If we move in the universe with about 1500 km/s (earth with 30 km/s + sun with 230 km/s in the milky way + milky way....) why there is no Doppler effect on my WiFi when i change the position in the direction and opposite direction of earth direction of travel? And also does the signal arrives faster or respectively slower with 1500 km/s when i change the position in the direction and opposite direction of earth direction of travel?
The title says it all.  If I was on a bus at 60 km/h, and I started walking on the bus at a steady pace of 5 km/h, then I'd technically be moving at 65 km/h, right?  So my son posed me an interesting question today: since light travels as fast as anything can go, what if I shined light when moving in a car?  How should I answer his question?
Specific derivatives have specific names. First order is often called tangency/velocity, second order is curvature/acceleration. I've also come across words like Jerk, Yank, Jounce, Jolt, Surge and Lurch for 3rd and 4th order derivatives. Is there a widely agreed list of names for these? How many orders have specific names?  In this case, I'm dealing with NURBs curves, so the "tangency" and "curvature" related words are to be preferred over "velocity" and "acceleration" words. Is a closed subset of a compact set (which is a subset of a metric space $M$) compact? Is there a way to prove this using sequential compactness instead of open cover definitions?  My first gut reaction was that the fact was obvious since we can show that the closed subset $[a,b]$ is compact in $\mathbb R$. Product of quotient maps and quotient space that is not Hausdorff I am looking for easy(!) counterexamples that the product of two quotient maps is not necessarily a quotient map and that the quotient space of a Hausdorff space is not necessarily Hausdorff. Opening PDF generated by Python AddIn using Report (*.rlf) file automatcally? As a test I have:   Authored a test.mxd with one layer called Localities in a single data frame called Layers Authored a test.rlf using View | Reports > Create Report of ArcGIS 10.2.2 for Desktop Created a Python AddIn which creates the expected PDF file from the Report (*.rlf).   This is the code which all works to create the PDF report from the Localities features within the current extent:  import arcpy  import pythonaddins  class ReportForExtent(object):     def __init__(self):         self.enabled = True         self.checked = False      def onClick(self):         mxd = arcpy.mapping.MapDocument("CURRENT")         df = arcpy.mapping.ListDataFrames(mxd,"Layers")[0]         lyr = arcpy.mapping.ListLayers(mxd,"Localities",df)[0]         arcpy.mapping.ExportReport(lyr,r"C:\temp\test.rlf",r"C:\temp\test.pdf","EXTENT",extent=df.extent)         del mxd   Is there a way to have the Python AddIn not just create the PDF file but also open it in Adobe Acrobat Reader? How to add USB 3.0 port to your laptop Find the coefficient of the term $x^2$ in $\left(x+\frac 2x\right)^{4}$ Find the coefficient of the term $x^2$ in $$\left(x+\frac 2x\right)^{4}$$   This is what I have done so far.  We know $a$ = $x$ and $b$ = $\frac2x$ and $n$ = 4  So what I have done is $4c2$ x $(x)^2$ x ($\frac2x$)$^2$  As we know that $^2$ + $^2$ = 4, and 4 is the $n$ value.  The answer is one though?  What have I done wrong?   P.S.  was the tutorial that helped me. What would happen if I used regeneration on a creature that was the target of Annihilating Fire? For example, what would happen if a freshly cast  were to be regenerated in response to ?  My hypothesis is that it depends on whose turn it is. The regeneration being essentially a replacement effect, when two replacement effects were to be applied simultaneously, they are to be chosen in APNAP order. Is this correct?  I haven't thought this through to the end, though, so I'm not sure what would happen in the end. How to convert a factor to integer\numeric without loss of information? I am looking for a way to identify primitives types in a template class definition.  I mean, having this class :  template&lt;class T&gt; class A{ void doWork(){    if(T isPrimitiveType())      doSomething();    else      doSomethingElse();  } private: T *t;  };   Is there is any way to "implement" isPrimitiveType(). Let $\mathbb S = \varnothing$.      Then from the definition: $ \bigcap \mathbb S = \left\{{x: \forall X \in \mathbb S: x \in X}\right\}$      Consider any $x \in \mathbb U$.      Then as $\mathbb S = \varnothing$, it follows that: $\forall X \in \mathbb S: x \in X$ from the definition of vacuous truth.      It follows directly that: $\bigcap \mathbb S = \left\{{x: x \in \mathbb U}\right\}$      That is: $\bigcap \mathbb S = \mathbb U$. ()   Proofwiki uses the above "proof" to "prove" that intersection of the empty set is the whole universe.   My question is, is the use of vacuous truth really allowed in axiomatic set theory, like ZFC? I don't see how the use of vacuous truth is justified.   The next problem I can think of is that we cannot really "define" the elements of empty set (to my knowledge, there is no element in empty set) so how can we then prove as the above proof did? This seems to contradict the use of vacuous truth.  And of course, there is issue of using the whole universe as a set, and I don't think this is allowed.... (Maybe proof above is using a different axiomatic set theory, as I am using ZF-minded thoughts...) Prove that $\gcd(a^n - 1, a^m - 1) = a^{\gcd(n, m)} - 1$ As a bulk sender, is there a way to make Gmail show my avatar?    I would like to obtain this without creating a Google Account.  Maybe embedding my vCard? Or maybe ? How can energy be useful when it is 'abstract'? Can a continuous real function take each value exactly 3 times? Cartoon with a young unicorn and a demon In the late 80s or early 90s I remember watching an animated series that followed a young unicorn and a demon.   In one episode the unicorn gave the demon his horn, and the unicorn almost died.   In another episode there was a man who was able to turn people into human shaped building blocks and built a huge tower from them.   Those are the two scenes I remember with any clarity.   Does anyone have any idea? When we lie down, the "back part of the body" is in contact with the bed. It includes the heels, the calves, the backside, the back, and the back of the neck, and the back of the head etc.  How do we refer to the entire "back part" of the body? the problem of using "~\\" and blank line Recently,I found the code that cotains the"~\\" and blank line always shows the warning imformation "Underfull \hbox (badness 10000) in paragraph at lines"  \documentclass{ctexart} \usepackage{color} \usepackage{amsmath} \usepackage{amssymb} \usepackage{graphicx} \usepackage{epstopdf} \hfuzz=\maxdimen   $(A \pm  B)^{-1} \neq A^{-1} \pm B^{-1}$,$(A \pm  B)^* \neq A^* \pm B^*$~\\  $|(A^*)^*|=|A|^{n^2-2 n+1}$~\\  \end {document}   I add the code:  \tolerance=10000 \hbadness=10000 \begin{document}   However,fail to solve it! Unit testing code which has logic around the CreatedDate An example of the problem would be trying to test a trigger on a case which will fire on update, and look for time differences between when a case was created and now. Ideally in the unit tests I want to create a case with a CreatedDate in the past. The problem here is that CreatedDate is an audit field and not writeable[1]. Is there a standard work around to this problem?  [1] I know you can get audit fields turned on to be writeable temporarily when doing data migration. This is not a viable solution for every time you want to get your code coverage up for deployment. Inline suggested edit reviews are truncated in medium-width windows When reviewing a suggested edit inline (not from the queue) on a site with the new “responsive” design, at a window width where normal content does fit, the diff window is truncated on both sides, as is the edit window after cliking “Improve Edit” or “Reject and Edit”.    This is from  which happened to have a pending suggested edit at the time, after clicking the edit(1) button. Note how the scroll bar is all the way to the left, but there's content that vanishes to the left of the window. That's in Chrome 67.0.3396.87 on Linux at zoom level 100%, with a window width of 800.  Note that I'm not complaining that the user interface isn't responsive yet (although now that this has been deployed to SO I'd expect it to be), but that the interface is completely unusable even with scrolling. In sites with the old UI, you can see all the content even if it requires scrolling.  Reviews done from the suggested edit review queue are ok (not responsive, but you can see the content by scrolling). Inline edits are ok. The problem is specific to inline suggested edit reviews. Dell Latitude E7270