What is the nothingness in space between the galaxies. Is it really nothing or is it something? Like maybe the very same stuff in the rest of the universe, it just never clumped to form matter as we know it. Is there nothing anywhere?
Some people believe that a neutrino soup of sorts prevails even in the emptiest space although I don't see how anybody could hope to prove that.
Way upwards of 99% of the mass of the universe is in plasma form and the main thing which aggregates plasma into solid things like galaxies and stars and planets is the Z-Pinch effect which is associated with the cosmic Birkeland currents which move through plasmas. That is why you find strings of galaxies and why, as Peratt and Lerner note in the video, solid material in the universe is "clumpy" beyond what could be explained by "big bang". Certainly the big bang offers no way to picture strings of galaxies forming.