Monthly Archives: July 2012

Q: How many people riding bicycle generators would be needed, in an 8-hour working day, to equal or surpass the energy generated by an average nuclear power plant?

Physicist: A person on a bike can optimistically generate around 200 watts, and an average nuclear power plant generates 800 MW of power (although a big nuclear power plant generates many times more power than a small one). Given those … Continue reading

Posted in -- By the Physicist, Engineering | 1 Comment

Q: Why is hitting water from a great height like hitting concrete?

The original question was: I know that if you hit water at a certain speed it is supposed to crush your body like you have hit concrete. Is this the case for all liquids or is something to do with … Continue reading

Posted in -- By the Physicist, Physics | 12 Comments

Q: How does instantaneous communication violate causality?

Physicist: You may have heard that if a technique can be found that allows you to send a signal faster than light, then you can send a signal back in time.  The very short answer for why is that relativity … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 27 Comments

Q: What is the “False Vacuum” and are we living in it?

Physicist: The False Vacuum is just another item on the long list of things to worry about, that are not worth worrying about, and that nobody can do anything about.  If you have any other worries, worry about those first. … Continue reading

Posted in -- By the Physicist, Particle Physics, Physics | 23 Comments

Q: How would the universe be different if π = 3?

Physicist: We sometimes get questions about physical constants changing, and those questions make sense because there’s no real reason for the constants to be what they are.  But π is mathematically derivable; it kinda needs to be what it is.  You … Continue reading

Posted in -- By the Mathematician, -- By the Physicist, Geometry, Math, Philosophical, Physics | 22 Comments

Q: Is it possible for an artificial black hole to be created, or something that has the same effects? If so, how small could it be made?

Physicist: Not with any current, or remotely feasible technology.  The method in use by the universe today; get several Suns worth of mass into a big pile and wait, is a pretty effective way to create black holes. In theory, … Continue reading

Posted in -- By the Physicist, Astronomy, Particle Physics, Physics | 9 Comments