• Question: how did you discover how to move objects with just light?

    Asked by u12woodburnj to Susan on 8 Nov 2013. This question was also asked by goldeyes202.
    • Photo: Susan Skelton

      Susan Skelton answered on 8 Nov 2013:

      Great question!

      This story starts 400 years ago when the German astronomer, Johannes Kepler, noticed that the tails of comets (smallish objects which whizz around the solar system) always point away from the sun. He guessed that this is because the light from the sun exerts a pushing force on the gas and dust particles that make up the comet’s tail.

      But Kepler’s theory was only tested for the first time 40 years ago, when an American scientist called Arthur Ashkin used a strong light beam called a laser to first push, and then hold, small particles in his laboratory.

      Today this technique is used by lots of scientists for holding small objects including cells, bacteria and even single atoms so that they can be studied.

      My job involves trying to improve the technique to hold even smaller objects so we can learn more about how the world behaves on the smallest scale.

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