We all talk about the big bang as this moment the Universe begins by popping into existence with simple hydrogen and some helium. Hydrogen and Helium are gases that are able to carry sound. Today, space has expanded so much that there is vacume beyond where matter clumps together to form stars/planets, which means the sound couldn’t propagate, but the early early Universe wouldn’t have clumped like today; there would have been hydrogen everywhere. This means it would have been loud everywhere.

*Edit: I know we call it the Big Bang because of the rapid expansion of spacetime, but I always just pictured the general motion of expansion as the “bang”. Never thought of how loud it would have been.

  • OwOarchist@pawb.socialEnglish
    45·
    22 hours ago

    the Universe begins by popping into existence with simple hydrogen and some helium

    Not quite. The universe begins with a (mostly) homogeneous soup of sub-atomic particles that are far too hot and have far too much energy to be able to form stable atoms, not even simple ones like hydrogen – they’d get blasted apart again just as fast as they formed. It takes some expanding and cooling until heat/energy levels drop low enough for electrons to start orbiting protons and form atoms. (Not even protons could exist in the extremely early universe – fundamental quantum particles coming together to form protons, neutrons, and others would have been quite the development just a bit earlier in expansion.)

    Hydrogen and Helium are gases that are able to carry sound.

    And they did. This isn’t just speculation, we can actually see it!

    The sound waves in this very early universe (called baryon acoustic oscillations) went on to develop into the high and low density parts of the universe. They effectively ‘froze’ in place once the gas became too sparse to carry sound waves, and the pressure waves that were left at that moment formed regions of high and low pressure, high and low density. High density areas formed more stars and more galaxies (and attracted more dark matter) than low density areas. The sound waves in the early universe are actually what created the large-scale structure of the universe as we know it today.

    And that’s not just hypothetical speculation. These wave patterns have been detected and have been known for decades. Yes, the early gas-filled universe was very loud – and we can still see that today!