I recently watched this remarkable video which was produced (I assume) to coincide with yesterday’s publication of this article in Nature. Even if you have little interest in astronomy/cosmology, I urge you to take a peek at the video. It is an absolutely glorious presentation of a ‘big’ topic (and is only four minutes long).
Much of the video revolves around The Great Attractor and the research published in Nature demonstrating that the number of galaxies drawn toward it is truly astronomical (or equivalently, that The Great Attractor ‘drains’ a truly enormous ‘basin’ of space).
My question, then, is: what is the nature of The Great Attractor? In the Wikipedia link above, it’s stated that The Great Attractor is a “gravity anomaly in intergalactic space”. I’m not sure I understand the “anomaly” part; in fact I’m certain that I don’t. Wouldn’t the formation of an attractor be expected? Won’t one inevitably form ‘somewhere’ as a result of the chance distribution and subsequent attraction of a large number of otherwise randomly placed galaxies? In other words, gravity guarantees that any distribution of masses will attract one and other, and thus tend to coalesce (eventually), no? Why is that an “anomaly”? Or is it an “anomaly” only in the sense that most points in space are not attractors? (although, eventually, they’ll become part of one, I suppose)
I apologize for being vague in phrasing my question. Still, any ‘answers’ or relevant information about The Great Attractor would be appreciated. And, even if my question turns out to be misconceived (a common problem for my physics and astronomy questions), I’ll take some solace in knowing that I’ve pointed people to that amazing video.
Well first thing - ignore what wiki says. These new findings make anything we knew about the great attractor irrelevant. What this research is showing is what we thought was an gravity anomaly is simply the densest part of our super-cluster.
What has made studying and understanding the nature of the great attractor is its location relevant to our own galaxy. There is a section of sky called the zone of avoidance which makes studying objects outside our galaxy very hard. Over the last 30 years there have been great advances in finding ways to observe through this zone.
It seems that they use the word “anomaly” or “Great Attractor” to mean anything with a mass great enough that it attracts galaxies within its supercluster. It’s not in any other way different from any other cluster of galaxies, except for its mass. Yes, I wish they hadn’t used the word “anomaly”; it’s very misleading.
Nice video. Galaxies flowing in a direction suggest a force that is very like or is gravity. Perhaps such a large supercluster “breaks” near the gravitational attraction of another universe. And other superclusters might be nearer other universes. I think there will be huge strides in the coming years into explaining what gravity is. But we just don’t know, and that is the beauty of it.
So it really is the idea that gravity sculpts spacetime, on the most massive scale yet seen? I liked how in the video the narrator equated it to water flowing. Laniakea is the “watershed” we are in, so to speak.
To extend the metaphor, since we are in one of the furthest reaches of Laniakea (the beginning of a “tendril”, if you like), we are in the “heights” or the “mountains” of the configuration, where a raindrop starts to flow towards either the Atlantic or Pacific Ocean. Here, though, what our galaxy cluster is flowing down is not a mountainside but gravitationally warped regions of spacetime.
ETA : I see that this is touched on in the OP. It does make for a fascinating way of visualizing it.
Not really - when the Great Attractor was first detected through indirect observation it was indeed an anomaly. Nothing visual could be seen in the area even though whatever was there should have a mass that dwarfed the Virgo cluster.
Remember much of the language about the Great Attractor pre-dates the understanding of the massive structures that dominate the universe, and how galaxies move around etc
It’s probably a massive rift in the space/time continuum which is inexorably dragging our entire universe into the Great Colossal Void. Theyre be dragyns.
Well, maybe it’s something else…
As the saying goes, the most exciting phrase in science isn’t, “Eureka!” The most exciting phrase is, “Hmm, that’s strange…”
I think it’s a reasonable word. When you look at solar systems and galaxies, you can see a few patterns that they follow. In both cases, they’re circular and spin.
These super-structures seem to have no particular defining structure like that. One might guess that, in time, they’ll normalize due to similar effects (e.g., matter moving in a vacuum). Until that point, they’re non-normal AKA anomalous.
