In everyday physics, transport refers to the movement of something from one place to another. This can include electricity traveling through a wire, heat spreading through a metal, or water flowing inside a pipe. In each case, the behavior of the flow depends on how freely charge, energy, or mass can move through a material.
Under normal conditions, interactions such as collisions and friction create resistance, which gradually weakens these flows or brings them to a stop. Researchers at the Vienna University of Technology have now demonstrated an unusual exception to this familiar behavior.
In their experiment, thousands of rubidium atoms were restricted to move only along a single line by carefully controlled magnetic and optical fields. This setup produced an ultracold quantum gas in which both energy and mass can move without any loss at all. The findings, reported in the journal Science, show that the flow stays constant even after an enormous number of collisions between atoms. This surprising stability points to a form of transport that behaves very differently from what is seen in ordinary materials.
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