Astronomers witness energetic switch on of black hole | Hacker News Reader

Astronomers witness energetic switch on of black hole

phys.org

74 pointswglb39 comments

What does it mean for an AGN to "turn on"?

It ate a star.

But that would take infinite time (as we perceive the event) because of time dilation.

You would not see it "turn on", you would see a slowly, very slowly, changing signal.

I think this is good evidence in favor the plasmoid model from Eric Lerner as a replacement for black holes. Some key differences.

* Instead of a black hole eating a star, a plasmoid is having an increased load. * Black holes are "gravitational" machines while plasmoid are "electromagnetic" machines. * With the plasmoid model there is no time dilation * With the plasmoid model, the load is any source of plasma, not necessarily a star

https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=eric...

https://www.google.com/books/edition/The_Big_Bang_Never_Happ...

> With the plasmoid model there is no time dilation

But there is time dilation, so the plasmoid model isn't very good at explaining observations.

It might be good evidence for something else if it were correct. It’s not correct, though. As I mentioned in another comment, infinite time dilation (from the reference frame of an external observer) is only an issue exactly at the event horizon. But the events that lead to a supermassive black hole “switching on” are happening at the accretion disk, far enough away from the event horizon for time dilation to be an effect we’d have to measure carefully to detect.

Also, the idea that you’d want a model that avoids time dilation here makes no sense. We know gravitational time dilation is a real effect because we’ve measured it, it matches the predictions of general relativity, and GPS would be very inaccurate if they didn’t correctly take the effect into account. To say that time dilation doesn’t occur near a black hole is completely inconsistent with well-verified facts.

From this, we can conclude that Lerner’s conjecture is wrong. We can’t even call it a theory, because it doesn’t match the evidence.

You'd be hard pressed to ever directly observe something that is astronomically tiny and emits extremely low frequency radiation, if any at all.

When an accretion disk is actively ripping apart a celestial body the plasma is some of the hottest material in the current universe. It's extremely violent and bright. You're seeing a gravitational well converting a huge quantity of mass to energy.

Yes, as I understand it, the “turn-on” effect is from the plasma generated while the star is falling into the gravity well. The bit of the star that passes the event horizon would be tiny.

Moreover, I believe that the radiation from an object falling into a black hole is redshifted so rapidly, that it effectively disappears from view in a very short time. An outside observer would not see anything “lingering” near the event horizon.

Yeah, the redshift and the slowing down due to time dilation are exactly the same phenomenon.

If the wavelength is a million longer, any event that would take 1 second to happen, appears to us as it took 12 days.

No, infinite time is only an issue exactly at the event horizon.

At the radius of the accretion disk, the effect will usually be small enough that we’d need some careful measurements to detect it.

It didn't actually "eat a star." A star passed close enough to it that the tidal forces ripped the star apart and the star became a ring (accretion disk) around the black hole. Matter in an accretion disk gets very hot because of gravitational acceleration and friction -- so hot it can shine more brightly than the original star.

And what probably really happened is that the star was massive enough that it caused the black hole to start emitting jets. There are always two of these pointed opposite one another, and one happened to be pointed toward us.

https://en.wikipedia.org/wiki/Astrophysical_jet

And this is a cosmic burp.

How can an entity that is inescapable eject anything?

As stellar matter is consumed by a black hole, some of it is ejected through gravitational flinging (think gravity assist maneuvers). It isn't ejected after consumption, but during. In some cases, the acceleration of matter causes energetic radiation (x-rays... etc) in the opposite direction. This is often how we detect black holes in the first place (gravitational lensing, detecting of accelerated matter are others).

It confused me too. At first I thought it meant that a collection of matter became dense enough to form an event horizon and become a black hole. Instead, from https://www.livescience.com/space/black-holes/gargantuan-bla...

> If J221951 is indeed a supermassive black hole, its sudden burst of brightness has two possible explanations, according to the researchers. First, the black hole could have pulled an orbiting star into its clutches, stretching and tearing the star to shreds in a messy process called a tidal disruption event or "spaghettification." The second, more mysterious possibility is that the black hole could have shifted states from dormant to actively feeding, as it suddenly began gorging on the fast-moving disk of gas that surrounds it.

“Very Large Telescope”, I love this name. Any better ones out there?

The checklist is accurate: https://xkcd.com/1294/

Is the "final telescope" massive enough to be its own black hole?

The OWL was cancelled?

Can we propose the Obnoxiously Large Telescope to replace it?

Now they're building the ELT –– Extremely Large Telescope.

They're great with names haha.

Don't forget OWL: Overwhelmingly Large Telescope ( https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope ).

Or, "Once Was Larger"

"The ESO specialists expect resolutions from OWL that are up to 40 times higher than those of the Hubble Space Telescope. If the 100-meter mirror cannot be financed, a 60-meter variant is being planned. The name OWL would remain the same. Because then the project is jokingly called »Once was larger«."

https://www.itespresso.de/2006/04/17/groesstes-observatorium... --> Google Translate

Still waiting for the Stupendously Gigantic Telescope.

What, no BFT?

Big Ass Telescope?

TEAT Telescope to End All Telescopes

They should build one ten times the size of the next largest one, and call it the Quite Sizeable Telescope

There is the "Very Large Array" too! the VLA. I love these naming standards. Way better than any startup or open source project name

Potentially inspired by Very Large Scale Integration.

Go read about the solar gravitational lens telescope proposal by physicist Slava Turyshev

It is the most mind blowing thing that could actually be built someday by humans imho, well if we decide to stop blowing all our budget on killing other people

https://google.com/search?q=solar+gravitational+lens

It would be able to image exoplanets, 10 square kilometers for objects 100 light-years away.

>solar gravitational lens telescope

Here is a great video about it:

https://www.youtube.com/watch?v=NQFqDKRAROI

...and a paper:

https://arxiv.org/abs/1802.08421

Astronomers are great at this. Three postulated categories of dark matter include:

* WIMPs: weakly interacting massive particles

* MACHOs: massive compact halo objects

* RAMBOs: robust associations of massive baryonic objects

There's also the HERO (hyper extremely red object), which isn't quite dark, but close.

Astronomers and Astrophysicists are great at naming things.

The rest of the scientific community...notsomuch.

> https://www.youtube.com/shorts/uNnq2GrC01o

Morbid but if I’m the future I’m terminally ill and we somehow find a cheat code to travel to a supermassive black hole in years instead of hundreds of millions of years I’d like to hop in a space suit and get launched into one Dave Bowman style.

Today they witness energetic switch, tomorrow - energetic router.

And still no reception in the kitchen.

kitchen must be beyond the event horizon.

That's because of the CMB (cooking microwave in the background)

Followed by a wireless gamma ray burst. Aimed right at us.

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