Book featuring digital Artificial Life, virtual reality using idle compute cycles

Question: In the early to mid 90's I recall reading a book where a computer scientist is asked to create a virtual reality for life to exist after death, using the idle cycles of networked computers from around the world. At the same time, a separate 'simulation' with all the building blocks of life to create a completely artificial life. The book focuses on the creation of the virtual reality. At the end, from the virtual world, the MCs peek into the separate simulation to find a 'hive-like' digital race who until then didn't realize there was 'another universe'.
Answer: Could be Permutation City by Greg Egan, published in 1994. There are VR worlds, and something called the Autoverse, The Autoverse is an artificial life simulator based on a cellular automaton complex enough to represent the substratum of an artificial chemistry.
From the Wikipedia plot description:

Copies form the conceptual spine of the story, and much of the plot deals directly with the "lived" experience of Copies, most of whom are copies of billionaires suffering terminal illnesses or fatal accidents, who spend their existences in VR worlds of their creating, usually maintained by trust funds, which independently own and operate large computing resources for their sakes, separated physically and economically from most of the rest of the world's computing power, which is privatized as a fungible commodity. ...

At the opposite end from the wealthy Copies are those who can only afford to live in the virtual equivalent of "Slums", being bounced around the globe to the cheapest physical computing available at any given time in order to save money, while running at much slower speeds compared to the wealthy Copies. Their slowdown rate depends on how much computer power their meager assets can afford, as computer power is traded on a global exchange and goes to the highest bidder at any point in time. When they cannot afford to be "run" at all, they can be frozen as a "snapshot" until computer power is relatively affordable again.

Observing one of the Autoverse worlds is an important plot point, and if the inhabitants can be convinced they were created by a force outside of their world.
Comment: Hmmm, I will pick this up and double check, but perhaps this is it. What's confuses me is that I am pretty sure I read this in '93 or earlier, but maybe I'm remembering the wrong bedroom.
Comment: Skipping to Part 2 (If I'd read it before then wasn't a spoiler right?) confirmed this was what I was looking for. Thank you, I'd been waylaid by the fact that I could only find the "2nd Edition", released in 2013/2014, in my prior searches.


CircuitLab schematic editor not working?

Question: Is anyone else unable to insert schematics into answers/questions at the moment? I can load the schematic editor but when I try to insert it, it just hangs, and either it closes without having inserted, or I have to close it myself and I lose the diagram.
Answer: I had the same problem just a few minutes ago -- each time I pressed "save and insert", then closed the editor, only to find nothing had been inserted. After 3 drafts starting over from nothing, the circuit got simpler and simpler...
Anyway it appears to be working now. The thing I was editing is here: https://electronics.stackexchange.com/a/166993/35022
Comment: It's just started working for me again too
Comment: And yeh my circuit ended up just having a ground terminal :-p Something very Zen about that. Good thing too, as I was nearly throwing the damn thing out the window


Did the entire world submerged during Nooh's (Noah) time?

Question: Assalamualaikum, I actually had this question, did the entire world submerged during Nooh's time, Nooh went on a mountain with some people and animals to protect from that flood,but did the entire world submerged during that or just some part of it? And if the world submerged completely, how was it restored?
Answer: AOA.
In Surah Hud, we learn that the Ark of Nuh (AS) traveled on the water for many days until Allah said to the clouds to hold the rain and the earth to swallow the water.
The Qur'an 11:44,
And it was said, "O earth, swallow your water, and O sky, withhold [your rain]." And the water subsided, and the matter was accomplished, and it [i.e., the ship] came to rest on the [mountain of] Jūdiyy. And it was said, "Away with the wrongdoing people."
As for if it did affect the entire world or not, I myself am not sure about that. But I am sure that wherever there were humans the flood did affect, as Allah simply wiped out ALL the disbelievers and CARRIED ALL the believers in the Ark of Nuh (AS).


How to create event registration form that sends AUTOMATIC CONFIRMATION EMAIL using SharePoint 2010 anonymous custom list?

Question: I'm trying to develop event registration form using anonymous SharePoint 2010 custom list.
Now, I got all the features I want; form fields, submit button that leads to confirmation page, but I want this form to send confirmation email; whenever a user register to the event he/she suppose to receive confirmation email to attend.
Answer: If your SharePoint has SMTP configured you can use following helper function to send email:
You can pass SPWeb object using

SPContext.Current.Web

<code>public static void SendEmail(SPWeb web, string mailTo, string mailSub, ref string mailMsg)
{
    var header = new StringDictionary();
    header.Add("to", mailTo);
    header.Add("subject", mailSub);
    header.Add("content-type", "text");
    SPUtility.SendEmail(web, header, mailMsg);
}
</code>
If you don't have SMTP configured in SharePoint, use code something like this or search web for "send email .NET".
Comment: Just a notice, if you will send e-mail in the event receiver code, you cannot use SPContext.Current objects there. You will need to use properties.Web instead
Answer: I'm not sure if i understood you well, but you want that when a new event is added to the list, an email is sent to someone is that correct?
Basically to do that you should check the list event receivers here, this way you can add to your list the events and basically on the items add you can write some code to send emails, you can either write your own code using .Net mail objects or you have a sharepoint email system which you can also use to send emails.
I hope i could help you a bit or send you to a right direction


How to translate all bones of an armature in pose mode without destroying the animation?

Question: I have a simple blender file with a mixamo animation imported as fbx. The animation is pushed down to the NLA and I have added a new (corrective) NLA track to do some tweakings. On this new NLA track I have a new action which includes a keyframe at the first frame of the animation in which i moved the whole armature (in pose mode) along the x axis. I just want to move the whole animation on the x axis (but not the object!) but this totally destroys the animation (random bone movement).

Blend-Exchange:
Comment: Hello could you please share your file? https://blend-exchange.com/ Why not moving the whole object?
Comment: @moonboots I added my blender file. I want to get a smooth transition between two mixamo animations but they have been captured with totally different (translated) armature positions in pose mode (while object/armature origin is the same).
Answer: If you want to do it the way you are trying to do it, select the parent bone (bottom spine), select its X Location track only (ShiftH to hide the other tracks, AltH to make them come back), move its curve on Y in the Graph Editor:
Comment: Correct result, but the destructive way without layers.
Comment: I began by creating an action for the spine bone only (if this is what you mean) and delete all the other bones keyframes, but I was not entirely sure what he wanted  ;)
Comment: Let me reformulate:  you used layers as a backup to make a change in a destructive way that doesn't make use of what layers are excellent at: iterative changes. It's like in photoshop the difference between duplicating layers and paint new stuff on the duplicate, instead of creating a new empty layer on top and draw completely new things on it. None of the methods are wrong, just different.
Comment: @moonboots Thank you for answering my question. Your solution works, but I was looking for a non-destructive way.
Answer: If you look at your corrective layer's Blending mode: it is set to "Replace".

That means, whatever keyframe you put in that layer is considered as the new value for the corresponding bone.
When you are editing an action in the action editor, you can access its Blending mode in the NLA editor by selecting the top track which represents the Action Editor.
Add is usually the simplest, though sometimes you will want Multiply. Feel free to experiment.
Though be aware, you should avoid keying any parameter or controllers that you don't want to change. Especially scale.
Here's how it looks when just keying the hip bone when moves up one unit in global space:
Comment: Thank you. It looks like the key to success is to really only keying the relevant bone and properties (in this case Translation), as you have already pointed out. "Combine" worked fine for me. +1


Show CPU core usage for parent process and its child processes

Question: Is it possible to display CPU core usage just for a single process and its child processes on Linux?
Answer: Do you mean all processes started by some process (have the same parent PID)?
If you have pgrep you can filter all the processes with the same parent ID:
top -p $(pgrep -P 2069 -d,)

If not you can filter all process ids through awk and use them with top -p:
top -p $(ps -eo pid,ppid |awk '($2==2069){printf "%s%s",delim,$1; delim=","}')

Change $2==2069 with the actual parent pid you want to track.
Comment: That would show information about a single core usage, wouldn't it?


VMWare - Import Amazon EC2 AMI?

Question: I've seen lots of post regarding the opposite direction, e.g. porting a VMWare image to an AMI, but none about what I'm trying to do.  I have an AMI - the Amazon Linux AMI [Beta] - and I'd like to do some testing on a duplicate VM box before I make modifications to the current running one; anybody done this?
Answer: Not yet. Currently, Amazon only supports VMWare import, and even then it's only for Windows 2008 Enterprise Server.
They've made statements, however, saying that they're currently working on support for not only exporting AMIs, but also supporting a wide variety of Linux distributions as well.
It's just not here yet. :( I'm looking forward to that feature as well.

VMWare - Import Amazon EC2 AMI?


Microsoft flow reading list user field value

Question: My scenario,i have a SharePoint list that upon creation of a new item should send a mail to someone.(that someone is read from the TO field(user field) in the list).Can you suggest me if is possible to use Microsoft flow directly and how. OR we need SharePoint designer for it
Answer: You don't need sharepoint designer for flow.
login to https://flow.microsoft.com with your O365 account.
You will need 2 Actions to fulfill your requirements (refer screenshot below)

When item is created where you select the Site Collection in which list is present and then select the list for which the flow needs to be created.
Second action is Send an Email, quite self explanatory. you can refer screenshot below. when you click in To field, you will se dynamic content on right side which are nothing but the column names from the list selected in step 1, and create the Flow.
Comment: i dont see the To field in the dynamic content list,i see the other columns and To email,To Department,To Picture--can you explain please
Comment: just select your user column in To field of Send email action
Comment: If i add an attachement in the sharepoint list,how will that be send in that email then? can you enlighten me please
Comment: Click on show advance option in send email action and browse the attachment column
Comment: which option should i choose for Attachement Name/content.


When you fly to Beijing (PEK) and then to a domestic final destination, when do you go through passport control?

Question: I am planning a trip to China and will be flying to my final destination via Beijing (PEK). At what point do I go through passport control: at Beijing (i.e. before boarding my second, domestic flight) or at my final destination? I want to make sure there is enough time in my layover for a long passport line.
Comment: Is there anywhere in the world where you wouldn't go through passport control after disembarking an international flight and before embarking on a domestic flight? Imagine if you didn't: how would they make sure you went through passport control when you got off the domestic flight, which you will share with many domestic flyers who never left China and thus don't need to go through passport control? In summary: you will definitely go through passport control in PEK!
Answer: Ooh, I was literally there last night...well, yesterday their time!
I arrived from Tokyo, Japan.  All passengers disembark at the same time, and then around the corner there are two lines - international transit, and other.  If you're flying domestic, this is the point at which you enter China, as anyone who wasn't joining me for more international flying was going through that line on the right.
After that it was chaos at security, bag checks, they confiscated my big phone charger for not having power labels on it, go figure, but it took me about 30 min in transit, so I'd add on a bit.  They did seem to have a lot more passport officers for the line you'd go through than they did for us transit people - although we still got checked, for some reason.
For more information, Beijing Airport has a page on the steps of the process from international to domestic transfer.
Comment: Thanks - so did you have to retrieve your checked luggage from your international flight and re-check for your domestic (in-China) flight?
Comment: No no, as I said, I was doing more international flying.  I saw the line for domestic immigration, is all, so I can tell you that you'd immigrate at that point.
Luggage-wise, I don't know as I didn't see past that point - mine was checked through for more international (I'm in Vancouver now)
Comment: Have added a link from their site, hope that helps
Answer: I did this once - a few years ago.  I arrived in Beijing on Emirates Airways and was transferring to a domestic flight on China Airlines.  The three legs (London to Dubai to Beijing to Dalian) were on the same ticket/reservation.
If I remember correctly, I did have to go through the passport and visa checks in Beijing airport.  I also had to get and recheck my luggage onto the domestic flight - but this was done similarly to how you get/recheck your luggage if you are transferring in the USA (i.e. separate location).
All of this was in the middle of a night (flight arriving in Beijing about midnight with the flight to Dalian leaving around 6 am) - yet, I remember there being quite a few passport officers. The whole process (walking from the gate, passport checks, luggage reclaim/recheck) took about 45 minutes.
This was about 7 or 8 years ago though, so I don't know whether anything has changed since then.  I also don't know whether it matters that the internal flight was on a different airline; although this part would have no impact on the passport/visa control.
Comment: There is a new international terminal now at PEK, there is a shortcut back to the domestic side via a short passport line if you do not have any luggage to claim and recheck
Comment: @Calchas good point.  However you still need to go through the passport control - right?  And, if I do have luggage, would I have to still re-check it?


How do I evaluate $\lim _{x\to \infty }\left(x\left(5^{\frac{1}{x}}-1\right)\right)$ without using L'Hopital, and what concept/theory do I use for it?

Question: My teacher gave me this homework after he explained how to do problems such as $\lim _{x\to \infty }\left(\frac{3^{x+2}-7^x}{7^{x-1}+5^{x-1}}\right)$ or $\lim _{x\to \infty }\left(1+\frac{2}{2x+1}\right)^{3x+1}$, but I don't see any resemblance whatsoever between the question and the forms that he explained to me earlier.
Comment: If you have covered derivatives, rewriting it with $h=1/x$ to read
$$\lim_{h\to0+}\frac{5^h-5^0}h$$ might ring a bell. But, please search the site. Similar questions have been asked many times.
Answer: Hint: Substitute $y=\frac{1}{x}$ and your limit becomes
$\lim _{y\to 0}\dfrac{5^{y}-1}{y}=\lim _{y\to 0}\dfrac{5^{y}-5^0}{y-0}=f'(0)$, for $f(y)=5^y$.
(Assuming that the problem has not risen from an attempt to calculate the derivative at the certain point. In this case, it would be circular reasoning.)
Also, the examples you've given do not seem to have connection to this.
Answer: I assume you are allowed to use

$\lim_{u\to 0}(1+u)^{\frac{1}{u}} = e$

Now, you may set

$u = 5^{\frac{1}{x}}-1 \Leftrightarrow x = \frac{\ln 5}{\ln (1+u)}$

and consider $u \to 0^+$:
\begin{eqnarray*} x(5^{\frac{1}{x}}-1)
& = & \frac{u}{\ln(1+u)}\cdot \ln 5 \\
& = & \frac{1}{\ln(1+u)^{\frac{1}{u}}}\cdot \ln 5 \\
& \stackrel{u\to 0^+}{\longrightarrow} &\frac{1}{\ln e}\cdot \ln 5 = \ln 5
\end{eqnarray*}
Answer: Let $y=\frac{1}{x}$ and note that $5^y=e^{{y\ln5}}$.
Since $e^t=1+t+t^2/2+...$, your expression becomes $\frac{e^{y\ln5}-1}{y}=\ln5+$ terms in $y, y^2,... $
As $y$ tends to $0$ the expression tends to $\ln5$.


Creating a new random variable with the same distribution

Question: Let $X,Y$ be two random variables taking real values. Suppose
that $P(Y\leq t) \leq P(X\leq t)$ for any $t\in{\mathbb R}$. Is there
always a random variable $Y^{*}$ with the same distribution as $Y$,
such that $P(X \leq Y^{*})=1$  ?
Answer: The question you asked is about Coupling of two independent random variable. Coupling of $X,Y$ are random variables $X',Y'$ such that they have the same marginal as $X$ and $Y$ but different joint distribution.
To see an example of coupling, let's start with $X$ and $Y$ two independent Bernoulli random variable such that:
$$
p=P(Y=0)\leq q=P(X=0)
$$
Suppose that $X$ and $Y$ are related to two distinct events and we want to compare some probabilistic features of these events. But to do that, it is interesting to see if we can somehow couple the behavior of these two events, which is whether we can find $X^*$ and $Y^*$ such that they are dependent but still have the same marginal. If we do that it seems that we have found a hidden random variable that connects these two events.
Now consider a uniform random variable $U$ over $[0,1]$ and define:
$$
X^*=\mathbb{1}(U>q), Y^*=\mathbb{1}(U>p)
$$
These two random variables have the same marginal as the original $X,Y$, as it can be seen here:
$$
P(X^*=0)=P(U<q)=q ,P(Y^*=0)=P(U<p)=p
$$
But they are not independent and they are related by $U$. Moreover we have $X^* \leq Y^*$.

The previous example is not the same as your question. In your example, $X$ should remain untouched and in previous example, $X^*$ is not equal to $X$.
The solution is to construct $U$ based on $X$. Define $U$ based on $X$ as follows. If $X=0$, then $U$ is drawn uniformly from $[0,q]$ and if  $X=1$, then $U$ is drawn uniformly from $[1-q,1]$. Therefore $U$ is dependent on $X$ however it can be seen that $U$ is uniformly distributed over $[0,1]$. Now we can define $Y^*=\mathbb{1}(U>p)$. $Y^*$ has the same distribution as $Y$ and for each $U=u$, it can be seen that $Y^*\geq X$.

The question is whether we can generalize this approach for random variables on $\mathbb R$. The answer is yes.
Let's start with finding a coupling of $X$ and $Y$. First we define the generalized inverse function of $F_X(t)=P(X\leq t)$ and $F_Y(t)=P(Y\leq t)$ as $G_X(t)$ and $G_Y(t)$. Of course $F_Y(t)$ and $F_X(t)$   are not in general invertible and hence we have to define the inverse as follows:
$$
G_X(t)=\inf\{x\in\mathbb R; F_X(x)\geq t\}\\
G_Y(t)=\inf\{y\in\mathbb R; F_Y(y)\geq t\}
$$
Note that $F_Y(t)\leq F_X(t)$ and therefore $G_Y(t)\geq G_X(t)$.
Suppose that $X^{-}=G_X(F_X(X))$. Take $Y^*$ and $U$   random variables defined as follows:
$$
X^{-}=G_X(U),\\
Y^*=G_Y(U)
$$
First, it can be seen that $U$ has uniform distribution on $[0,1]$. Then it is easy to see that $Y^*$ have the same marginal as $Y$ and of course $X\leq Y^*$.
Comment: +1. The last part (X and Y*) assumes that the probability space X and Y are defined on is large enough so that one can define U on it as well.


A children's Sci-Fi story where a boy overeats food pills and floats

Question: Looking for the title of a 50's or '60's children's sci-fi story where a greedy child (boy?) of the future eats too many food pills and swells so much he floats up into the sky.
Comment: Seems similar to a couple scenes in one or both of the "Willie Wonka" movies, so likely existed in the book *Charlie and the Chocolate Factory* as well.
Comment: No dice under http://tvtropes.org/pmwiki/pmwiki.php/Main/FoodPills
Comment: @ZeissIkon - Having read the book, they did.
Answer: In Roald Dahl's 1964 classic Charlie and the Chocolate Factory (and in both version of the movie) there are two scenes you might be conflating in this memory.
First, the (excessively) gum-chewing girl gets a piece of gum that includes a complete seven-course meal - though Wonka warns her (faintly) that it's still in testing.  When she reaches the dessert, blueberry pie, she begins to swell, and turn blue (like a berry), eventually having to be rolled off to juicing in an attempt to keep her from exploding.
Later, Charlie (and his grandfather, at least in the first movie) take unauthorized sips of a soda drink that fills them with lighter than air gas and causes them to float in the air, coming dangerously close to a huge exhaust fan before they find they can belch to release the lifting gas and lower themselves.
Answer: In L Frank Baum (of wizard of oz fame)'s novel The Master Key there are the two elements you mention, but they are separate.

a silver box of food tablets, each one of which provides sufficient nourishment for a whole day
  a "small tube" which can direct "an electric current" at a foe, rendering him unconscious for the period of one hour
  a wristwatch-sized transportation device, which allows the wearer to fly at any height and travel at high speeds in any direction, when it is working properly. It is, however, somewhat fragile and becomes damaged and unreliable during Rob's adventures, creating predicaments for him.

Wikipedia article here
It is also available in full here
Comment: TBH I should probably have made mine a comment, but I was using the mobile app and we don't always get along very well
Comment: This seems very tenuous
Comment: Perhaps - but then so does Charlie and the chocolate factory.
Comment: I thought they were separate events, happening to separate children however.
Comment: You're right. My upvote is now a downvote.


Could a planet with lower atmospheric nitrogen be habitable?

Question: I'm designing a lower gravity planet that I want to stay relatively warm despite having less atmosphere. My solution to this is to increase relative the amount of greenhouse gas, so this planet's atmosphere would have, say, 40% CO2. I was thinking it could be around 10-20% oxygen and 40-50% nitrogen. Would this be viable for life? Does complex life need as high a percentage of nitrogen in the atmosphere as Earth has or could it be substantially lower?
Comment: you had picked two mutually exclusive tags, conflict clearly stated in their description. I have removed one.
Comment: Viable for Earth life or its own, homegrown life? Because 40% CO2 would be an issue for humans, to put it mildly.
Comment: (1) Increasing the amount of greenhouse gas works only up to a point. Once the saturation point is reached, that is, the greenhouse gas traps all available infrared, adding more won't do much. (2) Earth itself had lots and lots of CO2 in its primitive atmosphere. The problem is that once you have photosynthetic organisms, they will happily eat all that CO2 and turn it into oxygen. (Most of the oxygen will then oxidate whatever it finds and be trapped in rocks.) This is why Earth no longer has an atmosphere with lots of CO2, and instead it has an atmosphere with only trace amounts of CO2.
Comment: AlexP - I've been wondering how to solve that problem. My first solution was to use a different form of phototrophy, like retinal-based phototrophy, but that's less efficient than photosynthesis, so complex life probably wouldn't evolve. Then I was wondering if this was a moon of a gas giant, if tidal effects and increased volcanism could keep the CO2 at proportionally high levels. The moon would be 0.25M earth, with maybe like a 0.3bar atmosphere. Not sure if it could stably maintain this atmospheric composition and pressure though.
Answer: Atmospheric nitrogen is practically unavailable to most of life form, because of its low reactivity.
It takes nitrogen fixing organisms like bacteria and plants to make it available in a way that other life forms can process.

nitrogen-fixing bacteria, microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen (inorganic compounds usable by plants). More than 90 percent of all nitrogen fixation is effected by these organisms, which thus play an important role in the nitrogen cycle.

Therefore also on a planet with lower atmospheric nitrogen life can thrive, as long as you have species which perform the task of fixing whatever nitrogen is present.
Comment: Thanks! Yeah, that's kind of what I was thinking, too. But I wonder if it's somehow beneficial to have the majority of the atmosphere made of a practically inert gas or if it really doesn't matter at as long as life has all the basic building blocks available and cycling of resources is possible.
Answer: Given that you have supreme authorial fiat, I don't see any reason why you couldn't declare life to be able to develop there. There are various (largely bacterial) processes that makes atmospheric nitrogen available to other living things by converting it into forms that can be more easily taken up and used, and I don't believe that these need very high partial pressures of nitrogen in order to work, but even if they did you can handwave in a process that works with much lower partial pressures without worrying that you've made a chemical impossibility.
Having a very high partial pressure of CO2 is potentially problematic, though.

CO2 is soluble. This means that your clouds are going to be somewhat acidic (carbonic acid) and so any exposed surface life will have to be acid resistant, but it also means that your seas are likely to be highly acidic as they'll be able to absorb CO2 from the air until they reach some kind of equilibrium.
Acid oceans aren't uninhabitable necessarily, but they won't be hospitable for anything that expects to form carbonate shells, so no molluscs for you. That also means no chalk, and no limestone. You might get more complex forms of the silicate frustules that some kinds of marine microbiota produce, and hence other kinds of mineral formation, but the kinds of interesting landforms and cave systems you get on Earth in limestone are probably going to be entirely unavailable to you.

The density of CO2 at STP is ~1.977kg/m3, oxygen is 1.4290kg/m3 and nitrogen 1.2506kg/m3 (source). Gasses stay pretty well mixed in our atmosphere under normal circumstances, but it has been demonstrated in the real world that carbon dioxide can form low-lying gas pockets capable of causing asphyxiation:

Because it is heavier than air, in locations where the gas seeps from the ground (due to sub-surface volcanic or geothermal activity) in relatively high concentrations, without the dispersing effects of wind, it can collect in sheltered/pocketed locations below average ground level, causing animals located therein to be suffocated. Carrion feeders attracted to the carcasses are then also killed. Children have been killed in the same way near the city of Goma by CO2 emissions from the nearby volcano Mount Nyiragongo.

This makes various kinds of geographic depression potential deathtraps for aerobic life forms, along with other structures such as caves, mines and basements. Keeping your air well mixed could be problematic.
Comment: Water can pretty much saturate for Ca ions at any possible CO2 partial pressure. Molluscs are safe afterwards. It won't be much more acidic than now - we all drink soda with no immediate ill effects. Low lying gas pockets are only possible with a source of pure CO2. Gases cannot separate by themselves.
Comment: @fraxinus https://en.wikipedia.org/wiki/Ocean_acidification#Impacts_on_oceanic_calcifying_organisms
Answer: Elhammo could simply put his planet closer to its star, and/or make the star more luminous, so the planet will receive more radiation from the star to heat it up. If the planet receives enough radiation from the star, it might be as warm as Earth or warmer despite having no more greenhouse gases than Earth, or even less, in its atmosphere.
How close could Elhammo's planet get to its star?  Obviously one should take the inner edge of the Sun's circumstellar habitable zone, and adjust it for the relative luminosity of the star compared to the Sun. That should be easy.
Here is a link to a list of estimates of the inner and outer edges of the Sun's circumsellar habitable zone.
https://en.wikipedia.org/wiki/Circumstellar_habitable_zone#Solar_System_estimates
Notice how "well" they agree.  Some of the estimates require specific atmospheric compositions to have liquid water temperatures at the inner or outer edges.  And those specific atmospheric compostions might be unsuitable for oxygen breathing organisms.
Here is a link to a table of the atmospheric composition of Earth.
https://en.wikipedia.org/wiki/Atmospheric_chemistry#Atmospheric_composition
I note that most of the atmosphere is nitrogen, and only a fraction of its present amount is necessary for life.  So a planet with the same amount of oxygen, and with only a few percent as much nitrogen as Earth, could have a very thin atmosphere while retaining all the minor atmospheric gases, including the greenhouse gases.
And if the planet receives more heat from its star than Earth does, such an atmosphere should enable it to be at least as warm as Earth is.
I note that the carbon dioxide, methane, and water vapor in Earth's atmosphere are greenhouse gases.

The primary greenhouse gases in Earth's atmosphere are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Without greenhouse gases, the average temperature of Earth's surface would be about −18 °C (0 °F),3 rather than the present average of 15 °C (59 °F).35

I see that nitrous oxide and ozone are also listed as atmospheric gases.  And there are other greenhouse gases listed as being in Earth's atmosphere.
Habitable Planets for Man, stephen H. Dole, 1964, discusses the constituants of a breathable atmosphere - breathable for humans (and thus for beings with similar atmospheric requirements).
https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf
Dole discusses atmospheric composition on pages 13 to 19 and concludes:

To summarize then, the atmosphere of a habitable planet must contain oxygen with an inspired partial pressure between 60 and 400 millimeters of mercury, and carbon dioxide with an inspired partial pressure roughly between 0.05 and 7 millimeters of mercury.  In addition,the partial pressures of the inert gases must be below certain specified limits andother toxic gases must not be present in more than trace amounts.  Some nitrogren must be present so that nitrogen in combined form can find its way into plants.

Since a habitable planet must have bodies of water on its surface, it must also have water vapor in the atmosphere.
Table 2 on page 16 lists the approximate upper limits of various inert gases.
Table 3 on page 18 lists tolerable concentrations of other gases.  I note that apparently the greenhouse gas methane could have a much higher concentration than in Earth's atmosphere before it would start to burn.
Alien life forms which evolved on a different planet could have much greater telerances for greenhouse gases in the atmosphere than humans.  But probably the same biological reasons which would make them toxic to humans would also make them toxic to the alien lifeforms, just at greater concentrations.  So you shouldn't assume that you can crank up the greenhouse gases as much as you need to make a planet at the distance of Pluto as warm as Earth, for example.
Anyway, a planet with oxygen near the lower limit, and very little nitrogen, should have plenty of leeway to increase the levels of greenhouse gases to as high as is humanly tolerable, while the total atmospheric pressure is about a third that of Earth.  Once the greenhouse gases are all at their highest tolerable levels, a writer would probably have to increase the oxygen above the minimum level to get a total amospheric pressure one third that of Earth.
I note that calculating the temperature ranges on a planet with a specific atmospheric compositon receiving a specific amount of radiation from its star can probalbly be quite complex.

...Then I was wondering if this was a moon of a gas giant, if tidal effects and increased volcanism could keep the CO2 at proportionally high levels. The moon would be 0.25M earth, with maybe like a 0.3bar atmosphere. Not sure if it could stably maintain this atmospheric composition and pressure though.

If you are considering a habitable moon of a giant planet, you should remember that tidal heating not only releases greenhouse gases, which can heat up the air, it also heats up lower rock levels, which heat up higher rock levels, which heat up higher rock levels, and so on, until the heat reaches the surface of a world.
Scientists speculating about life on exomoons of giant exoplanets have calculated that tidal heating could be very significant.  In fact they have calculated that tidal heating could be too strong and make a moon uninhabitable.
Too much tidal heating could produce so much vulcanism that moon would become a volcanic hell, like, for example, the Jovian moon Io.
A lesser amount of tidal heating might lead to a runaway greenhouse effect.  If the surface becomes too hot, too much liquid water will become water vapor in the atmosphere.  Since water vapor is a greenhouse gas, a lot of water vapor in the atmosphere will increase the temperures, evaporating more water vapor until all the water is in the atmosphere and none on the surface.  Ultraviolet light in the upper atmosphere will separate water into the hydrogen and oxygen.  The hydrogen will escape into space while the oxygen will combine to form solid matter on the surface of the world.
A really low amount of tidal heating will not contribute significant heat to the surface of a world.
And obviously, there is a range of tidal heating in between those extremes which is just right. Which can be enough to keep a world warm enough for liquid surface water without making it hot enough for volcanic hell or runaway greenhouse.
in this paper: https://arxiv.org/ftp/arxiv/papers/1209/1209.5323.pdf the authors create the concept of the "habitable edge".  The "habitable edge" of a giant planet in the minimum possible distance for a moon to orbit around it without suffering from a runaway greenhosue effect.
In this paper: https://arxiv.org/abs/1309.0811 The authors also suggest a maximum distance for a habitable moon to orbits its planet.

The moon would be 0.25M earth, with maybe like a 0.3bar atmosphere. Not sure if it could stably maintain this atmospheric composition and pressure though.

One way to check whether a moon would maintain an atmosphere pressure would be to check Habitable Planets for Man, Stephen H. Dole, 1964.
https://www.rand.org/content/dam/rand/pubs/commercial_books/2007/RAND_CB179-1.pdf
On pages 34 to 35 Dole discusess a ratio that determines the time period required for a gas in a planet's atompshere to be reduced to 0.368 (1/e) of its former amount by escape of gas into space.  The ratio is the escape velocity (not the surface gravity) of a world divided by the root-mean-square velocity of particles of that gas in the exosphere (outermost atmosphere) of the world.
The velocity of gas molecules depends on their temperatures, and the temperatures in the exospheres of worlds are usually much higher than their surface temperatures.
According to table 5 on page 35, multiplying the ratio a few times can make the difference between reducing a gas to 0.368 of its orginal amount in mere seconds and in reducing it to 0.368 of its original amount in billions of years.
Of course gas that escapes from an atmosphere into space can be replaced, but no doubt natural process couldn't replace any gas nearly as fast as the maximum rate it could be lost into space.
And there are other factors which can make a world lose atmospheric gases faster than by thermal escape into space alone.
https://en.wikipedia.org/wiki/Atmospheric_escape
Dole calculated a minimum possible mass for a world to retain an oxygen rich atmosphere for geological eras of time.
On page 53 Dole calculated the parameters of a world with a surface gravity of 1.5 g, which he considered the maximum for a colonizable world.  He believed such a world would have a mass of 2.35 Earth mass, a radius of 1.25 Earth radius, and an escape velocity of 15.3 kilometers per second, 1.367 that of Earth.
On page 54 Dole said that the temperatures in Earth's exosphere are between 1000 K and 2000 K. Dole said that if the maximum exosphere temperatures of a world could be as low as 1000 K while still having liquid water temperatures at the surface, such a world could retain oxygen in its atmosphere while having an escape velocity of only 6.25 kiometers per second.  Dole calculated it whould have a mass of 0.195 Earth, a radius of 0.63 Earth, and surface gravity of 0.49 g.
However, Dole didn't believe that such a small world could produce an oxygen rich atmosphere, and so eventually decided - correclty or not - that a world with 0.4 the mass of Earth, 0.78 Earth radius, and a surface gravity of 0.68 g would be necessary to produce an oxygen rich atmosphere. It would have an escape velocity of 8.01 kilometers per second, 0.716 thatof Earth.
In more recent times scientists have speculated about planetary habitability, but considering the more general case of habitable for liquid water using life forms in general, instead of the more specific case of habitable for humans and for beings with similar enviromental requirements.
So some of the worlds which scientists consider habitable for some liquid water using life forms might be swiftly deadly for humans or for beings who require the same type of environment.
Anyway, in this 2013 paper, various estimates of the mass range of habitable worlds are mentioned onpages 3 to 4.
https://arxiv.org/ftp/arxiv/papers/1209/1209.5323.pdf

A minimum mass of an exomoon is required to drive a magnetic shield on a billion-year timescale (Ms ≳ 0.1M⊕,
Tachinami et al. 2011); to sustain a substantial, long-lived atmosphere (Ms ≳ 0.12M⊕, Williams et al. 1997; Kaltenegger
2000); and to drive tectonic activity (Ms ≳ 0.23M⊕, Williams et al. 1997), which is necessary to maintain plate tectonics and
to support the carbon-silicate cycle. Weak internal dynamos have been detected in Mercury and Ganymede (Kivelson et al.
1996; Gurnett et al. 1996), suggesting that satellite masses > 0.25M⊕ will be adequate for considerations of exomoon
habitability. This lower limit, however, is not a fixed number. Further sources of energy – such as radiogenic and tidal heating, and the effect of a moon's composition and structure – can alter our limit in either direction. An upper mass limit is
given by the fact that increasing mass leads to high pressures in the moon's interior, which will increase the mantle viscosity
and depress heat transfer throughout the mantle as well as in the core. Above a critical mass, the dynamo is strongly
suppressed and becomes too weak to generate a magnetic field or sustain plate tectonics. This maximum mass can be placed
around 2M⊕ (Gaidos et al. 2010; Noack & Breuer 2011; Stamenković et al. 2011). Summing up these conditions, we expect
approximately Earth-mass moons to be habitable, and these objects could be detectable with the newly started Hunt for
Exomoons with Kepler (HEK) project (Kipping et al. 2012).

So they mention sources which claim a world could retain an atmosphere for long periods of time with a mass only 0.12 Earth mass.  And possibly those sources have a differnt result than Dole because of different assumptions they make about various factors.
They believe that when all the factors are considered, exommons with mass greater than about 0.25 Earth mass are potentially habitable, though that is not a hard limit.
A world with a mass of 0.25 Earth, and 0.8 the density of Earth would have a volume of 0.125 Earth, a radius of 0.6786 of Earth (4,323.36 kilometers, aurface gravity of  0.54 g, and an escape velocity of 6.79 kilometers per second, 0.607 that of Earth.
And I guess that would not be too far from the minimum values for a habitable exomoon capable of retaining an atmosphere for geologic eras of time.


Google Analytics behaviour flows multple interactions same page

Question: I am looking at Google Analytics behaviour flows report and can see multiple interactions for the same page name some are on the same column and some are on different columns but with traffic flowing between. What are the reasons for this to happen? The only one I can think of is different query strings though these aren't being shown. Are there others?
Comment: Hi! Are you referring to the two instances of "reports" in the second column, or something involving both columns and/or the numbers displayed?
Comment: Both. I have multiples on the same column and multiple columns.
Comment: Some people visit "reports" as their first step and some people visit it as their second step.   I don't see any traffic flowing from "reports" in the first column to "reports" in the second column.   In the second column you also have a separate reports URL that doesn't have the trailing slash.   If that is the same page, you should probably redirect that.
Answer: The Behavior Flow report is about the path taken through the site during sessions in your date range. The columns correspond to first page, second page, etc. You should expect to see duplication of pages in different columns because not everyone will visit a given page at the same point in their session.
The duplication you are seeing within the second column is due to your site allowing both /reports/ and /reports as URLs. If these are actually the same page, it would be good to standardize, as Stephen Ostermiller advises in his comment. Since it appears there are other pages in that directory, /reports/ is the better one to allow (that is, force /reports to add a trailing slash). That way your Behavior > Site Content > Content Drilldown report will work properly.
Here is how to read your screenshot:

The most common page people land on when they visit the site is /login.php; the second most common is /reports/.
About half the people who land on /login.php depart without visiting another page (the red part of the flow chart). Most of those who do not leave go to /reports/ as the second page of their session.
Most people who land on /reports/ next visit to a page that's shown below the bottom of the screenshot. A significant percentage, however, go to /reports - via a form submit or link click that loads the page without the slash, I would assume, but that requires investigation.

You'll note no one goes from /reports/ in the first column to /reports/ in the second column; the Behavior Flow only shows movement between distinct pages. The duplication in the second column is because GA only knows one page is the same as the other by the URLs matching.


Flash swf file to run as an application on android

Question: I have a flash application(.swf format). I wanted to package the entire swf file and other content(related images, xml files) into a single file and access in a tablet. So basically i need to make it into a single .apk file to access in my tablet.
         Please let me know if its possible to do it, and what are the tools required to do this.
Regards,
Answer: First, download Flash Professional CS5.5 from Adobe's site and install it.
Then, read the instructions on How to publish Android AIR applications
Answer: For play swf with android, you need to develop your project in android 2.2 version or above so Flash player 10.3 are install and run which support your swf(shock wave file at background) and you can easily play swf.
You need to drag Webview and attach those swf source path.
you can get player in you mobile from here :: https://market.android.com/details?id=com.adobe.flashplayer&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5hZG9iZS5mbGFzaHBsYXllciJd
Now if you plan to play swf directly, then Adobe Air will help you because it provide sdk in which in Flash you can convert your flash file to apk.(that is the easy to flash developer)
Comment: I want it to be browser independent as well


Could Shelob have kept the ring for herself?

Question: In the Lord of the Rings, Gollum/Smeagol's plan is to lead Frodo and Sam into the pass of Cirith Ungol, where he was gonna leave them to be consumed by Shelob and take the ring from the remains. However, is it possible that Shelob might've kept the ring for herself? She is the last child of Ungoliant, the Primordial Spider, and is capable of intelligent thought since she allowed Gollum/Sméagol to leave the tunnels the first time around after he made a pact with her to bring tastier meals than him to her, so is there any reason to believe she wouldn't keep the ring for herself?
Answer: She might, but she would not have used it.
The spiders and spider-things we read about in Tolkien's work are all motivated primarily by the same thing: hunger. The spiders of Mirkwood capture Bilbo and the dwarves for food: the fact they're also foiling Gandalf's plan is merely a coincidence. So it is with Shelob. We read in the conversation between the Orcs that all she's interested in is capturing them to eat, and nothing in Frodo and Sam's encounter with her suggests otherwise.
This is in accordance with the description in The Silmarillion of the primal "spider", Ungoliant.

But she had disowned her Master, desiring to be mistress of her own lust, taking all things to herself to feed her emptiness; and she fled to the south, escaping the assaults of the Valar and the hunters of Oromë, for their vigilance had ever been to the north, and the south was long unheeded. Thence she had crept towards the light of the Blessed Realm; for she hungered for light and hated it.

It's worth noting that this hatred of the light extends to Shelob and her hatred of Sam's phial. It seems reasonable to assume, then, that Shelob and Ungoliant are similar creatures in many respects.
Everything we read about Ungoliant centers around her insatiable hunger:

But when Ungoliant understood the purpose of Melkor, she was torn between lust and great fear;

And later:

But Ungoliant sucked it up, and going then from Tree to Tree she set her black beak to their wounds, till they were drained;

And later:

Then perforce Morgoth surrendered to her the gems that he bore with him, one by one and grudgingly; and she devoured them, and their beauty perished from the world. Huger and darker yet grew Ungoliant, but her lust was unsated.

It's worth noting in the above passage that Ungoliant is eating the gems of Valinor. While magic is a complex and amorphous concept in Tolkien's work we might, at a stretch, imagine many of these gems as sources of "magic" and "power" just as the Silmarils - and later the Ring - are.
And most extreme of all:

Of the fate of Ungoliant no tale tells. Yet some have said that she ended long ago, when in her uttermost famine she devoured herself at last.

A being so ruled by hunger, then, that she would eat herself.
Given that Shelob is a child of Ungoliant, clearly a closely related creature, and everything we read about her revolves around eating, it would seem that she, also is motivated entirely by hunger and not by power.
In fact, this is confirmed in The Two Towers:

Little she knew of or cared for towers, or rings, or anything devised by mind or hand, who only desired death for all others, mind and body, and for herself a glut of life, alone, swollen till the mountains could no longer hold her up and the darkness could not contain her.

So if she did gain possession of the ring, it is likely that she would simply either ignore it or attempt to eat it, with uncertain results.
Answer: She didn't care about it.

Little she knew of or cared for towers, or rings, or anything devised by mind  or hand, who only desired death for all others, mind and body, and for herself  a glut of life, alone, swollen till the mountains could no longer hold her up  and the darkness could not contain her.
-- The Two Towers, chapter "Shelob's Lair"

This is consistent with what we know about her character. She shows intelligence only in a brutish, beastly sort of way. Her existence revolves around luring creatures into her traps and devouring them; a Ring of Power would have little interest to her.
This doesn't, of course, account for the effect the Ring has on everyone (except Tom Bombadil) who comes into contact with it. Perhaps even a creature usually unmotivated by powerlust would be affected by the addiction of the Ring. But given that Gollum would come to take it almost immediately after she first came into contact with it, the Ring wouldn't have much time to take hold of her. Her lack of care for such things would probably take time to wear down, especially given her immense age, and the Ring wouldn't be able to do that in the short time that she would 'possess' it before Gollum seized it.
Further reading:

What exactly was the understanding between Gollum and Shelob? at Sci-Fi & Fantasy SE (with an excellent detailed answer which touches upon the aspect of Shelob's potential desire for the Ring)
Would Shelob have been interested in using the One Ring and its power for herself? at Quora (essentially identical to your question here)
Comment: I started writing this a couple of hours ago, and then went AFK for a while. Matt Thrower's answer is better, but I thought this was worth posting anyway.
Comment: Absolutely worth it, for the reflections on ring-desire, Gollum and the further reading, thanks.
Answer: Idk...but I have some guesses.
Shelob could be addicted to the ring thinking it is a yellow body part from the insides, thus eating it, or possibly ignore it. We DO know that Shelob loves eating, and has gained plenty of weight from eating the flesh and drinking the blood. (Thus a text saying Shelob is bloated.)


Possibility commuting using GA aircraft between rural towns?

Question: Last week I went to visit my friend out in California City and noticed they do have an airport over there, so here is my idea.
Would it be practical to fly GA aircraft between California City and Los Angeles on a commuting basis, multiple times every week if not daily? Or generally commuting using aircraft in the rural area?
I know some areas in Alaska people doing exactly just this, but is this doable everywhere?
Comment: LA specifically could be hard to do. They are often cloud covered, making landing for small planes difficult.  Takeoff into zero-zero conditions is not something I would do, in case  you needed to make an emergency return landing. I would suspect LAX has high fees too. You might find other nearby airports more affordable.  I would imagine California City is almost always clear, being inland of the coastal mountains and on the edge of the Mojave.
Answer: As for the latter part of your question, is it doable everywhere, the answer would be a resounding no.
Unless you are a proficient IFR pilot, the climate would be one of the limiting factors in many places. For example where I live in, we have four seasons, of which the fall, with mostly IMC weather, lasts for about 6 months, leaving the other half of the year somewhat doable for a proficient VFR pilot. Now, I'm not kidding, it really is like that here: a couple of years ago it was cloudy (low level overcast) for three months in a row. Most of the cloudy days then were of the sort that would have made commuting under VFR very risky to say the least.
Another hurdle might be the cost. Again, as an example, where I live flying a private plane is ridiculously expensive. Even more so, if you want to hold an IFR -licence, which would be an absolute necessity if you wanted to commute by private plane here.
And one thing is scheduling. Unless you live and work very near an airport, you must consider transit times between your home, departure airport, destination airport and your workplace, and the other way around. Add half an our of flight preparation twice per day, and any time savings you might have thought of will quicky dissapear.
Generally I'd say it depends heavily on local conditions, but commuting by a private plane is (unfortunately) not a viable option everywhere. And I do not think it's a financially viable option anywhere...
Answer: This should be reasonably practical. For three years I have commuted daily in my Lancair from one urban SoCal airport to another, except for a couple of months when I was going to MHV every day instead. Very occasionally I'm forced to drive due to weather, airport/airspace closures or aircraft maintenance.


Mistake in our lease

Question: We entered into a 2 year lease agreement in July 2016. I have since discovered that the end date is wrong in our lease. It should have been June 2018, not August 2018. My landlord is being is not being respective to there was a mistake. But I do have a recent email from the landlord stating that the lease was for 2 years. Any suggestions on steps I can take in North Carolina.
Comment: What document are you looking at?
Comment: What exactly did the landlord say in the e-mail message?
Answer: The terms of a contract that has been reduced to writing are definitive. If it says August then August is what you contractually agreed irrespective of prior communication or discussion. The law presumes that parties will adopt many positions during negotiations, however, when they come to actually writing down what they agreed, that written record is definitive.
There are exceptions where the mistake is obvious and makes the agreement absurd. In such circumstances if one party refuses a correction a court might order it. However, a date that is wrong by a month doesn't qualify. Even one that is wrong by years might not - there are leases that run for decades and a court would need to be satisfies that this isn't one of those.
Unless both parties agree that it is a drafting mistake it is not subject to correction. Of course, both parties can agree to vary the contract notwithstanding if they agree it was a mistake.
Comment: If a landlord accidentally added a century (writing that a lease ends in 2118), and the renter plain missed the point while signing, I think you would answer this differently, right?
Answer: Meet with him to explain the mistake more clearly.  Assuming he agrees that it was a clerical error, just cross out the old date, write the correct date, and sign and date (by both parties) this correction on all copies.
Comment: "assuming he agrees that it was a clerical error": I suspect that the landlord "not being respective to there was a mistake" means that the landlord refuses to recognize that it was a clerical error.
Comment: I saw that phrase and took it to mean that the tenant was not 100% sure, so since nobody wins much going to court, I'd still meet with him to try to understand his view...hopefully, he's reasonable.
Comment: Fair enough.  I've had a couple of reasonable landlords in my life, so I know that they do exist.  I don't suppose that most reasonable landlords have many tenants asking for help on the internet, however.

Mistake in our lease


Meaning of Einstein's equation $E=mc^2$?

Question: Meaning of Einstein's equation $E=mc^2$? How can a $1\,\mathrm g$ mass possess energy equal to $9\times10^{13}\,\mathrm J$? What does it actually mean?
Answer: To understand the answer you should have understood well a point. Energy is conserved, mass is not. Moreover, masses possess an  energy content pictured by the equation you wrote and thus this part of energy must be taken into account when writing the energy conservation law.
For instance, suppose you have a particle at rest in your (inertial) reference frame with a mass $M>0$. It may happen that the particle spontaneously breaks into a pair of different particles with masses $m_1$ and $m_2$ respectively (when measured at rest with them, I am assuming that all particles I consider are massive), but these particles are no longer at rest with you. Consequently they have kinetic energies, $K_1$, $K_2$, depending on their velocities.
Well, classically one expects the mass is conserved and thus $$M = m_1+m_2\:.$$  Instead this equation is experimentally violated.
Energy however is conserved, but part of energy is associated with the involved masses in accordance with the identity $E=mc^2$. Summing up the correct conservation rule is:
$$Mc^2 = (m_1c^2 + K_1) + (m_2c^2 + K_2)$$
where $Mc^2$ is the total energetic content before the transformation of the initial particle: the energy is completely due to the initial mass. After the transformation, there are two types of energy to sum for each particle, the one due to the mass of the new particles $m_1c^2$ and $m_2c^2$ and their kinetic energy $K_1$ and $K_2$.
You see that, as $K_1+K_2 \geq 0$ you have that $m_1+m_2 \leq M$, so that the total mass decreased in this process.
There are other different kinds of transformations (for instance the inverse reaction $m_1+m_2 \to M$) also involving different types of energy (e.g. chemical or thermodynamical) but the point is that
(a) there always is part of energy due to the (rest) mass of the involved bodies, and here the celebrated equation $E=mc^2$ enters the picture;
(b) the total energy (for isolated systems in inertial reference frames) is conserved in time in any transformation process.
Answer: It means that this mass is available for transformation in some other kind of energy. It means that there is a type of energy that is only a function of a mass of a particle. There are processes in nature in which entire mass of a particle transforms in some other type of energy...like annihilation of particle and antiparticle.How to calculate this energy? mc2 formula. It originates from relativistic form of equation for energy of a particle..if you put that speed is zero, you have mc2 term left. Like kinetic energy turns into potential or electromagnetic, so this rest energy can turn in something else. This is something that just comes out from equations. You have to know that energy is not a clear and simple topic, but regardless, it is a good device for describing processes in nature. Einsteins equation mc2 gives another proof that it is a good device indeed.
Comment: "It means that this mass is available for transformation in some other kind of energy." No, conservation rules may prevent that.
Comment: True, may prevent that.
Answer: It is what it seems to be at first glance: matter intrinsically contains energy even if it is stationary and thus has no kinetic energy. This energy defined as $E=mc^2$ is called rest energy. All matter carry rest energy.
Now, due to the large numerical value of c, even the lightest objects contain such immensely huge energy. But this is not energy that is easily harnessed or transferred, because this rest energy lies within the fundamental particles that constitute matter. What the $E=mc^2$ equation really implies is the equivalence between mass and energy.
This is actually hard to explain, since I'm not yet knowledgeable on particle physics. But what I do know is that to truly extract the billions or trillions of joules in a particle would mean converting its mass into energy.
Answer: The rest energy of mass...is really a vibratory energy, caused by gravitons colliding with the protons and nuetrons mass, as the gravitons flow thru them at the speed of light, in a vibratroy fashion.  The total energy of gravitons contained in the mass, is transferred to the mass (proton), for example.  I can send you a paper that explains this.  Ed Wilke
Comment: As it's currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-ask).


Why isn't the universe full of electrons?

Question: The probability of an electron found outside the atom is never zero. Consider building an electron detector, it must receive permanent signals from all electrons in the universe, as they can exist everywhere. Of course the probability decreases with increasing distance from the atom, but for the huge amount of atoms in the universe the probability of finding an electron at every point in space cannot be negligible.
Comment: If the probability of winning the lottery is non-zero, how come you don't win the lottery all the time? Because "non-zero" can still be very small.
Comment: I think this question is analogous to [Olber's paradox](https://en.wikipedia.org/wiki/Olbers%27_paradox) except that instead of the light from stars we are talking about the wave function of electrons.
Comment: Please clarify your definition of "being full of something" I feel like when you do that you may answer your own question.
Comment: The amplitudes of several electrons can add up to zero because they are complex-valued, so non-zero probability everywhere is not actually a given. Of course, in any finite volume the probability will be non-zero but small for the reasons the other answers pointed out.
Comment: @klm123, nah, the question is fine IMO. From the POV of a lay person I find it very easy to understand how it was meant, and how to give a helpful answer (like the top-voted one right now, or really just the top-voted comment here).
Comment: It's *full of* the *electron field*, no?
Comment: Just because a probability is non-zero doesn't mean it equals (or even comes close to approaching) 1. Even infinite sums can be less than 1.
Comment: Please accept the highest scoring answer.
Answer: I think this is a very creative question. You are thinking: There are so many atoms in the universe that all of their electron wavefunctions should overlap and lead to a detection everywhere.
But remember that the radial wavefunction of the electron very roughly goes as $e^{-r/a_0}$, where $a_0$ is the Bohr radius, which is (also very roughly) $10^{-10}$m, and $r$ is the distance. The estimated amount of atoms in the observable universe is something of the order of $10^{80}$, but it does not matter if its some other order close to that. Let's now assume they are distributed not as in the observable universe, but ALL of them are just ONE meter away (which would of course lead to other complications). But still, this means the calculation of detection probability will contain a factor (or even the square of) $10^{80}e^{-1\mathrm{m}/a_0}=10^{80}e^{-10^{10}}(\approx0)$, which for all intents and purposes is zero. You cannot beat the exponential suppression at larger distances even with very large numbers of electrons. Since you seem to be an outside of the box thinker: Keep in mind that even more atoms in the maybe un-observable universe do not matter, since they are so far away that their exponential suppression is even stronger. Does not matter how much you add.
Comment: @BЈовић Very very roughly take the mass of an average star to be the mass of the Sun $\approx10^{33}$ g/star $\times10^{23}$ roughly the number hydrogen atoms/g $\times 10^{12}$ (Sun-like-)stars/galaxy $\times10^{12}$ galaxies/observable universe $\approx10^{80}$.
Comment: @Koschi Ok, I see your logic. Considering how much we really don't know about our universe, that is a good guess :)
Comment: Does the Dirac equation make the probability of electrons from outside the observable universe exactly _(rather than "effectively")_ zero ?
Comment: @BlueRaja-DannyPflughoeft You are most probably right. I did not go into any details about that in my quite heuristical answer. Since the solution for the hydrogen atom is found in non-relativistic quantum mechanics, you do not see this, but of course relativistic QM cares about if events are causally disconnected, i.e. have spacelike separation.
Comment: The answer seems to imply that the probability of detecting a single electron at distance exactly $d$ equals the probability of detecting $10^{80}$ electrons all sitting at distance exactly $80\cdot \ln 10\cdot d = 184\cdot d$.  It is impressive how little effect the number of the electrons has.  However, we believers in the Dirac sea have _way_ more electrons than atoms in the observable universe, and we have also strategically placed them nearly everywhere, hoping that the detectors will go mad anyway.
Comment: wtf? who and how estimated number of atoms in observable universe?!?!?
Answer: Let's suppose we are surrounded by an approximately uniform density of hydrogen atoms $\rho_h$, then the number of atoms in a shell around us of radius $r$ and thickness $dr$ is:
$$ dN = \rho_h 4 \pi r^2 dr $$
where if we average over the whole universe $\rho_h$ is about $0.2$ hydrogen atoms per cubic metre.
The electron density of a hydrogen $1s$ orbital at a distance $r$ is:
$$ \rho_e = \frac{1}{\pi a_0^3} e^{-2r/a_0} $$
Then the electron density due to the atoms in our shell at distance $r$ is:
$$ d\rho_t = \frac{\rho_h 4 \pi}{\pi a_0^3} e^{-2r/a_0} $$
Then the total electron density is just the integral of this from $r = 0$ to $\infty$:
$$ \rho_t = \frac{4\rho_h}{a_0^3} \int_0^\infty e^{-2r/a_0} dr $$
And $\int_0^\infty e^{-2r/a_0} = a_0^3/4$ so the whole expression simplifies to:
$$ \rho_t = \rho_h $$
Which is of course exactly what we expect since each hydrogen atom has one electron so the density of electrons has to be the same as the density of the hydrogen atoms i.e. about $0.2$ electrons per cubic metre.
As Koschi says in their answer the electron density falls exponentially with distance and this totally swamps the $r^2$ increase in the number of atoms with distance. The end result is that the electron density is only affected by the atoms very near to our position.
Answer: I think, you are underestimating the effect of the electrons' amplitudes exponential decay.
While the wave function of a bound electron is indeed non-zero everywhere, the amplitude of the wave function falls off exponentially with distance. When you square the amplitude, you get the probability density function of finding the electron somewhere it shouldn't be classically. I.e. the probability also falls off exponentially.
Now, the number of electrons that may tunnel to some place grows with the cube of the distance. This growth is fast, but it's still just a cubic function. The exponential probability fall-off completely dwarfs the cubic growth of available electrons.
As such, the contribution by far-away electrons to finding an electron at some specific place is practically zero.
Answer: The Universe isn't even full of matter, it's more space than matter. From micro to macro this is true. The empty space is far more than what matter actually occupies. The probability of electrons outside an atom is low and being in a specific space is even lower, since probability of finding matter in space is also low and especially since the size and mass of electron is considered negligiable already when compared to protons and neutrons.
Being negligiable doesn't mean it's zero but it does mean that it's impractical, we might not have suitables tools for even measuring such small values or getting anything of practical value from such.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).


XmlException in WCF deserialization: "Name cannot begin with '<'" - in automatic property backing fields

Question: I have started experiencing errors in WCF deserialization today - in code which has been unchanged and working for months.
The issue is that I am getting runtime XmlExceptions saying 'Name cannot begin with the '<' character'. I have debugged into the .NET source, and it seems the error is in deserializing return objects from our WCF service calls. These objects are defined using automatic properties, and it seems the backing fields are given names like <MyProperty>k_BackingField, which is where the XmlException is coming from.
I've seen a couple of other references online where the solution people accept is "I changed my code to not use automatic properties", which isn't really acceptable to me, as I would have 100s of objects to change, (with 1000s of properties amongst them). Also, this same code was working fine when I ran it last week, and doesn't seem to affect all serialized DTOs, only some.
To make it even more frustrating, it seems mildly intermittent. On occasion this morning, there has been no exception thrown...!
Questions;

Why has this problem suddenly appeared in unchanged code and unchanged framework source?
How do I fix this without modifying all the DTOs to use fully implemented properties?

UPDATE: After a day or so of working fine, this issue has reappeared - no reason I can find why it would work/not work/work again, but here we are.
I have tracked the problem down further to be related to some code I have on my ServiceContracts using the ServiceKnownType attribute, which is used to define known types for serialization. It seems that although the types being reported with errors are not even part of the service call I am making at the time, that this error is occurring on types which are part of this known types 'publishing' behaviour.
The problem occurs when I use some proxy creation code to apply some service behaviours;
IOperationBehavior innerBehavior = new PreserveReferencesOperationBehavior(
    description, this.preserveReferences, this.maxItemsInObjectGraph);
innerBehavior.ApplyClientBehavior(description, proxy);

I cannot debug the ApplyClientBehavior code as it is part of System.ServiceModel (or can I?), but something in that method is trying to validate all types I have published using my ServiceKnownType attribute, and breaking on some of them with this XmlException. I have NO IDEA why some of the types are failing - and only for some of their properties.
This is an example of the types which are getting errors reported against them;
[Serializable]
public class MyDataObject
{
    public ActivitySession(string id)
    {
        this.Id = id;
        this.IsOpen = true;
    }

    public string Id { get; set; }

    public bool IsValid { get; set; }
}

The exception reported an error against Id -> <Id>k_BackingField cannot start with '<'
So nothing controversial in that class, and no inheritance to consider. It's not even part of a service contract, only it was previously published as a known type for serialization.
This is getting quite esoteric now, so I'm not expecting an answer, but just updating where the problem is at.
Comment: Can you post an sample DataContract?
Comment: I will try to isolate it further to where the problem is occurring. At present, it has decided to work again... :-(
Comment: Have updated this issue with the latest as the problem is reoccurring. I have isolated further why certain types are getting reported as errors...
Answer: I think I have found more information to help explain this issue, (at least in so far as why the error is appearing on certain types only).
The DTOs which are getting exceptions reported against them are;

published as part of my [ServiceKnownType] attribute
marked with [Serializable]
NOT marked with [DataContract]

Adding the [DataContract] attribute to the type resolves this issue. I have no idea why, and still no idea why this error is intermittent in when it happens, but consistent in what it affects.
Comment: This helped me enormously. In my case, one of my base classes was not decorated with the [DataContract] attribute.
Comment: After adding the `[DataContract]` attribute, make sure to also mark what needs to be serialized by `[DataMember]` attribute. Otherwise nothing gets serialized and the object is deserialized as blank.
Comment: Should it happen to help anyone else, this is the best solution I have come up with, though I still have no explanation, so I'm happy to accept a better answer.
Comment: Really appreciate this tip; saved me _a lot_ of time just now. My DTO was **never** marked with the `[DataContract]` attribute and it worked fine for months. One day I had to restart it and got hit with this issue out of nowhere. Adding the attribute resolved it immediately.
Answer: I looked at this question also: WCF Service Reference - Getting "XmlException: Name cannot begin with the '<' character, hexadecimal value 0x3C" on Client Side
regarding this exception:

System.Xml.XmlException: 'Name cannot begin with the '<' character,
  hexadecimal value 0x3C.'

Check if you load any xml files that they are valid (e.g. do not contain typo's like < or >
If you are using services + WCF, have a look at your Service interfaces (the interfaces with ServiceContract). This will be a good starting point. Now check to see if you have any DTO parameters in methods from the interface. Go to these DTO's and see if these DTO classes have [Serializable] or [DataContract] or similar attributes. If these classes also contain automatic properties, change them the properties to the notation with your own backing field like:
private Foo _Bar;
    public Foo Bar { get { return _Bar; } set { _Bar = value; } }

If you are lucky you will see the errors go away!
There seems to be a problem with automatic properties where the automatically generated backing field has a name similar to e.g. <>something, <>d_whatever or things like that. These names start with '<' character, resulting in that error.
In case of services and WCF, your service interfaces and callbacks (with datacontract) are a good place to start replacing the automatic properties. At least it gives you an idea where to start instead of replacing thousands of automatic properties.
Additionally try to catch FirstChanceExceptions by adding this code at the start of your application and write the messages to the console.
This will help a lot to see if the number of "Name cannot begin with the '<' character" messages is reduced or not.
AppDomain.CurrentDomain.FirstChanceException +=
        (object source, System.Runtime.ExceptionServices.FirstChanceExceptionEventArgs e) =>
        {
          Console.WriteLine("FirstChanceException event raised in {0}: {1}",
              AppDomain.CurrentDomain.FriendlyName, e.Exception.Message);
        };
https://learn.microsoft.com/en-us/dotnet/framework/app-domains/how-to-receive-first-chance-exception-notifications
This is what I found so far. Hope it helps.
Answer: I have a workaround in place now, however it's not something I can rely on -> the DTOs which are causing the problem have been removed from the [ServiceKnownType] publisher, which makes the error go away.
I'm wondering if the problem is to do with the member names I am getting exceptions on. So far I have seen it complain about;

Id
Address
UserName

It would be reasonable to expect those particular property names are in use somewhere else in the serialization or service model, causing them to be compiled differently, I guess.
Comment: Turns out maybe not - tried renaming some of these fields and get the same problem with 'MyId', 'BogusAddress', 'UserNameX'. The problem is certainly related to the types though - it doesn't like *some* names in *some* types irrespective of what the names are....!
Answer: I was hitting this issue today (first-chance exception, no apparent problem otherwise). In my case NetDataContractSerializer (NDCS) was serializing IFieldData[] (from CSLA.NET library). NDCS can serialize arrays, it is also able to serialize objects that don't have [DataContract] attribute applied to it. In that case the serializer infers the contract – all public read/write properties and fields of the type are serialized. It is documented here: https://learn.microsoft.com/en-us/dotnet/framework/wcf/feature-details/using-data-contracts
So in my case, one of the objects in the array had a reference to Fraction (my own class) defined as follows:
public sealed class Fraction
{
    public int Numerator { get; private set; }
    public int Denominator { get; private set; }
    public double Value { get; private set; }
}

It is causing WCF to throw the "Name cannot begin..." exception, which is caused by the fact that the automatic properties are using generated private fields named like <Numerator>k__BackingField. If you add [DataContract] attribute to the class, then you must explicitly mark what needs to be serialized by [DataMember] attribute. That makes the exception go away. The serializer is not touching the private fields anymore.
In my opinion, it is a bug in WCF. The inferred contract should be only using the public surface of the class, which does not have any naming problems. It should not be snooping on private fields (compiler-generated or not).
My answer supports/supplements what RJ Lohan and juFo said earlier and I upvoted their answers.
Answer: The best way to figure out which field is giving you the problem is to inspect the StackTrace as the error comes up:

The answer, in my case, was to change the auto property to have explicitly declared backing fields to avoid the possibility of this naming.  So
public string ScreenName { get; set; }

becomes:
private string _screenName;
public string ScreenName { get { return _screenName; } set { _screenName = value; } }

Answer: For anyone else having this issue: If you have XmlException checked in Visual Studio's exception settings, it'll throw even if the exception will get handled in System.Runtime.Serialization. I spent a good 20 or so hours trying to work out why my code had suddenly stopped working when I turned on all exceptions - it wasn't actually a fatal exception, it was just ~1200 caught XmlExceptions.


How do you link questions you asked on a different computer after creating an open id?

Question: I'm new to these sites and posted a question on a work computer. I got great results and when I got home made an open id and signed up. Is there any way to connect that question to this account or is it lost forever in the ether?
Answer: Assuming you can find the question you can flag it for moderator attention and ask for the accounts to be merged.
There will probably be some e-mailing between the team and you to verify ownership, but that's normal.


Why do cathay pilots forget their flight number?

Question: I hear so many times over frequency "cathay.. uh.. xxx" and always wonder if they have some kind of reason why pilots cant seem to memorize it.
Answer: Commercial pilots rarely fly the same flight number twice in a row, they may be on flight 010, then 218, then 037. Commercial airplanes have a place to put the flight number in the cockpit so the pilots can read it, sometimes a pilot will start to transmit and realize they can't remember the callsign and they have to look at the piece of paper, which is why they pause.
The same is true with GA airplanes, I belong to a flying club with 10 different planes, each with a different registration, and I may fly any one of them on a given day. The registration is generally placarded on the dashboard, I have more than once started a call and had to refer to it.
Comment: yes sir I understand, I fly for airlines also, and we use a memory aid on the yoke where we can set the flight number. It's pretty conveniently located so you can see it easily, which is also why im wondering
Comment: Nobody knows for sure @Dededkd, there's many competing scientific theories on memory. My personal view is that when Aviating, Navigating and Communicating in a complex and challenging environment callsign is a low priority for mental processing.
Comment: It is a abstract number with little or less meaning to some existing memory, while a city as destination should have already some mapping in the brain to existing information.


What is more grammatically correct?

Question: I can never understand why some people always got something negative to say. or
I can never understand why some people always have something negative to say.
Answer: Neither is wrong; this is what's called a difference of register by linguists:

In linguistics, a register is a variety of a language used for a particular purpose or in a particular social setting. For example, when speaking in a formal setting, an English speaker may be more likely to use features of prescribed grammar than in an informal setting—such as pronouncing words ending in -ing with a velar nasal instead of an alveolar nasal (e.g. "walking", not "walkin'"), choosing more formal words (e.g. father vs. dad, child vs. kid, etc.), and refraining from using words considered nonstandard, such as ain't.
— This excerpt is from the Wikipedia page Register (Sociolinguistics) and CC-BY-SA 3.0 licensed.

 "Some people always have ..." is the preferred form in formal registers, and in some informal register+dialect combinations.  In other informal register+dialect combinations, "some people always got" or "...have got" would be preferred.
From another perspective, what's going on here is the beginnings of a language change: early modern English only permitted have in this context, but contemporary, informal spoken registers have begun the process of changing the preferred verb to got.  Since the formal, written register of the language is slower to change, it still prefers have.  (Note: I do not know how long got is attested in this context; this kind of change typically takes centuries to complete.)
Comment: Here at Stack Exchange, we "[insist that opinion be backed up with facts and references](https://english.stackexchange.com/help/dont-ask)", and while you start off decently in this regard by using a reference, the opinion that this is merely a matter of register is still uncorroborated. A more detailed account of our expectations can be seen in [Good Subjective, Bad Subjective](http://tinyurl.com/mcov4oq). Can you back up your claim by showing instances of the variations in use, inform us how you learned this or explain something about your own experiences with the varying forms of register?
Comment: @Tonepoet I _could_, but considering that this has been closed as a duplicate, I don't think I can be bothered.

What is more grammatically correct?


working with multiple remote desktop sessions

Question: I remote desktop from my home pc to my work pc. When on my work pc I often have to remote desktop from it to a web server. This expands in the whole the screen which means if I have to return the my work pc I must close down the remote desktop session in web server. The only way for security reasons I can access the web server is through work pc. Is there any way to minimize a remote desktop session (web server) and not having to close it?
Comment: Do you have the latest remote desktop client installed on your work PC?  You should be seeing a bar at the top o the screen that will allow you to minimize the second connection.
Answer: We often use Remote Desktop Connection Manager for managing our multiple RDP sessions.  It supports many of the features of Terminals and is free.
I hope that this helps.
Comment: +1 I **LOVE** RDCMan - the ability to arbitrarily group servers is brilliant, especially if you have servers at multiple sites.
Answer: Using windows RDP client, the pinned toolbars at the top of the screen are covering each other so you can't see the toolbar on the web server. Two options I can think of:

Unpin the tool bar that appears in your work PC RDP session. This will make the tool bar auto-hide, exposing the toolbar of the web server
Before opening the RDP session to the web server, go to Options >> Display section of the RDP client and force the web server RDP session to open in a smaller window.
Answer: You didn't mention your operating system.  If you are on Windows and have the ability to install software on your work system, you might find the Terminals application useful (http://terminals.codeplex.com/).  Among other features, it has a tabbed interface for remote sessions.  We use it quite a bit for exactly the situations you describe.
Answer: No not really, VPN to work computer then directly RDP to server? I am not sure but it sounds like the title bar is going away, click the thumb tac and it will stay up.
Answer: I use Royal TS:
http://www.code4ward.net/main/RoyalTS/Overview.aspx


What verb or phrase do you use to describe the situation where someone is sitting in a rolling chair and they push against the floor to move around?

Question: What verb or phrase do you use to describe the situation where someone is sitting in a rolling chair and they push against the floor to move around.
Answer: I would use the word slide. If being in a chair isn't obvious from context, you'll probably need to make it clear.

Let me get a closer look. I'll slide over to you.
The boy got hurt after sliding quickly around in a rolling desk chair.

You could also use push as you did in your question:

I'll just push myself over to the conference room.

These all are informal, but mostly because it's a fairly informal topic of conversation to begin with.
Answer: Other options are scoot (as in "(kick) scooter") or skate (as in skateboard).
Of the two I'd prefer to use the former, for example, "In one old job I could scoot my chair to my boss's desk and turn it to face the right way in one push" (which is true, though not acceptable in all workplaces).
Answer: There are a number of possibles, but there probably isn't one specific word that fits particularly well. Here are three possibles, but there are probably a lot more.
In a small boat, if you are using an oar on each side like the picture, it is called "sculling." So that might work for using both feet.

If the person was using one foot only, it might be "poling."

If they are using furniture by grabbing it in addition to pushing with their feet, you might call that "crawling."
Comment: The answer is good, but what if I am changing position around an office siting in an chair with casters by pushing against the floor with their feet?


Could Space Travel be achieved using a very strong magnetic field to warp space?

Question: An Alcubierre Warp Drive could theoretically achieve faster than light space travel but requires exotic matter or negative energy to compress space in front of the spaceship and expand space behind it. Could a similar effect be achieved by only compressing space in front of the spaceship?
As the spaceship fell into the gravity well and moved forward, space would automatically expand back to normal behind the ship as it rode the distortion wave. If this propulsion method worked, it would require only a fraction of the energy needed by the Alcubierre Warp Drive.
Also, if space could be compressed ahead of the spaceship using a very, strong magnetic field, no exotic matter or negative energy would be needed, just the electromagnetic force. Even if faster than light travel could not be achieved this way, a small constant acceleration, maintained over a long period of time would achieve a high near light velocity.
Comment: More Phys.SE questions about Alcubierre drive: http://physics.stackexchange.com/search?q=is%3Aq+alcubierre
Comment: Neat article: http://www.hawking.org.uk/space-and-time-warps.html and this video: http://www.youtube.com/watch?v=YzMrNFd4oOk
Answer: Yes if it was possible the focus the magnetic field like a laser and use another planets magnetic pole as a tether. The magnetic beam would have to be very fine not to collect metal space junk.
Comment: I don't see why a laser-like magnetic field would be able to make warp drives.


A Massive Organism Living In The Vacuum Of Space

Question: Okay, here me out: I am designing an massive, kilometers-long at the absolute minimum, creature that lives in asteroid belts in the vacuum of space. It hosts an entire ecosystem of living things like macroscopic unicellular organisms inside its body. It eats asteroids, using enzymes to break them down for sustenance, and has skin that keeps its insides pressurized and safe from harmful UV radiation. Its body retains heat so that it doesn't freeze in the vacuum of space that it spends its whole life in, and it is capable of reproduction. In order to move, it orbits its sun, and ejects waste to propel itself, slow down, and turn. How would that organism be scientifically plausible?
Comment: If you are the same Tyson Dennis as this other [user](https://worldbuilding.stackexchange.com/users/80933/tysondennis) you can request the two accounts to be merged to keep the reputation
Comment: The hardest part is that there is *no liquid solvent*. Chemistry without a solvent is very, very hard. Another really difficult challenge is getting between asteroids because "space is big" (TM).
Answer: Hard to believe scientifically speaking
There is a bit of a misconception about asteroid belts: they are not that dense of elements. First of all they are not uniformly spread. Secondly you can find some information about the approximative average distance between two "big-enough-to-be-detected" asteroids: ~3 million kilometers (we are speaking about asteroids >1km large). You can find this information on the Physics Stack Exchange if you want the maths behind.
I get you don't have to focus only on the big rocks (let's say it has a really slow organism so he don't need to eat alot) but you are saying your living entity is moving by using the ejection of wastes and at the same time this monster is kilometers long so it has to use something big to counterweight that to move to the next asteroid (which supposely is ~3M km, and by guessing your monster can detect them). Orbiting the Sun does not give you deltaV so if it slow down it has to reaccelerate.
So hardly believable in my opinion if you want to back this idea with hard science.
Comment: It's implausible, but not exactly impossible.
Answer: Scientifically possible, though unlikely
On the question of biological possibility, space does pose some challenges: a vacuum, radiation, and wild temperature variations to name a few. Luckily, we are aware of extremophiles capable of surviving in many of these conditions. Radiotrophic fungus found in Chernoybl lives off radiation. Thermus aquaticus can survive up to 80°C/176°F (a feature we've much exploited). Tardigrades can survive exposure to space itself as well close to absolute zero. Simply put, if life evolved on Earth can handle many of the worst problems of space (though not necessarily thrive), an organism specifically evolved for space should be possible.
Such an organism would exist in a symbiotic relationship with the ecosystem inside it, providing protection from the vacuum in exchange for the ability to process the contents of its food (similar to the gut microbiome of humans). The creature would have to be sole primary source of energy to the system, similar to how plants/phytoplankton allows Earth's ecosystem to capitalize on solar power. Nutrients are fairly scarce in space, and supplying the energy for both a kilometers long creature and its internal microbiome is no easy task. Evolution does not favor the inefficient, so max utilization of available energy is expected. Therefore, it should evolve the ability to passively absorb the light and radiation energy going through space via photosynthesis and radiosynthesis, respectively.
That's not to say there is no use for eating asteroids. For starters, in order to propel itself around the it needs to acquire mass to do so. For Newtonian physics reasons. In addition, the materials gained from an asteroid will probably be necessary to preform many hyperspecfic biological functions, which we can offload to the microbiome inside.
A creature that large should require a similarly sized amount of energy. However, not all parts of an organism actually need to be "alive". Only about 1% of a tree is actually alive. Similarly, many animals have developed shells which are hard but not full of living cells that need to be supported. This is a simple way to keep the desired size while reducing the energy needs. Since you can just float your way around in microgravity, the drawbacks of large amounts of dead weight like that are relaxed. Such would also block and leaked radiation from reaching the core. I'm imagining most of the creature is a hard shell/skeleton and the living part is merely essential organs and systems connecting them.
Asteroids are fairly far apart, which gives a long lead time to intercept them. Without any natural born space predators, it moves at the slowest speed it can get away with, minimizing the muscle mass it needs to support. Move in this sense would mean angling its propulsion or adjusting its angular momentum, as Newton's first law handles the actual locomotion part. Another organ I can presume is highly advanced eyes to scope out any asteroid hundreds/thousands of kilometers down its trajectory.
The biggest issue with its existence is its evolution. I simply can't see how such a creature would evolve nor how all it's evolutionary ancestors would survive in space. Though perhaps if the universe really is infinitely large, then a panspermia like process might have just the creature, or one that can conveniently adapt to its new situation floating in in asteroid ejected from some cataclysm on a planet where life actually evolved which happens to get trapped in the orbit of a star with just the right type of asteroid belt is one of the infinite possibilities the universe has to manifest.
Comment: I would be thinking that such a creature would be mostly its hard outer shell.


How C. Elegans is used for siliencing genes

Question: The experiment that is using C. Elegans to silence the Genes. I have a question about Why and how C. Elegans can use the DNA plasmid that is generated with the gene of interest in the bacteria by being fed the bacteria?
Comment: If you describe your procedure in a little more detail it will be easier to tell exactly what you are doing, but basically the cells of the C. Elegans can be induced to take up the plasmid and that can be transcribed by an RNA polymerase. The Messenger RNA is then translated by the ribosomes to produce a protein that inhibits the transcription of the gene of interest. If it is RNAi, then the RNA produced will hybridize with the mRNA transcripts that are being produced by the gene of interest. dsRNA cannot be translated and even if some of the mRNA is, the protein will be nonfunctional.
Comment: If you are actually doing recombination, then you likely linearized your plasmid with a restriction enzyme and the plasmid has homology arms that will allow it to be combined into the genome of the worm's cells. The success rate is usually low without some form of technology like CRISPR or Talens, so if you are using those, then there is likely some form of targeted DNA break that is happening to allow for homologous recombination to integrate the linearized plasmid into the chromosome of the worm.
Comment: It sounds like you are performing RNAi... this procedure explains what is going on. http://www.jove.com/science-education/5105/rnai-in-c-elegans They take the bacteria up in vesicles, digest then which releases the RNAi that the bacteria has produced and that intern goes on to hybridize with the mRNA of the gene of interest, as I said above, that binding either stops translation altogether or the protein product is no functional.
Comment: If it's what I'm thinking of, you probably have GFP+ worms that end up getting fed some DH5-α *E. coli* that were transformed using CaCl2. The outcome is your control worms should nicely fluoresce, and the experimental worms will be a noticeably weaker color. The RNAi process is explained nicely in that link provided by AMR.
Comment: Thank you AMR and Kendall for explaining this to me!! and Thanks for the video. It helps a lot to understand the concept. Thank you!!!
Answer: From the way that you have described your experiment, feeding C.elegans bacteria that are expressing a plasmid that will induce gene silencing, then both @Kendall and I think that you are likely performing an RNAi (interference) experiment.
As @Kendall writes:

If it's what I'm thinking of, you probably have GFP+ worms that end up getting fed some
DH5-α E. coli that were transformed using CaCl2. The outcome is your control worms should nicely fluoresce, and the experimental worms will be a noticeably weaker color. The RNAi process is explained nicely in that link provided by AMR. –  Kendall

The bacteria will transcribe RNA molecules encoded by the DNA plasmid. These RNAs will have complimentary sequences to sequences from your gene of interest.
When the nematode eats the bacteria, they RNA molecules that the bacteria has produced will be taken up by the cells of the worm.
The Dicer enzyme then cleaves the dsRNA into small fragments. These fragments are then able to hybridize with the mRNAs transcribed from the gene of interest. This will either cause the ribosomes not to bind properly or will start translation out of frame or without key amino acids or will terminate translation early.
The net effect is that the cells will either not produce the protein encoded by the gene of interest or will produce a non-functional protein. If, as @Kendall said, the gene of interest is a reporter gene such as GFP, then the result of the interference experiment will be C.elegans that do not fluoresce. If the gene of interest is a structural protein such as actin, then you will see the effects of knocking out the actin gene on the cells of the worm.
This online video protocol from JoVE.com gives a detailed overview of the RNAi in C.elegans experiment and also demonstrates how the protocol is carried out.