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Comment by Facemelters | Hacker News Reader

Light fills the universe, but a telescope will be blinded if you shine a flashlight into it.

right, because of light's interaction with matter which is different from neutrinos

a quick google estimates that a human has about 100 trillion neutrinos pass through their body every second, but only about 25% chance that even a single one will interact with any atom in your body over a lifetime.

it is a detection issue, not a quantity issue.

No, the telescope will be blinded because you shine at it with a lot of the kind of photons it has been constructed to detect, the actual space filling photons are only visible in the radio band which (optical) telescopes don't see and so aren't bothered with.

The situation with neutrinos is exactly analogous: IceCube looks for high energy cosmic neutrinos, not low energy background neutrinos. The latter are only of interest to dark matter searches.

its really not though. Detection is fundementally different. Neutrinos have no electric charge. the only thing you have to work with is the weak interaction. you have to literally wait for the low probability event of a neutrino-neuclei collision or detect by a second hand effect.

Dude, the only important difference is the interaction cross section, in practice virtually all particle detections happen via secondary effects: for example CCD chips also observe the secondary interaction effect (of a electron being kicked out), and with gamma ray detectors you often don't see the entire secondary effect because the photon exists the detector before being fully absorbed.

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