This one's for us physics nerds. - Is the speed of light our universe's only true constant? And does this explain why time dilation occurs most for extremely massive objects? - Does time dilation only occur when an observer is present?
posted by jfid1 on Sep 21, 2009 - 14 answers

Does modern science prove the theory of heliocentrism wrong? [more inside]
posted by wigglin on Apr 28, 2008 - 18 answers

"A human is halfway in size between an atom and the known universe"... This is a paraphrased quote I have come across several times. I like it. Who said it first? How true is it in the most literal sense? And, finally, what errors arrive in postulating a universe, or an atom, which can be measured AT ALL from our singular, relativistic, perspective? [more inside]
posted by 0bvious on Feb 18, 2007 - 14 answers

Remember the ABC show, Relativity, with Isabel and Leo? [more inside]
posted by evariste on Sep 12, 2006 - 13 answers

If General Relativity is accepted as true, why do Physicists talk about (and look for) Gravitons? [more inside]
posted by grahamwell on Mar 28, 2006 - 14 answers

Time dilation and relative speed. If the speed we travel is relative to the thing we're travelling away from, then how does the universe know which of the two things is actually moving? (so time dilation can occur) Is there a known universal "zero-speed"? If so, at what speed is the earth moving, and would it make a difference to the time dilation depending on the direction a spaceship moved away from the earth?
posted by seanyboy on Jul 13, 2004 - 17 answers

trying to get my head around special relativity filter: Can someone explain to me, in terms as devoid of mathematical formulae as possible, how something traveling less than the speed of light cannot be accelerated to the speed of light?
posted by xmutex on Jul 6, 2004 - 17 answers

Ok, I want to get my friend a poster of MC Escher's Relativity. The catch is I need it by Sunday, and I can't afford to spend more than a tenner. Can anyone suggest anywhere either online or in London that I can get it?
posted by Orange Goblin on Dec 16, 2003 - 5 answers