Science · 147 lessons in the app
Why you can't tickle yourself, why we haven't heard from anyone else in the galaxy, how CRISPR edits DNA. Each lesson takes one finding, explains it and cites the paper or textbook behind it.
Lesson 1 of 4
Your cerebellum predicts the sensory consequences of your own movements and dampens responses to self-produced stimuli. When someone else tickles you, the touch is unexpected, triggering a startle response. The brain literally cancels your own touch before it reaches consciousness, a feature, not a bug.
Source Blakemore, S.J., et al. (2000). Why can't you tickle yourself? NeuroReport.
Quick quiz
Why can't you tickle yourself?
Lesson 2 of 4
The universe is 13.8 billion years old with hundreds of billions of galaxies, each with hundreds of billions of stars. Statistically, intelligent life should be everywhere. Yet we detect complete silence. Enrico Fermi asked: "Where is everybody?" The answer remains one of science's deepest mysteries.
Source Hart, M.H. (1975). Explanation for the Absence of Extraterrestrials on Earth.
Proposed solutions include the Great Filter (some stage kills civilizations), the Zoo Hypothesis (they're watching us), rare Earth (complex life is extraordinarily rare), or the Dark Forest (they're hiding).
Quick quiz
What does the Fermi Paradox describe?
Lesson 3 of 4
CRISPR-Cas9 is molecular scissors that can cut DNA at precise locations and edit genetic code. Discovered in bacteria as a viral immune system, scientists repurposed it in 2012. It can potentially cure genetic diseases, create disease-resistant crops, and eliminate inherited conditions. The first CRISPR-treated patient had sickle cell disease, and was cured.
Source Doudna, J.A., & Charpentier, E. (2012). Science.
Quick quiz
What natural role did CRISPR-Cas9 originally serve before scientists repurposed it?
Lesson 4 of 4
The second law of thermodynamics states that entropy (disorder) in a closed system always increases. This is why ice melts in warm water but warm water never spontaneously forms ice. It's why we remember the past but not the future, the low-entropy past created more 'records' (memories, fossils, documents) than the high-entropy future. Entropy is the arrow of time's physical basis.
Source Carroll, S. (2010). From Eternity to Here.
Quick quiz
Why does entropy explain why we remember the past but not the future?
Every title here is a lesson in Scroll, with its own quiz. Five a day are free; Premium has no daily limit.
Each one cites the paper, textbook or book it's based on, printed under the lesson in the app and on this page.
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