Category Archives: Probability

Q: How likely is it that there’s dark matter in me right now?

Physicist: Probably very likely!  Probably! When we look out into the universe we find that on galactic scales and up that most of the mass in the universe is “dark”.  Based on how galaxies form, move, collide, and bend light … Continue reading

Posted in -- By the Physicist, Astronomy, Paranoia, Particle Physics, Physics, Probability | 8 Comments

A Quantum Computation Course

Physicist: I’ve been a little busy to post much here for a while, but you may be interested in what I’m working on, so here it is.  I’m teaching an introductory course on quantum information and computation, and the primary … Continue reading

Posted in -- By the Physicist, Computer Science, Entropy/Information, Experiments, Math, Philosophical, Physics, Probability, Quantum Theory | 9 Comments

Q: Half-life?

The original question was: If you have a lump of radioactive material with a half life of say 10,000 years, then how come it could start steadily decaying right away? Why wouldn’t everything be relatively stable for 10,000 years and … Continue reading

Posted in -- By the Physicist, Logic, Particle Physics, Physics, Probability | 8 Comments

Q: If you double your bet every time you lose, won’t you eventually win and come out ahead?

Physicist: Yes, but… There are good reasons why casinos make money and “how to gamble” books are longer than two sentences.  According to the law of large numbers, if you’re likely to lose a little bit of money in a … Continue reading

Posted in -- By the Physicist, Math, Probability | 3 Comments

Q: How many samples do you need to take to know how big a set is?

The Original Question Was: I have machine … and when I press a button, it shows me one object that it selects randomly. There are enough objects that simply pressing the button until I no longer see new objects is … Continue reading

Posted in -- By the Physicist, Combinatorics, Math, Probability | 4 Comments

Q: How do we know that everyone has a common anecestor? How do we know that someone alive today will someday be a common ancestor to everyone?

The original question was: From biology and genetics we know that any group of living organisms had a mitochondrial most recent common ancestor (mitochondrial Eve): a female organism who lived in the past such that all organisms in this group … Continue reading

Posted in -- By the Physicist, Biology, Evolution, Probability | 3 Comments