Can we settle this: how many holes does a straw have?
At work we somehow landed on the topic of how many holes a human has, which then evolved into a heated discussion on the classic question of how many holes does a straw have.
I think it’s two, but some people are convinced that it’s one, which I just don’t understand. What are your thoughts?
1 ‘hole’ if you can call it that. Imagine if the straw started life as a solid cylinder and you had to bore out the inside to turn it into a straw: if that were the case, you would drill 1 hole all the way through it.
Another analogy is a donut. Would you agree that a donut has just 1 hole? I would say yes. Now stretch that donut vertically untill you have a giant cylinder with a hole in the middle. That’s basically now just a straw. The fact you stretched it doesn’t increase the number of holes it has.
Imagine if the straw started life as a solid cylinder and you had to bore out the inside to turn it into a straw
This would mean a straw has a hole, yes. It would be like a donut indeed - donuts are first whole, then have the hole punched out of them. This meets a dictionary definition of a hole (a perforation). A subtractive process has removed an area, leaving a hole.
But straws aren't manufactured this way, their solid bits are additively formed around the empty area. I personally don't think this meets the definition.
Your topological argument is strong though - both a donut and straw share the same topological feature, but when we use these math abstractions, things can be a bit weird. For instance, a hollow torus (imagine a creme-filled donut that has not yet had its shell penetrated to fill it) has two holes. One might not expect this since it looks like it still only obviously has one, but the "inner torus" consisting of negative space (that represents the hollow) is itself a valid topological hole as well.
But straws aren’t manufactured this way, their solid bits are additively formed around the empty area. I personally don’t think this meets the definition.”
By this logic, how I make a doughnut changes whether it has a hole.
If I make a long string of dough and then connect the ends together and cook it (a forming process) it doesn’t have a hole.
If I cut a hole in a dough disc and then cook (a perforation) it has a hole. Even though the final result is identical?
On the matter of the doughnut: If you make them at home, you’re almost always just rolling a cylinder and then making it a circle. I have never actually punched a hole out of a doughnut. That would mess up the toroidal shape.
Maybe she’s not, but I am. An intact straw has zero holes. If you stick a pin in the side, it has one. If you stick a pin all the way through, it has two.
No, topologically there would be no holes until the moment of contact. This is the same as there being no hole when drilling through from only one side until the surface on the opposing side is broken.
But here’s the thing. Take that doughnut and stretch it until it’s a cube with two square cutouts in it. Stretch in some of the inner walls. Now you have a house, with a door and a window. Now: does the house have two holes - a door and a window - or does it have one hole?
Locally has two extrinsic holes, that is holes relative to things outside and inside the house, globally has one intrinsic hole. We say that the door is a hole respect to the wall no to the house itself. So both the door and the window are holes locally. But we never say the house has holes, we talk about walls and ceilings so globally that house has 1 hole. Another way of thinking it is that if the house can be deformed into a filled doughnut then it can be compressed to a circle and that’s the definition of a 1-hole.
So as you begin to bore, that is one hole. But when you go through the other side, you have in fact made two holes. I think a donut can actually be thought of either as one hole or two holes, or more correctly; two holes that are the same hole.
Back to the straw; if you make another hole in the side of the straw half way up, would it still have one hole? Or two holes? Or three holes?
A bit like thinking of the human digestive tract, most of us would agree that your mouth is a different hole to your anus, but we agree that they are in two ends of the same system
Topologically a rubber band, a donut, and a straw have the same number of holes. The hole at either end of the straw is just a continuation of the same one hole.
A straw's "in" and "out" are completely arbitrary. You can flip a straw either way and it'd still work.
Anything with a hole through it that isn't perfectly 2D could have a "in" and "out" side. Your rubber band your doughnut only don't have one because nobody ever thought to define one.
Take that cylinder and stretch it until it’s a cube with two square cutouts in it. Stretch in some of the inner walls. Now you have a house, with a door and a window. Now: does the house have two holes - a door and a window - or does it have one hole?
I assume that's how OP's debate of how many holes a human had ended up being about straws: someone argued that the mouth and the anus are just one hole
IIRC humans have 7 holes topologically (assuming both vsauce and my memory are correct). I'm not sure how many a flatworm would have, but I bet you could group animals by number of holes topologically, which might be interesting.
Flatworms have a single opening that leads to a branching cavity (an incomplete digestive system). This means that the single opening is for both ingesting nutrients and expelling waste. While your mouth may be attached to your anus via the alimentary canal, I think it beats the hell out of having one multi-purpose opening, imho.
Right, technically a human only has 1 hole for ingesting nutrients and expelling waste as well though, assuming you are talking about the mouth and anus. Does a flatworm have any other through holes though e.g. nostrils or tear ducts? I have no idea what the biology of a flatworm is haha.
No, gas exchange is by simple diffusion across the skin and gut. No ears or eyes per se, just some photosensitive cells in slight depressions on the head. Planaria are pretty simple as far as animals go.
A hollow cylinder has a single hole, with two openings. A hole can be open on one end only (e.g., a well is a hole in the ground), or it can have multiple openings (e.g., a straw has a hole with two openings).
If one cannot immediately tell whether two openings are connected to one another, then one assumes they are not; e.g., if you see a well in Florida you don’t assume it is the opening of a hole that extends to connect to another opening in Australia.
None. Colloquially, we use "hole" in all kinds of weird ways. As others have pointed out, topologically a straw is no different to a torus (donut) that clearly has one "hole"... but I'd like to focus instead on the linguistic definition of "hole", not the colloquial or mathematic definitions.
A hole can either mean:
a perforation ("a hole in my shirt", "a bullet hole", etc) - which is, specifically, "a hole or pattern made by or as if by piercing or boring"
a gap ("a hole in your reasoning", "a hole in my heart", etc)
a hollowed out or burrowed place ("a hole in the road", "a fox hole", etc)
i think we're not talking about 2. It seems to require some larger uniform structure or set of items in which an item is missing. 1 and 3 seem really similar to me: both seem to require some active removal of matter to qualify. All of these definitions point towards a subtractive process, where something of a larger whole (heh) is removed or absent.
Most straws, I'll venture a guess, are not manufactured solid and then bored out.. so I don't think it applies here. So I don't think a straw matches a fitting definition of "hole". A straw is created additively by assembling the "shell" by some means, not subtractively. Donuts, by comparison, had holes punched in them. A subtractive operation. Rubber bands have not had holes punched in them... they're additive. Not holes.
Similarly (because I see a lot of talk about buttholes and mouths here too), your esophagus and digestive tract (and veins and all kinds of other things) were formed in a similar additive manner, not by forming a mass of meat and boring through the passage, and thus would similarly not qualify as "holes" (in my opinion).
I’m seeing a lot of this kind of taxonomical argument relying on material being removed, but it’s not convincing. A taxonomical argument that relies on commonly accepted definitions, but does not include commonly accepted examples, is logically flawed.
It’s normal, accepted usage to describe your anus and so forth as holes, despite no material having been removed.
Similarly, it’s normal to describe Cheerios as having holes in the middle, or bagels as having holes in the middle, or a pool noodle as having a hole through it, or any number of similar things that are formed without any material being removed. It extends to the metaphysical, in fact; one can have a hole in their logic, for instance, without the implications that their logic must once have contained this item, until it was somehow removed.
A hole is an entirely contained negative space; I don’t think it requires anything to have been removed.
A straw is geometrically the same as a circular piece of paper with a z depth of zero and a hole in the middle. Because the z depth is zero there is only one hole. As you add thickness the one hole remains. Therefore, a straw has one hole.
I’m a weirdo who learned how to ‘click’ their ears (opening eustachian tubes on demand) on their own possibly before Google existed, and have done a little research between now and then :p
What about a tank that has one input and one output hole, technically much like a straw? This is why I call the edges of a straw a hole, so straw has two holes.
Or, what about drinking straws with more than one succy pipe?
I completely agree. That’s what I’m saying. Topologically if you dig into the earth with a shovel, it hasn’t changed at all; there is no hole, but connotatively there clearly is.
And what I’m saying is that answering this with topology is quite misplaced because topology explicitly doesn’t deal with physical objects, ever. It uses very specific abstract definitions which cannot apply to everyday life.
That is not to say it isn’t useful. It’s an amazing discipline with wide applications, but answering questions about the properties of physical objects is not its intended use.
I was explicit that there are two topics here. You seem to agree. Why you think bringing up topology when asking a famous topology question that people like Riemann have been talking about for a few hundred years is just weird. That’s like saying you can’t talk about geometry when asking how many sides a house has. Feels very akshually.
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