Thread: story problem..

assume that the galaxy is a group of 400 billion stars distributed along a cubic lattice, each star separated from it's nearest by about 5LightYear. If 100 currently signaling civilization are randomly distributed somewhere in this galaxy

(hint: let N be the number of stars in cubic galaxy; . If each star is separated by a distance D = 5LY, then the total volume of the cubic galaxy is . Now the number of civilizations in the galaxy is = 100. Let each one of them be surrounded by an "empty" cube of volume = in which there are no other civilizations--on the avg. So x is the avg distance between these civilization.)

How far away in LY is the nearest civilization likely to be?

from the hint I got Vgal = = .
I'm not sure how to solve the rest.

Originally Posted by viet

(hint: let N be the number of stars in cubic galaxy; . If each star is separated by a distance D = 5LY, then the total volume of the cubic galaxy is . Now the number of civilizations in the galaxy is = 100. Let each one of them be surrounded by an "empty" cube of volume = in which there are no other civilizations--on the avg. So x is the avg distance between these civilization.)



from the hint I got Vgal = = .
I'm not sure how to solve the rest.

Vgal= which is NOT so even that is wrong.

Divide that by 100 to get as the average volume of a "civilization". x is the cube root of that number.

Thanks for your help HallsofIvy. I cuberooted 5x10^11 and got 7937.0