Saturday, February 21, 2009
is time real, or is it just a handy illusion humans created so that we know when to turn on the tv and watch coronation street?
science writer dan falk had a go at killing time in a smu public lecture friday night and postulated that the sensation we have of time is maybe like spinning in an office chair: when you stop, you have the convincing sensation the world is spinning, but it isn't. maybe the strong sense we have that time is moving forward is equally mistaken. the reason scientists wonder if time is real is because nobody's sure what it measures. ok, seconds, but what are seconds marking? time is compared to a flowing river: rivers flow in comparison to the river bank. what's time flowing beside?
another weird thing is that time isn't constant - it's relative. astronauts travelling at high speeds in space actually go into the future (the same thing happens to atomic clocks in space, as they no longer agree with matching atomic clocks when they return to earth). russian cosmonaut sergei krikalyov has been in space longer than anyone else: a total of 804 days. that has blasted him 1/50th of a second into the future!
ok, not impressive, but if he toured the milky way for 23 years, he'd return to an Earth 150,000 years in the future.
what about the other way? that seems trickier. it's the old kill-yer-granddad paradox. if you travel back in time and knock off young gramps, he doesn't sire your dad, who doesn't sire you, and so you don't kill your gramps. which means he does sire your dad... you can see the problem here.
dan puts it another way in the downing street dilemma.
from this, different people have reached different conclusions:
a) it's impossible. simple enough, but frigging around with quantum mechanics suggests it is possible.
b) it's possible, but it's not possible to change the past. so what prevents you from changing the past? some supernatural force ties your arms down and muffles your throat, or you just can't be arsed? seems fishy.
c) it's proof that your grandmother had a fling with the milkman. (ha! more science humour for ya).
d) every time you change the past, you create an alternate universe in which that path proceeds. so presumably that means a universe where you are unborn, and an eternal orphan. i think it also creates the gigantic problem of where all those alternate universes come from. if i hop in the delorean and knock off grampie, what xeroxes every single thing in the universe? what vast source of energy makes a million new cars, lamps and plutos?
a guy called lee smolin said we'd better find out what's going on, or we'll be stuck in 'a world frozen in eternity.'
please send me your answers on the back of a postcard.
ps - for the very second time, pay-per-hack writer is pleased to illustrate a blog with marty mcfly.
Posted by Pay-Per-Hack Writer at 6:53 PM