You forgot it was memento...;)

How seams alter boundary layer separation points on baseballs - Experiments in Fluids Many sports balls develop forces that change their motion due to spin, or the Magnus effect. Spin causes the boundary layer separation points to change leading to an asymmetric pressure distribution o...

link.springer.com/article/10.1...

Yeah, I think you have to read and understand Smith et al. 2024 to understand why ;)

bsky.app/profile/leph...

Nerd alert: how much does air drag actually affect bat speed? Here’s my quick back-of-the-envelope take.
www.laphysiquedubaseball.ca/2026/04/09/o...

I made a quick back-of-the-envelope calculation with a lot of approximations. If only air density changes, then for a 25°F temperature difference, I get that the bat speed would change by about 0.1 mph. I’ll try to write everything out more carefully tomorrow.

This is one example, but you see this frequently when looking at sliders in slow motion.

Supported by numerical simulations, I’ll answer:
What role does SSW play in this phenomenon?
Why doesn’t it happen all the time, and what conditions are required?
How does it affect SSW?

Stay tuned.

Before diving into seam-shifted wake, Part 2 will take a short detour to explain in detail the physics behind the evolution of the seam pattern seen in this clip (originally shared by either @themagnuspi.bsky.social or @pitchingninja.com on Twitter a few years ago, I lost track of the exact source).

4/ À mon avis, on devrait cesser d’utiliser le mot "science" de cette manière, comme si c'était une personne (la science dit que…la science a montré que…la science croit que…)

3/ Quand on parle de la science comme si c’était une personne qui affirme des choses, ça devient un peu comme écouter l’opinion de mononcle Pierre.

Il dit parfois des choses intelligentes, mais aussi des niaiseries, et à la longue on finit par ne plus toujours le croire, même quand il a raison.

2/ La science est un processus collectif, itératif et autocorrecteur qui nous permet de mieux comprendre le monde. Elle se trompe parfois, et c’est normal.
Sa force vient justement du fait qu’elle se corrige elle-même avec le temps.

1/Je pense qu’une partie du problème de crédibilité de la science vient de la façon dont on en parle. On parle souvent de la science comme si c’était une personne : "La science dit que…", sujet, verbe, complément.

Mais la science n’est pas une personne. Ce n’est pas une autorité. C’est une méthode.

Me holding a baseball while wearing a ‘Seam-Shifted Wake and Bake’ T-shirt.

I’ve been postponing writing about seam-shifted wake for ages. Time to finally dive in. Part 2 once the semester is over and grading is behind me.

www.laphysiquedubaseball.ca/2026/04/05/m...

This is how we nerds relax.

Really good read so far (I am at chapter 5), very interesting. Too bad chapters don't have titles as it makes it harder to find something again if I want to go back (my only very very minor complaint ;) ).

Just ordered it. Will read it on the beach during Easter break...

The Tacoma Narrows Fallacy YouTube video by minutephysics

You mean aeroelastic flutter ;) youtu.be/6ai2QFxStxo?...

The differences in time and velocity are much less important than that in movement. For example, I calculated that for a 10 mph headwind, 85 mph slider slows down to 75.1 instead of 77.2 without wind (or 473ms vs 466 in flight time) but the break can be 2-4 inch more depending on spin rate and tilt.

@rhettallain.bsky.social You might recognize the animated ball texture that I shamelessly borrowed from you ;)

video of steel ball oscillations: aip.figshare.com/articles/med...

vpython simulation for the steel ball: www.glowscript.org#/user/Patric...

Oscillation of a Ball on a Concave Surface A simple method to measure the coefficient of rolling friction, µR, is to allow a ball to roll back and forth in a curved track or on a concave lens or mirror.1

Cute little project I did with Rod Cross. pubs.aip.org/aapt/pte/art...

Looking forward to seeing this. My lecture on vibrating bats is approaching. I am debating about giving an homework on torpedo using my code this year but am afraid it might be too advanced stuff for some.

yeah, they use chatGPT now...;)

I do not have the book with me right now so I go from memory, but I think there are a few chapters in the book ''sports physics''. If you don't ahve the book, if you search for Rod Cross, you will find many many interesting papers on the bouncing and rolling of balls in various sports.

Nice. After a few oscillations it should reach a steady-state temperature. I haven’t done the full calculation, but if the rise is a few degrees your FLIR One might be able to detect it. I have the iPhone version of the camera, but I can’t use it anymore now that I’m on Android.

Yes, this is what my simulation shows. Can all be explained using Euler’s equations + a few reasonable assumptions that however need experimental validation, but nothing unusual in terms of physics. I’ll write more about this once I finish my SSW piece, which I’ve been procrastinating on for ages...

If his starting lead had been about the same as the distance of Muncy to the bag (more than that is a risk of double play in case of line drive), it would not even have been close at home plate...

I thought you said that you didn't care who wins ;)