- In physical cosmology, the power spectrum of the spatial distribution of the cosmic microwave background is near to being a scale-invariant function. Although in mathematics this means that the spectrum is a power-law, in cosmology the term "scale-invariant" indicates that the amplitude, *P*(*k*), of primordial fluctuations as a function of wave number, *k*, is approximately constant, i.e. a flat spectrum. This pattern is consistent with the proposal of cosmic inflation.
- In physics, mathematics, statistics, and economics, scale invariance is a feature of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor.
- Wikipedia, Scale invariance
- The Wiener process is scale-invariant. You have to watch the gif here to get the idea.