  Attempts to understand zero temperature phase transitions have forced
physicists to consider a regime where the standard paradigms of condensed
matter physics break down [1-4]. These quantum critical systems lack a simple
description in terms of weakly interacting quasiparticles, but over the past 20
years physicists have gained deep insights into their properties. Most
dramatically, theory predicts that universal scaling relationships describe
their finite temperature thermodynamics up to remarkably high temperatures.
Unfortunately, these universal functions are hard to calculate: for example
there are no reliable general techniques [4,5] to calculate the scaling
functions for dynamics. Viewing a cold atom experiment as a quantum simulator
[6], we show how to extract universal scaling functions from (non-universal)
atomic density profiles or spectroscopic measurements. Such experiments can
resolve important open questions about the Mott-Metal crossover [7,8] and the
dynamics of the finite density O(2) rotor model [1,9], with direct impact on
theories of, for example, high temperature superconducting cuprates [10,11],
heavy fermion materials [12], and graphene [13].
