"Newton had assumed that the system he observed was stable and changeless. <br><br>Nothing in the universe is static: “…world will not remain in an unchanging condition even for a short while. Second after second it undergoes change and transformation. Every foundation will finally become collapsed; every glory and splendor will at last vanish and disappear…”<br><br>scientific theory… the entire universe might be either expanding or contracting", composing or decomposing…if, by definition," it could not be stationary…<br><br>A discovery by Austrian physicist Christian Doppler in 1842. By employing a spectroscope to examine spiral nebulae", he discovered that the light emitted from these nebulae shifted toward the red end of the spectrum—that is, the light assumed a lower frequency. Were these nebulae at a constant distance, the spectral lines would remain constant, or if the nebulae were approaching the observer, the light would shift towards the blue end of the spectrum and become higher in frequency. The “Doppler Effect” also holds true for sound and you can observe it, for example, in the way the sound of an approaching or receding noise from a truck on the highway assumes different frequencies when it passes us by.