Tuesday, 19 April 2016

cosmological inflation - The gravitational waves from the big bang? How can we know?


The latest news says that scientists detected gravitational waves from the Big Bang. My question is how do they know the waves originated in the big bang verses any number of supernovae and or spinning black holes?



Answer



After the Universe became transparent to electromagnetic waves, the first wave produced from whole mass lump was Cosmic Microwave Background (CMB) radiation which we can still receive from farthest point of the observable universe (CMB causes your radio to hiss on blank stations). Universe has expanded since then, so CMB is still running trapped inside Spacetime. CMB is also called Afterglow of Big Bang.


By analyzing CMB, we can visualize the Universe of past. That was the time when astronomical bodies started to take shape due to Gravity.


But, the problem was: CMB seemed uniform throughout the universe. It didn't contain any non-uniformity which is essentially Gravity signature of that time. Without non-uniformity, the universe we know today wouldn't exist.


The recent discovery found this non-uniformity in CMB with high accuracy.



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