Are the sound waves from the big bang still traveling through space? Have they long since dissipated to being negligible?
Sound waves can’t travel through space-- they require a medium to travel in. The Bang in “Big Bang” was not a liberal noise.
Big Bang didn’t make any noise. “Big Bang” was a derogatory term invented by Fred Hoyle to suggest how ridiculous the idea was (at least to him.)
Space simply started to expand and time started to run (as best we can understand). The universe at this time was very very homogeneous, so despite the unthinkable energy density, it was (arguably) silent.
The growing inhomogeneity is seen in the anisotropy of the CMBR. But that arguably isn’t propagating through space either, so isn’t a wave of any kind, It is expanding as space expands, but that isn’t the same as travelling though space.
So the answer is, there was no sound, so there isn’t anything to be still about.
Yes, there were sound waves from the Big Bang. We think of space as empty, but early in the Universe’s history, it was very dense indeed.
And while they aren’t propagating anymore, we do still see the variations in density from those early sound waves, because those variations in density are what became the present-day galaxies and other structures.
Hmmm, but were they sound in the sense in which we think of sound? A propagating wave that moved through space? More to the OP’s point, are they a manifestation of the instant of creation? I guess we rely on inflation to get us the homogeneity we see, so before that things were may have been much more lump, but do we ascribe that to propagating waves of matter?
Yes, they were waves of variations of the pressure and density of a material medium propagating through space, sound waves in every sense of the word. As to what they’re a manifestation of, well, they were caused by the conditions of the Universe at a time, which conditions were of course ultimately a result of the Big Bang. Decide for yourself whether that counts as “a manifestation of the instant of creation”.