[SamBam]

> Lastly, there’s the “line-of-sight” problem; lasers shoot perfectly straight, meaning a laser shot toward the horizon will eventually hit the Earth’s curves.

Huh, and here I thought the Hollow Earth theory had been discredited, but I guess I might believe Raytheon and its lasers. Cyrus Teed would be so pleased.

[gnode]

I'm not sure what the earth being solid or hollow has to do with this. If you're on the surface of a ball, you can only project a laser / straight line over the hemisphere above you; not through the ground.

As an example, if you're at the North Pole and the South Pole base fires a ballistic missile at you, you can't aim a laser at it, as it would diametrically intersect the Earth.

Instead, you have to wait until the missile passes your horizon. The point at which it does this depends on its altitude. Hypersonic vehicles attempt to make interception harder by reentering the atmosphere from space earlier than a traditional ICBM, and travelling at a lower altitude in their final phase.

[chc4]

I think it was a joke. The way the quote was worded makes it sound like the Earth is curving upwards - if you shoot straight to the horizon you'll hit air, not the ground.

[Mvhsz]

To me it sounded like a journalist's awkward wording of a description from an engineer. Some frequencies of light will bend to the curvature of the earth due to the atmosphere[1]. Lasers apparently "hit the Earth's curves" rather than bending with them.

[1]https://en.wikipedia.org/wiki/Atmospheric_duct

[a_e_k]

This happens everyday with the sun during sunrise and sunset [1]. When you first see the apparent top of the sun during sunrise, the sun is still well below the horizon physically. It's just that the image of the sun is refracted around the curvature of the earth a bit.

[1] https://en.wikipedia.org/wiki/Sunrise#Angle

[JudgeWapner]

but it's also ~6 minutes ahead of where we see it due to the time it takes the light to get there. I wonder which effect wins?

[SamBam]

The original quote said "a laser shot toward the horizon will eventually hit the Earth’s curves."

No, on a sphere a laser shot towards the horizon will not hit the Earth's "curves."

Shooting towards the horizon is by definition shooting tangentially to the surface you are on. The horizon is the point where the sky meets the land or sea. If you make a straight line from your laser to the horizon, it will continue out into space.

Your explanation of what they meant makes sense: a laser shot towards a distant target, not towards the horizon. But that's not what they said. And, obviously, I did not actually think the fault was the engineers' but the journalist's explanation.

[jakedata]

Now that really depends on how powerful your laser is, doesn't it?

[wysifnwyg]

>That’s a problem when you’re trying to hit a missile on the other side of the world.

It's certainly an issue when that "other" side is the outside.