There's more gravitational force in our galaxy (and others) than can be explained by counting stars. So why not lots of dark planetery systems (ie without stars) ? Why must we assume some undiscovered ...
Why is there something rather than nothing? And before you answer "God did it," consider Carl Sagan's reply "then how did God come about?"
I beg your pardon in advance if this question is naive. In Quantum Mechanics, discrete values of measurements occur only in relation to bound states. This is because of the general solution for the ...
Don't worry... I won't actually do it, just would like to know how.
Interstellar space is pretty empty but there a small number of of atoms (mostly hydrogen?) floating around. How many atoms per light year would a photon encounter while traversing interstellar space?
I have a question about cosmology. At popular level people explain the time of decoupling of matter and radiation as the moment when temperature falls enough for nuclei and electrons to recombine into ...
The current "standard model" or concordance model of cosmology is Lambda CDM which includes late time acceleration due to a cosmological constant, cold dark matter as the missing matter component and ...