How far can a beam of light travel if there is no obstruction in its path?

2 Answers
Mark C.
Jan 20, 2018

In theory infinitely far.

Explanation:

The beam will reduce in intensity as it spreads out (#prop 1/r^2#) but if there is no obstruction, in principle there is no limit.

Steve J.
Jan 20, 2018

As far as
#s = c*t#
where #c# is the speed of light and #t# is as much time as you want to give it.

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