Gigantic jet spied from black hole in early universe | Hacker News Reader

Gigantic jet spied from black hole in early universe

phys.org

95 pointsdnetesn56 comments

The fact that we can see back in time ..... to the early universe no less... is really one of the most underrated and miraculous things humans have achieved.

When you think about it, it’s truly astounding.

Well anyone can see a few million years back in time just by going outside on a dark night and looking at one of the nearby visible galaxies with their eyes. Knowing that this is what is happening is indeed a great achievement.

Unfortunately, that's not quite true in many populated cities. Light pollution means the night sky is starless.

Not starless, surely. Stars like Sirius and Betelgeuse should be visible just about anywhere, and that gets you 8-500ish years back at least.

Well, it’s sort of true. There are places within cities where you can’t see the Andromeda Galaxy, but you don’t have to leave those cities entirely in order to see it to some degree.

To be a bit pedantic: that’s only true for the Andromeda Galaxy (distance ~ 2,4 million light years), which is very hard to see with the naked eye. The Large and Small Magellanic Clouds are easy to see (from the Southern Hemisphere), but are only about 150,000-200,000 light years away.

Can you clarify? Aren’t we still observing an old state of any galaxy we see in the skies, simply due to the fact that light takes time to travel to us?

I believe OP's point is that which state you're seeing varies by distance. We see Andromeda as it was millions of years ago, but we see other stars as they were "only" hundreds of thousands of years ago. Closer = more recent picture, Farther = older snapshot.

Yes, exactly.

(The Triangulum Galaxy, M33, can sometimes be seen; at ~ 3 million light years, it’s further away and thus an even older “snapshot” than Andromeda.)

> the Andromeda Galaxy (distance ~ 2,4 million light years), which is very hard to see with the naked eye

That's due to light pollution in populated areas.

If you're out in the deep desert, it's not that hard to see. The night sky in the desert is a very, VERY different experience from what most people have seen from the city. It's like you're on a different planet.

I’ve seen it from fairly high in the Sierra Nevadas, far from any cities, and I still think it’s very faint.

Make sure your eyes are dark-adapted. I.e. you've spent at least 20 minutes in pitch darkness, with no sources of light other than the sky. And no Moon.

Altitude is not relevant in most cases.

You could also argue that "seeing" doesn't necessarily mean "perceiving". I can point my eyes to the exact spot where the Andromeda Galaxy is, or even other galaxies further away, and not actually perceive anything. But tint amount of photons from that galaxy still hit my eye. But that's being obtuse..

To be more pedantic, you are incorrect that this is only true for Andromeda. Several other galaxies are visible with the naked eye under excellent conditions, though they can certainly be challenging. These include M81 and M33.

Technically every thing you look at is in the past.

> The fact that we can see back in time ..... to the early universe no less

It seems to me that this one is a freebie.

Being able to look out into the universe and understand what it is we live in is truly a magical thing. It is all there but seems to be so far from most people’s comprehension

That's more of a property of our universe, specifically, light speed.

The telescopes are an engineering achievement, no doubt.

The observable universe is a representation of its own history.

Maybe it is too early, but I envisioned some ancient alien civilization’s jet plane spied in a black hole. Quite the observation indeed.

it would be a truly advanced civilization that could make a jet work in space :)

If other civilizations see Elon's car in space, will they assume it worked in the past?

When i read about observations like this, it makes me realize what a small jewel our planet is.

And HN an even smaller jewel within it ^_^

And this comment an even smaller jewel within HN.

Everything is a jewel if you look hard enough.

The real jewels were the friends we made along the way.

Jewels all the way down.

dunno why you're downvoted : I thought about eh very same sentence :-)

https://garage.vice.com/en_us/article/9kexqp/in-a-rebours-a-...

> Everything is a jewel if you look hard enough

#rub touchstone

damn... another worthless piece of green glass

The universe is super fascinating. In another life I want to be a theoretical physicist studying black-holes etc. I find them and the universe super interesting just I could never get past Calculus II.

Some years ago i was thinking about the idea to study astronomy. I read an article back then in which it was told that most astronomy students end up beeing a computer scientist. I don't know if thats true. But I took it as an advice to study computer science :) and I'm pretty happy with that.

I think this is pretty true. I think almost all of the hard science researchers are part software developers. Pretty much every professor I had in mechanical engineering was doing some type of programming or had graduate students/post docs doing it. My masters in oceanography was almost entirely built in Matlab and Python. One of the physics professors was studying black holes and their work revolved around making a cheap super computer with PS4s and running his black holes merger simulations on it.

I think that there's an inherent connection to this - code is an incredible tool that can take scientific research, not just in "traditional" natural sciences, but also in fields like sociology.

It has revolutionized all the other parts of our lives, so it makes sense that an inherent programming skill, if you're working in academic research, would follow.

We were strongly encouraged by both physics and astronomy professors to major in physics rather than astronomy if we wanted to work in astronomy. We were told (by the astronomers) that although an astronomy major has more of the needed skills, the physics majors were seen as better hires. We were told by the physicists that of course physics majors had those skills (that seemingly weren’t anywhere in the curriculum). :)

I’d settle for a spaceship with life-extension tech to wander around for an eternity.

Tech breaks, dude :) sleep for all eternity, alright.

Imagine what else must be there.

And all the other jewels that must have already gone extinct without anyone ever knowing about them.

Jeez I hope it's not a 737...

If it's a DC-8 then we're really in trouble.

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

Don't tell me you read Scientology

How can the jet length to be determined? In my very limited understanding jet is a continuous stream of particles/radiation. Doesn't it continue forever, unless the flow hits some barrier?

It gets diffused to the point where it’s no longer distinguishable from the background.

I guess it's similar to determining where the sun's atmosphere ends and the solar system begins, or where earth's atmosphere ends. You have to draw a line somewhere.

If the jet only turned on a finite time ago, then it will only have gotten so far in that time, so it will have a length = (jet velocity) * (time jet has been active).

is this the same as the 8 billion light year void that was posted yesterday? It made me think of blackholes, but I didn't read up to put the dimensions of these things into scale.

FYI: Sagittarius A*, the Quasar at the center of the Via Galaxis, is ca. 20 Mio. km wide; It's not a Jet, and far from 8 Bio. LY, lol.

How are supermassive black holes able to grow so quickly to reach such an enormous mass in this early epoch of the Universe? >>> That simpley means that, matter was already there before the Big Bang isn't it?

No, it means what it says - the growth rate is too high for known mechanisms, so they’re looking for explanations. The mass in the universe isn’t the issue, it’s that there are limits on the growth rate of black holes which grow through accreting matter.

The article opines that the accretion disk converts velocity of particles around the black hole into the jet, causing more matter to fall in.

That misses the point - jets are one mechanism whereby the matter can lose some energy and fall in, but they occur due to the high energy of accreting matter, and their existance does not solve the problem of the growth rate of these things. We are able to detect and characterize this object in part thanks to the jets, but the problem of mass remains.

There wasn't anywhere for the matter to be yet. The big bang didn't just create matter and energy, it created spacetime as well. That's just a footnote though, gbrown's is the right answer.

I gather this is somewhat disputed. In particular, spacetime already exists in some capacity in eternal inflation models.

That's not quite correct either. I don't think it created... itself?

Maybe you read one of many attempts at an explanation somewhere that used anthopomorphism as a rhethoric device, but the only creative effort in that sense lies with the author.

Unless something changed recetnly, we don't know what has happened in the first moments of the big bang, because "time" stops making sense in these models. The details are beyond me. It seems to imply two things. First, if the model is naively extrapolated in a thought experiment, then back tracking the rapid expansion means you arrive at a singular point, but, as said, we don't get that far mathematically.

Second, arguably then it's still a matter of interpretation of what was "before", and where, or just what!?! As for the creative author, that's not challenging the universe, rather our conceptual space.

Third, the Grand Parent trivially suggests that if an event can't have happened so quickly, then naive extrapolation implies it must have started before the beginning of time. This seems to be a contradiction only because it rests on a paradox, that time had or was started.

There might be more logical, less trivial ways to state and inquire about the paradox, granted.

Probably built on Electron. Supergrowth of anything!

"Growth" is one option. Another is that some black holes may be chunks of a pre-bang singularity that never expanded/exploded into normal matter. Or they may be matter that contracted into singularities shortly after the big bang when everything was closer together. Black holes that are either giant (billion+ suns) or very small (<1 sun) don't fit into accepted models of how these things are created. That they absolutely exist, at least the big ones, means we don't understand everything just yet.

...after 10 seconds...ok this isn't about the A380.

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