According to what I've learned from physics professors, no object can go faster than the speed of light. So if you have object A moving .8c one way and object B moving .8c the opposite way...relative to each other that is 1.6c? How do they appear to each other (or to a third stationary point in the middle in communication with each side)
Let's say we have $2$ particles facing each other and each traveling (almost) at speed of light.    Let's say I'm sitting on #$1$ particle so in my point of view #$2$ particle's speed is (almost) $c+c=2c$, double light speed? Please say why I am incorrect :)    EDIT: About sitting me is just example, so in point of view of #1 particle, the second one moves at (almost) $c+c=2c$ speed?
Changing CSS Values with Javascript Is it costly to do array.length or list.count in a loop I know that in JavaScript, creating a for loop like this: for(int i = 0; i &lt; arr.length; i++) is costly as it computes the array length each time. Is this behavior costly in c# for lists and arrays as well. Or at compile-time is it optimized?  Also what about other languages such as Java, how is this handled? How to remove illegal characters from path and filenames? Elegant way of obtaining the envelope of oscillating function Redirect to SSL only if browser supports SNI There was recently another release of , but it is  a pain to have to manually go to their website and download the packages every time there is a new release. Is there a PPA that always has the latest version of LibreOffice? Is there a fast way (without looping over all edges/faces/verts) using ops.mesh or bmesh to get the lists of indices associated with mesh islands as shown below? These islands are part of one mesh but are disjoint from each other.    I know how to select the boundaries by running the operator Select boundary Loop or calling bpy.ops.mesh.region_to_loop() but can't find any API calls to return the vert/edge/face indices associated with the individual islands. The keyboard I am trying to create has a lot of Unicode and looks like this:   Being unsuccessful with the following tutorial:    (There are a few errors in the tutorial, and it uses imprecise language such as "Cutting" things instead of "Deleting" them, and it is formatted strangely)   I was wondering if anybody would be so kind to provide a better tutorial with step by step instructions? I posted a question recently regarding my Windows 10 upgrade which ended up with a black screen and cursor.   I reverted back to Windows 8.1 using the "Revert to previous build" option in recovery, and all seems fine, except that Virtualisation is disabled.  I tried to open BIOS settings but it just boots into Windows. I've tried the usual F2 key and Shift F2, all the other F keys, tried pressing B and Shift+B but no luck.  I tried pressing the Lenovo key on the laptop when it is powered down, which shows a menu to either boot into BIOS, recovery, or show boot menu. I choose BIOS and it just boots into Windows.  I tried going into advanced startup options from Windows (Shift+Restart) and choosing "UEFI FIRMWARE SETTINGS" but it just reboots back into Windows.  Before the Windows 10 upgrade it was working perfectly.  Lenovo G580 laptop - Core i3 with Intel 4000 graphics. 8GB of RAM and a Crucial MX100 512GB SSD (replaced the original hard drive with this SSD). Why $f(x) = \sqrt{x}$ is a function? Why do you need to know who I know on Google? I just created a SE account using my Google account. It said that it needs to "Know who you are on Google" (I guess my connections). As far as I know, SE is not a social network. I can't even follow other people (seeing when they post questions and answers).  What is the reason you need to know my Google connections?  This was on code review. Actually I have an account there, but for some reason it asked me to reconnect. This is the same on MSO; one sees this explained as "This app is requesting permission to associate you with your public Google profile": Are there some good overviews of basic facts about images and inverse images of sets under functions? How to find $ \int_0^\infty \dfrac x{1+e^x}\ dx$ Simulating draws from a Uniform Distribution using draws from a Normal Distribution I recently purchased a  in which one of the probability questions was as follows:     Given draws from a normal distribution with known parameters, how can you simulate draws from a uniform distribution?   My original thought process was that, for a discrete random variable, we could break the normal distribution into K unique subsections where each subsection has an equal area under the normal curve. Then we could determine which of K values the variable takes by recognizing which area of the normal curve the variable ends up falling into.   But this would only work for discrete random variables. I did some research into how we might do the same for continuous random variables, but unfortunately I could only find techniques like inverse transform sampling that would use as input a uniform random variable, and could output random variables from some other distribution. I was thinking that perhaps we could do this process in reverse to get uniform random variables?  I also thought about possibly using the Normal random variables as inputs into a linear congruential generator, but I'm not sure if this would work.  Any thoughts on how I might approach this question? Was the "Eye of Sauron" Sauron's actual physical form? During the time frame of the Lord of the Rings, was the Eye of Sauron Sauron's actual physical form? If not, what form did he have? Trigonometric fraction Inequality question I have researched and found out long time no see is a direct translate from the Chinese phrase, 好久不见. As much as we use it almost everyday in our lives, is it actually grammatically correct? Since it is a direct translate, is it grammatically approved? The comment pop-up is too far away When you click the add a comment button when you don't have enough rep, you get a pop-up saying that you need more rep in able to comment. Except, it is too far away and users might be confused for a while before realizing the pop-up is on the other side of the page:     Clearly, that is very inconvenient for a lot of people, like me. Can we move the pop-up to be right next to the add a comment button? "In a while" vs. "for a while" Do the same camera settings lead to the same exposure across different sensor sizes? Let's say I have a micro-4/3rd camera and a full frame camera, both set to 1/60 at f/2.8, taking a picture of the same scene in the same lighting. Will the exposure be the same across both cameras despite the different sensor sizes?  The reason why I'm asking is because of the difference in depth of field between micro-4/3 and full frame sensors. I'm finding that, in order to take a picture of certain scenes with the full frame camera at the same depth of field as the micro-4/3rd camera, I have to increase the aperture, which in turn forces me to crank up the ISO.