I have watched . The idea is that gravity pulling it is just lots of mass bending space-time, and natural direction of movement becomes moving towards the mass, and since we have earth already there we get to sit on top.  This got me thinking what about lack of matter to bend space-time, could it be that space-time bends in the 'opposite' 'direction' like create a slope where everything's natural movement direction is away. Could this be used to explain dark energy's anti-gravity properties?   EDIT: Duplicate is about dark matter while this one is about dark energy that are two completely different things...
Could Dark Matter actually just be spacetime with curvature "leftovers" from the big bang or the inflationary epoch?
How can I make environment variables "exported" in a shell script stick around? adb device doesn't listed on cmd {Lenovo K8 Plus} I am trying to root my Lenovo K8 Plus after unlocking bootloader. I try to install TWRP and somehow the TWRP recovery doesn't open and the phone is struck in the bootloop. I then fastboot the device and connect to PC and open minimal fastboot cmd. The phone wasn't listed in adb device, but listed in fastboot devices. I think usb debugging is not turned on because the system doesn't restart (maybe there is no ROM). What should I do? What is the correlation if the standard deviation of one variable is 0? Invariance of a maximally entangled state under unitary operation $U \otimes U^\dagger$ Apparently the (d-dimensional) maximally entangled state, $|E \rangle = \sum_{i} |ii\rangle /\sqrt{d}$ is invariant under operations of the form $U \otimes U^\dagger$. I want to prove this result, which amounts to showing that  $$\left(\sum_i U | i \rangle \otimes V |i \rangle = \sum_i | ii \rangle \right)\Rightarrow (V = U^\dagger )$$  I have no idea how to even start. I suppose it's some simple linear algebra result, but I don't see it. A hint would be appreciated. I need to pass an ID and a password to a batch file at the time of running rather than hardcoding them into the file.  Here's what the command line looks like:  test.cmd admin P@55w0rd &gt; test-log.txt I would like to enable the root account on my Ubuntu installation.  I realize the security implications of this. Do we need inertial frames in Lagrangian mechanics? Windows 7 / 8 tool for amplifying sound / equivalent to pavucontrol? I'm watching live streamed videos, but the volume sometimes is barely loud enough.  With Windows, I can only turn the system volume and the flash volume up to maximum, and then bad luck if that's still not loud enough.  On Linux, on the same notebook, I have the same problem, but I can use pavucontrol (pulseaudio volume control) to amplify the sound volume beyond 100%.  Unfortunately, I can't always work on Linux, since Visual Studio and SQL-Server only run on Windows.  Is there any tool or way to amplify volume on Windows 7 / 8 , without having to resort to run Linux in a virtual machine? How does Motherboard and CPU affect RAM choice? Best way to reward an exceptionally good answer Have you ever gotten an answer soooo good, you wished you could give a +20 instead of +1 ?  Bounty System  That's a good mechanism, but they're not always right for this situation:   Bounties are usually associated with giving incentive to answer or draw traffic. I would expect that most users offered bounties before getting an answer, not after. Bounties are usually offered by people with plenty of reputation. "New" users should be able to reward exceptional answers too.   Thanking in a comment  A warm comment on the answer is always nice, but I'm not sure comments are intended for saying thanks - but to clarify / improve the answer itself.  So what is the recommended way to reward this truly exceptional answer?  Other suggestions?  I know there is an answer of the week blog, is there a way to nominate an answer to be there? Sometimes exceptional answers are hidden in low-interest questions that receive less traffic - so those will never be upvoted enough to become noticed.  Or maybe instead of a single blog for the entirety of SO, there should be an entire section called "Answer of the week" with more than one answer (maybe on a per-tag basis). Answers should arrive there based on manual nominations and not on upvotes so unpopular questions will not be discriminated against.  Clarification:  It's not that I'm personally against bounties - I use them plenty of times. I'm mostly concerned about what other people tend to do. I suspect the bounty post-answer reward is not used as much as it should. I believe the majority of people don't consider bounties for this purpose. Assume $0 &lt; a_0 \leq a_1 \leq \cdots \leq a_n$, show that equation   $$ p_n(z) = a_0 z^n + a_1 z^{n-1} + \cdots + a_{n-1} z + a_n = 0 $$   does not have root in $|z| &lt; 1$. Here $z$ is complex.   I started by considering the case in which $n = 2$, and tried to use the triangle inequality, while no progress was made. Any hints will be appreciated. What is the isomorphism between the fields $(Z_2[x]^{<3},+_{x^3+x^2+1},\times_{x^3+x^2+1})$ and $(Z_2[x]^{<3},+_{x^3+x+1},\times_{x^3+x+1})$? Tourist Visa (30 days) Dubai valid until date Today I was informed by VFS that my tourist visa for UAE got approved. I'm travelling to UAE on 16th December 2014 and returning on 7th Jan 2015. But when I checked the "valid until" date on the visa it states 30 December 2014.    Does this date mean I should return before December 30th? Should I get it corrected from VFS? How do I fix "The expression of type List needs unchecked conversion...'? In the Java snippet:  SyndFeedInput fr = new SyndFeedInput(); SyndFeed sf = fr.build(new XmlReader(myInputStream)); List&lt;SyndEntry&gt; entries = sf.getEntries();   the last line generates the warning   "The expression of type List needs unchecked conversion to conform to List&lt;SyndEntry&gt;"  What's an appropriate way to fix this? Finding an isomorphic subring of matrices I'm struggling a fair amount with this exercise:     Find a subring of $M(2,\mathbb{Q})$ which is isomorphic to a) $\mathbb{Q}$ x $ \mathbb{Q}$ b) $\mathbb{Q}$ c) $\mathbb{Q}[x]$/$x^2$   Now I know a subring must be a subgroup, must contain the elements $0,1$ and must be closed under multiplication. As we are looking for isomorphisms then they must also be ring homomorphisms and must be bijective.  I tried to come up with a random subring and attempt to prove it is an isomorphism. E.g $\left\{\left.\begin{matrix}  a &amp; b \\ c &amp; 0  \end{matrix}\right|a,b,c \in \mathbb{Q}\right\}$ is a subgroup of $M(2,\mathbb{Q})$ and then try and show it's an isomorphism. However I'm stuck here as I don't actually know how to go about finding these specific isomorphisms and I completely lose what I'm doing. Any help would be great. Proving that a function has a removable singularity at infinity What gear do I need for a newborn photography session? I am an amateur photographer and I have a newborn session coming up for a family friend.   My current gear is:   Canon T5i (crop sensor) Canon 18-55 IS STM Kit lens 85mm f/1.8 lens   I plan on buying a reflector for the shoot and will be using natural light as my light source.  So my question is: is this enough gear to get some nice photos? Should I get another prime lens besides the 85mm? I don't really use the kit lens.  I also have another 8 month old baby shoot coming up and an informal wedding shoot coming up so it would be nice to use the lenses in all situations. I don't need a telephoto at the moment and will probably not use one any time soon. How to switch window controls to the left (Gnome Shell)? Is there a way to the switch gnome-shell window buttons to the left? I've gotten so used to them being on the left that them being on the right has thrown me way off.  (gnome shell has them defaulted to the right corner) How can I replace spaces with new lines on an input like:  /path/to/file /path/to/file2 /path/to/file3 /path/to/file4 /path/to/file5 etc...  To obtain the following:  /path/to/file /path/to/file2 /path/to/file3 /path/to/file4 /path/to/file5   Note  I'm posting this question to help other users, it was not easy to find a useful answer on UNIX SE until I started to type this question. After that I found the following:  Related question No group of order 200 is simple Show that any group of order 200 is not a simple group.   I have started with the sylow 5-subgroup, but the sylow 2 subgroups i found that they are 25 subgroup but i couldnt proceed in the proof any more! Please help.