Just as a burning coal (around 1500 K) glows red, and a hot bright star (around 6000 K) glows yellow or blue, the CMB glow with a characteristic colour associated with it’s temperature. So instead of seeing the afterglow at 3000 degrees, we see it at just 3 o above absolute zero, or 3 Kelvin (-270 o C). The expansion of the Universe has stretched out the CMB radiation by around 1000 times, which makes it look much cooler. We can measure the afterglow of the Big Bang. The light from this time has been travelling through space ever since, and can be detected all around us from here on Earth or in space. By around 400,000 years through its life it was cool enough (though still around 3000 Celsius) for the simplest atoms to form, and it became transparent. ![]() The Universe was made of a “plasma”, or ionised gas, which is what the surface of the Sun is made of.Įver since the Big Bang, the Universe has been cooling and expanding. Not even simple atoms could form without instantly being ripped apart into their constituent protons and electrons by the intense radiation. Before this time, the Universe was so hot and dense that it was opaque to all radiation. That may sound like a long time on human timescales, but it really is the blink of an eye when compared to the age of the Universe, which is around 13.7 billion (13,700,000,000) years old. ![]() The Cosmic Microwave Background (or “CMB” for short) is radiation from around 400,000 years after the start of the Universe.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |