The smallest possible measurement of length is known as the Planck Length. Anything smaller than this would break everything we understand about physics.
100 Mind-Blowing Planck Facts
A jiffy is a proper unit of time. It is exactly 1/100th of a second. This is slower than a Planck which is sextillion times faster.
The heat from the Big Bang is still around today. The early Universe consisted of a hot soup of ionised gas: a sort of opaque plasma. About 380,000 years after the Big Bang, this gas cooled sufficiently enough that atoms were able to form. Radiation left over from the Big Bang is still around us today and is known as the cosmic microwave background (CMB). It can’t be seen with the naked eye, but various missions over the years have been able to study it in microwave light, including ESA’s Planck satellite and the WMAP mission.