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Posted February 19, 2018 By Presh Talwalkar. Read about me, or email me.
How many holes does a straw have? This question has generated a lot of debate online. Recently BuzzFeed made a video that already has over 450,000 views.
It’s amazing to see topology go viral like this! Topology is a branch of mathematics dealing with the study of shapes and spaces. And it was an important part of the 2016 Nobel Prize in Physics.
This also brings me to a point about math in the news. When the media discusses science, they ask scientists for quotes. When they discuss law, they get quotes from lawyers. What happens when a mathematical topic goes viral? The media often covers the debate without any expert opinion.
I am begging BuzzFeed and the media to please consult with math people (like me) or others. It would be a great chance to educate people on math topics they are discussing.
Instead, we have debate about how many holes a straw has. Here are some of the common answers.
2 holes
This camp states a straw has one hole at its top and one hole at its bottom.
1 hole
This group points out the straw doesn’t have 2 holes–the opening is one really long hole.
0 holes
This is a semantic argument. If you puncture one side of the straw with a needle, you would say “the straw has 1 hole.” So the undamaged straw would have 0 holes.
So which camp is correct mathematically?
Watch the video to see the answer.
How Many Holes Does A Straw Have? The Correct Answer Explained
Or keep reading. "All will be well if you use your mind for your decisions, and mind only your decisions." Since 2007, I have devoted my life to sharing the joy of game theory and mathematics. MindYourDecisions now has over 1,000 free articles with no ads thanks to community support! Help out and get early access to posts with a pledge on Patreon.
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Answer To How Many Holes Does A Straw Have?
The mathematically correct answer is 1 hole.
A straw is topologically the product of a circle, which has 1 hole, and an interval, which has 0 holes. So the straw has 1 hole. Formally, a straw is topologically equivalent to S1 × [0, L], where S1 is the unit circle and L is the length of the straw.
This is a summarized form of the explanation in Drinking Straws: How Many Holes? by Kevin Knudson, a professor of mathematics at the University of Florida.
Intuitively, we can agree a circle has 1 hole–the simple closed curve contains a 2-dimensional hole inside of it. Adding depth does not increase the number of holes. So a straw could theoretically be stretched and continuously deformed into other shapes with 1 hole–like a filled donut (torus), or a coffee mug.
I show how a circle with 1 hole becomes a straw in an animation in the video around 3:17:
How Many Holes Does A Straw Have The Correct Answer Explained
I like that this problem has gone viral. Now the media should be sure to quote math people so everyone gets a taste of topology and we can inspire more people to appreciate mathematics.
Sources and further readings
BuzzFeedVideo
https://www.youtube.com/watch?v=W0tYRVQvKbM
Drinking Straws: How Many Holes? Kevin Knudson, professor of mathematics at the University of Florida
https://www.forbes.com/sites/kevinknudson/2018/01/29/drinking-straws-how-many-holes/
More about holes mathematically (many more details!) Evelyn Lamb.
https://blogs.scientificamerican.com/roots-of-unity/what-we-talk-about-when-we-talk-about-holes/
Coverage of debate on number of holes in straw
http://metro.co.uk/2017/11/17/how-many-holes-does-a-straw-have-debate-drives-internet-insane-7088560/
More debate on number of holes in straw
https://www.reddit.com/r/NoStupidQuestions/comments/7mdylb/does_a_straw_have_2_holes_or_1_hole/
Even coverage of debate on number of holes in straw
http://www.news.com.au/technology/online/social/how-many-holes-does-a-straw-have-question-drives-fierce-debate-on-social-media/news-story/693383aa6d1192445396cd94b5a35bf6
2016 Nobel Prize in Physics
https://www.nobelprize.org/nobel_prizes/physics/laureates/2016/
Published by
PRESH TALWALKAR
I run the MindYourDecisions channel on YouTube, which has over 1 million subscribers and 200 million views. I am also the author of The Joy of Game Theory: An Introduction to Strategic Thinking, and several other books which are available on Amazon.
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By way of history, I started the Mind Your Decisions blog back in 2007 to share a bit of math, personal finance, personal thoughts, and game theory. It's been quite a journey! I thank everyone that has shared my work, and I am very grateful for coverage in the press, including the Shorty Awards, The Telegraph, Freakonomics, and many other popular outlets.
I studied Economics and Mathematics at Stanford University.
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