Yesterday (November 10, 2012) I spoke about black holes at the Richmond Public Library. For those who couldn’t make it, or who were there but want more information, here’s the essence of the talk, along with the relevant images that formed my slides. Please leave any questions you have in the comments, and thanks to everyone who came out (despite the insane marathon-related traffic)!
Black Holes Don’t Suck
(Yes, I’ve used that joke before. So sue me.)
Discussions of black holes fall into two distinct categories. The first is the sexy string theory/quantum gravity/Stephen Hawking category, all about time warps, wormholes, extra dimensions, Bekenstein entropy, and baby universes; the second discusses the real black holes discovered in our galaxy and beyond. While the sexy stuff is a lot of fun to talk about, that’s not what I discussed: it’s speculative, and at the present time impossible to test. (Some of it by its very nature is impossible to test, since we can’t get access to the region inside a black hole. More on that shortly.) However, I think real astronomical black holes are just as interesting, and over the last several decades astronomers have realized how important they are in shaping the galaxies they inhabit. Continue reading
Did I mention the talk is informal? It’s an informal talk.
Today—November 10, 2012—I will be speaking about black holes at the Richmond Public Library. The talk is free and for all ages (though I think older children may appreciate the topic more). No prior knowledge is assumed, so bring your questions and curiosity!
See you there!
Somewhere, something incredible is waiting to be known. – Carl Sagan, born November 9, 1934
Carl Sagan in 1980. [Credit: NASA/JPL]
Like many science writers, I count Carl Sagan as one of my inspirations and influences. However, I think there’s a tendency to mourn his absence (he died relatively young) in the wrong way: by negatively contrasting current science communicators with him, as though there needs to be One True Sagan, with everyone else failing to meet his standard. That’s a fallacy of thought and a failure of imagination
I think there is a tendency to idolize Sagan, which is (as usual with idolization) unfair both to him and to others who would try to communicate science. In this era of media fragmentation, it may not even be possible for a single figure to be as popular or recognizable, but I don’t think that’s necessarily a bad thing. Instead of a single Sagan, why not many? [Read more…]
We have a lot of reasons to be interested in the earliest stars that formed in our Universe. Particularly, these stars were the first to fuse hydrogen and helium into (nearly) all the heavier elements that exist today, including the carbon, oxygen, iron, calcium, and the like that make up life as we know it. However, not only are these stars too far away to observe directly, much their light is hidden by foreground sources, including our Milky Way. A new indirect observation may have solved that problem, though:
Now a study using the Fermi Gamma-ray Space Telescope has used the light emanating from supermassive black holes known as blazars to measure the diffuse light produced by reionization. When high energy gamma rays interacted with the ultraviolet photons produced by early stars, they were converted to particle/antiparticle pairs, and this creates a dropoff at a specific point in the blazar spectrum. This absorption was evident in a sample of 150 blazars, and the data can help constrain models of the very first stars in the Universe. [Read more…]