Its 12 billion light years away. Just keep in mind that this is what it looked like 12 billion years ago => it takes the light 12 billion years to reach the Earth. So the image as seen is really that old!
That's not how it works. If we observe an object that's currently 12 billion lightyears away (i.e., its co-moving distance is 12 billion light years) the light we observe was emitted much less than 12 billion years ago. While light is in transit, both the distances ahead and behind it will increase due to Hubble expansion, so once you get up to cosmic scales like these the normal distance/velocity formulas don't apply.
In general, if you point a flashlight into space and wait one year, the distance between you and the photons of light will be slightly higher than one lightyear. As you wait longer, this difference becomes less slight. When you get up to much larger scales (billions of lightyears) the Hubble expansion dominates the equations.
In the most extreme cases, you get counterintuitive things popping up like distances that are so large they can't be traversed in any amount of time, even at light speed. Until you're using equations that make that seem natural, you shouldn't rely intuitive calculations from NASA press releases like this. Convincing science journalists of this fact is one of my minor life goals.
That depends greatly on when in the history of the Universe the light was emitted. The scale factor varies over time. What you probably meant though was "How long did the light that we're seeing from this particular quasar take to get here?" That we can figure out.
When you get a problem like this one, the quickest way to get an approximate answer is by interpolating from the following rule of thumb: If we see light today that we know has been in transit since the start of the Universe (15.3 billion years ago), the point it was emitted from is now 46 billion light years away from Earth. If you just assume that the impact of the Hubble expansion is more-or-less proportional to the current distance of the object in question, we can just linearly interpolate between the observed Universe-scale answer and the intuitive Newtonian answer that applies on normal scales.
By "light today that we know has been in transit since the start of the Universe" may I presume you mean the microwave background often referred to as "remnants of the big bang"?
Where should I go to understand the derivation of the figure "now 46 billion light years away"? It's not clear to me what you mean by "now" and "away", since time and distance depend on the frame of reference, and it's not clear to me what it means to be "at rest" in an expanding space. "At rest" enters in because we're not going backwards in time, and thus we cannot reach the source of the radiation (the event which generated the radiation at a specific space-time coordinate), but only the event's spatial coordinates, and, absent other specification, those spatial coordinates are "at rest" with respect to our own frame of reference. But again, what does "at rest" mean in expanding space?
AFAIK, there is such a thing as a CMB 'rest frame' (the Earth-Sun is moving relative to it at about 600km/s).
As for the weird distances, just imagine an ant moving across a rubber surface at constant velocity. The rubber is slowly stretched over time, so while the ant continues at the same rate it will actually cover less space. If the rubber continues to stretch, there is an event horizon effect, meaning some distant parts of the rubber sheet will become inaccessible.
The answers to the first two questions are related, and unfortunately complicated. I was almost referring to the Cosmic Microwave Background Radiation (CMBR), but I actually meant a slightly older event, the end of the inflationary epoch.
The inflationary epoch is rarely understood, but it's really so qualitatively different from everything that came after that it's worth referencing as a starting point for the Universe as we know it. Intuitively, you can think of the inflationary epoch as an extremely brief flash of time where things were so bizarre that nobody really has any firm idea what the hell happened. What we do know is that somehow the Universe expanded by a linear factor of at least 10^26 (it could actually be septillions of times higher; we just have a lower bound) within a tiny, tiny fraction of a second and then pretty much stopped.
Theoretical physicists mostly agree that the Big Bang happened a tiny fraction of a second before the inflationary epoch ended, but it's all speculation at that point. Pragmatically, it's very useful to call the end of this epoch the "beginning" of the Universe even if strictly speaking it started a few trillionths of a second earlier. Inflation was so fast that you can't really describe anything useful in terms of pre-inflationary distance. Everything that we could ever observe or care about in the Universe all emerged from some volume of space that was smaller than an atom until right before inflation stopped.
Why inflation stopped is very much beyond my understanding, but the metric expansion process that took over afterward, Hubble expansion, is negligibly slow by comparison. It's so slow that it's generally ignored in any context with time scales shorter than hundreds of millions of years. This is an important point for establishing what exactly we're talking about when we say the "beginning of the Universe". As far as the expansion of the Universe goes, the places that things were in 10 seconds after the Big Bang is more-or-less where they were the next day, and the next year, and the next millenium. Hubble expansion only matters over really big distances or really long times, like billions of years.
So, to finally answer your question, this is why I just said "in transit since the start of the Universe" without any other explanation. In practice, it doesn't matter whether you take it to mean "10 seconds after the Big Bang" or "10,000 years after the Big Bang", just so long as you're referring to distances that applied somewhere near the start. Most notably, the Cosmic Microwave Background Radiation was emitted by an event that occurred only 300,000 years after the Big Bang, and there's good reason to think we're not likely to ever do better than that in terms of what radiation we can feasibly detect. This is why you hear it described as "remnants of the Big Bang", though really it was more directly caused by the formation of hydrogen 300K years later.
The 46 Glyr figure is admittedly ambiguous, and could refer to either of two things. The first is what's known as the surface of last scattering. This is what the CMBR is all about. The CMBR basically happened everywhere at once, and as you go further into the future the light that you're seeing from it came from somewhere that was further and further away at the time the CMBR was emitted. Right now, the light we're seeing from the CMBR came from points in space that are currently 45.7 Glyr away. (In cosmology, distances are almost always given in terms of present-day distance for consistency. This is called the "co-moving" distance if you want to be explicit, which alleviates confusion that might result from just calling it the "current" distance.)
The second thing the 46 Glyr could be is what I was actually referring to: the radius of Earth's particle horizon. This is the co-moving distance between us and the most distant point that would be reached if you emitted a light-speed signal from Earth's location right after the end of the inflationary epoch. This also coincides with the "observable universe", the portion of the Universe that was sufficiently close to us at the end of inflation that signals emitted from it could in principle reach us today. The two concepts are really equivalent, just with different frames of reference. This region has a boundary that's about 2% larger in diameter than the surface of last scattering. That extra 2% corresponds to the distance that radiation could have traversed theoretically (but not actually, due to plasma interference) during the 300,000 years that elapsed before the CMBR was emitted.
I don't have time to give a proper answer to your "at rest" question, but very tersely: The assumptions about simultaneity and privileged reference frames that get pulled out from under you by special relativity are actually pretty reliable in cosmology. You can, as a practical matter, be very sure whether or not your space ship is moving or not by looking at the stars around you. Most people are so caught up in the idea that the Earth is moving around the Sun and the Sun is moving around the Milky Way that they never bother to learn that the pattern doesn't actually go any further. The largest-scale structures of space are foam-like clusters of billions of galaxies, which become less distinct and more homogenous as you zoom out. Galaxies themselves do very little movement beyond drifting along with the metric expansion of the space time they're sitting in. Most "peculiar movement" is caused by gravitation within galaxies, not between them. This is quite literally what a galaxy is: It's a cluster of matter where gravity causes stars to have a peculiar velocity that cancels out the metric expansion of the space between them.
Given that its distance was more than likely measured by the light, I would assume that 12 billion light-years was the distance when the light was emitted; not its current distance.
So, correct me if I'm wrong, that renders your whole point about Hubble expansion moot, no?
Nope. If the quasar were 12 billion light-years away when the light was emitted, the light would never have even reached us! In this scenario, the distance between the quasar and Earth that the light needs to traverse would undergo metric expansion that would hugely outpace any progress made by the light's motion (more precisely, its peculiar motion) in the direction of Earth.
Even the photos take artistic license. More often than not, the spectrum used is out of the visible range, and therefore has to be translated into a visible color scheme.
Firstly this kind of vulnerability requires no white-boarding. It is fair to assume that a dev with a reasonable understanding of how the web protocols work will not need a white board to figure this out. So firstly the argument of catching this on a WB is a little juvenile.
Associating TDD to being haphazard is pretty random. Being hap hazard and TDDing are really in 2 different math spaces. Care not to mix em?
Here is the ruby library that I used https://github.com/ashwinraghav/marvin. It can help you write a pure ruby application that you can later convert to an event-driven app(If you wish)
Thanks for bringing up the web-app vs chat bot straight away. I did get some questions on these lines during the conference itself.
1) I do not agree that maintaining bots and web apps are the same effort-wise. An IRC can very easily be served of a framework that is event driven in nature -- on the lines of a node.js or eventmachine with barely any additional effort. On the other hand, doing this for a web application would require extensive effort for writing your code the right way and bringing in the right tools like a templating engine. You will build your own framework almost.
2) Since the application is process heavy and take over 45 seconds to serve a request, this would involve extensive tweaking of your forward proxy which in the case of most data centres and clouds will simply respond with a "Service Unavailable" after 30 seconds. Off course you can defer this to a background job and provide the results elsewhere on your application. But like I said, you would be doing things that the user actually does not need.
3) How would you scale up such an operation heavy application if it were a web app. Have 1000 background jobs running for a 1000 users? An event driven approach will pay off for sure. And 1) illustrates why its easier to do this with a bot.
The real disadvantage I came across was to be able to get it to work with a load balancer. I can write about this if there is more interest.
