Watched Brutalist. This might be the best movie I’m going to watch in 2025. It’s sometimes disturbing, but also gentle, caring, and beautiful.

Feynman’s Lectures Exercises 6.9

Before firing, the total momentum is:

${\displaystyle (M+m_b)V_0=0}$

After firing one bullet, the platform moves with velocity $V_p$. By momentum conservation, total momentum remains zero:

${\displaystyle M{V}_p+m_b{V}_b=0}$

Solving for $V_p$:

${\displaystyle V_p=-\frac{m_b{V}_b}{M}=-0.005\text{ m/s}}$

A negative sign indicates the platform moves opposite to the bullet’s direction.

A bullet travels 5 m at 500 m/s, thus its travel time is:

${\displaystyle t=\frac{5}{500}=\frac{1}{100}\text{ s}}$

Since bullets are fired every $\frac{1}{10}\text{ s}$, only one bullet is airborne at a time.

Approach 1: Considering 10 bullets per second

Each bullet provides a velocity of $0.005$ m/s to the platform, then it flies for some time and then it stops. In total, the platform moves for due to 10 bullets per seconds:

${\displaystyle t_{\text{total}}=nt=10\times \frac{1}{100}s=\frac{1}{10}s}$

Thus, the effective average velocity is:

${\displaystyle V=0.005\times \frac{1}{10}\times 10=5\times 10^{-4}\text{ m/s}}$

Approach 2: Using total distance traveled by the platform per bullet fired

The distance traveled by the platform per bullet fired is:

${\displaystyle s_p=V_{p}t=0.005\times \frac{1}{100}=5\times 10^{-5}\text{ m}}$

With 10 bullets fired each second, the effective velocity is:

${\displaystyle V=5\times 10^{-5}\times 10=5\times 10^{-4}\text{ m/s}}$

Reading quotes from the book in the previous post made me think that this nightmare bicycle is the main reason design is so bad right now.

Designers confuse the simplicity of having gears with the minimalism of hiding them entirely and reducing controls to a few buttons.

A few examples:

• Avoiding tables, even when they are the best way to present dimensional data.
• Hiding important elements under menus because multiple controls in a UI are supposedly confusing.
• Prioritizing flat UI over visual structure and hierarchy.
• Designing transparent buttons with no clear indication of action, making them blend into the background.
• Using low-contrast text that sacrifices readability for aesthetics.
• Replacing labels with contextless icons—while a well-designed icon can be effective, it often fails to convey meaning.
• Slowing down interactions with unnecessary animations and transitions in the name of “smoothness.”
• Hiding information in sliders that users don’t even realize exist.
• Auto-hiding UI elements just because it looks “cleaner.”
• Implementing touch-optimized controls on desktop, such as oversized buttons and excessive whitespace.

This all comes from the desire to force certain aesthetics, and unfortunately, web technologies provide too few constraints to prevent this abuse.

From Avoid the nightmare bicycle:

Imagine a bicycle where the product manager said: “people don’t get math so we can’t have numbered gears. We need labeled buttons for gravel mode, downhill mode, …”

Good designs expose systematic structure; they lean on their users’ ability to understand this structure and apply it to new situations. We were born for this.

Thus, Changing Minds by Andrea diSessa is an instant buy.

Finished reading Lost in Math by Sabine Hossenfelder.

This book is about Sabine being frustrated with the current state of physics and science in general. She makes a strong case for why she’s upset: many physicists devote their efforts to unfalsifiable theories, motivated purely by their aesthetic appeal.

It’s hard to deny that ideas like the multiverse and wormholes are fascinating, but if they’re closer to science fiction than science, what’s the point? Why do we invest so much time and money into theories that can never be tested or applied?

PhD stands for Philosophiae Doctor because science was once called natural philosophy. Before Newton, theories were accepted based purely on plausibility. Then came the scientific revolution, when ideas had to be tested against reality. Today, many theories are chosen solely for their mathematical beauty, making it feel as if we’ve taken a step back by a few hundred years.

I recommend this book to anyone interested in science, history of science, philosophy of science, and epistemology. It’s well-written and provides all the context needed to go through it.

Definition of stupidity from The Basic Laws of Human Stupidity (haven’t read):

A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring loss.

The Ideal Candidate Will Be Punched in the Stomach is one of the best things I’ve read in a long time. It feels like reading Camus or Kafka set in modern times.

It’s good to see more people talking about the strange mix of apathy, anxiety, and boredom they feel. I haven’t figured out whose fault this is, but something has changed in the past ten years in how we work.