Time reversal technology probes blue cheese and red planet alike

This post is written in response to the contest I posted on my Twitter feed earlier today:

SciencePunk challenge: give me two unrelated topics and I will attempt to write a blog post combining them. Your time starts now.

Of several excellent and perplexing replies, I decided to seize the gauntlet thrown down by Martin of The Lay Scientist blog:

@SciencePunk Pigs, and the flu. No? Oh alright... erm... Mars and cheese.

So here it is Martin!

If you heard the words "time reversal technology" you'd be forgiven for thinking it was a plot point from the new Star Trek movie. Yet across the world, physicists and engineers are using it to explore the world around them, from astronomy to cheese-making.

Whenever waves pass through a medium, they respond to changes in the properties of that material. Sound waves passing through the ocean, for example, are warped and garbled by differences in the density of the water, making acoustic communication with submarines troublesome. Similarly, astronomers are vexed by atmospheric blurring, where the turbulent gasses that cocoon our planet can distort an otherwise BAT-worthy image of Mars.

However, help is at hand. Time reversal technology replays the signal in reverse, and subtracts this from the original. Because the distortions cancel out one another, the result is a much cleaner image or sound. You can read an incredibly complex article about it here.

So what does this have to do with cheese? Later this month, a group of French and Uruguayan scientists will attend a conference in Portland, Oregon, to discuss their work using the same technology to probe "soft solids". Directing acoustic waves through a material, they are using time reversal to analyse the distortions and draw conclusions about the properties of that object. This low-cost technology has various applications in the food industry, e.g. allowing cheese makers to test the ripeness of their Brie stock.

And that is how you combine Mars and cheese in a blog post.
Image is a composite, CC two Flickr members: Jason Burmeister and psd.