'Dark fluid' with negative mass could dominate the universe
&gt; Air bubbles in water can be modelled as having a negative mass.<p>Forgive the naive take on this, but it&#x27;s a weird point to me... if air bubbles in water can be <i>modelled</i> as having negative mass, but clearly do <i>not</i> (they are made of particles with positive mass), then they are only &quot;negative&quot; in relation to the material surrounding them.  So even if they can be modelled this way successfully, clearly the model doesn&#x27;t imply for certain that they do have negative mass.  So by analogy, just because a negative-mass model can explain the observations of dark matter, doesn&#x27;t it still leave the question of whether anything &quot;real&quot; is implied by it?  Perhaps it&#x27;s just a reflection of a negative relative to some unknown bias (field), like the Higgs field, but in &quot;absolute&quot; terms is not actually negative.<p>(Not sure &quot;absolute&quot; has any meaning here..)