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Featured guide
What Is a Total Solar Eclipse? How It Works, What You See, and When the Next One Is
Understand total solar eclipses, totality, safe viewing, and when the next one happens.
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Explore Heartbeats
Understand the science behind the one-billion-heartbeats idea, then use the calculator to explore heart rate, lifespan and lifetime heartbeat totals.
One Billion Heartbeats
Why mammals can fall into a similar lifetime-heartbeat range—and why the rule is not a biological limit.
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Lifetime Heartbeats Calculator
Estimate lifetime heartbeats or convert totals such as 1 billion or 2 billion beats into years.
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More from Science
How to Make Antimatter: How CERN Produces, Traps, and Stores It
See how CERN actually makes, slows, traps and stores antimatter — and why a gram remains far beyond today's technology.
What Are Disappearing Polymorphs? The Ritonavir Crystal Crisis Explained
How can the same drug suddenly form a crystal that changes its behavior? The ritonavir crisis explains why.
Which Asteroids Could Hit Earth? The Real Risks We Should Worry About
See which asteroid risks are real, how scientists measure them, and why a risk-list entry is not an impact prediction.
How Does Google Maps Find the Fastest Route So Quickly?
See how modern navigation can search millions of roads without checking every possible route.
Is Spider Silk Stronger Than Steel? What the Science Actually Shows
Is spider silk really stronger than steel—or is the famous claim misleading?
What Are Shade Balls? Why Los Angeles Put 96 Million Black Balls in a Reservoir
Why Los Angeles covered a reservoir with 96 million black balls — and why evaporation was not the main reason.