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?
The other day, I was reading a post by Ethan Siegel on his excellent blog, Starts With a Bang, about whether it makes sense to consider the universe to be a giant brain. (The short answer is no, but read his post for the details.) Something he mentioned in the post caught my attention. But … Continue reading 97% of the observable universe is forever unreachable
The Fermi Paradox is the question that, if the conditions for life in the galaxy are as ubiquitous as they appear to be, so that there should be hundreds, if not thousands of alien civilizations out there, then where is everyone? Why have we found no evidence for any for those civilizations? And why aren't they here? … Continue reading Snowden’s answer to the Fermi Paradox and its assumptions
For those interested in the post about finding advanced civilizations in other galaxies by their heat emissions, Paul Gilster at Centauri Dreams has a write up about the study, including links to additional material as well as the actual paper. I found that this part clarified the seeming contradiction in the Science Daily article. The currently reported work … Continue reading G-HAT (Glimpsing Heat from Alien Technologies)
At first, this article seems like a bit of a downer: Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies -- ScienceDaily. After searching 100,000 galaxies for signs of highly advanced life, a team of scientists has found no evidence of advanced civilizations there. The idea behind the research is that, if … Continue reading Searching for advanced civilizations in other galaxies: 50 possible candidates found?
This is interesting. Astronomers discovered dark energy, the energy causing the rate of expansion rate of the universe to speed up, by looking at large numbers of Type 1a supernovae. Type 1a supernovae are white dwarfs (collapsed stars after their fusion has gone out) that explode. What causes a previously stable white dwarf to explode? … Continue reading Dark energy may be less energetic than previously thought
Sometimes it's amazing how much settled science, even something as longstanding as the size of our galaxy, can get called into question: The Milky Way May be 50 Percent Bigger Than Thought : Discovery News. A ring-like filament of stars wrapping around the Milky Way may actually belong to the galaxy itself, rippling above and below … Continue reading The Milky Way May be 50 Percent Bigger Than Thought
First, in case you haven't heard: 70,000 Years Ago, Another Star Flew by the Edge of the Solar System | RealClearScience. According to an international team of astronomers, about 70,000 years ago a red dwarf star -- nicknamed "Scholz’s star" for the astronomer who discovered it -- passed by our solar system just 0.8 light years … Continue reading A close pass by a red dwarf star, and a note on interplanetary and interstellar distances
At least, according to a couple of astrophysicists: Complex life may be possible in only 10% of all galaxies | Science/AAAS | News. The universe may be a lonelier place than previously thought. Of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth, a … Continue reading Complex life in the universe may be much rarer than previously thought
Gabriel Popkin as an article at Inside Science about a study that looks at the possibility of intercepting communications between other alien civilizations. The idea is that communicating across interstellar distances is best done with lasers. So far, the optical search for extraterrestrial intelligence has focused mainly on the hope of receiving—and recognizing—an intentional, laser-encoded … Continue reading Eavesdropping on E.T. and the possibility of interstellar travel