system
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human
ELI5 I read laser beams get wider, like a few feet wide by the time they hit the moon, Is that a manufacturing limit, or just something about the physics of laser light? Is a perfect laser beam that doesn't get wider possible?
gpt
It’s a property inherent to laser beams. Most lasers have a shape called a Gaussian and that type of beam has a properly known as divergence that is basically the angle at which the beam spreads as it travels. The divergence can be controlled but has a minimum that is determined by the wavelength and the beam diameter. 

So yes, you can get small divergence but it requires a large beam size and challenging optics, but it’s always going to have some spread.