# Search results

1. ### Looking for good introduction to coherence/decoherence

Hi all, does anyone here have a good internet source that explains coherence and decoherence in layman's terms? My intro modern physics class left off at the beginning of schrodingers wave function due to time constraints and I am trying to teach myself a bit of the stuff we missed. Thanks =)...
2. ### Radiowaves bouncing off of ionosphere

What is about the minimum wavelength that can bounce off of the ionosphere?
3. ### Schrodinger eqn and 1/2 spin

Hi all, In class Ive recently been taught the schrodinger equation and about spin(couple weeks apart). My questions are- 1. In laymans terms, what exactly does the S-eqn mean? What I have taken it to be so far, is an equation that determines the probability of the position of an e- in "orbit"...
4. ### Relativistic speeds going perpendicular

Couldnt find anything from 15min of forum searching... If 2 objects are travelling along say, an x and y axis(or just 90 degrees apart really) at close to c, how do they interpret each others speeds? 0<theta<90 are easy enough. Couldnt find anything about perpendicular though. A newtonian...
5. ### Lorentz contraction

Hi all, modern physics student here. If the Lorentz contraction occurs at relativistic speeds, how does it gain mass yet get shorter? The best I can think of is that it has to depend in which reference frame one is in at the time. Does anyone know any useful links where I can read about this?
6. ### Analemma: Earth vs Mars

How come the analemma for Earth is in a "figure 8" form and Mars is circular? Does it have to do with radial velocity?
7. ### Automated control

Here is a link to Cal Polys ACS they built. My question is: they claim each reaction wheel is angled at 29.3 degrees. Why would that be? My only guess is that they are each pointed at the CoM.
8. ### Plasma on space shuttle

How exactly is plasma generated when space vehicles reenter earth's atmosphere? How do the ions show up? I get how the air drag creates the initial heat, but from there I do not know. Have been searching the net for about 30min and came up with nada.
9. ### No dark matter after all?

I read an article explaining how all the stars in the milky way revolve around the galactic center at the same velocity, which is obviously different than the way the planets in this solar system revolve around the sun. They say this is because the C.O.M. isnt located in the galactic center, but...