Category Archives: Personal

Seeing sound and other changes in air density

Here’s a video on a technique which we can use to see changes in air density that are otherwise invisible to the human eye.

It’s called a Schlieren Flow visualization and, together with a high-speed camera, it lets us see the changes in air density caused by examples like the travel of sound, the natural heat coming from our hands, and sneezes and coughs.

Thinking of what else is actually there but invisible to our eyes because of the types of waves that they can see is a fascinating exercise.


Following a day trip from Menlo Park to New York yesterday, I’m leaving the US for London today. This marks the beginning of the European leg of my international investor meetings.

While the suburbs of Menlo Park were nice, I’m looking forward to going to an urban city. And London is just that.

Although London is 2 hours behind Istanbul, the time difference is small. This means that I’ll return to publishing blog posts closer to their regular early morning Istanbul time.


If you look for it, there’s always something to worry about in lıfe.

When you’re in school, you can worry about what grades you’re going to get or whether your classmates will like you. When you’re working, you can worry about whether you’re going to complete a project on time and whether you’re going to be promoted. When you have a family, you can worry about whether you’ll be a good husband or wife, a good father or mother, and whether you’ll be able to provide for your family.

Worrying is, to a certain extent, beneficial. The reason is that it helps you focus to solve a problem and thereby avoid what you’re worring about from materializing.

However, most people, myself included, often worry beyond a beneficial point. This becomes clear when you look back at the things you worried about and realize that most of your worries didn’t materialize while, among those that did, you overcame most of them and time has healed the rest.

Technology and entitlement

On yesterday’s flight from Istanbul to San Francisco, I was hoping to connect to the inflight WiFi to do some work that required internet connectivity. Unfortunately, the inflight WiFi didn’t work for the duration of the 13 hour flight.

At first I was disappointed. Since I had set my mind on what I wanted to be doing during the flight, I was upset when I realized that I wasn’t going to be able to do what I had planned.

But then I thought to myself how inflight WiFi didn’t even exist until a few years ago. I realized that, over the span of the last few years, I had gained a sense of entitlement to a technology whose absence I didn’t complain about in the past and whose presence is, even if it doesn’t always work, pretty miraculous.

So rather than complain, I simply did the work I could do in the absence of an internet connection.

And I even had time left over to read a book.

Feelings, unique and in perspective

All that you feel has been felt before. Depending on the feeling, somewhere between hundreds and billions of people have felt it and its variations before. And many more will feel it in the future.

Seeing this helps you keep things in perspective.

But you can only feel what you feel as an individual. You cannot access the feelings of those that came before you, those that will come after you, or those lives with whom your life overlaps. So, from your perspective, your feelings are uniquely meaningful.

Seeing this helps you immerse yourself in all that life has to offer.

Learning from your and others’ experiences

There are two ways to learn. The first is from the experiences of others and the second is from your own experiences.

The advantage of the first is that, since multiple people have more experiences than a single individual, you can learn more faster by relying on others’ experiences.

The challenge is that it’s harder to learn from others’ experiences than it is to learn from your own. The reasons for this are that you’re more likely to discount others’ experiences by thinking that they don’t apply to you, and even if you don’t discount them, it’s difficult to internalize the learnings of others’ experiences without having felt the pleasures and pains which result from having lived through them.

In other words, others’ experiences provide breadth while your own experiences provide depth. Once you appreciate the benefits and shortcomings of each, you recognize that both are necessary.


We live in a time period where technology has greatly increased our productivity. This means that, on an individual basis, we can get things done much faster than before.

Thanks to the content available on the internet, we can learn faster than before.

Thanks to the extensive storage and processing capabilities of software and hardware, we can apply our learnings to quickly produce outputs from inputs.

And thanks to online communication tools like email and messaging apps, we can instantaneously relay the outputs we produce, and the decisions based on these outputs, to the people we interact with.

In other words, technology makes it easy to act fast.

However, acting fast isn’t always in our interest.

Although there is a limitless amount of content that we can learn from, our brains remain single track processors that need to recharge regularly. We therefore need to choose what to learn, and allow enough time for the learning to actually take place.

Although we have, for most practical purposes, virtually infinite storage and processing capabilities, that doesn’t mean that we should store and process everything.  We need to ask the right questions based on our learnings in order to store and process data that’s likely to produce meaningful answers. We also need to cross-check the assumptions behind our answers before using these answers to drive our decisions.

And although we can instantaneously communicate the outputs we produce, and the decisions we take based on these outputs, to others, we need to take into account the fact that the recipients of these outputs and decisions are humans. Humans process information differently depending on when they receive it, both on an absolute basis (for example, the time of day or on weekdays versus weekends) and on a relative basis (for example, relative to when they expect to receive it, which is in turn influenced by the importance of the output or decision and when you last communicated). As a result, the first moment when an output or decision is available for communication isn’t necessarily the right moment for its communication.

In other words, while technology makes it easy to act fast, as a result of our humanity, there are important benefits to inaction.


Mert Salur is the son of Nazim Salur, the founder of Bitaksi, where we’re investors, and Getir.

I still remember when I first met Mert. At the time, he was training for the half Ironman. That’s a 1.9 KM swim followed by a 90 KM bike ride followed by a 21.1 KM run. It’s daunting to say the least, but Mert successfully completed it about 2 years ago.

Fast forward 2 years and Mert is now a full Ironman. That’s a 3.8 KM swim followed by a 180 KM bike ride followed by a 42.2 KM run.

It took Mert 11 hours, 12 minutes, and 55 seconds of non-stop physical extertion to complete the journey. Even people who exercise on a regular basis like myself find it difficult to exercise at that level of exertion for over an hour or two.

Here’s a blog post in which Mert shares his learnings from the arduous process of becoming an Ironman. The learnings are:

  1. Achievement necessitates preparation
  2. Listen
  3. Be patient
  4. Accept that you may not succeed this time, and that that is OK

As Mert shares, “now that I am an Ironman, I can set more difficult, distant, and unclear [mental] goals.” And that’s a goal worth striving for.

Congratulations Mert.

Learning the fundamentals to create the application

In a post from October 2016, I wrote that “if we hope to create or support the creation of an application, in other words if we’re an entrepreneur or an investor, we need to understand the textbook fundamentals [behind the application]”.

This is in contrast to diving straight into the application without engaging with the primary sources necessary to understand the fundamentals behind the technology, or, even worse, trying to get a grasp of the fundamentals by reading secondary accounts (like most blog posts and podcasts) of the technology. Since the latter doesn’t take a structured approach to building your knowledge base in a particular technology from the ground up, you’re left with many holes in your understanding.

The best source for acquiring textbook fundamentals (or video or audio fundamentals, depending on the medium of your choice) is schools. Fortunately, we live in an age when many leading global universities make available the content of their classes online, and often for free.

For example, Princeton University offers a Coursera course on Bitcoin and Cryptocurrency Technologies. I recently completed the 11 week course and have learned more about cryptocurrencies in general and bitcoin in particular through the course than through the hours I’ve spent reading secondary accounts of the same technologies.

John Roberts’ commencement speech

US Supreme Court Chief Justice John Roberts recently gave the commencement speech at his son’s 9th grade commencement.

It’s a very strong speech overall, and the excerpt below is excellent:

“From time to time in the years to come, I hope that you will be treated unfairly so that you will come to know the value of justice.

I hope that you will suffer betrayal because that will teach you the importance of loyalty.

Sorry to say but I hope that you will be lonely from time to time so that you don’t take friends for granted.

I wish you bad luck again from time to time so that you will be conscious of the role of chance in life, and understand that your success is not completely deserved and that the failure of others is not completely deserved either.

And when you lose as you will from time to time, I hope every now and then your opponent will gloat over your failure. It is a way for you to understand the importance of sportsmanship.

I hope you will be ignored so you know the importance of listening to others.

And I hope that you will have just enough pain to learn compassion.

Whether I wish these things or not, they are going to happen. And whether you benefit from them or not will depend on your ability to see the message in your misfortunes.”