  Market bubbles emerge when asset prices are driven unsustainably higher than
asset values and shifts in belief burst them. We demonstrate the same
phenomenon for biomedical knowledge when promising research receives inflated
attention. We predict deflationary events by developing a diffusion index that
captures whether research areas have been amplified within social and
scientific bubbles or have diffused and become evaluated more broadly. We
illustrate our diffusion approach contrasting the trajectories of cardiac stem
cell research and cancer immunotherapy. We then trace the diffusion of unique
28,504 subfields in biomedicine comprising nearly 1.9M papers and more than 80M
citations and demonstrate that limited diffusion of biomedical knowledge
anticipates abrupt decreases in popularity. Our analysis emphasizes that
restricted diffusion, implying a socio-epistemic bubble, leads to dramatic
collapses in relevance and attention accorded to scientific knowledge.
