Why, in 2013, are we still forcing people to construct images in their head based on words instead of showing them the full picture on their computer?
"[...] a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam of light as an electromagnetic field at rest though spatially oscillating. There seems to be no such thing, however, neither on the basis of experience nor according to Maxwell's equations. [...]"
You can also make a reasonable argument that this is relativity's greatest thought experiment:
In an internet long past, when it was small enough to have such a thing as a physics FAQ, this was among them.
The first chapter of the referenced Taylor & Wheeler 'Spacetime Physics' can be found here:
This paradox does not say anything about the objectiveness of reality. Rather it just points out an interesting scenario in which individual perceptions of objective reality won't match up.
Relativity Paradox - Sixty Symbols http://www.youtube.com/watch?v=kGsbBw1I0Rg
You will have the same effect sitting at the other door. If you are sitting in between you must apply the corrections to both doors, and then you will realize that they really closed at the same time. The only point were you "see" at the same time that both doors close is in the middle, and obviously after the corrections you will realize that they really closed at the same time.
The important thing is your velocity. Let's suppose that you are traveling (very) fast with the ladder, holding it at the middle point. You will first "see" that the back door closes (and reopen) before the top of the ladder get to that point. Then you will see that the front door closes (and reopen) after the bottom of the ladder passed that point. But you still have to make the corrections because both doors are far away. Even after the corrections the back door close and reopens before the front door close and reopens.
If you hold the ladder form one extreme you will "see" essentially the same things, and after the corrections you will be sure that never were both doors closed at the simultaneously. An important detail is that the difference of time between the reopening of the back door and the closing of the front door doesn't depend on where are you holding the ladder. After the corrections you will get the same time interval.
> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.
> Off-Topic: Most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. Videos of pratfalls or disasters, or cute animal pictures. If they'd cover it on TV news, it's probably off-topic.
Wikipedia has a great explanation of it though: http://en.wikipedia.org/wiki/Ladder_paradox