Speed of Light As a Maximum Speed Limit I know the speed of light problem has been beaten do death by hundreds of questions and answers, but I wanted to explore a new possibility and perhaps show an indication that light-speed as a constant is a man-made theoretical limit.  Would you please tell me if my musings are incorrect?  Now onto the subject at hand.   Suppose somewhere in the universe there are about 5000 different celestial bodies in a gargantuan solar system, each spread out the distance between the earth and the moon, each weighing approximately the size of 1 earth.   If by certain miracle, the orbits of those celestial bodies (planetoid objects) are arranged as such that 1) they are on the same plane, and b) all bodies line up almost perfectly with one another (at the time of the experiment).   It follows that if we launch a space vehicle, say a shuttle, and use gravity assist around those celestial bodies, we could theoretically increase the speed of that vehicle (provided that it doesn't rip itself apart from the inertia) 5000 times. As we have already achieved speeds of 150,000 mph using gravity assist in the past - wouldn't it follow that doing this 5000 times in sequence would eventually break the light speed barrier?
Will free-fall object into black hole exceed speed of light $c$ before hitting black hole surface? In Newtonian mechanics, if we throw an object in against direction of gravity with speed $v$ and it achieve max height of $h$. Now if we allow object to fall from that height $h$, it will eventually attain speed $v$ when it reach position where we launch it.   Now applying same idea to a black hole in general relativity. Speed require to escape black hole gravity is greater than $c$, so if we throw something into black hole with almost the speed of light, the object speed will exceed speed of light $c$ before hitting black hole surface! How relativity explain this? Can space-time curvature reduce speed of this freely falling object from attaining speed of light?
Beamer - create subsubsection page Story whose final line is "Let there be light!" I read this series around 5-10 years ago. There were two parallel universes, ours and the universe of demons, and much of the series revolved around attacks in which demons created gateways to cross into our universe to kill people and wreak havoc, and had to be stopped by human magicians. Three youngsters (one guy from modern times, one from a few decades ago, and a girl from ancient Celtic times, all with funny names) end up being the key to the war when it's revealed that they are the three components of a mythical superweapon. These three are the only point-of-view characters in the series, each book being told from the PoV of just one of them. At the very end, they   destroy our entire universe so that, after killing all the demon masters, they can rebuild it and make sure everything happens as before up until the very last moment.  As they begin recreating the universe, the current PoV character (the one from modern times) says something like the following, the very last lines of the series. (sic on the quotation marks)  &quot;In the beginning, there was nothing but darkness. Then [name] said, 'Let there be light!'&quot; And there was light. Coolio! Another domain name pointing to my server IP? I was checking out my reverse-DNS entry of my domain the other day which is run from a dedicated server.   I noticed that another person/company had their domain pointing to my server? I have no idea who this company is or why they are pointing their domain at my server IP?  How can I go about stopping this or forcing them to change? How can I make schematic of this board? I want to make a schematic of this board. Can anyone tell me how? Intuition of the meaning of homology groups Display the original question beneath the answer edit form Often when I edit one of my answers, it's because I want to better address the original question. The only problem is that I can't see the original question while I'm editing my answer!  I'd love to see the original question text beneath the "answer edit" form. This way I could scroll down slightly to read it if I wanted to, or just ignore it if not.  Current workaround is to click the 'return to answer' link and hope that you remember to launch it in a new tab/window, then tab back and forth.    Imported from this uservoice item: Reserved words as names or identifiers Is there any tricky way to use Java reserved words as variable, method, class, interface, package, or enum constant names? How do I dynamically create the variable name in a PHP loop? Laptop power supplies, does current matter? I have two laptops (same manufacture), with the same type of power connector.  However, the power supplies/transformers are slightly different.    The output on the first laptop's power supply is 15.6&nbsp;V at 8.0&nbsp;A. The output on the second laptop's power supply is 15.6&nbsp;V at 5&nbsp;A.  Clearly the voltages are the same, but the currents are different. I assume the second laptop's power supply can not be used on the first, because it can't supply enough power to the laptop.   However, can the first laptop's power supply be safely used on the second laptop? How do I programmatically update the allowed values of a list field? I have created a field_time_zone field for the Article content type. I want to set the allowed values for that field to the values returned from system_time_zones(). For this, I implemented hook_form_alter() using the following code. $zones = system_time_zones(); $entityManager = \Drupal::service('entity_field.manager'); $fields = $entityManager-&gt;getFieldStorageDefinitions('node', 'local_market'); $options = options_allowed_values($fields['field_time_zone']);  if(empty($options)) { $options =  $zones; $form['field_time_zone']['widget']['#options'] = $options; }  The code adds the desired values, but the node cannot be saved, as it throws the following error.  The value you selected is not a valid choice.  How can I set the allowed values for a text (list) field? Substitute fresh garlic instead of garlic powder? I have a recipe that calls for garlic powder, but I only have fresh garlic on hand.   What ratio should I use to substitute? Changing sfdc header and footer without creating new VF pages I need to change the header and footer of standard salesforce pages (sfdc pages) with a custom CSS that I have. Now I am not sure if this is a customer portal (it is probably not). I searched and found out it can be done by changing the Self-Service as given in the following link:   However the problem is when I go to Name | Setup | Customize | Self-Service, I do not see the Self-Service Portal - Settings anywhere (as given in the step 1 of the link). Instead there are two options, 1) Public Solutions 2) Web-to-Case.  Basically what I want is to replace the Blue header and footer of the salesforce standard pages with the CSS given to me. The changes will be in actual org.  Any guesses on how to go ahead with this? Am wondering if somewhere there is a list of industry "minimums" for browser support. My company release two "portals" over the past 6 months and did very little to support IE8 users, who at this time, according to my G Analytics makes up about 14% of all IE visitors. Amazingly enough IE7 is 25%...  Figured support for IE7 was out the window already, but figured 14% was significant enough to warrant some support.  Any arguments to support my side of wanting to support IE8?  Any arguments to NOT support IE8? Proving that a normal, abelian subgroup of G is in the center of G if |G/N| and |Aut(N)| are relatively prime. How can I stop being prompted to unlock the 'default' keyring on boot? Whenever Ubuntu boots up, a dialogue pops up asking me to unlock my default keyring. Is there some way this can unlock automatically through PAM or some other magical way? How do I find out which version and derivative of Ubuntu is right for my hardware in terms of minimal system requirements? A Product function for matrix products Why is the complex number $z=a+bi$ equivalent to the matrix form $\left(\begin{smallmatrix}a &-b\\b&a\end{smallmatrix}\right)$ Possible Duplicate:          On Wikipedia, it says that:     Matrix representation of complex numbers   Complex numbers $z=a+ib$ can also be represented by $2\times2$ matrices that have the following form: $$\pmatrix{a&amp;-b\\b&amp;a}$$   I don't understand why they can be represented by these matrices or where these matrices come from. Quick question: what is the compiler flag to allow g++ to spawn multiple instances of itself in order to compile large projects quicker (for example 4 source files at a time for a multi-core CPU)? Where can I find Vagrant packages? is a tool to build and manage virtual machines for developers.  It has a  guide that contains iffy-looking suggestions like  $ sudo ln -s /usr/bin/ruby1.8 /usr/bin/ruby  # wtf???   or installing RubyGems from source rather than from Ubuntu packages, and then using gem install to install vagrant itself.  I'm not feeling comfortable just following those instructions.  Is there perhaps a PPA?  Are there, perhaps, alternative tools that are packaged for Ubuntu?