## Could a dryer randomly fold clothing? (ongoing debate)

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Someguy945
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### Could a dryer randomly fold clothing? (ongoing debate)

There is a debate on reddit at the moment. The question is as follows: "Is there an infinitesimal chance that, upon running and then opening the clothing dryer, the contents inside will be neatly folded? Or is the probability strictly zero on the basis that the dryer is not a random clothing configurator?"

Or, my best guess, it depends on the dryer?

WibblyWobbly
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

I would suggest using a Monte Carlo approach.

davidstarlingm
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

I'm going to stick my neck out and say no.

As has been pointed out, dryers tumble clothes in a pattern. Now, there's obviously some degree of randomness in that pattern. But I'm guessing the number of "random moves" necessary to orient all the clothes in the folded fashion would take longer than the cyle of any dryer.

LaserGuy
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

I think it would depend a bit on the dryer, but in a conventional dryer, I think it's possible the probability may be exactly zero. My intuition is that the dynamics of the dryer would prevent all of the pieces of clothing from being folded simultaneously because they aren't all being rearranged simultaneously by the dryer. For a single piece of clothing, there may be a non-zero probability, I suppose.

I'll throw in an obscure possibility that if the clothes are placed in the dryer prefolded, it may be possible that there's some sort of a resonance in the dryer cycle that would refold them. I really, really doubt it could happen, but I can imagine that there's a non-zero probability that such a resonance could exist.
Last edited by LaserGuy on Thu Aug 08, 2013 8:59 pm UTC, edited 2 times in total.

poxic
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

Could we do the monkeys-on-typewriters scenario? "If every molecule in the universe were a dryer, running for the life of the universe and stopping every 45 minutes for a minute (to check for foldedness), how many times would we find a neatly folded pile of clothes?"

Would it happen never or many times?
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

poxic wrote:Could we do the monkeys-on-typewriters scenario?

I would say we can't, because of the geometry of the problem. If we consider that random walks behave very differently in one and two dimensions than they do in three dimensions. In fact, I feel that if a dryer was demonstrated to actually be random then the answer is " never". However, dryers are not really random, and they continuous nature of dryer motion seems to fundamentally opposed to discontinuous nature of folding so I would again speculate that the answer is "never".
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

The dryer can take a batch of folded clothes, and unfold them quite thoroughly.

By the time-reversal property of physics, it is thus possible (though exceedingly unlikely) for a dryer to take at least some configurations of clothes and fold them back up. I think it's fairly obvious that the end-states of initially-folded clothes aren't special in any way; any reasonable bundle of clothes is probably producible through a plausible tumbling. (And if you've ever done much laundry, you'll know that dryers can produce some very unreasonable bundles!) Thus, any reasonable bundle of clothes placed into a dryer is probably reversible. (I could easily make a stronger argument and say that *any* bundle of clothes can be reversed, as the necessary applications of force to do so are well within the energy constraints of a tumble cycle, but I don't need to.)

Of course, this is as relevant as saying that it's possible to drop shards of glass and have them reassemble into a cup when they hit the floor, or that it's possible to cook an egg, put it on your plate, and have it spontaneously revert back to an uncooked albumin and yolk before you can eat it. These things are *possible*, but so unlikely as to not happen within the observable universe before the heat death of the universe.
(defun fibs (n &optional (a 1) (b 1)) (take n (unfold '+ a b)))

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### Re: Could a dryer randomly fold clothing? (ongoing debate)

I think I'm inclined to agree that it's possible but incredibly unlikely.

I feel like it's somehow relevant that there's likely a whole range of configurations of clothes that one might consider 'folded' depending on ones folding style so that makes getting randomly folded clothing easier than if you want one very specific configuration (potentially specific to the point of it being probability 0 but still possible kind of unlikely), but I suppose the net result ends up being it's possible regardless of how picky you are with you definition of folded. (For very very loose definitions of folded such as 'Theres a bend in it' you could make it extremely likely to get 'folded' clothes, but that's perhaps pushing the spirit of things.)

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### Re: Could a dryer randomly fold clothing? (ongoing debate)

I agree with Xanthir's time-reversal argument, and I'd also add that there is an incredibly tiny, but non-zero probability that the clothes will suddenly become folded without any external input of energy, so the presence of a running dryer shouldn't be able to completely nullify that possibility.
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Zamfir
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

The reversibility thing feels slightly like a cop out to me. At least, when applied to physical laws as a whole. When someone asks if Elvis might be alive somewhere, you wouldn't typically include the possibility that molecules have seeped into his grave in exactly the right pattern to reanimate his corpse.

The intuition behind the question seems to be that running the tumbler should gravely improve on the situation, compared to the base rate of clothes getting folded by colluding thermal vibrations. If it doesn't, you might as well answer No to the question.

Basically, is tumbling also a reversible process if you only consider the macroscopic system, with the engine compensating for energy loss to microscopic subsystems? That seems possible, but time-reversal of physical laws as a whole do not shed much light on that.

davidstarlingm
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

Zamfir wrote:The reversibility thing feels slightly like a cop out to me. At least, when applied to physical laws as a whole. When someone asks if Elvis might be alive somewhere, you wouldn't typically include the possibility that molecules have seeped into his grave in exactly the right pattern to reanimate his corpse.

The intuition behind the question seems to be that running the tumbler should gravely improve on the situation, compared to the base rate of clothes getting folded by colluding thermal vibrations. If it doesn't, you might as well answer No to the question.

Basically, is tumbling also a reversible process if you only consider the macroscopic system, with the engine compensating for energy loss to microscopic subsystems? That seems possible, but time-reversal of physical laws as a whole do not shed much light on that.

Good point. The way the question is phrased, answering "yes" would imply that the action of the moving dryer somehow contributes positively to the probability of the clothes spontaneously folding themselves.

Xanthir
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

Yes, my answer was technically correct (the best kind of correct!) but useless. ^_^ For all practical purposes (that is, would an observable-universe volume of dryers running for lifetime-of-universe length of time ever fold some clothes), the answer is no, just like the "unscrambled egg" or "unbroken glass" or "undead Elvis" possibilities.
(defun fibs (n &optional (a 1) (b 1)) (take n (unfold '+ a b)))

letterX
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

So, this actually just happened to me! Or rather, one shirt out of an entire load ended up correctly folded (the rest of the load was the usual jumble). This is probably largely confirmation bias because I was already primed to look for folded laundry after the dryer, but it puts an upper bound for an entire load to come out folded of "not completely impossible".

davidstarlingm
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### Re: Could a dryer randomly fold clothing? (ongoing debate)

letterX wrote:So, this actually just happened to me! Or rather, one shirt out of an entire load ended up correctly folded (the rest of the load was the usual jumble). This is probably largely confirmation bias because I was already primed to look for folded laundry after the dryer, but it puts an upper bound for an entire load to come out folded of "not completely impossible".

Define "correctly folded".