Category Archives: Astronomy

Q: Do aliens exist?

Physicist: Yuppers.  In as much as the probability that they don’t is effectively zero. The statistics on this are a little weak, since we only have one real data point.  If you define intelligent life as tool-using, then (based on … Continue reading

Posted in -- By the Mathematician, -- By the Physicist, Astronomy, Biology, Evolution, Physics | 11 Comments

Q: If the universe is expanding and all the galaxies are moving away from one another, how is it possible for galaxies to collide?

Physicist: Because the universe isn’t expanding fast enough.  On average all the galaxies are moving apart, but often a given pair will be moving together. Hubble observed that the farther things are away, the faster they’re receding.  Specifically, in the … Continue reading

Posted in -- By the Physicist, Astronomy | 6 Comments

Q: What happens when you fall into a blackhole?

Physicist: Terrible, terrible things. The first thing you’ll be likely to notice as you approach the hole is the tidal forces.  Tidal forces are nothing more than the difference in gravitational force between the near and far side of an … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 89 Comments

Q: Why does oxygen necessarily indicate the presence of life?

Physicist: Short answer: Life is the only thing that makes lots of oxygen. This question comes in the context of a conversation about the Kepler mission.  So far (as of January 11, 2010) 424 “exoplanets” have been discovered and confirmed … Continue reading

Posted in -- By the Physicist, Astronomy, Biology, Physics | 3 Comments

Q: Will black holes ever release their energy and will we be able to tell what had gone into them?

Physicist: In any reasonable sense the answer to both of these questions is a dull “nope”.  In theory however, the answer is an excitable “yup”! Blackholes lose energy through “Hawking Radiation”, which is a surprising convergence of general relativity, quantum … Continue reading

Posted in -- By the Physicist, Astronomy, Entropy/Information, Physics, Quantum Theory | 4 Comments

Q: How far away is the edge of the universe?

Physicist: If you ever hear a physicist talking about “the edge of the universe”, what they probably mean is “the edge of the visible universe”.  The oldest light (from the most distant sources) is around 15 billion years old.  Through … Continue reading

Posted in -- By the Physicist, Astronomy, Physics, Relativity | 79 Comments