Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hubble sees possible runaway black hole creating a trail of stars

hubblesite.org

Post reply on HN
Print view View original

101–110 of 191 posts

Re: Hubble sees possible runaway black hole creating a trail of stars

#101

Post by christkv »

lvncelot wrote: post #95
once_inc wrote: post #86

For those replying to this article with "imagine living there", please note that if life is a verdant, resilient and common as many of us hope it is, the universe might contain quite a number of insane places to live: - Near the center of a galaxy, where stars are so closely packed together that the night sky is filled with bright lights, perhaps illuminating their world to what we experience around twilight, or even…

> Inside a 'thick' nebula, obscuring all other entities in the sky except for their own star and planets. Imagine an interstellar object like Oumuamua passing through and the complete perplexity of a civilization observing it and wondering where it could have come from. This is almost the exact premise of Life, the Universe and Everything, the third book in the Hitchhiker's Guide to the Galaxy series.

The start of the cricket wars.

Re: Hubble sees possible runaway black hole creating a trail of stars

#102

Post by jb1991 »

alex_duf wrote: post #99
ww520 wrote: post #75

Earlier quoted context omitted.

Asimov's Nightfall tells the story of the beings living on a planet surrounded by 6 suns. The sky is always bright with at least a sun over head. They've only known the universe consisted of bright sky and the 6 suns for centuries. On a rare eclipse event where all the suns are hidden, they are suddenly in darkness and looking into billions of stars at the night sky.

surely such a system would be extremely unstable right?

Isaac Asimov is a science fiction author (a good one, too), but the work he created was not a real description of our universe -- it was fiction, and playing with ideas.

Re: Hubble sees possible runaway black hole creating a trail of stars

#103

Post by tehforsch »

quickthrower2 wrote: post #26

What I don’t understand is where the material for the stars is coming from? Is there that much dust in deep space? Or did it collect it from the galaxy?

The primary stuff you need to form stars is hydrogen and helium which is absolutely everywhere in the universe. In order for stars to form, however, you need a lot of it. This usually happens if you have a strong gravitational force, which pulls in more and more gas (very very slowly). If the gas cools sufficiently, at some point the gravitational force will overcome the thermal pressure of the gas, causing it to collapse and form stars.

This is the basic mechanism of star formation everywhere and it probably isn't much different in this particular system. The strongest gravitational forces are caused by dark matter haloes which are usually larger than the galaxy itself and much heavier. On smaller scales, the main gravitational force is caused by the collapsing gas itself. Both probably still exist in this system and provide the required gravity for stars to form.

A note: While dust has an impact on star formation (it might help the gas to cool, for example) it is not a required ingredient for stars to form. In fact, the first stars formed at a time when there was no dust in the universe.

Re: Hubble sees possible runaway black hole creating a trail of stars

#104

Post by backpackviolet »

once_inc wrote: post #86

For those replying to this article with "imagine living there", please note that if life is a verdant, resilient and common as many of us hope it is, the universe might contain quite a number of insane places to live: - Near the center of a galaxy, where stars are so closely packed together that the night sky is filled with bright lights, perhaps illuminating their world to what we experience around twilight, or even…

What would it be like for civilization to have evolved on a world with a moon (or other large natural satellite) in geosynchronous orbit. There’s just this … thing, in the sky, hovering over one spot. How sacred would that spot be to those people

Re: Hubble sees possible runaway black hole creating a trail of stars

#105

Post by gattr »

once_inc wrote: post #86

For those replying to this article with "imagine living there", please note that if life is a verdant, resilient and common as many of us hope it is, the universe might contain quite a number of insane places to live: - Near the center of a galaxy, where stars are so closely packed together that the night sky is filled with bright lights, perhaps illuminating their world to what we experience around twilight, or even…

> Inside a 'thick' nebula, obscuring all other entities in the sky except for their own star and planets.

Similarly to the alien planet in Eric Flint's "Mother of Demons"; there was a permanent thick cloud cover, and the the slowly moving sky illumination due to the unseen sun was called "the mother of pearl" by the locals.

I also like the idea of living in a dense globular cluster. Interstellar probes and, later, manned missions would be feasible quite early into civilization's technological development - since you're just a few light-weeks (or less) from another star, not a few light-years like us.

Re: Hubble sees possible runaway black hole creating a trail of stars

#106

Post by askvictor »

brotchie wrote: post #83
dividefuel wrote: post #29

Earlier quoted context omitted.

This would be an interesting premise for a science fiction story. You could imagine a species realizing that the only way to survive long term is to keep hopping to new star systems every billion or so years. And when they get ready to hop to another system for the first time, they realize almost all the viable star systems are already colonized by past species who came to the same conclusion

Greg Egan’s Incandescence is along these lines except replace star in the trail of a black hole with asymmetric asteroid around a black hole accretion disk.

I read that, but have either forgotten, or missed the entire black hole thing. I think, for any given Egan novel, I miss about half of the ideas while trying to wrap my head around the other half, but he's still one of my favourite authors.

Re: Hubble sees possible runaway black hole creating a trail of stars

#107

Post by maneesh »

mach1ne wrote: post #52
Helmut10001 wrote: post #44

Earlier quoted context omitted.

This is an analogy to the Three Body Problem from Liu Cixin!

I’ve heard that book(series?) pop up quite a lot recently. Is it worth a read?

The best sci-fi trilogy I’ve ever read. I don’t know why there is a lot of hate on hn towards it.

Re: Hubble sees possible runaway black hole creating a trail of stars

#108

Post by IanCal »

ww520 wrote: post #75
andrewstuart wrote: post #20

If you lived on a planet going around one of those stars it sure would be hard to make sense of the universe. "Oh I have it! In addition to all the incomprehensible things in the universe, we happen to live in a star system that is extremely, extremely rare and exeptional, unlike the rest of the universe!"

Asimov's Nightfall tells the story of the beings living on a planet surrounded by 6 suns. The sky is always bright with at least a sun over head. They've only known the universe consisted of bright sky and the 6 suns for centuries. On a rare eclipse event where all the suns are hidden, they are suddenly in darkness and looking into billions of stars at the night sky.

Is Krikkit in HHGTTG a playful take on this?

Re: Hubble sees possible runaway black hole creating a trail of stars

#109

Post by nuccy »

lvncelot wrote: post #95
once_inc wrote: post #86

For those replying to this article with "imagine living there", please note that if life is a verdant, resilient and common as many of us hope it is, the universe might contain quite a number of insane places to live: - Near the center of a galaxy, where stars are so closely packed together that the night sky is filled with bright lights, perhaps illuminating their world to what we experience around twilight, or even…

> Inside a 'thick' nebula, obscuring all other entities in the sky except for their own star and planets. Imagine an interstellar object like Oumuamua passing through and the complete perplexity of a civilization observing it and wondering where it could have come from. This is almost the exact premise of Life, the Universe and Everything, the third book in the Hitchhiker's Guide to the Galaxy series.

Thickness (or rather its optical depth) of this nebula would be wavelength dependent - in IR you could see through all the distant stars, while in all other wavelength, including X-rays, that nebula would glow.

Re: Hubble sees possible runaway black hole creating a trail of stars

#110

Post by QuesnayJr »

mach1ne wrote: post #52
Helmut10001 wrote: post #44

Earlier quoted context omitted.

This is an analogy to the Three Body Problem from Liu Cixin!

I’ve heard that book(series?) pop up quite a lot recently. Is it worth a read?

Yes. It's the best science fiction I've read in years.

If you go in expecting adventure fiction, then it's not enjoyable. It's more like reading something like Olaf Stapledon.

Post reply on HN