They are at the level of only one part in one hundred thousand.
COSMIC MICROWAVE BACKGROUND RADIATION FULL
These appear as temperature variations on the full sky picture that COBE obtained. These are the imprint of the seeds of galaxy formation. In spectacular fashion in 1992, the COBE team announces that they had discovered 'ripples at the edge of the Universe', that is, the first sign of primordial fluctuations at 380,000 years after the Big Bang. The COBE satellite was launched twenty five years after the discovery of the microwave background radiation in 1964. The radiation has the same intensity and spectral character as a thermal continuous source at 3 K (more precisely, 2.728 0.004 K) as measured by the COBE satellite in every direction. The theoretical best fit curve (the solid line) is indistinguishable from the experimental data points (the point-size is greater than the experimental errors). Arno Penzias and Robert Wilson observed in 1965 a radio background source that was spread all over the universe-the cosmic microwave background radiation. The diagram to the right shows the results plotted in waves per centimetre versus intensity. The Cosmic Background Explorer (COBE) satellite measured the spectrum of the cosmic microwave background in 1990, showing remarkable agreement between theory and experiment. This is a dramatic and direct confirmation of one of the predictions of the Hot Big Bang model. It is approximately described by thermal radiation distributed throughout the Universe with a temperature of about 2.735 degrees above absolute zero. The brightness of the relic radiation is measured as a function of the radio frequency. Measurements of the cosmic microwave background radiation (CMB) allow us to determine the temperature of the Universe today.