From a more fundamental point of view

Yeah that's fine

Both theories explains this effect

It does not prove either

why does light sag @Logrian ?

so why does it bend back up

?

A circular earth exhibits the same effect if light travels in a straight line

So

We have two propositions

Light travels straight => Round Earth
Light sags => Flat Earth

So now we have to prove that light sags and does not travel straight over a large distance

Plz text I have no internet

My data small

I cannot see the image

@Logrian that doesn't suggest that light bends down...

That says the surface of the water bends down

light bends up

That contradicts the first gif

Which seemed to have suggested that light bends down then up

an the other image explains that

That's a Sheeple gif! Been a while since I saw that.

🙂

Please explain I don't understand it

Refraction causes light to bend upwards

This is what I need explaining

Wait

Bend upwards as in

The claim is boats *appear* to disappear over the horizon, because of up curving refraction.

Wait wait wait wait wait

Okay.

It's miserable how I cannot post an image to explain what I wanna know

Let me describe it

First: light travels down then up
Second: light travels forward then up
Third: light travels in a straight line with a downward component

Which one do you mean