The typical way that I've seen Einstein's gravity expressed is by taking some spherical object, placing it into some sort of low-resistance space (like a very relaxed trampoline), and noting how it creates a funnel-like shape. Then, one proceeds to take an additional ball and spin it around the central object, thus explaining the concept of a planet's orbit. In the trampoline example, the central object cannot completely collapse through the material. In space, however, I'm not sure that there would be any reason that the sun shouldn't continually &quot;fall.&quot; There's nothing holding it up. I'm sure that there is a scientific explanation for it (perhaps the black hole at the center of our galaxy is creating a funnel in space that the Sun is riding), but since I'm uneducated, I do not know it. So, is the Sun continually falling or is it static? What processes explain it?
Whenever I read about the curvature of spacetime as an explanation for gravity, I see pictures of a sheet (spacetime) with various masses indenting the sheet to form &quot;gravity wells.&quot; Objects which are gravitationally attracted are said to roll down the curved sheet of spacetime into the gravity well. This is troubling to me, because, in order for objects on the locally slanted spacetime sheet to accelerate, gravity must be assumed. Therefore I ask; does the explanation of gravity as the curvature of spacetime assume gravity? If yes, what is the point of the theory? If No, what am I missing?
Why is OpenJDK 10 packaged as openjdk-11-*? While looking to compile OpenJDK from source, the newest General Availability version () insists on OpenJDK 9 or 10.  JDK 11, however, is not due to be released until .    However, to my surprise, when I do apt search openjdk the result is:  ... openjdk-11-jdk - OpenJDK Development Kit (JDK) ... openjdk-8-jdk - OpenJDK Development Kit (JDK) ...   No OpenJDK 9 or 10!  And wait, is that OpenJDK 11?  Maybe a Beta release?  Nooo....  So I looked at apt show openjdk-11-jdk:  Package: openjdk-11-jdk Version: 10.0.1+10-3ubuntu1 ...   Why has OpenJDK 10 been packaged as openjdk-11-*?? How to animate text over a twisted mesh (or text flowing along an infinity loop) Which site is more reasonable for questions about R, SO or stats.stackexchange.com? I've been using SO for a little over a year now, and recently I've noticed a shift of users between SO and stats.stackexchange.com.   I'm wondering if there has been any discussion on where questions about R, a statistical environment, best fits. Would you say it's better to ask R questions on SO or would it be better to ask over at stats.stackexchange.com? What, if any, determinants would you use to decide to post between the two? What about cross posting? How to sort a list of objects based on an attribute of the objects? I want to burn a Windows ISO to a USB device in Ubuntu. How do I do this?   I know how to burn a Ubuntu ISO into a USB device, but with a Windows ISO it's not the same. When is a function too long? Does the new guidance on duplicate questions suggest closing a question as duplicate, if the original answers the OP's question? In other words, should we now look at the content of the answers when we are evaluating questions for possible duplication?  Is it sufficient to say "Your answer can be found in this question over here, therefore your question is a duplicate?"  The new guidance is here:    Among other things, it describes the new close banner:     This question already has an answer here:   Link to the Duplicate Question   ... which seems to suggest that, if some other question in the system answers the OP's question, then the OP's question can be closed as a duplicate on that basis (even if the question itself is not necessarily duplicated).  Example Here:    Note the comments below the question, where I dispute the assertion made there that it is a duplicate question.  The original question doesn't mention unit testing. So I have a torus, and I need it to "telescope" open -- kind of like Pacman's death animation, but with a torus instead of a sphere.  I'm very new to 3D modeling/animating so I really have no clue how to tackle this problem.  Any advice to help me get pointed in the right direction would be most appreciated :) $\Bbb{Z}_{26} \rtimes_{\alpha} \Bbb{Z}_{5} \cong \Bbb{Z}_{26} \times \Bbb{Z}_{5}$ as groups. Why does this double arithmetic give two different answers on a single machine? Is this series known to converge, and if so, what does it converge to (if known)?  Where $p_n$ is prime number $n$, and $p_1 = 2$,  $$\sum\limits_{n=1}^\infty \frac{1}{p_n}$$ Showing a compact metric space has a countable dense subset I want to click on file to inherit the name for the file being saved. I can't read file names in the dialog box because the color is too faint. This is the same question as   That question does not have an answer but I don't have enough points to interact there so I have to post a new question.    Edited to add screen shots I tried to calibrate the monitor which no effect and did not change the readability of "unavailable" file names. I have added screenshots of previous operating systems to compare: Please tell me how Mojave is not to blame here: Why does ( exit 1 ) not exit the script? Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$ A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called even if $f(-x) = f(x)$ $ \forall x \in \mathbb{R}  $   A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called odd if $f(-x) = -f(x)$ $ \forall x \in \mathbb{R}  $   Let $U_{e}$ denote the set of real-valued even functions on $\mathbb{R}$ and let $U_{o}$ denote the set of real valued odd functions on $\mathbb{R}$.   Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$   This question from Q24 of "Linear Algebra Done Right" 3rd Edition - Chp 1.4 (Subspaces). The author of the book does minimal work with functions during the chapter. I have no idea how to approach the question. There are two 9-digit numbers on the back of the Global Entry card. The one on the upper left corner is the Known Traveler Number or PASSID. But on the upper right hand corner there is another 9-digit number, slightly larger than the PASSID. What is the purpose of this second 9-digit number? How to develop RPG Damage Formulas? No association bonus for Area51? My Area51 account crossed 200 rep today, but still other accounts don't reflect the change in reputation. When will the changes be applied? or is there no association bonus for Area51 account? I've always been one to simply use:  List&lt;String&gt; names = new ArrayList&lt;&gt;();   I use the interface as the type name for portability, so that when I ask questions such as these I can rework my code.    When should  be used over  and vice-versa? Converting point layer to raster grid that shows frequency of points per cell uisng QGIS I have a point layer that shows the distribution of a species.   Is it possible in QGIS to convert this point layer to a raster grid in which the value of each cell corresponds with the amount of points within that cell?   Until now, I only managed to attach attribute values to the grid cells. I have already added a column in my attribute table that has the value '1' for each point, hoping that there is a way to use a sum of attributes for each grid cell.