Saying that no such observer exists is a rather boring way of not answering the question Not all answers should be answered. Some must be refuted.

A good point but wrt the 'question' at hand quite moot: Even with an infinite number of possible speeds, the speeds would not disappear.

But surely the cat knows

Yes and no. For all practical purpose it will work. But: It is not the same as, while you keep the linear volocity yu have you will no retain the rotational impulse you pick up when standing on a rotating surface.

This is a physics forum but the question is much more about biology. You can go down a stair spending more or less or next or even no energy than when ascending it, depending on the grace and fitnes of your movements. When I was young I could go down stairs without ever slowing on any of the steps. Today I can't and descding stairs it is a real effort..

@Aron: Given that smell is increasingly thought to be a QM process AND photosynthesis IS a QM process How are these 'given', other than that they involve atoms and molecules? To be called a QM process I would expect behaviour that can't be explained otherwise..

Well, it would if you could (make all molecules have the same temperature)..but of course you can't even get close to that. Try a microwave and test how explosive you can get your test cup to be..

There is no "water" out there Citation needed!

The last time I heard about radiation damages, there was agreemant that a high (singular or limited number of) energy damage is less dangerous, as it simply kills the cell whereas lower energy impacts are far more dangerous as they can change the DNA and create a cancerogeneous mutation. But that was in 1986..