Kerr black holes images and videos (2012) | Hacker News Reader

Kerr black holes images and videos (2012)

madore.org

24 pointsp4bl013 comments

"In fact, from the distant observer's point of view, nothing beyond the horizon really exists, and a physical black hole's mass could be said to consist of the mass of the collapsing star, ever frozen in the last stages of its collapse."

Mind blown.

I remember reading that we cannot see a black hole with the naked eye, but never go an explanation as to why...

This is a really good article.

As a wannabe-black hole scientist I love pages like this!

Brings back memories of Frederick Pohl's Gateway [1] book...

(Spoiler)

In the end, we learn that the main character (accidentally) abandoned his friends to a black hole. However (plot twist), it is discovered that because of gravitational time dilation (?), decades later from Earth time's perspective means that his friends are still falling towards the black hole.

This always irked me, and this page explains why: the falling would have happened in a microsecond, it's just that the light from the falling ship will appear to slow down because of gravitational effect.

[1] https://en.wikipedia.org/wiki/Gateway_(novel)

I see that you are considering only the light, but there is more than that. Time dilatation around gravitational fields is real (we have it on Earth too). Given the extreme setting in this regard around a black hole, it may be possible that, even if the falling object has not yet arrived at the event horizon, there to be a significant and increasing time frame difference between that of a distant observer and that of the object moving closer to gravitational center, which lets the observer see a progressively slower fall. I find this to be more likely the reasoning behind the novel's depiction.

Yes, you are quite correct! Nevertheless, the nitpick applies: in the timeframe of the narrator outside the black hole, it's already way too late.

Since, as the article explains, an outside observer would never see things falling towards the black hole actually reach the 'black' part - they'd just get slower and redder as they get close. So - wouldn't a black hole appear entirely surrounded by all the things that ever 'fell into it', still there outside it? I've never seen an 'artist's impression' of one that looks like that..a big ball of dust, rocks, ice etc.

(Imagine if garbage bins looked like that..)

So... the black hole may look like a collapsing star but also like a planet? The only thing distinguishing it then would be its escorting (but not yet fallen) world around it?

Off topic. Whenever I waste a lot of time on youtube looking into some subject(today it was black holes) it ends up on Hacker News also. Surely, somebody has a name for this effect.

Baader Meinhof, possibly?

Thank you. https://en.wikipedia.org/wiki/Baader–Meinhof_effect

Yep. See also the sudden run of paranoia about phones surreptitiously mining audio around them for targeted advertising.

Related: visualizing travelling through a Schwarzschild black hole:

http://jila.colorado.edu/~ajsh/insidebh/schw.html

As OP page indicates, the Schwarzschild description is simpler as it doesn't take into effect the rotation, but their visualization, especially with the distorted space background, are impressive nevertheless.

Great page, the software builds really easily. Try it!

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