We all know—generally speaking—how a car works: The gas pedal makes it go, the break pedal makes it stop, and the steering wheel deter­mines its course. But pop open the hood and you’ll find there’s a lot more nuance to those maneuvers.

With macro­scopic machines, get­ting under the hood is a straight­for­ward process, but when it comes to the mol­e­c­ular machines dri­ving bio­log­ical func­tions inside our cells, things get a lot more com­pli­cated, according to Paul Whit­ford, an assis­tant pro­fessor of physics.

That’s because the envi­ron­ment in which they operate has a much greater impact on the machines them­selves. For example, water mol­e­cules are con­stantly bom­barding them, and since the energy of a water mol­e­cule is very close to that of the mol­e­c­ular bonds in these micro­scopic machines, the impact is significant.

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