If one photon is fired at the slits at a time it will will take one of the curved paths of light and make the wave pattern in sequential dots on the screen destination at the end.
You didn't need to provide a source for that, the double split experiment is a well known demonstration of quantum theory.
The really weird thing about it is if you put a sensor at one of the slits to detect which slit the photon is going through then the interference pattern disappears and they start acting like particles again. This is a weird, but well known phenomenon
The point is clearly that it is wrong that light travels in straight lines. Light travels in curved lines.
It travels in straight lines unless...
And the unlesses are well known. This is like you hearing Newton's first law of motion - that objects remain at rest or continue at a constant velocity unless acted on by a force - and then rolling a ball, noting it stops after a time and saying "haha, see?!". No, don't see - there was a force acting, friction.
As mentioned above, a single photon can travel on a curved path on its own without any known influence.
While not being an expert in quantum mechanics, I don't think that effect is because of the photon travelling on a curved path.
It's because of the photon acting like a wave and going through both slits at the same time and interfering with itself.
As I said, it stops happening if you observe which slit it goes through.
A weird, but well understood effect in quantum theory.
Refraction is well understood too and Einsten's theory about light being affected by gravity has been verified experimentally during eclipses and gravitational lensing is used in astronomy.
None of this is the gotcha you seem to think it is.