Well I am really nitpicking as well. I must win because Greg stated "Using only mental calculations and guestimates ..."
So, considering I didn't use anything other than a vague recollection of the answer to a similar Trivia Night question, my 'guess' of 3 km was damn close! Chris From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Friday, 15 July 2011 10:57 AM To: [email protected] Subject: RE: [OT] Renting a data projector Also nitpicking: If the numbers in red are meaningless then you only know dist to AC to two significant figures. Therefore the rescaled distance is 21 km. I'm happy to round my 20.8 km to 21 km so I'm glad we agree ;-) And if we're getting *reeeally* nitpicky then the grain of sand was only ever defined to one sig figure so the answer is 20 km.... Ben ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Greg Keogh Sent: Thursday, 14 July 2011 7:34 PM To: 'ozDotNet' Subject: RE: [OT] Renting a data projector Yeah well, despite all the expected nitpicking (it's supposed to a fun educational night): My calculations in Excel make it 20.65 km (not metres!) Sun diameter = 1,400,4000 km Light year = 9,460,730,472,581 km Sand grain diameter = 7e-7 km Size scaling factor = 5e-13 Distance to alpha Centauri = 41,296,088,512,815 km (4.365±0.007 LY) Re-scaled distance = 20.65 km Although to be a nitpicker myself, the red digits are meaningless due to the rounding error on the exact distance to Alpha Centauri. The resulting distance is in the range 20.615 to 20.681 km. Even worse, the exact diameter of the sun is a bit fudgy, and you could argue about the size of the beach sand grains, and you can dispute how they measure the speed of light, but the important thing is the shocking realisation of how much empty space there is out there. It is a binary system, but it's not a trick question. If someone wants to work out the variation of distance of the A and B stars taking into the account the eccentricity and high inclination of the plane of orbit of A and B and scale that back, then I leave it as an exercise for the reader. My guess is that it would be less than a couple of metres variation over the 20 km. And don't mention Proxima Centauri, that dilapidated crappy star should be erased like Pluto. We know that the space between us and A Centauri is not empty, as Lost in Space showed us it's full of space hippies, pirates, miners, teenagers, dragons, vegetables, beauty quests and prison planets. Greg This email is intended for the named recipient only. The information it contains may be confidential or commercially sensitive. If you are not the intended recipient you must not reproduce or distribute any part of this email, disclose its contents to any other party, or take any action in reliance on it. If you have received this email in error, please contact the sender immediately and delete the message from your computer.
