Archive for: August, 2010

The History of the Universe

You're going to read a lot about science on Scientopia. This post is to help you put it all in context. I'm not going to go into great depth, because that would take, well, the effort of humanity over many lifetimes. This is just a drive-by overview.

The slide below is one that I show in a substantial fraction of the talks that I give:

A History of the Universe

The first thing to notice about it is that it's a logarithmic scale. In the top line, at each tic-mark the universe is about 10 billion times older than it was a the previous tic-mark. That sounds like a lot, until you look at the labels on the tic-marks... the last mark on the top line is 109 seconds, or about 30 years.

Since the Universe is only about 14 billion years old, another factor of 10 billion past that step would take the Universe past the present day. Thus, the black circled region on the right of the top line is expanded into the bottom line, where each step is only typically a factor of 30 in age. This isn't exactly right, because really it's a step of a factor of 10 of redshift. That's what the variable "z" is in the figure, and it's very important, but I'm going to have to save it for another post. Likewise, the variable "T" along the timeline is the ambient temperature of the Universe, which also requires a lot of additional exposition, and so I will put that off to a future post. Continue Reading »

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Welcome to my blog!

Aug 02 2010 Published by under About the Blog

Welcome to the scientopia iteration of Galactic Interactions! At the moment, I'm deep in the process of unpacking after moving from the USA to Canada, having arrived just there days ago, so there's no meaty post just yet. The archives from when this blog was at ScienceBlogs have been imported-- those go through 2007. The more recent archives at the blog's last location aren't imported yet, and I'm working on it.

Stay tuned; if I get a chance amongst all of the unpacking I'm doing, later today I will post the history of the entire Universe....

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