# Lowest temperature possible in the universe?

The third law of thermodynamics states that nothing can reach to absolute zero temperature. What is the lowest possible temperature that can be in the universe? Has any experiment reached to a billionth of a Kelvin? Is there any restriction on how low it can be? Is $10^{-1000}\;\rm K$ possible? Or is there a lowest quantum of temperature?

The temperature of the blackbody radiation predicted from the event horizon of a black hole with mass $M$ is $$T = \frac{\hbar c^3}{8\pi k G M} = \frac{62\,\mathrm{nK}}{M/M_\text{sun}}.$$ So a supermassive black hole with $M=10^9M_\text{sun}$ would have a horizon temperature in the neighborhood of $10^{-16}\,\mathrm K$.