Invisible force? Aren't all forces invisible?
Oh, I see. The title of the HN submission has been creatively edited and is not the title of the original Nature article.
Clickbait.
Oh, I see. The title of the HN submission has been creatively edited and is not the title of the original Nature article.
Clickbait.
This is the key bit of context:
> When describing the gravitational dynamics in co-moving coordinates, by which the expansion of the Universe is factored out, underdensities repel and overdensities attract.
So it's basically a coordinates transformation thing.
And in considering airflow, for example, one doesn't say that underdensities repel air, or that overdensities attract air. Rather, it's the non-uniform flows that create the underdensities and overdensities.
Anyway, it seems to me that Hoffman and coauthors should have stuck to describing correlations, because that's all they have. Using the language of causality is confusing. They don't mention it, but maybe they have an agenda to promote varieties of dark matter with positive and negative gravity.
Well yeah, they seem to have put it into laymans terms, but as a layman it appears to be an accurate representation of the article. It's certainly more descriptive than "The Dipole Repeller", so not click bait.
This is about the Local Group *motion
>The presence of a large underdensity, the dipole repeller, is predicted based on a study of the velocity field of our Local Group of galaxies. The combined effects of this super-void and the Shapley concentration control the local cosmic flow.
The Dipole repeller and Shapley attractor are ~30000 km/s apart, which is ~1.5 billion light-years.[0]
0) http://www.as.utexas.edu/astronomy/education/spring06/komats...
"Milky way pushed around" would have been sufficient to convey the interesting part. It's interesting because at galactic scale isn't it usual to be pulled around rather than pushed around?
Not sure if deliberate