So I read the Wiki entry, and from what i gather ultrarelativitic speeds are speeds that almost the speed of light (I mean $$\gamma >>1$$ is the same as $$v \to c$$).(adsbygoogle = window.adsbygoogle || []).push({});

Now what is the boundary where where you regard a particle's speed as ultrarelativitic compare to nonrelativitc speeds.

Is $$v \geq 0.9c$$ regarded as ultra (I guess that it is), but then what about speeds such as 0.8c, 0.7c etc?

My naive notion was that the lowest boundary is 0.5c that below this we would have nonrelativitic speeds, but I am not sure.

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# Ultrarelativitic speed

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