RE: The Extinction Challenge

Billy Brown (
Fri, 30 Jul 1999 22:58:38 -0500

John Clark wrote:
> Billy Brown <> On July 28, 1999 Wrote:
>> However, at a
>> distance of 1 light-year (9x10^12 kilometers), the energy density drops
>> less than one erg per square meter. That isn't even enough energy to
>> damage electronics, let alone harm people.
> Energy density is not a realistic measure of danger.

If it arrives as IR or UV it is completely harmless. If it arrives as visible light it is not nearly as bright as the sun. X-rays or gamma-rays will be completely blocked by a planetary atmosphere, and any space habitat capable of surviving a solar storm will likewise be unharmed. If it were all neutrinos an average human would stop a grand total of maybe 10^-17 % of that flux, which amounts to around 10^-7 electron volts - in other words, less than one interaction.

Do I really need to write up a complete treatment of all the calculations here? It doesn't matter what exotic form you want the energy to arrive in, because there simply isn't enough of it to do anything. The target civilization will be exposed to much higher levels of every type of radiation (including neutrinos) simply by living near their own sun.

Billy Brown, MCSE+I