challenge-accepted

Ok, did I get too obscure?

Well the site is named Sci-ence dammit, I’m allowed!

No but seriously, this comic is just a reaction to some recent reading I was doing on special relativity and it’s consequences in various thought experiments. There always seems to be something new to discover that can keep you up at night stress eating. And my doctor tells me I haven’t been getting enough of that.

The ‘apparent’ contraction you always hear about in objects nearing the speed of light, the so called Lorentz Contraction, is a phenomenon that tinkers and tickles the very definition of reality. Is it a physically ‘real’ contraction or an illusion? Obviously when one is dealing with relativity the answer is going to be, well, both and neither. Depending on who you ask, or more precisely, how exactly you ask it.

It appears objects will indeed compress from an outside observers perspective (using measurements, not observation of a moment*). So if a fast moving object (close to light speed) like a ladder, or pole or your johnson (say 80m) was going to attempt to fit in a space that is clearly too short to contain it (say 40m) unless it remains contracted, what would happen? This is the barn ladder/pole paradox. Colloquially known as the 10 pounds of shit in a five pound bag, paradox. I think.

And it works out, so it’s counter intuitive but not exactly a paradox. From an outside observers frame of reference the speeding ‘rod’ would be so contracted that it could enter the much shorter barn and be contained momentarily as it passed through (by closing the doors simultaneously before opening them again and allowing the rod to exit the other end). Does this mean the rod ‘in reality’ was crunched up while moving? From the rods point of view, no. In fact, at it’s speed, it was the barn that was getting even shorter. No matter. From the rods point of view the doors, which you saw from the outside close simultaneously, actually close and open at different times. The back door closes and opens before the rod hits and is allowed to pass through. Then the entrance closes as the back of the rod passes inside the barn and exits the other end which is already open. And if you kept the doors closed it would crash into the back door, continue accelerating from behind until the ‘stop’ signal from the front had reached the back (because the two ends would be moving at different relative times making it unable to stop all at once), at which point the whole pole would already be smooshed into the barn, and would then presumably explode like awesome.

There are other variants and explanations, but I think this example gets to the heart of how relative ‘reality’ is when we start observing it at it’s limits. Now if you’ll excuse me, the fridge beckons.

-

-
This post was brought to you by Platinum (Pt).

-
*there are a bunch of more in depth references about Terrell rotation and invisible contraction to be found but I think this link does a decent job, with the added benefit of not wasting too much of your time.