Physics Weekly Newsletter - Monday, September 29, 2014

Top new questions this week: Did the Big Bang happen at a point? TV documentaries invariably show the Big Bang as an exploding ball of fire expanding outwards. Did the Big Bang really explode outwards from a point like this? If not, what did happen? general-relativity cosmology big-bang   asked by John Rennie 39 votes answered by John Rennie 72 votes Why is Earth's climate so stable? Earth wasn't always the only water-world in the solar system. Mars also appear to have started out wet but, as conditions changed, Mars lost its oceans. So, how has Earth managed to avoid a … earth solar-system geophysics   asked by Achmed 33 votes answered by David Hammen 53 votes How far ahead can we predict solar and lunar eclipses? The solar system is non-integrable and has chaos. The sun-earth-moon three-body system might be chaotic. So, how far into the future can we predict solar eclipses and/or lunar eclipses? How about … orbital-motion solar-system celestial-mechanics chaos-theory   asked by Jiang-min Zhang 33 votes answered by David Hammen 42 votes Why is the sky never green? It can be blue or orange, and green is in between! I, like everybody I suppose, have read the explanations why the colour of the sky is blue: ... the two most common types of matter present in the atmosphere are gaseous nitrogen and oxygen. … visible-light atomic-physics atmospheric-science meteorology   asked by Alb 30 votes answered by David Hammen 18 votes Why do computers generate heat? Computers generate heat when they work. Is it a result of information processing or friction (resistance)? Are these just different ways to describe the same thing? Or does some definite part of the … thermodynamics friction information computer   asked by isarandi 26 votes answered by lemon 29 votes If I squeeze something really hard, will it ever become two-dimensional? A mosquito just wanted to bite me! Päng - and it stuck to my hand, hardly recognisable anymore. I said to my girlfriend: "Just reduced the dimension of the mosquito by one!" Therefore the question: … dimensions   asked by dani 19 votes answered by John Rennie 47 votes Can gravitational waves be red-shifted? Whenever the Doppler effect is mentioned, it's typically in the context of sound waves or electromagnetic radiation. On the cosmological scale, red-shifting is also important because of the enormous … gravitational-waves doppler-effect   asked by HDE 226868 14 votes answered by Ben Crowell 13 votes Greatest hits from previous weeks: Why can Hiroshima be inhabited when Chernobyl cannot? There was an atomic bomb dropped in Hiroshima, but today there are residents in Hiroshima. However, in Chernobyl, where there was a nuclear reactor meltdown, there are no residents living today (or … nuclear-physics radiation biophysics isotope   asked by user14154 50 votes answered by Jim 31 votes What is a good introductory book on quantum mechanics? I'm really interested in quantum theory and would like to learn all that I can about it. I've followed a few tutorials and read a few books but none satisfied me completely. I'm looking for … quantum-mechanics resource-recommendations   asked by PhaDaPhunk 19 votes answered by Man 25 votes Can you answer these? Does tunneling transmission probability depend on the density of states or velocity? In some quantum text books [1], the tunneling transmission formula depends only on the density of states of 2 regions (DOS) involved in tunneling. ($T(E) = C \times DOS_1(E) \times DOS_2(E)$, where C … quantum-mechanics quantum-field-theory velocity density tunneling   asked by Hesam 4 votes If you toss a handful of confetti onto a comb, why does some of it stick and some of it fly away? My guess is some paper pieces happen to be charged with the opposite charge compared to the comb, so they are attracted, but once they touch the comb, their charge is neutralized. But the comb is … electricity induction   asked by Antonio Bonifati 2 votes Do doomsday arguments influence doomsday hypotheses? The doomsday argument supposes that in the absence of any other knowledge, if we know the age of something now, we may assume that we are seeing it in the middle of its lifetime and then calculate our … orbital-motion simulation units probability   asked by user121330 3 votes

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