How does a pinhole aperture convert incoherent monochromatic light into coherent light?
How coherent light is created for single slit experiment?
Does higher education exist in Harry Potter? Running Windows 7  I'm trying to boost the startup speed of my computer and I'm going through "msconfig" and "services.msc" to disable some applications from starting up automatically when the computer turns on.  There are some good sites that document the entries found in the "Processes" tab of the task manager.  You can find out if they are safe to kill, who the manufacturer is, and what the process in question is used  for.  Are there any sites that list startup processes &amp;| services that are safe to kill?  For example, there is an entry in msconfig that just says "Computer Browser" - pretty vague, but seems like something to not kill.  On the other hand, there is an entry in msconfig that says "Extensible Authentication Protocol" - pretty specific and seems like it shouldn't be killed, but how can I know for sure?  Does anyone know if there are any websites documenting the "killable" items listed in both msconfig &amp; services.msc? Compute the moment generating function of $Y = X_1X_2 + X_1X_3 + X_2X_3$ It is becoming more common for people to explicitly state the pronouns to be used in addressing themselves: he/him, she/her, or they/them. For example, a name tag for a conference might read:  Cory Lopez Some Company She/Her   Usage seems to have settled on the singular they and them as gender neutral pronouns. Alternatives that were once widespread in niche communities, such as sie/hir, seem to have died out.   Whether or not one agrees with this language  shift, the pairing between subject and object case is fixed.  It's difficult to imagine someone who uses "he" as his subject case using anything but "him" as object case, and it's even harder to imagine that such a person would succeed in getting people to use a non-obvious collection of personal pronouns. (And you may see what I did -- flat out assumed that "he" and "his" automatically go together.)  What are the roots of the practice of presenting subject and object case pronouns as opposed to just subject case, subject and possessive, or some other combination?   (Note: I am not interested in a discussion of the gender politics and cultural shifts involved, just the mechanics of how the current representation was chosen.) I heard that there was a twitter bot which automatically posted questions and asked for answers for specific questions on every site. How do they work? Is there an algorithm for doing this or is it purely random? I know that it doesn't tweet closed questions, but that's it. How can I use GDAL to batch define a projection? This is a  about Active Directory domain naming.   After experimenting with Windows domains and domain controllers in a virtual environment, I've realized that having an active directory domain named identically to a DNS domain is bad idea (Meaning that having example.com as an Active Directory name is no good when we have the example.com domain name registered for use as our website).   , but I'm still not sure about what other rules there are around naming Active Directory domains.  Are there any best practices on what an Active Directory name should or shouldn't be? Was there any reason why Dr Soong chose for Data's eyes to be yellow?  I can understand that he wasn't going for a completely human-looking android based on his skin color, but why yellow eyes? markdown doesn't work properly What does a "real" quantum computer need for cryptanalysis and/or cryptographic attack purposes? The cryptographic world has been buzzing the word "quantum" for a while now (even the NSA is currently preparing itself for a post-quantum crypto world) and quantum-related hardware engineering is evolving constantly. For example: the 5-qubit quantum computer created at MIT by using the technique of ion traps succeeded in prime-factorizing 15. Does that mean that since it succesfully managed that, that it is a all-purpose quantum computer which could be used for cryptanalysis and/or cryptographic attacks?   If that's not the case, what exactly would a "real" quantum computer need (think: rough description of expected technical abilities, aka specs) to enable its users to use it for cryptanalysis and/or cryptographic attack purposes? And - ignoring rumours about potentially existing but confidential governmental projects - does any such system already exist today? Help with proving that $\pi$ is irrational Having some trouble proving this:     If $f:\mathbb{R}\rightarrow \mathbb{R}$ is differentiable and $\lim_{x\to \infty } f^\prime(x)=0$ show: $\lim _{x\to \infty } (f(x+1)-f(x))=0$   Attempt: from $\int \lim _{x\rightarrow \infty } f^\prime(x) \mathrm{d}x=0$ we can say that $f^\prime(x)=const$ would we then have to show that  $\lim _{x\to \infty } (f(x+1))$ is also a constant? From there if we show that both are equal then the difference is zero. I am on the right track?  Thank you for the help. How to illuminate the darkness inside glass objects in Cycles? My model has a clear plastic (or glass) dome with objects inside.  The objects appear dark.  I've tried the glass shader with color 100% RGB, with very small IOR, and using just a refraction shader.    I know Cycles has problems with caustics, but I just want broad illumination to fall clean through the glass.  The light-to-column path can ignore refraction, but is blocked or tremendously attenuated. The camera-column path needs refraction, and seems to work fine anyway.  This demo image offers all optical paths of interest:   light upon object, seen directly light upon object, seen through glass (looks okay) light through glass onto object, seen directly. This is the shadow on the lit side of the column just below the glass tubing.  I expect full illumination, but there is shadow.  There is some light, but it's diffuse light from the floor. light through glass onto object, seen through glass. This     I did at one point try non-progressive rendering, and find extremely coarse light where there shouldn't be shadow, but this is not a practical way to make nice images. I've even tried cranking up certain sampling settings to many thousands, but still get bad noise though less, at the cost of long render times. I  would like to finish my creations sometime before "Star Trek, the Generation After the Next" becomes real life, if you know what I mean.  The next image is an example. I think Transmission in Sampling was 5000, but not sure.    I'm using Cycles in Blender 2.67 on a quad core Linux machine, 16GB RAM. Machine limits have never been a problem for 3D rendering.  Possibly, I screwed up some setting when I made my startup file, and just need to fix it. OTOH maybe this is just a limitation of path tracing, or of the way Cycles does it. If that's the case, what to real-world Blender artists do when they need to produce images on a budget and schedule?  What is the practical real-world fix? This particular version of the "doesn't work after suspend" came after upgrading to 16.04. It seems that the upgrade includes a Wicd applet (added to Metacity Classic Gnome task bar alongside regular network icon), but doesn't seem to work after a suspend. A sudo service network-manager restart duplicates this problem. It takes a complete reboot to get Wifi going again. Any ideas why? Composition of two Riemann integrable functions How to mitigate the Spectre and Meltdown vulnerabilities on Linux systems? Prove $\operatorname{rank}A^TA=\operatorname{rank}A$ for any $A\in M_{m \times n}$ How do I remove the LAMP stack so I can start over? I'd like to start over with my webserver and I'd like to reinstall all the LAMP packages, how do I do that? I need to upload my signature in a PDF document, but I do not know how to edit the background of this image.   I wish to remove the bluish-tint background, and make it pure white.   Can anyone help me with this, please? If Eren Jaeger dies without transfering his titan powers, will both powers transfer to the same child? It's told in the story that if a titan shifter dies without transferring his power, this power will go to an eldian person who just was born. If Eren Jaeger dies without transferring his titan powers, will the attack titan and the founding titan go to different persons?  Note that his is not a duplicate of  as this is not about what happens when a titan shifter dies. But what happens if a titan shifter with 2 powers dies, which is not answered in the answer.