Interview with Kenneth Libbrecht, Professor of Physics at Caltech, who took these wonderful snowflake photographs.
How do you photograph a snowflake in the wild?
First one needs a microscope and camera that can sit out in the cold. Cameras especially don't like the cold, so they need to be heated. I have a picture of my set-up at http://www.its.caltech.edu/~atomic/snowcrystals/photo2/photo2.htm.
Then I stand outside and collect snowflakes on some kind of collection board, typically a piece of cardboard or foam-core. When I find one I like, I pick it up using a small paintbrush and place it on a
microscope slide (it's not as hard as it sounds). Then one has about a minute, less when it's relatively warm, to get a good picture before the snowflake starts to evaporate away.
I find I can do this for hours on end; it's really quite pleasant, especially since you just don't know what great crystals you'll find next.
You also create snowflakes in a lab. Is that difficult?
That depends on what you consider difficult. Anyone can make snow crystals using a pretty simple apparatus (see
http://www.its.caltech.edu/~atomic/snowcrystals/project/project.htm),
but these will not have six-fold symmetry. I've spent years working on techniques to grow snow crystals in very controlled environments, in order to understand the crystal growth dynamics. Those experiments are quite difficult.
Most snowflakes have 6 sides, but some have 3 and some 12. Why do they only appear with these particular dimensions?
Snowflake symmetry derives from the crystal structure of ice. The water molecules hook up in such a way that six-fold symmetry results. The 3-and 12-fold symmetric varieties still have the same underlying 6-fold symmetry.
You don't spend all your time on snowflakes - you're a research physicist currently working on a major astronomy project, the Laser Interferometer Gravitational-Wave Observatory (LIGO), trying to verify one of Einstein's theories. What do you hope to find with LIGO?
LIGO isn't so much an instrument to verify Einstein's theories, but rather a telescope (antenna would be better) for looking at violent events in the cosmos. We hope to see things like merging black holes and neutron stars, as well as signals from supernovae (collapsing stars).
In his book on Einstein, Lincoln Barnett described a physicist as Being "somewhat in the position of a blind man trying to discern the shape and texture of a snowflake. As soon as it touches his fingers or his tongue it dissolves." My guess is that you might not agree with that statement?
That's a fine statement, but it's more a reference to quantum mechanics, where the observer always affects the measurement. Snowflake growth can be nicely described by classical physics. If you want to discern the shape of a snowflake, you look at it; you don't touch it or put it on your tongue.
All photographs copyright Kenneth Libbrecht
More information about LIGO is at
http://www.ligo.caltech.edu/LIGO_web/PR/scripts/facts.html
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