Amazing illusion

[Propellor]

http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html

[manxie]

It`s 07.45 and my head it battered already!  Very good though! 

[iansoady]

Super. Background makes such a difference hence why it's not sensible to rely on hi-viz / headlights. Both can merge into the background in certain circumstances.

[Propellor]

It`s 07.45 and my head it battered already!  Very good though! 

It's there for your delectation whatever time of day suits. 

I was reading the book I saw it in at 6am. I have an hour's read most mornings.

[timbo]

That really is very good 

[Propellor]

That really is very good 

It's staggering.

So is this.

https://en.m.wikipedia.org/wiki/Slow_light

[Propellor]

That really is very good 

It's staggering.

So is this.

https://en.m.wikipedia.org/wiki/Slow_light

If someone could translate the section titled "different ways to achieve slow light" into actual words that would be great!