April 25, 2006

Slow and fast timescales

Posted by Arcane Gazebo at April 25, 2006 5:58 PM

Having just finished reading Spin (which I reviewed below) I found myself thinking about timescales. The novel did a good job of bringing long timescales into perspective, but what about short ones? In the book, the ratio between Earth time and solar time was about 108, one hundred million years outside the earth to each year in the Spin, or 3.17 years every second. This was an enormous ratio, with any timescale relevant to human civilization passing by in less than a day. It was mind-boggling to read about in the book. But I realized that I was sitting in the lab doing a diagnostic measurement in which I watched the response of a SQUID to an applied microwave field, and my software was acquiring about one point every second, at nanosecond resolution. That's a ratio of 109, ten times greater than the ratio in Spin. I usually don't think much about how long a nanosecond is, but it's really astonishingly short—as far removed from normal human timescales as stellar lifetimes.

It's not just in my lab—with gigahertz processors in wide usage, much of modern technology runs on nanosecond timescales. (And Windows still manages to be frustratingly slow at times, with billions of clock ticks in a second to work with.) Faster timescales are a bit harder to get to, at least in semiconductor electronics. The pulse generator I use in qubit experiments has a time resolution of 5 picoseconds, which always impresses me until I remember that the accuracy is only 250 ps. There's some research into a faster electronics technology using superconducting circuits and flux quantization, called Rapid Single Flux Quantum (RSFQ), which I believe gets to picosecond timescales. Berkeley professor emeritus Ted Van Duzer has been involved in this.

Anyway, I'm not sure I have much more insight into fast timescales than slow ones, but at least they're more accessible.

Tags: Books, Life, Physics, Science

I like problems with multiple scales... it makes for plenty of good perturbation theory (among other things).

Posted by: Mason | April 26, 2006 12:47 AM
Post a comment