samtímis

Samtímis is the Icelandic term for simultaneity, the relation that two or more events share the same time. The word is formed from roots meaning together and time, with a nominal suffix typical of Icelandic nouns.

In physics, simultaneity is a relative concept: whether two spatially separated events occur at the same time depends on the observer’s frame of reference. In special relativity, clocks in different frames can disagree on timing, which leads to the conclusion that simultaneity is not absolute. A common illustration is the train-and-platform scenario, where events judged simultaneous by one observer may not be simultaneous for another in relative motion.

In philosophy, discussions of simultaneity engage with questions about temporal ontology, such as presentism versus eternalism, and how to define temporal relations operationally. Clock synchronization methods, notably Einstein synchronization, are used to establish a working notion of simultaneity within a given frame.

In linguistics, simultaneity concerns how languages encode events that occur at the same time, including tense, aspect, and the use of temporal subordinators. Typological and cross-linguistic studies examine how different languages express concurrent events and the constraints on their interpretation.

Applications of the concept span experimental science, timing and data recording, and computing, where understanding whether events are simultaneous is important for coordinating processes and ensuring consistent observations.