Here's a riddle:

[Carl-Richard]

2 hours ago, Emotionalmosquito said:

@Carl-Richard You put a lid on the cup before inverting it.

I regret making any rules at all 

[Consilience]

15 hours ago, Carl-Richard said:

Let's say we have a normal-sized cup with some liquid water in it (it's about half-full). 

\=/

Then we turn it upside down:

/=\

(Force of gravity always points this way:↓)

How would you prevent the liquid water from exiting the cup?

 

Here are some rules:

1. You can't move or tilt the cup.

2. You can't change the shape or the material of the cup.

3. You can't use anything else than the cup itself.

4. The liquid has to be water at room temperature and you can't change the amount of liquid (constant volume).

5. The cup has to be stationary (not accelerating).

6. You can't change the laws of nature (gravity and physical forces apply). 

7. The rules only apply after the cup has been turned upside down.

 

If nobody gets it, I will start giving out hints.

Good luck!

I'm not going to bother to read through the thread to see if it's been answered.

If the rules don't apply until after the cup is turned upside down (rule #7) then I would wait for the Earth to rotate after 12 hours and the cup would be facing "upside down" relative to its starting position. And then the rules would apply, but the objective would be complete in that same moment... 

[Carl-Richard]

5 hours ago, Consilience said:

I'm not going to bother to read through the thread to see if it's been answered.

If the rules don't apply until after the cup is turned upside down (rule #7) then I would wait for the Earth to rotate after 12 hours and the cup would be facing "upside down" relative to its starting position. And then the rules would apply, but the objective would be complete in that same moment... 

It's not consistent with the implicit rule of the direction of the force of gravity relative to the tilt of the glass:

Quote

/=\

(Force of gravity always points this way:↓)

Since the rules only apply after it's turned upside down, you'll always end up in this configuration /=\↓, and therefore the water will always fall out from the glass.