Podcast Summary: Más de uno — El reto matemático: Plaga zombie

Host: Carlos Alsina, Onda Cero
Guest: Santi García Cremades
Date: February 26, 2026

Overview

In this engaging and humorous segment of "Más de uno," mathematician Santi García Cremades brings a new mathematical challenge themed around a "zombie plague." The episode draws inspiration from current pop culture—the series "The Last of Us"—to make math accessible, relevant, and fun for listeners. The central discussion revolves around modeling an infectious outbreak using the SIR (Susceptible-Infected-Recovered) model, challenging listeners to apply mathematical reasoning to a zombie scenario on a bus.

Key Discussion Points & Insights

1. Recap: The Snail Puzzle & Its Lesson (00:32–02:02)

• Santi revisits last week's math challenge, involving a snail climbing a high wall and highlights a common mistake among respondents.
  • Quote: "Por una vez tengo que decir que no hay ningún acertante. Ni siquiera Alsina, que ha mandado un montón de audios."
    (Santi García Cremades, 00:51)
• The lesson: Careful reading and logical reasoning matter in puzzle-solving.
  • Quote: "La gente respondió muchas veces 5 días, porque eran 2 metros por día... una vez que ya subió la pared, la noche no cuenta cómo bajar."
    (Santi García Cremades, 01:50)

2. Introducing the Zombie Math Theme (02:08–03:13)

• Santi shares his current fixation with "The Last of Us," leading to a segue about epidemics and mathematical modeling.
  • Quote: "Bueno, vengo porque estoy enganchado... a The Last of Us. En Murcia le decimos The Last of Us."
    (Santi García Cremades, 02:14)
• Humorous comparisons are drawn between fast modern zombies and classic slow ones:
  • Quote: "Esos zombies de mi generación eran muy lentos... Van a grossfit todo."
    (Santi García Cremades, 02:25)

3. SIR Model Explanation (03:13–05:34)

• Santi explains the SIR epidemic model, using everyday situations (like an infected person sneezing on a bus).
  • Quote: "Entonces me lo contó. Esto se llama el modelo SIR... La S viene de la gente sana, gente susceptible... la I es de los infectados... y la R son los retirados, pero no que se han jubilado... los recuperados."
    (Santi García Cremades, 03:13–03:57)
  • Quote: "El sistema inmune no es un superhéroe con espada, es un matemático silencioso que busca bajar el promedio."
    (Santi García Cremades, 05:14)
• Highlights the difference between individual and collective immunity.
  • Quote: "La protección no es individual, es colectiva. Y no estamos solos en la ecuación."
    (Santi García Cremades, 05:34)

4. The New Challenge: The Zombie Bus Puzzle (05:34–07:29)

• Santi presents this week’s mathematical riddle, incentivizing participation with a book giveaway.
  • Setup: 21 healthy people are on a bus. One infected person boards; at each stop, every infected infects 3 others. Additionally, 25% of infected passengers get dizzy and leave the bus at each stop.
    • Quote: "Estamos en un autobús de 21 personas. Son todos sanos, de momento... entra una persona contagiada... en cada parada, cada contagiado infecta a tres personas nuevas... El 25% de los contagiados se marea y se baja."
      (Santi García Cremades, 06:13–06:50)
  • The crucial question: "¿Hay algún momento, alguna parada en la que hay exactamente el mismo número de sanos que de contagiado?"
    (Santi García Cremades, 06:57)
• Santi encourages listeners to submit answers for a chance to win "Inmunidad en forma" by Alfredo Corel.

Memorable Quotes & Moments

• Classic math humor and wordplay: "Esto se llama el modelo sir, que eso es lo que decía Shakespeare: sir o no sir, esa es la cuestión."
  (Santi García Cremades, 03:10)
• On the impact of epidemiological models: "La enfermedad va muy rápido, crece. Como cuando algo crece mucho, ¿qué se le dice en matemáticas? Exponencialmente."
  (Santi García Cremades, 04:48)
• On the collective nature of health: "La protección no es individual, es colectiva. Y no estamos solos en la ecuación."
  (Santi García Cremades, 05:34)

Key Timestamps

• 00:32–02:02 — Recap and solution of the snail wall problem
• 02:08–03:13 — Introduction to The Last of Us and zombie context
• 03:13–05:34 — SIR model and application to everyday life
• 05:34–07:29 — The Zombie Bus mathematical challenge

Tone, Language & Style

The segment is lively and accessible, blending mathematical rigor with pop culture references and humor to connect with listeners. Santi's playful attitude toward math makes abstract concepts relatable. The dialogue flows naturally, filled with teasing between hosts and Santi, and frequent jokes about mathematics and zombies.

For Listeners: How to Participate

• Challenge summary: Calculate if there is a bus stop where the number of healthy ("sanos") equals the number of infected ("contagiados") individuals.
• Submit solutions via the number given in the show for a chance to win Alfredo Corel's immunology book.

Conclusion

This episode exemplifies how current events, science, and playful storytelling can combine to both teach and entertain. Santi uses a fictional zombie outbreak to encourage mathematical reasoning, highlighting the very real power of collective action and scientific literacy in public health.