# Death by Ultra High Energy Cosmic Ray

**URL:** <https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561>\
**Category:** Factual Questions\
**Created:** [August 7, 2013, 4:15am UTC](https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561 "2013-08-07T04:15:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![whc.03grady](https://avatars.discourse-cdn.com/v4/letter/w/a6a055/32.png) [@whc.03grady](https://boards.straightdope.com/u/whc.03grady)\
**Post date:** [August 7, 2013, 4:15am UTC](https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561/1 "2013-08-07T04:15:35Z")

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If you got hit by an ultra-high energy cosmic ray, would it likely kill you?

> **[Ultra-high-energy cosmic ray](https://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray)**
>
> In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray with an energy greater than 1 EeV (1018 electronvolts, approximately 0.16 joules), far beyond both the rest mass and energies typical of other cosmic ray particles.
> An extreme-energy cosmic ray (EECR) is an UHECR with energy exceeding 5×1019 eV (about 8 joule, or the energy of a proton traveling at ≈ 99.99999999999999999998% the speed of light), the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). This limit ...

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**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\
**Post date:** [August 7, 2013, 4:21am UTC](https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561/2 "2013-08-07T04:21:31Z")

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No, because, while the energy is high per individual particle, the particles are small and isolated.

It’s like getting hit by a bullet that is so much smaller than a grain of sand, that even if it’s moving at 2,000 feet per second…it doesn’t hurt. Cosmic ray particles may have billions of electron-volts of energy – but are still only tiny nuclear particles. Stand in front of an old-style cathode-ray-tube TV, and you’re getting a LOT more overall energy.

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [August 7, 2013, 5:12am UTC](https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561/3 "2013-08-07T05:12:37Z")

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Except a single cosmic ray particle can cause a cascade and produce a shower of particles. And exposure to these high-energy particles can cause damage to your DNA and increase your chance of cancer. Or even cause radiation burns or other acute symptoms.

The most powerful cosmic ray can have energy of tens of Joules. If all that energy turned into ionized radiation and got absorbed by one person, it should be enough to kill that person through acute radiation poisoning. I’m pretty sure such perfect conversion & absorption is impossible, but I’m not sure what a realistic maximum would be.

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [August 7, 2013, 11:14am UTC](https://boards.straightdope.com/t/death-by-ultra-high-energy-cosmic-ray/665561/4 "2013-08-07T11:14:01Z")

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Such extreme energy particles, or even the particles produced by their showers, tend to be extremely penetrating. Which means that they’ll mostly just pass right through you, depositing a very small fraction of their energy in you, and taking most of it right out the other side.