speed of light
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speed of light
The speed at which electromagnetic waves, such as light, propagate in a vacuum. It is a fundamental constant of nature and the highest possible speed in the universe.
Nichts kann sich schneller als mit Lichtgeschwindigkeit bewegen.
Nothing can move faster than the speed of light.
The word is made up of 'das Licht' (light) and 'die Geschwindigkeit' (speed). The 's' in between is a linking element that connects the two words.
Die Lichtgeschwindigkeit ist eine wichtige Konstante in der Physik.
The speed of light is an important constant in physics.
In the colloquial meaning, the fixed expression 'mit Lichtgeschwindigkeit' (at lightning speed / at the speed of light) is used almost exclusively to express extreme speed.
Er hat die Aufgabe mit Lichtgeschwindigkeit erledigt.
He completed the task at lightning speed.
In the figurative meaning, the expression is often combined with verbs such as 'sich verbreiten' (to spread), 'reagieren' (to react), or 'arbeiten' (to work).
Das Gerücht verbreitete sich mit Lichtgeschwindigkeit in der ganzen Firma.
The rumor spread through the entire company at lightning speed.
light-year
'Lichtjahr' and 'Lichtgeschwindigkeit' both belong to the topic of light and outer space. Still, they do not mean the same thing. A 'Lichtjahr' (light-year) is a distance: it says how far light travels in one year. 'Lichtgeschwindigkeit' (speed of light) is a speed: it says how fast light moves. The words can be confusing because 'Lichtjahr' contains the word 'Jahr' (year). But it is not about a length of time; it is about a very large distance. For distances between stars, you use 'Lichtjahr'; for the movement of light, you use 'Lichtgeschwindigkeit'.
Licht bewegt sich im Vakuum mit Lichtgeschwindigkeit.
Light moves at the speed of light in a vacuum.
Der Stern ist mehrere Lichtjahre von der Erde entfernt.
The star is several light-years away from Earth.