# If the EM field weakens over distance, then why doesn't light weaken as it travels further from the source?

Just something I can't wrap my mind around. If light is oscillating EM field, and the strength of EM field weakens proportionally to distance squared, then why light doesn't lose energy as it travels further from the source? Why wouldn't oscillating EM field weaken over distance same as non-oscillating field does?

P.S. I've found sources saying that EM radiation is a wave that "detaches" from the source. If it's the case, could you explain why exactly would detachment allow the wave to "ignore" the weakening over distance?

Thanks.

• If I live 100 miles from you and turn on my desk lamp, which of us do you think will receive more light? Commented Jul 1, 2020 at 11:45

My old high school physics teacher had a good mental image for this. Instead of a light source, imaging an automatic toast buttering machine at a restaurant. It melts a pat of butter and sprays it on the toast. Initially, the restaurant puts the toast at $$r = 1$$. For $$1$$ pat, $$1$$ slice of toast.
To save money, they moved out to $$r = 2$$. Now $$1$$ pat, $$4$$ slices of toast. Each slice gets less butter.