Discovery

Might This Brighten Up Your Day?

Dave Arns

You may have heard in recent weeks about a brilliant bluish glow
Created in a fluid in which bubbles do abound -- 
The bubbles can be made to grow and dwindle, to and fro,
And flash blue light, when energized by sound.

All you need is water and a little bit of normal air
Contained in bubbles much too small for you and me to see;
Then get a source of ultrasonic sound and place it where
It can blast a hundred ten or more dB.

The bubbles in the water, now bombarded with such piercing tones,
Begin the strange ballet that we call "sonic cavitation".
In which they're stimulated by the alternating zones
Of high pressure, then of low, of short duration.

The bubbles, with a radius five microns in extent or so,
Expand to fifty when the sound wave's pressure bottoms out.
And then the pressure rises, and the bubbles undergo
A million-fold collapse, without a doubt.

It's when their volumes shrink this much that fascinating things occur:
High pressures and high temperatures are surely of the essence.
Each bubble then becomes a tiny furnace, as it were,
And Voil! You've just made sonoluminescence!

The light created by such bubbles tells us they are very hot:
So strong in ultraviolet, near 100,000 K!
But the flashes are much shorter than most scientists had thought -- 
Only 50 picoseconds, so they say.

"But what good are such experiments? And are they practical?" you ask.
"And who would use this knowledge? Who would go to all the trouble?"
One group, I think, could use it in their normal, daily task:
The breweries, whose wares are known to bubble!

See, sonoluminescence will take all the breweries by storm -- 
The newest gimmick meant to grow their market share, and thus,
They'll want us all to drink their beer, no matter cold or warm,
At home, at work, or even on the bus.

You think I'm kidding, do you not? "Demented ramblings", do you think?
I tell you now, their ad campaign's been going many a year!
You've heard, no doubt, of beer's "warm glow" you feel after you drink?
The glow's from radiant bubbles, it is clear.

Once you see just how much money a lucent stout potentially brings,
You'll see why many people see it all through eyes of fear.
You'll know a luminescent brew is waiting in the wings
When you see commercials for what's called "light beer".

Dave Arns