In 1872 railroad magnate Leland Stanford wagered $25,000 that a galloping horse, at some point in stride, lifts all four hooves off the ground. To prove it, Stanford employed English photographer Eadweard Muybridge. After many attempts, Muybridge developed a camera shutter that opened and closed for only two thousandths of a second, enabling him to capture on film a horse flying through air (see movie on the left; note that temporal resolution of a stationary image on the right is not sufficient to resolve the details of the motion).

One hundred years later, motions of atoms were observed on their native timescales. Today, we can directly observe the atomic motions in both space and time (see animations below).

Photon-induced near-field electron microscopy, B. Barwick, D. J. Flannigan, A. H. Zewail, Nature 2009, 462, 902-906.
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Nanomechanical motions of cantilevers: Direct imaging in real space and time with 4D electron microscopy, D. J. Flannigan, P. C. Samartzis, A. Yurtsever, A. H. Zewail, Nano Lett. 2009, 9, 875–881.
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Nanomechanical motions of cantilevers: Direct imaging in real space and time with 4D electron microscopy, D. J. Flannigan, P. C. Samartzis, A. Yurtsever, A. H. Zewail, Nano Lett. 2009, 9, 875–881.
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Nanomechanical motions of cantilevers: Direct imaging in real space and time with 4D electron microscopy, D. J. Flannigan, P. C. Samartzis, A. Yurtsever, A. H. Zewail, Nano Lett. 2009, 9, 875–881.
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4D imaging of transient structures and morphologies in ultrafast electron microscopy, B. Barwick, H. S. Park, O.-H. Kwon, J. S. Baskin, A. H. Zewail, Science 2008, 322, 1227-1231.
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4D imaging of transient structures and morphologies in ultrafast electron microscopy, B. Barwick, H. S. Park, O.-H. Kwon, J. S. Baskin, A. H. Zewail, Science 2008, 322, 1227-1231.
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Nanoscale mechanical drumming visualized by 4D electron microscopy, O.-H. Kwon, B. Barwick, H. S. Park, J. S. Baskin, A. H. Zewail, Nano Lett. 2008, 8, 3557 - 3562.
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Unfolding and melting of DNA (RNA) hairpins: The concept of structure-specific 2D dynamic landscapes, M. M. Lin, L. Meinhold, D. Shorokhov, A. H. Zewail, Chem. Phys. Phys. Chem. 2008, 10, 4227-4239.
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