactly an obvious thing to describe. "Shadow" sort of works, but maybe it's more akin to an Inferior Conjunction eclipse (the Moon blotting out the Sun) but... still not quite, because there's as much "sun" this side of the "moon" (and not even outshone!), yet the "moon" is the most significant party.

(Ninjaed by a more concise summary.)

[Il Palazzo]

The shadow as it's used here has been defined precisely, though. It's the lensed image of the event horizon, approx. 2.5 times larger in angular diameter than the actual thing.

[LordBaal]

Did they found Bowman already?

[Starver]

This somewhat represents (from middle to one edge only, obviously you mirror for the other edge) where what you think you're looking at actually may be (somewhere along the 'parallel' path you choose, which might intersect with other such paths).


Bowman is in his hotel-room, watching TV.

[Max™]

Remember also that this is a 6 Gigasun object which has been horking down material long enough to hurl a jet of matter across thousands of light years, so the background glow around the shadow is matter screaming as it grinds together while whipping around an orbit wider than that of Neptune and it's doing it fast enough that you can see variations in the images they took, so we're talking fully out in deep relativistic effects land, super high percent of the speed of light type shit.

[Bumber]

matter screaming as it grinds together

( ͡° ͜ʖ ͡°)

[Starver]

*brings back vivid KSP memories*

[Kagus]

*brings back vivid KSP memories*

Bere-sheeit...

"We didn't make it, but we definitely tried"

Fuck it, this is the kind of quote that belongs in a frame on the wall.

[Starver]

On the same subject, almost... KSP plane - make it bigger, loads of engines, a lot of wing, and don't forget the wheels.

[Akura]

On the same subject, almost... KSP plane - make it bigger, loads of engines, a lot of wing, and don't forget the wheels.

That looks like they welded two planes together at the wingtip.

[wierd]

My hokum senses are tingling!!

https://www.livescience.com/65344-quantum-vacuum-gamma-rays.html

Faster than light charged particles?  MASSIVE particles!?  No no no no no no.

Oh, what's that? Local spacetime is distorted so that photons cant travel at the same speed?  But that is still the local spacetime medium, not a photon exchange medium! How?  What?

[Kagus]

Aren't particles by definition massive? It's not much mass, but I thought particles were the ones with the physical bits.


Then again, I am utterly without an education, so I probably shouldn't be talking.

[wierd]

Photon is a point particle (that can also behave as a wave, but meh) that is massless. 

[Arx]

Oh, what's that? Local spacetime is distorted so that photons cant travel at the same speed?

I am the first to admit I'm not a quantum physicist, nor did I especially enjoy my quantum-adjacent courses, but I've read through the paper and I'm pretty sure that's never claimed. What is claimed is that strong magnetic fields polarise quantum fluctuations (not new), that polarisation causes an effect on protons similar to that of a dielectric medium (i.e. reduction of phase velocity) (not new), and that as a result it seems reasonable to claim that a charged particle in a vacuum can, supposing it is within a powerful enough magnetic field, emit Cherenkov radiation the way one would expect in a dielectric medium (a completely logical follow-on to the previous statements).

Nowhere does it posit that c is exceeded, nor that this really changes anything other than presenting a potential explanation for some currently murky astronomical gamma ray emissions. Especially, the result you seem to be taking particular offense to (light in a vacuum behaving as though in a dielectric medium) seems, although I could be wrong here because I'm reading papers I barely understand, to be decades old:

It has  been suggested  that the nontrivial refractive  index  due  to  photon–photon  scattering could induce a lensing effect in the neighbourhood of a magnetar (Shaviv et al., 1999).

The general interactions between photons and nonlinear QED effects in vacuums have been researched since the 70s or before, too.

I'm sure if I hunted more I could find older results or understand the topic better, but like I said, I don't particularly care for quantum.

Oh, and as for

How?  What?

The paper is on arxiv and presumably, to a physicist in the field, explains those quite adequately.

[Starver]

(Though it warns me about thread being idle >120 days, I thought it's better here even than the more recently used Science+Engineering+Environment thread. Either that or some of that thread's stuff better here, so worth a bump just to bring it to the fore again...)

https://newatlas.com/space/first-manned-crew-dragon-flight-date/ ...is May 27th, apparently.
Site given was chosen mostly for the URL It's on BBC, Reuters and even SyFy sites if you prefer to go elsewhere for any reason.

Fingers crossed, of course.