# Modelling Question

We have 2 different sequences of real numbers, say s1, s2 obtained in the following fashion. We tie two unit point masses with a spring. Next we let the entire sping-mass system into one dimesional free space (zero gravity). However the space has spatial particles which can collide with either of the point masses and imapart their to them.

Sequence s1 is obtained by sampling the the location of the first point mass and s2 by the second.

Is it possible to distinguish arbitrary sequences from sequences which have been obtained in this fashion?

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don't conservation of momentum and energy impose some constraints (such as boundedness for a start)? – Yemon Choi Dec 27 '09 at 15:29
If I'm correctly imagining the system, s1 will always be on the same side of s2 and the length of the spring will impose a maximum distance between s1 and s2. Speeds won't reach the speed of light, so that's a rough upper bound on (change in position)/(change in time) for each of s1 and s2. I have no idea how many particles will collide with s1 and s2 and with what energies between 2 samplings, so beyond these restriction it seems anything could happen. – Jonas Meyer Dec 27 '09 at 19:15