How is it that we can detect evidence of sound waves in the early universe?
A)The energy-rich environment of the early universe gave these sound waves so much energy that, unlike ordinary sound waves, they have been able to travel through the vacuum of space.
B)Space is not a complete vacuum. The tenuous material that fills all of space has been enough to sustain these sound waves.
C)What we observe is not the sound waves themselves but rather the spectrum of light emitted from the compressions and rarefactions of the sound waves.
D)What we observe is not the sound waves themselves but the gravitational lensing caused by the increased mass density in the compressions of the sound waves.

Question

Quizplus · Accepted Answer

What we observe as evidence of sound waves in the early universe is not the sound waves directly but the imprints they left on the cosmic microwave background radiation. These imprints come from the density fluctuations caused by the sound waves, which affected the spectrum of light we see today.

How Is It That We Can Detect Evidence of Sound