Can I really not tell if I am in motion?

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SUMMARY

The discussion centers on the concept of motion perception while aboard a train, specifically addressing the relativity of motion as it pertains to thermodynamic principles. The user concludes that despite personal frame of reference suggesting otherwise, they are indeed in motion relative to the stationary platform. The argument hinges on the second law of thermodynamics, which states that heat cannot spontaneously flow from a colder body to a hotter body, thereby reinforcing the user's realization of their own motion. The role of friction and the need for constant acceleration from the train's engine is also highlighted as a critical factor in this understanding.

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Nanyang
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Sorry! I think I figured the mistake out right after I posted! This thread can be closed. :redface:

I imagine a train powered by an engine of this sort:

A region of hotter temperature evaporates some water and turn the wheels, and the evaporated water is at a lower temperature.

So I am in the train and I observe that the engine works in the way described above. Relative to myself, I claim that I am not the one in motion but the station platform is in motion.

But to claim that the station platform is in motion I must also claim that the wheel turns in the other way (edit: sorry, mistake here. give me a moment to sort this out). This implies that the evaporated water must fall back into its liquid form from a colder temperature to a hotter temperature. But by the second law of thermodynamics, this is impossible. So I must conclude that I am the one in motion and not the platform despite measuring in my own frame of reference.

So, can I really not tell if I am in motion?
 
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You're forgetting that the reason the wheels have to turn in the first place is because friction slows the train down and the engine needs to compensate by providing a constant acceleration.
 

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