Questions

When I connect to a website over HTTPS, my browser and the server agree on a secret key without ever having met before. How is that mathematically possible?

The equation e^(iπ) + 1 = 0 is often called the most beautiful in mathematics. What does it mean, and why does it connect five fundamental constants?

Mitochondria have their own DNA and replicate independently. What is the endosymbiotic theory, and what evidence supports it?

What does current neuroscience tell us about the purpose or function of dreaming during sleep?

The universe began in an extremely hot, dense state about 13.8 billion years ago. What do physicists understand about what caused or preceded it?

What is the mechanism that causes the ground to shake during an earthquake? What is the role of tectonic plates and fault lines?

When a bacterium or virus enters the body, how does the immune system distinguish it from the body's own cells and mount a response?

Alzheimer's is the most common form of dementia. What is happening in the brain at the cellular and molecular level, and what risk factors are known?

The oceans circulate in large-scale currents that influence climate around the world. What drives these currents, and what would happen if they stopped?

Iron corrodes readily in air and water while gold stays shiny for thousands of years. What is different about their chemistry?

What is the step-by-step process by which a cell copies its DNA before dividing? Which enzymes are involved?

Gravity pulls the Moon toward Earth, so why does it stay in orbit instead of crashing into us?

The factorial function is defined as the product of all positive integers up to n. So why does 0! = 1? Is it just a convention or is there a deeper reason?

I understand it has something to do with light, but what is the actual physical mechanism that makes the sky appear blue during the day?

How does a lightning bolt form? What is happening physically and electrically in the atmosphere that produces it?

Special relativity predicts that a clock moving at high velocity ticks more slowly than a stationary one. Why does this happen, and has it been experimentally confirmed?

Microwave ovens heat food very quickly compared to conventional ovens. What physical process is actually occurring at the molecular level?