Calculations about the absurd questions that pop up in daily life
50% of your body swaps to new material in about three weeks — mostly water and blood. Reaching 90% takes 10–18 years, because muscle and bone are slow. An exponential tissue-renewal model calculates the timeline tissue by tissue, then counts the burgers. The non-renewable 2.8% (neurons, cardiac muscle, ocular lens) stays original forever.
Roughly 109 billion humans have ever lived and died. If every one of them entered heaven, how large would it need to be? We treat floor area per soul as the key variable, calculate heaven's required footprint under three admission-rate scenarios, and compare the result against Earth's surface area and the specific dimensions Revelation 21 gives for the New Jerusalem — then ask what happens when you add the animals.
A single americano hides three numbers your receipt doesn't show: 0.78 m² of farmland, 0.067 kgCO₂e of carbon (ten times more if you add milk), and USD 0.0012 in harvest wages — 0.035% of the cafe price. Three lenses, one cup, all the math shown.
That viral claim — you eat a credit card's worth of plastic every week — already has a very aggressive assumption baked in. Change it, and the lifetime total swings from 76 cards to over 4,000. One variable, a 50-fold range. Here's how the math actually works.
A cotton tote bag has a much larger production footprint than a plastic bag. The break-even point is 52–131 uses under GWP alone, or up to 7,100 uses if ozone depletion is factored in. Average real-world use? About 51 times. And individual savings amount to roughly one 89-billionth of the annual global production growth in carbon terms. Two reversals, one calculation.