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I was super excited to go skiing for the first time as an 11 year old. My older brother and I had signed up for a ski trip run by our town, and we were on a bus with a bunch of people I didn’t know. Going skiing was something I had dreamed of doing ever since watching Olympic alpine skiing as a very small child. Every winter I would sled fanatically any time it snowed, but I longed to go skiing. This was my chance!

I ended up learning how to ski quickly and loving it. My first day, my brother and I stayed on the beginner hill, but by the end we were flying down that little hill. Since then I have gone on to ski black-diamond slopes.

Why did I learn skiing quickly, while other people struggle greatly? Since then I have failed multiple times trying to “teach” friends how to ski. But then I have another friend, Keith, who learned how to ski even faster than me and was on black diamond slopes on his very first day!

How people learn is a whole field of study that fascinates me. Today, let me share a few of my thoughts about how learning works based on my own experience and from what I have picked up from reading about learning.

I think that there are many, many mini skills that are needed to accomplish any physical skill like skiing, swimming, or even walking. Having a toddler in the house makes that very clear. My son will try all sorts of variations on manipulating objects and repeat again and again. I believe that these games help him to build up a suite of mini skills that can eventually be drawn upon to learn skills like shooting a basket or doing stand up paddle boarding.

Perhaps getting stuck when attempting to learn a new skill is just a sign that one needs to learn some more of those mini skills. I had that experience with snowboarding which I tried for the first time with my friend Keith who was trying skiing. I had hoped that my experience with skiing would help me to pick up snowboarding. No luck! I kept on falling, and just felt very unstable on the board. I couldn’t turn or stop, so I had to fall. Sometimes the falls were awkward half-falls, and other times I would do a face plant into the icy snow. In the end, I gave up and switched my snowboard rental for a ski rental. Then Keith and I had a blast for the rest of the day racing down the advanced hills.

I didn’t try snowboarding again for over a decade, but when I did try snowboarding I picked it up right away and I loved it! I’m not sure how this happened, but I attribute it to learning how to do the RipStik (see the image below). A RipStick is like a skateboard but has only a single wheel at each end attached with swivel casters. To move you have to swivel you legs back and forth which somehow generates motion. It was definitely a challenge to learn but I learned it during a summer living with a group of my friends while going to Rutgers.

RipStik_Classic_BL_Product
The Razor RipStik

Somehow when I returned to snowboarding I felt like I was able to transfer some of the skills I had picked up from the RipStik. I felt much more comfortable balancing on the board. I could swing my legs and hips to enter in to turns and I could control how the edge slid through the snow.

When I tried snowboarding as a teenager, I wasn’t good at it, but when I tried it again over a decade later I was a ‘natural’. This experience and others like it, make me question the idea that some people are inherently good or bad at certain skills or sports. Yes, some people will learn skills much faster than others. But do not write off the slow learners! Once they master the necessary mini-skills they can catch up pretty quickly and perhaps they can experience the joy of flying down a mountain on a snowboard!

Do you have the experience of failing to learn something the first time and then picking it up years later? I’d be curious to hear about it. I’m also interested in learning more about what the scientific research says about how people learn.

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I have decided that it is time for me to leave Facebook. It has a negative influence on me, my friends, and our larger society. This decision has not been easy since Facebook provides many useful services and most importantly lets me connect with so many of you. I want to explain some of the top reasons, and to share with you where I am going.

Facebook has lost my trust by:

  • Encouraging addictive behavior (infinite scrolls among other things).
  • Sharing our private information with whoever will buy it.
  • Not playing nicely with other applications. Instead of including the contents of a post in an email notification, Facebook forces you to pull up Facebook (and risk getting sucked into the news feed time sink).
  • Contributing to the fragmentation of our society by selecting posts full of outrage and provocation for our news feeds.

Facebook is “free”, but we pay in so many ways. I’m not buying it anymore. And I’m taking my data with me.

Before I go, I want to thank you, Facebook, for helping me to remember people’s names, for providing a way to share my thoughts and pictures, for giving me a sense of who got married or had a baby or took a cool vacation. 

My new home on the internet will be my website davidbruffner.com. Feel free to visit and say hi. I write little posts from time to time about what I am interested in. I’m still sorting out whether to spend time on other social networks. My favorite ways to connect are talking on the phone and meeting in person.

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The first weekend of December, I took part in the 2019 Omega Center conference titled Love at the Heart of the Cosmos. The Omega Center is an organization dedicated to building a new understanding of religion and science. The conference explored the idea that God’s love permeates the physical world and that the physical world matters to God. I attend online, but despite the distance, was still able to feel the excitement of the speakers and the attendees. I felt a sense of finding my “home”, other people like me who care deeply about religion, but are searching to find an understanding of religion they can wholeheartedly believe in.

To give a sense of the conference, here are a few examples:

  • Matthew Fox talked about the importance of holding on to a sense of wonder. He argued that God is not static, so we should be open to updating our beliefs and doctrines. I found it particularly encouraging how he has worked on new forms of liturgy.
  • Kathleen Duffy , a Catholic sister and physicist, described the struggle of Jesuit priest and paleontologist Pierre Teilhard de Chardin as he navigated writing about evolution and how it impacts his Catholic faith while facing censure from the Church. It is helpful to learn from Teilhard’s struggle, because we still face obstacles today. There is real resistance towards fully embracing evolution which necessarily causes dramatic changes to our understanding of God.
  • Ilia Delio, Catholic sister and theologian leading the Omega Center, spoke about the need for inner work, including contemplation, to contribute toward the future that God is calling us to. She described how technology is changing our very definition of what it means to be human, and the role of religion in this time of change.

Throughout the talks, the questions, and other events, there was a sense that we are on the edge of a big change in religion and society. In some way the current world religions will need to change to make sense of our changing world. There is a hope that a new religion or religions could emerge and help humanity face existential challenges.

I am just one person, and can not do much on my own, but I am part of something bigger. Maybe I can and we can, in some small way, contribute toward this epic story.

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I really like a little book called This Blessed Mess by Patricia H. Livingston. It is my go to book when my stomach is tied up in knots, and I am having trouble sleeping. I open it up to a random chapter, and tend to find a story that makes me laugh or sometimes to cry a little. Then I can sleep in peace.

Livingston describes how life can be chaotic and uncertain, but how there is goodness throughout. She describes how turmoil in her life forced her to challenge her ideas of God and the world. The science of chaos theory gave her a fresh perspective to appreciate the unpredictable nature of our lives and to make sense of where God is in all of the mess. Her personal stories make these ideas relatable and alive.

I find Livingston’s story to be hopeful and inspiring. Faith and science are both really important to me, so I love it when Livingston talks about faith in a way that takes science seriously. Chaos theory is great too; learning about it in college was part of what inspired me to go to grad school and study soft matter physics. I find chaos theory to be attractive because it shows that life can not be predicted. There is something wild and free about that. Livingston helps me to remember that I am not alone in the wilderness, but God is mysteriously there with me, ready to create something wonderful and new.

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I have been thinking of pasta, and the wheat it is made from, as a commodity. In my mind, it is all pretty much the same, a convenient and tasty source of energy. Recently, I came across organic pasta, and I am curious to know if there is a real difference between the organic and regular. If there is a difference, what are the benefits of organic?

I do not have first hand knowledge about how food gets to the grocery store. From what I’ve read, organic food certified by the USDA follows strict standards including restrictions on herbicides and pesticides and requiring plants be non-GMO (Genetically Modified Organisms). See for example this post by the USDA. I learned recently that some organic farmers even use fire to kill weeds. In contrast, regular farming of commodity crops like wheat involves heavy use of herbicides like RoundUp and GMO crops.

Here are some ideas about ways the organic food could be better:

  1. Less pesticide/herbicide residue.
  2. Happier, healthier plants leading to better tasting food.
  3. Maybe the non-GMO plants are better in some way.

The first reason seems plausible to me. If some substance is so deadly for weeds or for bugs can it be that great for me? But on the other hand, humans may not be affected because our biology is different than bugs or weeds or we may not be affected if the dose is too small.

The second reason, happier, healthier plants, also seems reasonable even though it is more subjective. I think of the difference in taste between food grown in home gardens and food we buy in the store. It seems reasonable that plants will thrive in an environment designed for them, instead of in a chemical warfare battleground.

The third reason, GMO, I’m not worried about except with how it plays into the first two reasons. Selective breeding has been used for ages, and breeding modifies plant genes. From what I have read, genetic modification really seems to be fine. The only concern I have is that farmers might drench the hardy GMO crops in herbicide and pesticide to make it easier to handle weeds and bugs. It seems like that could lead to more pesticide residue and it might be rough on the plants as well.

Are these ideas about benefits of organic food accurate? Are there other benefits to organic food? What are reliable sources for answering these questions?

How does the organic food affect our health? It seems that more people have trouble digesting wheat than they used to. Could farming practices be partially to blame, and could organic wheat help?

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Parallel parking is hard. Many of us avoid parallel parking if we can help it, and yet there are a select few that seem to be able to parallel park with ease. How do they do it? Over the past three years, I’ve been forced to parallel park a lot since our apartment doesn’t have enough parking in the lot. All the practice has helped me get a lot more comfortable about parallel parking, but it has also got me thinking. Parallel parking is an iterative process; somehow by going backwards and forwards and turning the steering wheel back and forth you can shift your car into a spot. I realized there must be an algorithm, a simple set of rules, that will always move the car smoothly into the spot. So I figured out a way to do it, and want to share it with you today. Maybe knowing the rules will help our parallel parking!

Shift car into spot by shifting back and forth according to an algorithm.

The basic problem with parallel parking is to shift your car into the spot, as shown in the sketch above. It would be easy if the front and back wheels could rotate 90 degrees, but with a normal car you have to deal with only the front wheels able to turn. Here is an algorithm I found for parallel parking:

  1. Start with car lined up with front of spot (not optimal but easier to understand the algorithm).
  2. Turn wheel right and reverse about half the length of the spot.
  3. Turn wheel left and reverse to the end of the spot. The car should be straightened out.
  4. Turn wheel right and go forward about half the length of the spot.
  5. Turn wheel left and go forward to end.
  6. Repeat until car is close enough to curb.
The car tires draw out concentric circles as the car turns.

As I was figuring out how to sketch the process of a car parallel parking, I actually learned something about car steering. It turns out that the front wheels do not point exactly in the same direction during a turn. Instead they follow the Ackermann condition so that every wheel draws out a circle with the same center point, as shown in the sketch above. With this insight, I was able to trace out the motion of the car as it parallel parks. The images below break down the process:

  • Car about to park in spot
    Line up car with open spot.

So if you trust my drawings, following these steps solves the parallel parking problem. Give it a shot! It is a little unnatural at first following a series of steps, but is nice once you get the hang of it. I like knowing that I can always shift the car where I want it just by going forwards and backwards.

To really learn something, I think it’s important to mess around and try things. I played around with making the turns uneven and found that this can cause the car to be crooked or straighten it out after I make a mistake. The slides below explore how this works.

  • The tracks of the back tires make nice symmetric curves if you follow this parallel parking algorithm.

Thanks for reading my thoughts into how parallel parking works. I hope it was helpful and interesting. Part of my inspiration was a nice article I read about visualizing algorithms. Please let me know if you have and questions or comments!

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I have been wondering about the long term prospects for the economy as I am trying to get things like retirement accounts and a 529 savings account set up. All the investment advice talks about the wisdom of holding stock for the long term. This advice makes sense because for the past few hundred years, there has been continual exponential economic growth (see great exploration of the economic growth at Max Rosen’s Our World In Data site).

But I am skeptical of anything growing exponentially forever. Exponential growth is relentless; it keeps getting faster and faster. There are lots of things that grow exponentially for short amounts of time, most commonly populations whether they are bacteria, rabbits, or people. At some point something will limit the growth. Are economies different? Can they grow exponentially forever?

I have read articles arguing both ways. The optimists feel that we will keep on innovating our way to growth (see for example a Freakonomics post). The pessimists (or realists) argue that economic growth is tied in some way to energy use (for example see this blog post). Consequently if we kept economic growth going then at some point the earth would would burn up from the waste heat emitted from all of the energy use. The optimists counter that we can have immaterial economic goods so production does not have to be tied to energy.

I would argue that gaining and maintaining knowledge requires a significant amount of energy. While computers make it look effortless to spreading knowledge, in fact every web page that is visited costs a little bit of energy. It is hard to see how we could create an ever more impressive virtual world without increasing energy costs in the real world. So for now I side with the realists!

Of course even if the growth does stop someday it is hard to know when it will stop. I have given up predicting when that will happen exactly. If I had to guess we might have some economic struggles in the short term, but over all keep with the exponential growth for a couple more decades.

If there are limits on growth, how do they work? Economic value depends on perception of value, but it is not clear to me how perception is related to physical quantities. How is energy related to economic transactions? How is knowledge, economic value, and information related?

 

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I didn’t know how RSS worked for a long time. It’s too bad because RSS is a great way to follow websites that you like. It stands for Real Simple Syndication (see wiki article for more info) and is a way for websites to create feeds of their content that users can subscribe to. This is one of those cases where a little barrier can be enough to block adoption. I wanted to share with you how RSS works in case you also are wondering how those little broadcast symbols work.

Following a website or blog on social media is pretty straightforward; you just click on the button for Facebook/Twitter/Instagram/etc. You can achieve the same thing with RSS, but you need to know a couple things first. If you just click on the button you might be asked to open a text file with a bunch of code in it.

rssText

That’s what I did, which is wrong. That code is actually a computer readable version of the latest posts from the website. Instead, you copy the link (right click and press “Copy link location”), and then you subscribe to that link in your RSS reader. But wait, I also had no idea what an RSS reader was. It turns out an RSS reader is just an app that automatically reads a website’s RSS feed and pulls the latest posts and updates from the websites that you follow. I’m using Inoreader right now which allows me to follow several blogs all in one place. Here’s a screenshot from my phone:

Screenshot_20190811-162619_Inoreader

If you want to start following websites outside of social media (and without spamming your email inbox) then sign up for a RSS reader. There are a bunch of options with readers, Feedly is a popular one. Many are free and you always can switch later if you realize that another has features that you like.

I’ll end by noting that you may already be using RSS without knowing it. iTunes or Spotify (or wherever you get your podcasts) are essentially readers for podcasts that are broadcasted using RSS! So if you want to create a podcast you just need to create an RSS feed and connect it to iTunes (see this tutorial for example).

I’m planning on looking into how I can use RSS more on this site. I hope you enjoy RSS too. May it help you break free of the social media silos and find the content you like.

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Diarrhea is definitely unpleasant, but how does it work physiologically?

What causes food and drink to pass through the system more quickly? Is the motion caused by mechanical action of the intestines, or could it be that the intestines somehow stop absorbing fluid? If they can turn absorption on and off, how does that happen?

The BRAT diet (Bananas, Rice, Applesauce, and Toast) is often recommended as a home remedy to diarrhea. The idea is that these bland foods are “easier” to digest than foods with a lot of fat, protein, or fiber. Why are some foods easier to digest than others? Is it related to the size of the food molecules, with small molecules more easily diffusing into the bloodstream?

Is diarrhea a response to fight against infection? Is it effective? How does it work?

Does diarrhea cause damage to the intestines? I could imagine that if stomach acid goes down into the intestines that it could damage all the little intestinal villi that are important in absorbing nutrients. I wonder if diarrhea could upset the microbiome as well.

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My colleague, Jarek Blusewicz, recently told me about autonomous RC cars and how they can be a fun project for playing around with AI and robotics. I didn’t know that autonomous RC cars were a thing, but it turns out that lots of individuals and teams are playing around with them, and doing awesome work. I found a video of a RC car autonomously drifting around in controlled circles. It is amazing to watch, especially when the camera zooms in on the front wheels steering back and forth to maintain the drift as the car slides over the surface. It looks like a professional driver, but the car is completely controlled by a computer.

Researchers at Georgia Tech created an autonomous rally RC car for “aggressive off-road driving”. They really mean aggressive! The car hits a turn at almost full speed and then power slides through it while kicking up clouds of dirt. Here’s a picture of their AutoRally car in action.

autorally_platform_header
Credit: AutoRally: An Open Platform for Aggressive Autonomous Driving. Brian Goldfain, Paul Drews, Changxi You, Matthew Barulic, Orlin Velev, Panagiotis Tsiotras, James M. Rehg. Control Systems Magazine (CSM), 2019.

The best part about the Georgia Tech work is that it is all open source, with a site on Github including detailed instructions about how to build the car (it wouldn’t be cheap, but could be great for a group or organization).

The AutoRally car is controlled with a reinforcement learning algorithm, which I have been finding to be widespread for controlling robots in general. It’s something that I would like to learn more about and play with.