In past posts, when I've written about the expansion of the universe, I've generally referred to the rate of that expansion, the Hubble constant, as being around 70 km/s/megaparsec, that is, for every megaparsec a galaxy is distant from us, it's moving away at 70 kilometers per second faster. So a galaxy 100 megapasecs away … Continue reading Is cosmology in crisis?
ratamacue0 called my attention to this interesting article on the possibility of dark matter "eating" neutron stars: Dark matter: Devourer of stars | Ars Technica. Neutron stars are collapsed stars that have used up all of their fusion fuel. Typically what happens at that point in a star's life is that they collapse, but the extent of … Continue reading Dark matter might cause neutron stars to collapse into black holes
The other day, I did a post on interstellar exploration which linked to one by Sten Odenwald on the problems with interstellar travel. Well, he posted some follow-up remarks, expressing some surprise at the response, doubling down on the aspects of the limitations of interstellar travel he identified, and urging people to be optimistically realistic. (I predict he'll get … Continue reading The movie ‘Interstellar’ and wormholes
Ethan Siegel's blog, Starts With a Bang, is one of the best science astrophysics blogs on the web. Ask Ethan #12: How far is the distant Universe? – Starts With A Bang. In this post, he tackles an issue I often see a lot of confusion over, even from science reporters. When talking about extreme … Continue reading Ask Ethan #12: How far is the distant Universe? – Starts With A Bang