Dark Matter
Tag archives for Dark Matter
Somethin’ Neat about our Galaxy
Posted by Ethan on March 26, 2008 So last week I was up at Pacific University in Portland, OR for a job interview. As part of a faculty interview, you have to lecture on a topic for undergraduates, but they give you the topic just a couple of days before. My topic was Gauss’ Law, which talks about the relationship between an…
Afraid of the Dark?
Posted by Ethan on March 11, 2008 So I gave a public lecture last (Monday) night called, “Afraid of the Dark: How We Know What We Can’t See” and videotaped it. Now, I’m pretty good at what I’m doing right now (research in theoretical cosmology), but I’m really good at public speaking and teaching, and here is me telling a public audience…
Why we need Dark Matter in the Universe.
Posted by Ethan on February 19, 2008 Last week, Pamela Gay over at Star Stryder pointed me to a press release which claimed that, among other things, perhaps dark matter wasn’t necessary. So I wrote a guest post on her blog explaining why it was. Apparently, some people still aren’t convinced. So I will lay out for you all the reasons I…
Great things await you online…
Posted by Ethan on February 15, 2008 Three awesome things are going on today for you, and I invite you to check them all out: The latest Carnival of Space is live, where you have your choice of 23 different astronomical topics to choose from. Of course, my post this week on galaxies and how they’re made is on there, too! Pamela…
What if I were made of Dark Matter?
Posted by Ethan on February 13, 2008 I’ve been talking about dark matter a lot, and yet there’s still so much to explain about it. For example, dark matter and normal matter (protons, neutrons, and electrons) have a few things in common: They both have mass. They both feel the effects of gravity. They both cause their own gravity. But that’s where…
Galaxies are made exactly how, now?
Posted by Ethan on February 13, 2008 Last week, Jamie (my significant other) came home from work and told me about a conversation she had with her coworker, Chris. This week she asked another one, Miguel, whether he had any questions about Astronomy, Physics, space, etc. This week’s question comes from Miguel: What is a galaxy, anyway? Why does it look like…
Dark Matter: Is it right in front of us?
Posted by Ethan on January 31, 2008 Last year, I had just finished my Ph.D. studies, and had moved to Madison, WI to teach introductory physics at the University of Wisconsin. I was working on this paper, and when I submitted it, I got a phone call from New Scientist magazine’s space division. Fast-forward two weeks, and I find this article online,…
An amazing discovery: a double Einstein Ring!
Posted by Ethan on January 24, 2008 
One of the perks of being a postdoc at a place like the University of Arizona, one of the top places in the US for astronomy, is that we get a number of really interesting visitors. Today we got paid a visit by Tommaso Treu, an astronomer at UC Santa Barbara. He spoke to us…
MOND vs. Dark Matter
Posted by Ethan on January 22, 2008 The first serious advocate of modifying Newton’s laws instead of postulating unseen (or dark) matter was Moti Milgrom, from whom today a new article appears on the astrophysics preprint archives. In particular, Milgrom asserts the following: MOND predictions imply that baryons alone accurately determine the full field of each and every individual galactic object. These…
First question!
Posted by Ethan on January 21, 2008 Dave, one of my online chessplaying buddies, asked me this question (edited for appropriateness): Now this speeding up of the expansion of the universe: Do I understand correctly that one of the theories to explain why relates to “dark matter”? In real simple terms, what in the dark blue blazes is dark matter, and why…
