# Ever Grander Conclusions from Ever Scantier Evidence Observations of ever smaller physical effects have been forcing ever greater changes in our world view. It may therefore seem that we are inferring ever grander conclusions from ever scantier evidence. What justifies these inferences? Can we be sure that just because a star appeared millimetrically displaced on Eddington’s photographic plate, space and time must be curved; or that because a photodetector at a certain position does not register a ‘hit’ in weak light, there must be parallel universes? This actually *understates* the fragility and indirectness of experimental evidence. For we do not directly perceive the stars, spots on photographic plates, or any other external objects or events. We see things only when images of them appear on our retinas, and we do not perceive even those images until they have given rise to electrical impulses in our nerves, and those impulses have been received and interpreted by our brains. Thus the physical evidence that directly sways us, and causes us to adopt one theory or world-view rather than another, is less than millimetric: it is measured in thousandths of a millimeter (the separation of nerve fibres in the optic nerve), and in hundredths of a volt (the change in electric potential in our nerves that makes the difference between our perceiving one thing and perceiving another). Even though [We do not accord equal significance to all sensory impressions](We%20do%20not%20accord%20equal%20significance%20to%20all%20sensory%20impressions.md), there is no getting away from the fact that we human beings are small creatures with only a few inaccurate, incomplete channels through which we receive all information from outside ourselves. We interpret this information as evidence of a large and complex external universe (or multiverse). But when we are weighing up this evidence, we are literally contemplating nothing more than *patterns of weak electric current trickling through our own brains*. --- Date: 20240913 Links to: [Fabric of Reality](Fabric%20of%20Reality.md) [We do not accord equal significance to all sensory impressions](We%20do%20not%20accord%20equal%20significance%20to%20all%20sensory%20impressions.md) Tags: References: * []()