First Successful Test of General Relativity Near Supermassive Black Hole - <AUTHOR> https://www.eso.org/public/unitedkingdom/news/eso1825/?lang <comment><USER2> I'm always a little disappointed when these experiments are unable to disprove General Relativity. I keep hoping that they'll discover something slightly wrong about it, which will quickly lead to us figuring out how to develop a practical warp drive which doesn't require negative or nearly infinite energy.

<comment><USER3> I never thought of c being a real problem to space travel. Sure, on the timescale of our lives c is sloooow because moving between stars automatically necessitates a multi-generational approach and/or huge amount of resources. The big problem however, is that we have no place to go. We are tied to earth. Our bodies are made for a specific gravity constant, specific distance from a specific star, specific atmospheric mix of gases, a pre-existing DNA-based fauna and flora, etc. Quite simply, when it comes to colonization: there's no place like home. Every other place sucks for our bodies.

Once we achieve the singularity(tm) and upload our consciousness (or get replaced by AI), we can turn down the clock speed on the matrix (say turn 1,000,000 real years into 1 matrix year), and like magic c stops being a practical limitation. Sending message (or travelling) from one side of the galaxy to another would take a 'matrix month' .. turn the clock down even further and you can make galactic communication instantaneous.

<comment><USER4> You could actually reach almost anywhere in the galaxy within a single human lifetime (the traveler's lifetime that is) using only 1-G constant acceleration: [https://en.wikipedia.org/wiki/Space_travel_using_constant_ac...](https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration)

No FTL required. We just need to figure out how to use propellant efficiently enough among a few other slightly difficult challenges.

<comment><USER2> The problem with this is that, by the time you get anywhere, a ridiculous amount of time has passed back on Earth, and also on the destination planet (since the reference frame for the other planet is very close to Earth's). So if you travel around to hundreds of planets, pretty soon all the stars have gone nova and you're nearing the heat-death of the universe, even though you may not have aged much.

<comment><USER5> I never really understand this. From the Wikipedia link: "At a constant acceleration of 1 g, a rocket could travel the diameter of our galaxy in about 12 years ship time, and about 113,000 years planetary time." But that's from the frame of reference of planet earth. If you are on the spaceship, earth will be moving away from you so time on earth will appear to be slower than your time. So if you come back to earth you will appear younger than should be to the people that stayed, but to you people that stayed will appear younger than should be. Frames of reference are equivalent, aren't they? Maybe I'm rambling, but I can't figure this out.

<comment><USER4> [https://en.wikipedia.org/wiki/Twin_paradox#Resolution_of_the...](https://en.wikipedia.org/wiki/Twin_paradox#Resolution_of_the_paradox_in_special_relativity)

<comment><USER6> Great article!

</comment></comment></comment></comment></comment></comment></comment><comment><USER7> Gravitational lensing has to be the coolest thing ever. That we can use a black hole as a telescope to see such incredibly distant bodies just leaves me with a childlike giddiness whenever I think about it. What's almost as incredible to me is that someone figured it out before we could prove it.

<comment><USER8> It's also nice that we apparently can "take" a black hole millions of times as massive as our own system, and use it for our purposes.

It's likely the single biggest part of a scientific instrument. (Not of an industrial tool... yet.)

<comment><USER9> There's not really any materials or conditions beyond one's immediate locality that would be worth seeking out in space. Interstellar communication is going to be limited at best, interstellar industry or trade may never be practical, and even if one is willing to accept the idea that there is some purpose for which a black hole is useful, I would still be skeptical that a _supermassive_ black hole would be of more use than a smaller one.

<comment><USER10> I agree. I don't think the aeroplanes will ever been able to achieve lift. I'm skeptical of anyone who attempts anything that hasn't been done before.

<comment><USER7> New revolutions in science have tended to be less "we were totally wrong" and more "in extreme cases things don't quite fit the models". It's conceivable that FTL communication and travel aren't as impossible as we currently think, but that would require that things we've demonstrated fairly well are completely wrong. The same wasn't true with heavier than air flight, which (as the other comment notes) we had proof of it being possible (in birds). We knew it was possible in theory, but figuring out how to actually work out the mechanics of the process were the sticking points.

[https://chem.tufts.edu/answersinscience/relativityofwrong.ht...](https://chem.tufts.edu/answersinscience/relativityofwrong.htm)

<comment><USER11> There are huge parts of physics that remain a mystery( dark matter, dark energy, the big bang, like how on Earth does inflation make sense, a ton of crazy particle physics that go completely over my head). And the funny part is that a lot of these can't be really fit into our current models in a meaningful way. So until we deal with all those I still have hope for an FTL drive.

<comment><USER9> Physics is very difficult, and magical thinking is much easier and more fun. Relativity is a description of the geometry of the universe, and any subsequent theory will need to explain the same observations. These observations both prohibit any form of FTL, and suggest that a universe with FTL would almost certainly contain causality violations. The hope that down will someday become up is ill-founded, and the effects of this would not be what you would want.

</comment></comment></comment></comment></comment></comment></comment><comment><USER12> I always hope the images in these articles will be real and not artists' impressions, but they never are

<comment><USER13> Until we sent a probe, this[1] was the best image we had of Pluto, taken by the Hubble space telescope.

Pluto has a radius of 1188 km. The supermassive black hole at the center of our galaxy[2] has a Schwarzschild radius of about 1e7 km, so roughly 10000x larger than Pluto.

However it's also roughly 50000000x further away than Pluto... which is why it remains a mysterious blob until the Event Horizon Telescope[3] delivers.

[1]: [http://hubblesite.org/image/2686/news_release/2010-06](http://hubblesite.org/image/2686/news_release/2010-06)

[2]: [https://en.wikipedia.org/wiki/Sagittarius_A*](https://en.wikipedia.org/wiki/Sagittarius_A*)

[3]: [https://eventhorizontelescope.org/](https://eventhorizontelescope.org/)

<comment><USER14> Given the sorts of scales, would there be a hard limit to what we can see? Where we get to such a distance the dispersion of photons from the source would never allow us to see it? Or do we just have to build bigger and bigger photon collectors?

<comment><USER15> [https://en.wikipedia.org/wiki/Diffraction- limited_system](https://en.wikipedia.org/wiki/Diffraction-limited_system)

The first problem is that we are limited to observing that photons that originate at the source; there's no way for us to bounce some small-wavelength photons off of our target and collect them.

So we could do long-baseline interferometry, instead. You need to spread your sensors over a large area and keep synchronized timing.

[https://en.wikipedia.org/wiki/Radio_telescope#Radio_interfer...](https://en.wikipedia.org/wiki/Radio_telescope#Radio_interferometry)

Naturally, you can build bigger systems in space. [https://en.wikipedia.org/wiki/Space_Interferometry_Mission#O...](https://en.wikipedia.org/wiki/Space_Interferometry_Mission#Optical_interferometry)

If we sent out satellite telescope stations to orbit the sun, with really good communications and clocks, we might be able to create a virtual lens that's really big:

[https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Ant...](https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna)

</comment></comment></comment></comment><comment><USER16> > GRAVITY creates such sharp images that it can reveal the motion of the star > from night to night as it passes close to the black hole — 26 000 light- > years from Earth.

Amazing.

</comment><comment><USER17> I have to admit that when I read this kind of stuff I am always amazed with those who truly grasp it. I feel the same when listening to great musicians and viewing great art.

</comment><comment><USER18> "More than one hundred years after he published his paper setting out the equations of general relativity, Einstein has been proved right once more — in a much more extreme laboratory than he could have possibly imagined!"

This sounds somewhat like an insult to Einstein's imagination.

<comment><USER19> Up to his death Einstein denied that black holes could physically form.

<comment><USER20> And he is right. Time dilation means it's impossible for them to form. (From the POV of me, here on earth.)

<comment><USER21> Considering astrophysical evidence to the contrary as well as multiple simplifications(∆) underlying your argument, I'd say he was probably wrong.

∆) (Some of) the assumptions underlying your argument are the following:

Assumption 1: We're observers at infinity, observing time as given by the usual Schwarzschild/Kerr coordinate t (let's focus on Schwarzschild for simplicity). Yes, the argument in favor of this is that such observers observe Schwarzschild spacetime to be flat at infinity (which is more or less what we see) but there are certainly other[1] asymptotically flat foliations of Schwarzschild spacetime which don't have a coordinate singularity at the horizon and thus don't exhibit the behavior you describe. I have yet to see a convincing argument for why we, as observers, couldn't perceive _any_ of these other foliations of Schwarzschild spacetime and for why we _definitely_ wouldn't live to see someone else cross the event horizon. (I mean, the fact that this doesn't work in the usual Schwarzschild coordinates is really a consequence of their singular behavior at the horizon, so should be resolved by _any_ smooth/non-singular choice of coordinates—of which there are infinitely many.)

Assumption 2: You're talking about a static black hole solution (or a simple spherical shell collapsing) while realistic scenarios of black hole formation are an entirely different beast.

Assumption 3: You cannot superpose / easily glue together solutions of Einstein's field equations. So I'd be at least careful making a statement about us, here on Earth, when it comes to a distant black hole.

[1] [https://en.m.wikipedia.org/wiki/Gullstrand–Painlevé_coordina...](https://en.m.wikipedia.org/wiki/Gullstrand–Painlevé_coordinates)

<comment><USER22> From our perspective and according to the general consensus idea that the universe is of finite age and fully in accordance with all black hole models and general relativity, blacks holes cannot exist in our universe. That does not mean what we have observed is not interesting, It is, but we don't know what it is, though we know it is not the "black hole" of theory.

There are no circumstance under the prevailing theories for which any kind of "black hole" can come into existence anywhere in our universe. Black holes are wonderful "flights of fancy" just like the Stargate and the Ancients Hyperdrive and just like the Star Trek Warp Drive.

"Black Holes" require certain assumptions for their formation in the theoretical sense and since those assumptions are not found in our universe, all models of "black holes" have an automatic failure point. All discussions about "black holes" being real, ignore those discrepancies and assume that they can exist. If you fail to agree with the "reality" of "black hole" formation, you become persona non grata.

The problem with the "black hole reality" assumption is that we cut off entire streams of investigation into what the observed phenomena may be. We are stuck in a very little corner of the universe and we cannot see many things up close. Our model assumptions colour our understanding of what we see. There are many of our observations that are anomalous to the prevailing theories that are considered "correct". Yet, if you (as an observational or experimental scientist) raise questions in relation to the consensus models, you will be quickly put in your place.

It is quite interesting that for a supposedly advanced civilisation, much of our technology and scientific endeavour is ruled by dogma. This does not lead to the advancement of our understanding of the universe around us. Just as other people have said before me and as I have said before - "There are no silly or stupid questions".

Science is one useful tool we have for investigation of the universe around us. But the outcomes we find using it in our investigations of the universe around us are predicated on the basic assumptions we bring to the table in those investigations. It is one tool among many that we have and when people use it as the only tool that has meaning, they have moved it from being a useful tool to being a dogmatic tool. they have made science into a religion.

<comment><USER23> _> There are no circumstance under the prevailing theories for which any kind of "black hole" can come into existence anywhere in our universe_

You are peddling misinformation here. You really need to get a correct understanding of black holes.

<comment><USER22> I have been occupied with other things and only now have the time to respond.

Every model of "black hole" has as a fundamental underpinning which is time dilation due to increasing gravity (by whatever definition of gravity you may use). At whichever "event horizon" you may choose (in discussions with physicists, they have claimed a minimum of three different event horizons), time at the event horizon as observed from the universe at large stops. The underpinnings of "black holes" requires an eternal universe, no "big bang", no finite age. Formation as we see stops and can never proceed in finite time. We live in a small isolated part of our galaxy and we are unable to observe clearly many sections of our own galaxy. We rely on proxies and a belief that these proxies are adequate to match to the models and theories that are considered to be correct by consensus.

If you think about "black hole" formation as described by the various models in use, there are a number of assumptions made that don't actually match what see in our observable universe or in any practical experiments we do.

I am no mathematician or theoretical physicist, but every source of mathematics that I have studied and am continuing to study makes it quite clear that our mathematics is approximate in its mapping to reality. There is nothing wrong with this technique, but it does mean that one has to take what results we get with a grain of salt when comparing to the actual universe around us.

I find that when any of the many mathematical models in use today is declared as "reality", then I see this as the peddling of misinformation. Mathematics can and does provide us with a tool that is useful in describing what we see around us. But it is limited and always has its failure points. It is interesting that I have had this discussion about disagreeing with the consensus view with someone (a physicist) who argue for it, yet they themselves hold a particular non-consensus view over other matters relating to cosmology and could not see the extended possibilities in looking at different potential models and theories.

The simple point is that the mathematical models and theories are possible maps of the territory and are not the actual territory itself. It doesn't matter how detailed that map appears to be, it is still missing a great deal of the detail of territory itself. When it is used to decry alternative models because they are different, without actually testing those models for any kind of veracity, then we have a problem.

The simple fact is, we actually have little understanding of the universe about us. When we find discrepancies or phenomena that don't match the current models, we should be big enough to allow people to investigate alternatives freely without treating them as pariahs and heretics. It may well be that those alternatives have no veracity, but then again, they may be the start of a new outlook and understanding of the universe about us.

It is an unfortunate fact of life that people who disagree with the consensus view will be treated badly. This is a function of what it is to be human.

<comment><USER23> _> in discussions with physicists, they have claimed a minimum of three different event horizons_

Huh? Where are you getting this from?

 _> time at the event horizon as observed from the universe at large stops._

Nope. The event horizon is a null surface--it is "made" of outgoing light rays. The concept of "time" does not apply to light rays.

 _> The underpinnings of "black holes" requires an eternal universe_

No, they don't. An "eternal" black hole is an idealization, but a real black hole does not have to be exactly the same as the idealized model. I mentioned numerical simulations in another post down-thread; any realistic black hole cannot be exactly described by closed form equations, it needs to be simulated numerically. Numerical simulations make predictions that match what we see, and show how realistic black holes can form by gravitational collapse of stars and star systems.

 _> If you think about "black hole" formation as described by the various models in use, there are a number of assumptions made that don't actually match what see in our observable universe or in any practical experiments we do._

I don't know what assumptions you're talking about.

 _> When we find discrepancies or phenomena that don't match the current models_

I don't know what discrepancies you're talking about as far as black holes are concerned.

 _> It is an unfortunate fact of life that people who disagree with the consensus view will be treated badly._

You can't effectively disagree with the consensus view if you don't understand it. You clearly don't understand the consensus view of black holes. I am simply trying to point out incorrect things you are saying about that view.

<comment><USER22> > Huh? Where are you getting this from?

From the physicists themselves. Public discussions on their respective blogs.

>Nope. The event horizon is a null surface--it is "made" of outgoing light rays. The concept of "time" does not apply to light rays.

Are you then saying that all the physicists who say time stops here as viewed from outside are wrong?

> > The underpinnings of "black holes" requires an eternal universe

> No, they don't. An "eternal" black hole is an idealization, but a real black > hole does not have to be exactly the same as the idealized model. I > mentioned numerical simulations in another post down-thread; any realistic > black hole cannot be exactly described by closed form equations, it needs to > be simulated numerically. Numerical simulations make predictions that match > what we see, and show how realistic black holes can form by gravitational > collapse of stars and star systems.

The theoretical basis for "black holes" is an eternal universe with a single mass in it. There are many things that can be numerically simulated. However, one must be very careful what you are simulating and on what basis the simulation exists. The "black hole" is a solution from a specific model and that model does not match the real universe as we observe it.

I have no issue with there being large gravitational entities. i do however have an issue with the declarations that said entities are "black holes". We do not know what they are. You cannot in any way "prove" that they are "black holes", no matter what level of consensus you display. We observe by proxy, we are at this point unable to directly test what we see.

All one can say is that there is a model that is believed to be appropriate to explain the phenomena observed.

I'll put it this way by example. We observed an entity that we call and electron that has various observable attributes and we use a variety of models to describe theoretically that entity. Are those models correct. Well, no. They are what we use to try and predict further tests and outcomes that we expect to find. We get some approximate closeness and then move forward. At no point, are the models "fully correct" or "truth", there are still anomalies found between theory and experimentation.

When we forget that our models and theories are only approximations to reality and fall into the trap that they are reality itself, then we will become incapable of actually advancing our understanding.

> I don't know what assumptions you're talking about.

Single mass existing only, asymptotically flat universe are just two of the fundamental assuptions required.

> I don't know what discrepancies you're talking about as far as black holes > are concerned.

We are not in a position to directly observe any such entity. The number of times that scientists have declared that we have now seen for the first time a "black hole" over the last how many decades. that alone says that each previous declaration has been a furphy.

> You can't effectively disagree with the consensus view if you don't > understand it. You clearly don't understand the consensus view of black > holes. I am simply trying to point out incorrect things you are saying about > that view.

When simple questions are raised against the model and are not answered by those who lead the charge for the model and when their responses amount to "you don't understand the model, so go away", then you can quite rightly take the view that they themselves don't have a clue about what they are agreeing with. I have yet to see a clear exposition of why such entities such as "black holes" should exist in our universe and answer the various simple questions that arise in opposition.

If such an explanation was to be given in a logically clear manner, then yes, we could then put "black holes" back on the table.

<comment><USER23> I have been tied up myself and am only now able to respond.

 _> From the physicists themselves. Public discussions on their respective blogs._

Physicists will say all kinds of things in a popular forum. Do you have any references to textbooks or peer-reviewed paper?

Even on physicists' blogs, I have never seen any reference to three different event horizons, so if you have any specific ones you can point to, it would really help me to understand what you are talking about.

 _> Are you then saying that all the physicists who say time stops here as viewed from outside are wrong?_

If any of them actually are saying that, yes, they're wrong. But I doubt you'll be able to find any textbooks or peer-reviewed papers that say that. I don't care what pop science sources say; they're not valid sources for learning the actual science.

 _> The theoretical basis for "black holes" is an eternal universe with a single mass in it._

No, it isn't. You are confusing an idealized model used for pedagogy with actual models used to make predictions about actual objects observed by astronomers.

 _> I have no issue with there being large gravitational entities. i do however have an issue with the declarations that said entities are "black holes"._

If you want to be very careful, you could say that black holes are the only entities consistent with our current theories that these "large gravitational entities" could be. It is true that our current theories are incomplete, and it could be true that a more complete theory would tell us that these entities are not anything like our current model of black holes. But even if that happens, it won't be for any of the reasons you are giving.

 _> Single mass existing only, asymptotically flat universe are just two of the fundamental assuptions required._

Again, you are mistaking an idealized model used for pedagogy with the real models used to make predictions about real observations. The latter do not depend on any such assumptions for the universe as a whole. They only require that a suitable region of spacetime around the object being studied contains only that object (or objects--models of this sort are used to make predictions about multi-object systems such as binary pulsars, for example, as well as black holes) and becomes flat enough at its boundary for asymptotic flatness in the model to be a reasonable approximation. These conditions are certainly met by the objects and systems to which the real models in question are applied.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER24> It appears astronomy articles have completely given up reminding us that the phenomena being observed at x light-years away, happened x years ago (26,000 in this case), so I'll do it. (Maybe it's more soothing to our human egos to feel like it's "happening right before our eyes" but I liked it better when talk of space made me feel small and insignificant.)

For example it's good for the ol' ego (and a fun flight of fancy back into the past) to be reminded that when this star was actually passing near the black hole, back here on Earth homo sapiens was enjoying his "cave paintings" phase, using stone tools (maybe juuust starting to get into metallurgy in some areas), and it was the peak of the last glacial maximum, which would've been quite noticeable while hunting wooly mammoths with spears in the northern latitudes.

<comment><USER25> Honestly, it would be pretty annoying for anyone even remotely familiar with high school level physics to he constantly reminded that a light year is the distance light travels in a year.

<comment><USER24> That's presumably why they don't do it, but you're being hyperbolic. An 8th grader is remotely familiar with high school physics. The janitor of the high school physics classroom is remotely familiar with high school physics. Yet they probably could both stand to be reminded a time or two what a light-year is.

<comment><USER25> >Yet they probably could both stand to be reminded a time or two what a light- year is

Ok, but you said:

>It appears astronomy articles have completely given up reminding us that the phenomena being observed at x light-years away

So how should the author decide on how often to remind their presumably educated audience (this is eso.org after all, not some pop-culture magazine) of the basic of light travel? Once every five articles? Ten? Or maybe they just assume as I do that anyone reading this article knows this already and to mention would be at best a waste of screen real estate.

This site is run by the people who run an observatory. It's not LIFE magazine, the writers know their audience.

<comment><USER24> That means first of all that they're somewhat more familiar with high school physics than "remotely familiar," and secondly that they also probably shouldn't tolerate factual inaccuracies such as "[new instruments] have now allowed astronomers to follow one of these stars, called S2, as it passed very close to the black hole during May 2018." Is that an inelegantly-placed prepositional phrase (since only the observation took place in May 2018 and not the passing), or do people in the field refer to these things in the present tense as a sort of shorthand? (I'm not one of them so I don't know.)

There are signs it's meant for a broader audience, e.g. "one of these stars, called S2" instead of simply "star S2" (since everybody's already familiar with it).

Or how about "The new measurements clearly reveal an effect called gravitational redshift. Light from the star is stretched to longer wavelengths by the very strong gravitational field of the black hole."

How often should experienced astrophysicists be subjected to the tedium of this explanation of red-shift? Once every 5 articles? I would say: Since it's a fact from their own field, they should be reminded of it less often than they get reminded of what was happening on Earth when this stellar event actually happened. Because if they're truly specialists, that means they probably know jack squat about archaeology/anthropology or anything besides astronomy/astrophysics, and might even appreciate the latter reminder.

</comment></comment></comment></comment></comment><comment><USER26> Very cool, it's too bad we can't see anything inside the event horizon yet (and possibly can't ever). That's where the really interesting stuff might happen. We know either our current understanding of GR or our current understanding of QM is wrong because of the way they handle singularities differently.

<comment><USER27> The more I think of it, while it's disappointing from a pure-science point of view, doesn't the lack of our ability to determine whether it's QM or GR that is flawed imply that each is already sufficiently powerful to probe any practical realm we'd care about?

</comment></comment><comment><USER28> In the 26,000 light years between the telescope and the star, I would guess that enough matter would exist, from stars to planets to dust, that it would complete occlude our view of the star. I would expect that objects would continuously be moving in and out of the way.

Is it that space is really so empty that you can get a direct view over 26,000 light years, or is it that we are looking at this star because it's one of the few we can see directly, or is it something else?

<comment><USER29> It really is that empty. Science fiction movies mess up our perception, but reality is way more mind-boggling that we realize.

Check this out: if you want to build a model galaxy to scale and you start with the Sun as a two-foot-diameter exercise ball, how far away do you have to travel before you can set down a smaller ball that represents Alpha Centauri, our nearest(-ish) stellar neighbor?

10,993.3 miles.

Just bask in that for a while.

([http://www.exploratorium.edu/ronh/solar_system/](http://www.exploratorium.edu/ronh/solar_system/))

<comment><USER30> It is empty, but its filled with "Space Grease"

[https://www.theguardian.com/science/2018/jun/27/space-is- ful...](https://www.theguardian.com/science/2018/jun/27/space-is-full-of- dirty-toxic-grease-scientists-reveal)

<comment><USER31> > found enough for 40 trillion trillion trillion packs of butter

What an incredibly useless unit of measurement. They somehow found something worse than "olympic size swimming pools".

<comment><USER32> How many packs of butter per Library of Congress?

The problem is that most people just cannot conceptualize really, really, really large numbers, but journalists and authors try to make them more relatable anyway, and end up just making it worse.

I think what they meant to say was that it could make a typical globular cluster satellite of the Milky Way galaxy, containing about 225000 butter- stars with the same mass as our sun.

<comment><USER33> > I think what they meant to say was that it could make a typical globular > cluster satellite of the Milky Way galaxy, containing about 225000 butter- > stars with the same mass as our sun.

I don't think it was anything near that complex: 40 trillion trillion trillion is just the number of tubs of butter it takes to get 10 billion trillion trillion tonnes if you assume each tub is 250 grams.

<comment><USER32> Even then,

      10^3 = thousand
      10^6 = million
      10^9 = billion
      10^12 = trillion
      10^15 = quadrillion, or thousand trillion
      10^18 = quintillion, or million trillion
      10^21 = sextillion, or billion trillion
      10^24 = heptillion, or trillion trillion
      10^27 = octillion, or thousand trillion trillion
      10^30 = nonillion, or million trillion trillion
      10^33 = decillion, or billion trillion trillion
      10^36 = undecillion, or trillion trillion trillion

One of those numbering conventions is not tremendously useful, and the other is very very very stupid. It compounds with the knowledge that some people call 10^9 "a milliard" rather than "a billion". This is why we have SI unit prefixes, and write numbers ending with an exponent of 10.

And here I was, assuming each "pack of butter" was one of those 10g single- serving packs (although some are only 7.65g). I didn't check it against the "tonnes" number in the article. In the US, a "pack of butter" could also be a box containing 4 sticks 113 g each, totaling 454 grams, because butter in the US is sold by the pound. Apparently, they are 250g elsewhere.

And a (metric) tonne is already 1000 kg, or 1 Mg. There is also the long ton, which is 1016 kg, and the short ton, which is 907 kg.

The obfuscated number is therefore 1x10^40 g, which is even larger than standard metric prefixes can express, so we'd probably write it as 1x10^37 kg, for some reason.

So my previous math was wrong. That's _5 million_ butter-stars the size of our sun, or enough butter to form a slippery, spreadable black hole as massive as the one at the heart of our galaxy. I guess from this, we can calculate the size of Audthumbla the giant space-cow?

</comment></comment></comment></comment></comment></comment></comment><comment><USER34> Anyone know why the black hole is marked well off the axis of the orbit of S2 in diagram [1]? Is there enough mass elsewhere at the center of the galaxy to have it orbiting a common mass so far off axis? The video of the orbit [2] seems to show it closer to the axis or the focus I'd expect but still seemingly a bit of an offset. The fulldome view video [3] does show that there is quite a bit of stuff moving around there so maybe my imaginations are wrong, I think of a black hole having so much mass that it completely dominates the local gravitational field.

1\. [https://www.eso.org/public/unitedkingdom/images/eso1825c/](https://www.eso.org/public/unitedkingdom/images/eso1825c/)

2\. [https://www.eso.org/public/unitedkingdom/videos/eso1825g/](https://www.eso.org/public/unitedkingdom/videos/eso1825g/)

3\. [https://www.eso.org/public/unitedkingdom/videos/eso1825g/](https://www.eso.org/public/unitedkingdom/videos/eso1825g/)

<comment><USER35> Keep in mind that you are viewing the orbit in projection. The axes are simply the angular offset from the pointing.

Before I give away the punchline, try to imagine the orbit in a reference frame centered at the location of the black hole. Obviously, the motion should be elliptic; lets define a Cartesian coordinate system such that, say, the x-y plane coincides with the plane of the elliptic orbit. Now, we know that the black hole should reside at the focus of this orbit. But, as a far away observer, what are the chances that you would be seeing the orbit exactly face-on - i.e., you are sitting on the z axis, just really far away?

So, yes, the black hole is at the focus of the elliptic _orbit_ , not the focus of the ellipse formed from the _projection of the orbit_ onto your plane-of-sky, which geometry tells us is also an ellipse.

BTW, this isn't a problem for the astronomers. You can back out exactly what that inclination of the orbit is, provided you can measure the line-of-sight velocities of the star. (Actually, relative velocities will do; no absolute calibration necessary.) This is easily done by looking for some distinctive stellar spectral features and noting their relative shifts at different parts of the orbit. From this you can reconstruct the orbit completely. The key scientific results they derived was the _even subtler_ redshift of these spectral features as the gravitational field grew stronger when the star approached the black hole.

edit: actually, you could do even better, and use the offset of the black hole from the elliptic focus, and use projective geometry to get the inclination angle!

<comment><USER34> Ahhh so simple! Thank you very much for the moment of enlightenment.

</comment></comment></comment><comment><USER36> Question, is it possible that our universe could be in a black hole? When you look at the way our existence is structured, everything has a parent. An an electron has an atom has it's parent, atoms have molecules has their parent etc. Germs, bacteria, humans, planets all have parents. Surely our universe has to have a parent.

<comment><USER37> Possible? Sure, anything is _possible_ \- but apply your argument the other way round. People contain molecules, molecules contain atoms, atoms electrons and so on - does it then seem reasonable to ask whether _that_ goes on forever? And if not, why should it be reasonable if you go upwards in the scale?

<comment><USER38> But it does seem reasonable. Very much so if going down far enough you find micro black holes at the center of atoms.

But you need some really funky geometry to make it more interesting then this played out trope. Say they are all the same black hole from different times seen through its own gravitational lense.

</comment></comment></comment><comment><USER39> Cool news! I'm curious though, couldn't a quasar possibly cause the gravitational redshift that was observed?

</comment><comment><USER40> Coolest thing I have seen in a long time. Watched a replay of the livestream and it is so good!

</comment><comment><USER41> Which of that imagery is actual imagery and not artist interpretation?

<comment><USER42> [https://cdn.eso.org/images/large/eso1825g.jpg](https://cdn.eso.org/images/large/eso1825g.jpg)

[https://cdn.eso.org/videos/ultra_hd/eso1825e.mp4](https://cdn.eso.org/videos/ultra_hd/eso1825e.mp4)</comment></comment>


32 GiB of texts from Philosophical Transactions of the Royal Society released - <AUTHOR> https://thepiratebay.org/torrent/6554331/Papers_from_Philosophical_Transactions_of_the_Royal_Society__fro

<comment><USER2> I find the statement of Greg Maxwell - who uploaded the text - courageous; quoting as to why he did not upload them anonymously:

"...that the obviously overzealous prosecutors of Aaron Swartz would probably accuse him of it and add it to their growing list of ridiculous charges. This didn't sit well with my conscience, and I generally believe that anything worth doing is worth attaching your name to.

I'm interested in hearing about any enjoyable discoveries or even useful applications which come of this archive..."

Any ideas for useful applications and legal implications?</comment>


Amazon Price Check app draws protests from some retailers  - <AUTHOR> http://www.chicagotribune.com/business/breaking/chi-amazon-price-check-app-draws-protests-from-some-retailers-20111209,0,1595833.story <comment><USER2> I think local retailers are given "special treatment" in that they don't have to add a shipping cost on top of the item price.

Consumer retail is evolving, as it has been forever, and will continue to do so into the future.

Local retail shops can cater to immediate gratification desires by shoppers. I can't just order up a latte on Amazon and have it NOW. If I need a new HDMI cable to watch a DVD with some friends tonight, then even free overnight shipping won't solve my needs.

But, for many other things... A new pair of shoes, a new coffee pot, a bottle opener, etc., I can wait 2 or 3 or 7 days to get the item. The Internet isn't going away, and even if I had to pay sales tax, I'd probably still continue to buy things on Amazon because it's easier for me than going to a retail store and dealing with potentially limited selection, crowds, etc.

These companies are simply NOT going to beat Amazon into submission. It's far too late for that, and I actively despise any retailers who try to increase my tax burden vs. offering a valuable service to me.

<comment><USER3> _I think local retailers are given "special treatment" in that they don't have to add a shipping cost on top of the item price._

Yeah, those lucky retailers get to blow off the shipping cost just because they aren't shipping anything. But they do have to pay a fee just for the privilege of doing business, and Amazon gets to do business without paying that fee. And now Amazon is using their dusty old brick and mortar stores as a showroom. I can see why the local retailers are feeling jilted.

<comment><USER4> No, they don't pay a fee.

You pay a fee for making a purchase. Local retailers should be arguing that they don't want to be the tax collectors, so their prices would look lower too.

Either way, you, the buyer, are responsible for paying the sales and use tax, regardless of whether you bought from BestBuy or Amazon.

Again, both BestBuy and Amazon "get to do business without paying that fee", as it's not something either of them pays.

To enjoy the competitive advantage of having a local presence, BestBuy does agree to help your local government collect your taxes (and in fact gets to KEEP a percentage of the taxes they collect!), while Amazon, who is not in your local jurisdiction, relies on you to pay the tax you owe.

<comment><USER5> So I assume you willfully pay your tax on all online purchases?

<comment><USER6> My state had line item on the tax form asking for the amount of goods purchased online so then they can tax them.

Always wondered what people put in there and if the state even did anything about it (audited people).

I guess they could ask Amazon for records (threatening a lawsuit) and cross- reference with all the reported taxes based on name and address. If user bought just from Amazon more than what they reported they they have obviously owe some money + fines & late fees.

(But I suppose I am making gross assumptions about the competence and general technical abilities of my state's tax collecting office).

<comment><USER4> > _could ask Amazon for records (threatening a lawsuit)_

[http://arstechnica.com/tech-policy/news/2010/10/judge- blocks...](http://arstechnica.com/tech-policy/news/2010/10/judge-blocks-north- carolina-attempt-to-get-amazon-sales-data.ars)

<comment><USER6> Oh wow. I was thinking of a different state, but this is interesting. It already happened and I missed it.

First it was anonymous purchase data. Then NC demanded user names and addresses but Amazon fought on 1st Amendment grounds and seems to have won:

"The First Amendment protects a buyer from having the expressive content of her purchase of books, music, and audiovisual materials disclosed to the government,"

I wonder if this was Zappos for example. What would have been the ruling.

</comment></comment></comment></comment></comment></comment></comment><comment><USER7> There's a local article in the Austin Business Journal quoting a guitar dealer who says "Amazon charges $1000 for a guitar, but when I charge $1000 for the same guitar, I have to charge $1082.50 because of sales tax".

What he doesn't consider is that Amazon is more than likely charging $800 for that guitar.

The "locals" make claims about price difference being solely due to sales tax, but overhead is more the reason than anything else.

</comment><comment><USER8> Last year, I needed a backpack for travel/multi-use/etc. Something that would fit my laptop, a small video camera, and misc other stuff.

I went to Best Buy to see what they had, and it wasn't much. They had one bag that looked nice though and the salesman told me how amazing it was.

It's Best Buy. Of course I didn't believe him. So I pulled up the iPhone Amazon app, scanned the product barcode, and saw what the reviews were. Turns out, the salesman was right - this bag was very well reviewed.

And Amazon had it for $20 less. So I left Best Buy, went home, and bought the backpack off Amazon.

There will always be a place for local, brick-and-mortar stores. As others have mentioned here, Amazon can't fulfill instant gratification.

But I think instant gratification is a small percentage of the overall buying experience. Amazon can help with the rest.

(If anybody's interested in the kick ass backpack I got, here's the Amazon link. Looks like it's more expensive now: [http://www.amazon.com/Lowepro- CompuDaypack-Camera-Bag-Slate/...](http://www.amazon.com/Lowepro-CompuDaypack- Camera-Bag-Slate/dp/B000EY5R8C/ref=sr_1_1?ie=UTF8&qid=1323462065&sr=8-1))

<comment><USER9> So what could Best Buy have done for you that this salesman couldn't? He apparently gave you good advice, and you had a chance to touch and feel the product.

I will admit that $20 out of $100 is not an insignificant discount...but how much less of a mark-up would Best Buy have to have so that you would purchase its product?

<comment><USER8> Best Buy simply would have had to match Amazon in order for me to buy it in their store.

Because I didn't need the backpack immediately, I'd rather save $20. The backpack was $80 at Best Buy and $60 on Amazon, so it was a pretty good saving.

</comment></comment></comment><comment><USER10> I think competing on price alone against behemoth like Amazon is a losing strategy for local businesses. For example I could be buying a case of wine online but I go to my local wine store because even though it is a little more expensive the owners are good at recommending wines and they constantly refresh their selection. Which is great for someone like me who isn't a connoisseur.

<comment><USER11> Although I agree with this for the most part, it goes both ways. A huge use case for this app (for me at least) is to be able to quickly look up product reviews by other consumers. If I'm already in the store, I might well buy the product there if it was given good reviews on amazon. In this case, amazon has spent the money to develop the app but the store gets my money.

</comment></comment><comment><USER12> Most stores will not match amazon's pre-tax prices today. Why would it be any different if amzn collected tax?

</comment><comment><USER13> Nice app but to totally circumvent the retailer and shipping fees, they should invest in quantum teleportation technology.

</comment><comment><AUTHOR> I was thinking that this was a particularly clever idea--given that Amazon seems to very good at "pricing arbitrage", as someone smarter than I said.

Some of the stated objections are that Amazon, who doesn't always collect sales tax, is taking business from local stores.

<comment><USER14> "Amazon [...] is taking business from local stores."

Why is this complaint even taken seriously? If your business model is superseded by someone else who can deliver a product in a manner that customers prefer (in this case, cheaper and delivered to their doorstep) then you either compete or you die. Because that's what competition is.

<comment><USER15> Their business model hasn't been superseded. Amazon is free-riding on the stores' display of physical goods. If the shoppers don't value being able to view, handle or browse the physical goods, why are they in the store? So they value having the store there but don't want to pay for it.

Maybe Amazon's plan is to drive these stores out of business and then open its own display stores where people can go to inspect merchandise before ordering it online.

<comment><USER14> I really haven't seen any evidence to back up your claims outside of fear- mongering news articles and general whining from the big box brick-and- mortars.

"Maybe Amazon's plan is to drive these stores out of business and then open its own display stores where people can go to inspect merchandise before ordering it online."

This cannot be a serious conjecture. Opening up quasi-retail locations with all the expenses of retail but no ability to actually making a sale? Didn't Gateway do this in the late 90s?

<comment><USER16> If it ever got to the point where brick-and-mortar stores for certain things ceased to exist since everyone was buying online, you could have a store that actually charged admission to browse (and to convince people to still come, you could make that admission count toward an online order or toward food at a store restaurant.)

Pretty unlikely, although maybe it would make sense in a less-developed community (third world countries, outer space) that does not already have modern brick and mortar stores.

</comment></comment></comment></comment></comment><comment><USER17> I know everyone thinks this is bad for retailers, but it really is only bad for them in the short run. In the long run the biggest negative impact will be felt by retail REITs, and those that have long term debt on retail buildings.

<comment><USER17> *this is because retailers will on average lower the rent they are willing to pay as they have to compete with online sales channels.</comment></comment>


Point Roberts,an American City Embedded in Canada - <AUTHOR> https://www.atlasobscura.com/places/point-roberts <comment><USER2> All I get is an illegal demand to agree to tracking. Anyone got an alternative site?</comment>


GaaP – Google as a Proxy - <AUTHOR> http://www.labnol.org/internet/google-proxy-server/28112/

<comment><USER2> Annoyingly enough I've been in a situation where a needed a proxy to get around the corporate firewall blocking (constructive) blog posts. But Google proxy services didn't work (tried translate). I presume URL was filtered based on words like blog. Is there a way to obfuscate the URL using these services that anyone knows of?

</comment><comment><USER3> Great !</comment>


The Future of Bookstores: Lead-Gen, not Dead Trees - <AUTHOR> http://blog.gaborcselle.com/2010/09/future-of-bookstores-lead-gen-not-dead.html

<comment><USER2> " _Except, of course, I didn't buy a lot of books._ "

I guess that explains why the author views books as entirely dispensable aspects of a bookstore.

If the future of bookstores is becoming coffeehouses, then, by definition, bookstores have no future.

<comment><USER3> Off-the-shelf retail prices for books are insane. $20 for a large-format paperback of _Under the Dome_? Please.

Perhaps the new model for physical bookstores should be that of a private library, except without the checkout aspect. The main income comes from impulse buys of high-margin foodstuffs and misc odds-n-ends, maybe even music and gift cards, but not from a high volume of book sales.

Bookstores have a lot of advantages over public libraries. Many libraries don't have many brand-spanking-new titles, and if they do they're tied up by patrons for months. The hours for public libraries (ignoring university stacks) generally suck. Many don't have free wireless, though that's rapidly changing. Most don't have, or allow the consumption of, food.

After some time, the store could sell off heavily discounted, gently-used copies that patrons thumbed through while sipping coffee and facebooking during their lunch hour.

I understand that book stores must mark up books to make a reasonable profit (at least, that's the benefit of the doubt I give them), but the markup is simply horrible. I once shopped around online for a set of books I wanted, found the best deal (think it was Amazon or maybe Wal Mart), printed it out, and took it to the nearest Barnes and Noble. I don't recall the price difference, but it was quite a bit. I wanted the books that day, so I snagged a sales droid and proposed they give me a price half-way between their price and the one on the printout. She looked at me like I was a moron, and curtly said they couldn't do that. So I kindly wished her a good day, walked out the door, and had the books delivered to my door a few days later.

I find it hard to believe that large chains must be so inflexible in their retail pricing. However, if they don't lower their prices, I won't shed a single tear when they go under.

<comment><USER2> I've often wondered about that too. My hypothesis is that there's still a large contingent of tech-shy readers who are scared of the Internet, but who really want to get their favorite author's latest material, so they're happy to pay whatever price as long as it's similar to what they've paid in the past.

</comment></comment></comment><comment><USER4> If you follow the link to the story about the Borders at 3rd and Townsend closing, there's a comment from the head of the HOA, saying its because their lease was not renewed, not because of their sales being poor. Kind of sucks the life out of that argument.

<comment><USER5> That's good, because the proposed business plan is apparently isomorphic to "become Starbucks". And that's a pretty crowded niche already.

</comment></comment><comment><USER6> Anyone who gets the majority of their books on Kindle has some pretty shallow reading habits. I have about 4000 nonfiction books, and at least 60 percent of them are not even available for Kindle. And from the descriptions of Kindle's graphics, at least half of the remainder would be a waste to get on Kindle.

</comment><comment><USER7> interesting idea IF (big IF) the average book reader was as much of an early adopter as the average HN reader/technophile w/a kindle. There are still millions of people who rely on printed books. Kindles may be selling well, but not as well as we'd like to think. What about people shifting their book buying to places like walmart and target where they get cheaper prices and only sift through the top 100 books out?

I read more on my ipad now than I do books, but still buy physical books from time to time. There are lots of situations where I can't use a digital reader (the beach for instance).

but the author's idea could work, in 2020. In the meantime how does the store support their costs and leases on physical spaces off of ever declining physical good sales?

I'd like to see bookstores turn more into community (for profit) spaces. Teach stuff, sell more coffee around these workshops/gatherings.

</comment><comment><USER8> For me, the chain bookstores are just a place to get a book when I don't want to wait for shipping. The only other store I visit is a local independent, which only stocks titles that the staff recommends. They're a great place to go if I want to read something recommended by people with taste. I don't go there very often, though. There are so many good books available, what I lack is time to read them all, not good recommendations.

I'm not sure how either gets by if ebooks really take off. The Internet is ultimately a better solution for recommending books and delivering them. They could turn themselves into coffee shops, as the article suggests, but at that point why wouldn't I just go to a good coffee shop?

</comment><comment><USER9> Bookstores don't pay for their books until they're sold, and they return the ones that aren't - so yes, they do have high overhead in terms of square footage / labour, but don't necessarily have the same inventory issue that other retailer operations to.

A more interesting question to ponder would be at what point in time (if ever) will it stop making sense for a publisher to print books and send them to bookstores? My guess is for niche publishers this has already happened, and it will never happen to the mass-books - it's the middle guys who will have to make the call sometime in the coming years...

</comment><comment><USER10> until fresh hot coffee can be downloaded over the Internet I think Starbucks has a brighter future than B&N.

I've sometimes thought B&N should turn into something closer to a cross between Starbucks and a library. Maybe make them members-only, so help filter the demographic that walks in.</comment>


[2018] State-of-the-art protections cannot prevent from inferring full records [pdf] - <AUTHOR> https://www.cs.cornell.edu/~shmat/shmat_vldb18.pdf <comment><USER2> Machine learning and large datasets</comment>


Google's DeepMind AI can lip-read TV shows better than a pro - <AUTHOR> https://www.newscientist.com/article/2113299-googles-deepmind-ai-can-lip-read-tv-shows-better-than-a-pro/ <comment><USER2> this is a definitely a boon to espionage/police work.

I wonder if you would have to get a warrant to make a video in public of someone walking and talking and then running it through your AI to find out what they were talking about.</comment>


3 Tesla Execs Dead In Palo Alto Plane Crash - <AUTHOR> http://jalopnik.com/5473942/3-tesla-execs-dead-in-palo-alto-plane-crash

<comment> brown9-2 Does anyone else find the editorializing in this article disturbing?

This is the second paragraph of the article:

 _Employees at the electric carmaker — a company that has done everything but paint its logo green in a bid to sell itself as environmentally-friendly — have always had a penchant for gas-guzzling private airplanes. But that's sort of been the Tesla way. An electric car without compromising speed or style. The roadster's perfect for the Hollywood and Silicon Valley elite — environmental credibility without having to give up your private plane._

3 people just died. Is it really necessary to slam the type of people that buy electric cars in an article reporting on their deaths?

<comment><USER2> Ban worthy IMHO. I think the whole Gawker network should be banned here though, all bottom feeders.

<comment><USER3> That's what voting is supposed to be for. I find this site disturbingly ban- happy.

<comment><USER4> We can't downvote articles.

<comment><USER5> You can not-vote. And if warranted, flag.

</comment></comment></comment></comment></comment><comment><USER6> Sad News. This reminds me of the time I was working at a startup and the office admin booked a flight for the three founders to attend a conference or some such. Same flight for all three, seemed reasonable to me, but after some stern discussion that never happened again.

<comment><USER7> It's interesting how some people do this, yet don't give a second thought to driving together all the time.

<comment><USER8> True, I imagine a plane crash is very much an all or nothing venture (major and few survivors vs. minor with just injuries). Perhaps not so much with driving.

Right now just speculating, but I'd be curious to if anyone's created a breakdown of traffic fatalities by # of passengers in each vehicle and # passenger fatalities. I've seen that sort of thing before, but almost always in the context of teen/new drivers.

Couldn't find anything quickly, will look after work.

</comment></comment></comment><comment><USER9> This is tragic. Very sorry to hear it.

As an intern, I worked for a company and found in the employee manual that there were explicit restrictions on the number of execs who could be on the same plane or even in the same car!

I thought it was a silly clause and asked about it and the execs said, "Yes, the probability is small, but multiplied by the damage that would occur gives a very big risk of damage." That made a lot of sense. It doesn't cost much to avoid the risk, just take different flights.

<comment><USER10> I knew plenty of kids growing up whose parents traveled separately when the kids were not with them. It's morbid stuff being responsible for other people...

<comment><USER9> It is. When I started a company and got customers who depend on me, I started driving slower. I stopped taking the kinds of risks I used to take. I even worry, briefly, when I go skiing.

</comment></comment></comment><comment><USER11> It was confirmed that Elon Musk was not on board.

Source: <http://twitter.com/kensweet/status/9247008924> (guy is a reporter for FOX Business)

<comment><USER12> My first thought was about Elon. Anyone passing away is tremendously sad. But in that sadness, I think it is good to acknowledge we didn't lose a great visionary today. We need them.

<comment><USER13> Speaking of lost visionaries, check out Daniel Lewin (<http://en.wikipedia.org/wiki/Daniel_M._Lewin>).

He co-founded Akamai and was killed on American Airlines Flight 11, possibly while trying to stop a hijacker. A very smart and influential guy who died tragically.

<comment><USER14> Wow. Didn't know that one. I guess you never know who you might be sitting with on a flight these days. I would not have guessed Daniel in a million years as formerly working for IDF.

</comment></comment></comment></comment><comment><USER15> Elon Musk has written this note on the Tesla Website:

"Three Tesla employees were on board a plane that crashed in East Palo Alto early this morning. We are withholding their identities as we work with the relevant authorities to notify the families. Our thoughts and prayers are with them. Tesla is a small, tightly-knit company, and this is a tragic day for us." \- Elon Musk, CEO

</comment><comment><USER16> FYI, and hopefully not just morbid:

Local TV news (sorry, no link) reports that planes taking off from that run- way must turn 10 degrees left or 10 degrees right after take-off. They can't go straight because of a nearby field (Moffet field) - a former naval air base currently owned by NASA and famous for being where the Google guys park their jet.

This plane was planned (or instructed, I'm not sure) to go right - they went left.

That they went left AND that they failed to gain enough altitude to avoid the power lines is tentatively _speculated_ to be indicative of a left engine failure.

They took out three high-tension power lines which, the plane geek quoted on the news pointed out, is "likely to seriously interfere with the forward progress of the plane". They came down in a very dense residential neighborhood with debris hitting a nearby day-care center.

A consolation is that as of this report, the pilot and passengers appear to be the only victims. The plane mostly came down in the middle of a street. Nearby residents report that they tried but could not get anywhere close to the plane because of the intensity of the heat from the fuel flame. It was the resident's impression that post-crash fuel explosions scattered debris which is what led to the structure fires.

The thought that occurs to me is that I wonder if the pilot retained enough control that he aimed for the street on purpose either hoping for a survivable crash landing or (shudder) in a heroic last act to save others knowing he had no chance, personally.

</comment><comment><AUTHOR> I wish I didn't get karma for submitting this :(

<comment><USER17> News organizations make a ton of money when lots of people die in some horrific way. You're not profiting from the bad news, you're gaining from informing others.

</comment></comment><comment><USER18> I recall reading a list of the top 10 ways to live a longer life somewhere, and pretty high up on the list was "Do not get a pilot's license."

Apparently, CEOs, doctors and the like assume that competence in one area of life implies that they're competent to do anything, like flying a plane.

<comment><USER10> While that sounds like great advice to trot out every time a small craft crashes, in the absence of data it is functionally worthless.

<comment><USER19> Exactly. "Don't get a driver's license" or "don't go outside" are just as valid.

My thought is, if I die or become horribly brain-damaged, I won't really care, because the capacity to care is gone. Existence only goes as far as you can interpret it.

<comment><USER18> So your point is that avoiding danger is pointless, because once danger kills you, you don't care?

Race you across the interstate! Go!

</comment></comment></comment></comment><comment><USER14> Still no report yet on which 3 it was. They're probably talking to family members, first. Sad, none the less.

<comment><USER20> Tragic, however, there is no confirmation that they were executives either.

</comment></comment><comment><USER21> Tragic...

It's seems like once every other month you hear about a small passenger jet crashing like this. This one happening yesterday: <http://www.nytimes.com/2010/02/17/nyregion/17plane.html>

Anyone know if it's certain types of small aircraft that are prone to this or is it just small civilian operated aircraft in general?

Don't think I'll by getting on one of these anytime soon in any case.

<comment><USER22> In general. Small civilian aircraft are death traps (although maybe not as bad as cars); [https://secure.wikimedia.org/wikipedia/en/wiki/General_aviat...](https://secure.wikimedia.org/wikipedia/en/wiki/General_aviation#Regulation_and_safety)

> According to the U.S. National Transportation Safety Board, in 2005 general > aviation in the United States (excluding charter) suffered 1.31 fatal > accidents for every 100,000 hours of flying in that country, compared to > 0.016 for scheduled airline flights.

(One can imagine many reasons for this; more professional maintenance, more professional pilots, more redundancy in the systems of big airplanes; whatever. But the safety differential is not imaginary.)

</comment></comment><comment><USER23> I was just on a conference call today with some coworkers out in the area when the power went out. Had no idea why.

This is truly sad news.

</comment><comment><USER24> What a crazy coincidence -- the CEO of the first software company I worked for was a pilot, and he also flew his personal aircraft into some power lines.

</comment><comment><USER2> <http://en.wikipedia.org/wiki/Cessna_310>

<comment><USER25> So, it's at least a 30 year old plane.

I'm not connected at all with the private aviation industry... What is the useful (safe?) lifespan of an aircraft like this?

<comment><USER26> It's common. GA aircraft have quite rigorous maintenance schedules, with inspection and overhaul every 50 or 100 hours, which (mostly) keeps even old planes airworthy. Almost all airfields will have plenty of 30 or 40 year old planes.

<comment><USER27> Much more likely than the age of the airplane was the visibility. PAO has been foggy in the mornings of the last few days, and the photo in the story makes it look like it was foggy when the crash happened.

</comment></comment></comment></comment><comment><USER28> It was crazy foggy in Palo Alto this morning and has been for the past of couple of mornings. I'm really surprised they tried to fly in those conditions.

The report suggests that the power outage in Palo Alto may have been caused by the plane crash. I find this hard to believe because the traffics lights were only down in the area near Stanford and downtown PA; as you drove closer to East Palo Alto, the lights were working. Of course maybe there was a larger outage earlier, and they just restored it in this pattern.

<comment><USER29> There's a picture somewhere on the web (sorry, no link) of a severed high- voltage power line linked to this crash.

</comment></comment><comment><USER30> Inside job, anyone?

<comment><USER31> How much karma do I need before I can down vote someone? This seemed like a good place to ask.

<comment><USER30> Irrespective of the down-votes, I do see another user expressing something similar. "I'm suspicious it is somehow related to the oil overlords. Big money, big risks."

<comment><USER9> c'mon, get real. Do you really think there are people out there looking for Cessnas flying around shooting them down if there are EV execs on board?

What did they do? Shoot a missile through the fog? Take it down with a privately owned F14? Plant a bomb on it before it took off?

It's a ridiculous hypothesis.

<comment><USER32> I don't know anything about planes, but my hunch is that sabotaging an airplane, especially a private one, is easier than you're making it sound.

<comment><USER33> Your hunch is largely mistaken. Of course it _can_ be done. But methods like a bomb or remote trigger are apt to leave forensic evidence, and sabotage _qua_ damage to the plane is likely to be found either during pre-flight checks and/or a pilot reporting a problem tower before the crash occurs. Unless an air crash takes place at sea or a very remote location, the chance of sabotage going undetected within the USA is low. All plane crashes in this country are subjected to detailed forensic examination by the NTSB.

<comment><USER34> For GA, the NTSB pretty much only responds to fatal crashes, and even there if the cause is "routine" (controlled flight into terrain, spatial disorientation loss of control) there won't be much in the way of a detailed investigation.

Have a non-fatal accident and you as pilot-in-command are required to report it within 72 hours, but no one from the NTSB is likely to ever see the aircraft in question in person.

Commercial Part 121 crashes get large amounts of attention and amazing levels of effort (the reconstruction of TWA800 is astonishing to me). If I bend my 182 and don't kill anyone, they'll only know about it because I have to tell them and they'll file my submission away.

</comment></comment></comment></comment></comment></comment></comment><comment><USER35> Fuc^W

My deepest condolences to their families.

I'm suspicious it is somehow related to the oil overlords. Big money, big risks.</comment>


Applitude is a domain-specific language for iPhone application development - <AUTHOR> http://applitude.org/

<comment><USER2> I really like this, especially this part:

        cell Default for inventor in inventors {...}

I never really liked Objective-C anyway!</comment>


Olympic medals per capita - <AUTHOR> http://www.medalspercapita.com/ <comment><USER2> Smaller countries can also get disproportionate representation in the olympics. When there's one team or competitor per country, the smallest country has the highest per-capita representation. While they have a smaller pool of athletes to draw from, I'd bet it changes the potential outcome where a straight up per-capita medal count is also somewhat misleading.

I wonder what medals per competitor per capita would look like?

<comment><USER3> They also have more variability. A tiny nation that gets one medal gets a huge per-capita frequency. You'd want to regularize it a bit.

<comment><USER4> Definitely. A similar example: at one point studies started coming out that showed the best performing schools were small. Cue a lot of noise on how small schools are better, if you want your kids to be successful, send them to a small school, etc. I think these findings even showed up in government reports/recommendations.

Problem is, the worst performing schools were _also_ small. Almost all of the effect could be explained by higher variance.

Unfortunately I don't remember where where I read about this, wish I could provide sources.

EDIT: found it. It wasnt government, it was the Gates foundation, who spent billions into supporting smaller schools.

[http://press.princeton.edu/chapters/s8863.pdf](http://press.princeton.edu/chapters/s8863.pdf)

<comment><USER3> Oh my God. They wasted a billion dollars and made education _worse_ because they didn't understand variance.

</comment></comment></comment></comment><comment><USER5> What I'm looking for is a chart of total medals vs. possible medals.

For example, for a country that only has one athlete in one sport, their total possible medals is 1. So if they get 1 medal, they have a 100% success rate, which is pretty good.

I've seen charts of total medals vs # of athletes participating, but that's not quite right, because it doesn't account for team sports. One country might have 4 people on the swim relay team, but that's still only one possible medal (and if they win it should only count as one).

I suspect someone will link me directly to what I'm looking for soon, but I've yet to find it on my own.

<comment><USER6> The breakdown by team vs. individual, and then unique individual athletes with medals would be interesting.

Weight Phelps and a bronze Judo winner equally, in order to better capture the individual talent and reduce "talent stacking" of having a single athlete winning 10 variations on swimming.

<comment><USER7> Yeah swimming is sort of combinatorially ridiculous. They really ought to be able to get by with two strokes rather than four. Backstroke and freestyle would make the most aesthetic sense to me, because I don't really see the point in a race using an inherently slower technique but I can see the point of going backwards. However, don't add a bunch of sidestroke races!

<comment><USER3> Freestyle isn't a stroke, technically. You can swim any stroke that you like[0], and swimmers usually choose the front crawl.

[0] provided that you don't swim the whole thing underwater

<comment><USER7> Yeah that's the point. They can get rid of the races in which the "proper" stroke is specified in complicated fashion.

<comment><USER8> I've always thought butterfly was a bizarre event. It's one of the most complicated strokes, and it's slower and more tiring than the front crawl. As far as I'm concerned, it's an arbitrary stroke.

I guess a lot of Olympic sports are arbitrarily limited though, walking and triple jump come to mind.

<comment><USER9> Butterfly is actually the second-fastest stroke, at least over the shorter distances. There have been swimmers in the past that have used the butterfly stroke in freestyle races at high level events.

<comment><USER8> But that's the issue. It's not an optimal stroke for anything. It's not the fastest, it's tiring, and it's difficult to do.

It's like making a running race where you have to do a small jump every step.

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER10> I just noticed India has no medals. Can someone with more knowledge on this perhaps shed some light? Of the remaining sports are there any that India is a medal contender? I find it odd that a country with more than 1.2 billion would go through the olympics empty handed.

<comment><USER11> The Indian culture does not value athletics or physical fitness activities (or medical health, for that matter) as much as other countries. And it is showing.

<comment><USER12> After spending a month there in March, I agree totally. EVERY adult male has a giant gut, and beyond their early 20's the women are all over weight as well. I was not really expecting that.

<comment><USER13> Obesity is not the issue causing this. India has an almost billion person population with a 15% obesity rate with 0 medals while the US has a 33% obesity rate with 80 medals and a third of the population.

Funding and culture are the biggest issues. The only sport Indians care about and that you can financially support yourself professionally is in cricket. Unsurprisingly India is quite good at cricket and would def. have some medals if it was an Olympic sport.

The truth is that indian has millions of potential athletes who never pursue their passion because they are pressured by parents to focus on academics and other areas. There is no culture glorifying athletes. The few who do end up being athletes play cricket.

<comment><USER12> I never said anything about obesity causing the issue with athletics. I was agreeing that the general Indian population doesn't seem to value fitness or health. Which from my limited experience, is absolutely true.

<comment><USER8> But the same can be said for the UK or the USA, and they both have very good Olympic records.

<comment><USER12> Which just reinforces the original statement, that India doesn't give a shit about fitness/athleticism. We value sports highly in the states, thus we have a large talent pool.

</comment></comment></comment></comment></comment></comment></comment><comment><USER14> It wouldn't be suitable for the general public, but here's how I would do the comparison for potential:

\- assume a normal distribution of innate ability.

\- assume a different normal distribution of each individual's variation in scoring (all with an expected value of zero and identical variance, smaller than that of innate ability)

\- assume each nation picks its best athletes in trials (doesn't really happen; for example, Bolt wouldn't have qualified for Rio if Jamaica did that)

What you will get is that China and India should each have about 15% of the best performers. However, top performers of other large countries will not be far behind them in innate ability, so that there is a decent chance that their form of the day will make them beat better players. Also, most of the best athletes will live in countries with large populations, and most of those will not make it to the Olympics because they get beaten by their compatriots in qualification, either because of lack of innate ability or due to 'luck'.

End result I guess will be that each country that is large enough (pure guess: 50 million+, say Argentina, Britain, Colombia, France, Germany, Kenya, South Korea or anything larger) should, aan else being equal, get about the same number of medals.

Of course, not all else is equal. Any difference will be due to other factors:

\- sport-mindedness (example: New Zealand)

\- money invested (example: Great Britain, Qatar (a country that _buys_ Olympic champions)

\- genetic make-up (example: Fiji in rugby)

\- culture (example: table tennis and China, or India as a negative example for almost any sport that isn't cricket or field hockey)

\- religion (many countries send a token female athlete because they have to, thus giving up about 50% of their potential number of medals)

Those are hard to quantify, and can change significantly over time. Britain is an extreme example, with 1 (one!) gold medal at the 1996 Olympics. Lottery money has changed that tremendously, not only for the home Olympics in London.

A final factor is that countries that are willing to spend money will influence what sports become Olympic sports. I don't think it is accidental that there are so many events in athletics and swimming, two sports that the US excels at. Advertising money buys events.

<comment><USER15> > A final factor is that countries that are willing to spend money will > influence what sports become Olympic sports. I don't think it is accidental > that there are so many events in athletics and swimming, two sports that the > US excels at. Advertising money buys events.

I don't doubt that advertising plays a role in which events exist, but athletics and swimming have had lots of events since the dawn of the Olympics, probably because they're easy to set up and they don't take a long time to run. If you were trying to get the US more medals, you might have 3-on-3 basketball, 1-on-1 basketball, 12 minute basketball, H.O.R.S.E., a dunk contest, etc.

</comment></comment><comment><USER16> The "all time" view is also interesting, although it's pretty heavily skewed towards northern Europe thanks to the origins of the competition:

[http://www.medalspercapita.com/#medals-per-capita:all- time](http://www.medalspercapita.com/#medals-per-capita:all-time)

 _Sic transit gloria mundi_ : Finland's at the top of the all-time rankings, but doesn't have a single medal so far in 2016 (although there's an unexpected one coming up in female boxing, as an essentially unknown boxer just beat the world champion and semifinalists are guaranteed at least a bronze).

<comment><USER17> > semifinalists are guaranteed at least a bronze

Huh. How does that work? Are the semi-finals a three person round robin, rather than a four-person bracket? Do they give out two bronze medals?

edit: yes, two bronzes in fighting sports, because the minimum rest period between matches makes a "bronze medal match" difficult to schedule. source: [https://www.quora.com/Why-are-there-2-bronze-medals- awarded-...](https://www.quora.com/Why-are-there-2-bronze-medals-awarded-in- combat-sports)

</comment></comment><comment><USER18> Slovenia should be updated, we got 4 medals so far, not 3.

</comment><comment><USER19> Amount of GDP versus medals would be interesting as well.

<comment><USER3> Was thinking Olympic medals per local dollar-equivalent spent on training. Who's got the most cost-effective sports programs?

<comment><USER20> It's a bit harder to estimate, it's like evaluating NASA and ROSCOSMOS, NASA's budget is considerably larger but it's not necessarily "less efficient" just because each mission costs more.

Olympic medals per portion of GDP spent on sports education and the olympic team in each country might be a better method.

Also a good metric is how much effort/cost does it take to get into the olympic team of each country, the US is somewhat special in this case since in some cases one needs to break a world record just to get pass the team's trials since they have a huge pool of athletes competing for spots.

But the US is an outlier in general, it's pretty much the only country where you can live as a semi-pro athlete and actually make money, college sports are better funded than most professional sports leagues in other countries (NCAA has a 700M club pool, UEFA champions league has a club pool of about 700M EURO's), and college athletic scholarships exist for virtually every sport.

</comment></comment></comment><comment><USER21> Why the lack of Winter Olympics data except for Sochi?

<comment><USER22> Unfortunately, there is no easily accessible API to get Olympic medal data, so the creator of this website undoubtedly has to do some semi-manual data input.

</comment></comment><comment><USER23> ( population * gdp ) / number of medals

Would be more interesting. Medals cost money. The UK has invested something like £5m per medal won.

</comment><comment><USER24> FWIW this SPA was written with plain javascript + jQuery and one of Google's visualization APIs. Pretty cool imo.

</comment><comment><USER25> I bet the smaller countries tend to have lower test-retest intra-class correlations, olympics to olympics.

</comment><comment><USER26> Man, I was excited to see Vancouver 2010 numbers.

</comment><comment><USER27> Grenada rocks.

<comment><USER7> Well, Kirani James does, anyway.</comment></comment>


Pathwright: Create, teach, and sell beautiful online courses  - <AUTHOR> http://www.pathwright.com

<comment><USER2> Nice, thanks for posting Dodd. Glad to have it shipped.</comment>


Decoding radio-controlled bus stop displays - <AUTHOR> http://www.windytan.com/2013/11/decoding-radio-controlled-bus-stop.html

<comment><USER2> Wonderful. This is the sort of stuff I love to read about.

Tfl in the UK use a similar system AFAIK so it's almost worth considering doing the same here.

</comment><comment><USER3> Nice touch that a tilde appears when the timetable time is shown instead of live data. They should introduce that here.

<comment><USER4> They used to show a "clock symbol", which is still present in the LCD screen. But I suggested them using tilde sign, when those were in beta. I never was quite sure if the clock did mean accurate real time information or time table based information. I assume it did mean time table based info.</comment></comment>


BlackRock Backs a Startup to Find Out What Young Investors Want - <AUTHOR> https://www.wsj.com/articles/blackrock-backs-a-startup-to-find-out-what-young-investors-want-1525868931 <comment><USER2> Based on my experience providing financial advice to <100 people under 30:

Copy new hotness roboadviser interfaces ("delight your users"), provide straightforward index investment advice at the lowest possible expense ratios.

Young investors want to make the best investment decisions with limited financial knowledge. Enable them to do so while stil acting as their fiduciary.

Vanguard's iOS app is getting there in the above regard, but still has room for improvement.

<comment><USER3> As a 27 year old I'll tell you what I want: the ability to invest in REITs. There's no way I'll ever be able to afford a home, especially with values going up by $800/day in San Francisco. From my experience the only way I can do this is via my brokerage account, but I really want to do it from a tax- protected account like a 401(k).

<comment><USER4> "there's no way I'll ever be able to afford a home".

That's how I felt in 2007 but in 2012 many of those homes were then selling for 30cents on the dollar.

I am not saying that 2018 feels like 2007 (or maybe...), but your are only 27 so there are likely a few 2007s that will occur in your lifetime.

<comment><USER5> yeah, no.

in sf, 2008 saw houses back to 2004 prices, just to skyrocket above the record a year later.

</comment></comment></comment></comment><comment><USER6> > _Acorns is a financial-technology firm that allows customers with balances > as small as $5 to invest in groups of funds based on their risk tolerance. > Users link their debit- or credit-card accounts to Acorns, and the firm > rounds up the users' purchases to the nearest dollar and invests the change > on their behalf._

So their entire business model is investing change from transactions into index funds? Why couldn't any major bank or credit card company implement this and blow them completely out of the water?

> _Two of the seven ETFs that Acorns includes in its portfolios are run by > BlackRock, while the remainder are run by Vanguard._

I guess I don't get who this service is for. People who want to invest but don't want to "invest" any of their time? Why not setup a Roth IRA and get the same thing but tax-free?

<comment><USER7> This is one of those interesting knee-jerk HN reactions that miss the entire point. Acorns built a product that people love.

As to "why couldn't any major bank or credit card company implement this and blow them completely out of the water", why not ask instead why they haven't successfully done so? They've certainly tried and failed, and for the most part seems like they are turning to investments/acquisitions of companies in this space since they can't build something successful on their own.

<comment><USER8> Honestly, I don't get this product. Aren't you dealing with minimal amounts?

How much can a customer who adds a few dollars a month to his account be worth anything to an asset manager? Won't it take years before even the user acquisition cost is recouped?

<comment><USER9> I don't really think it's an investment in the product itself, but rather a nice touch point that will be used to market other investment vehicles.

</comment></comment></comment></comment><comment><USER10> 26 year old here. I want a simple interface that automatically invests in tax- saving schemes and wealth generation schemes.It should do this by understanding my income, my goals, my risk profile and tax policies. It shouldn't ask me what I want to invest in or give me jargon about my portfolio. All I would care about is, how much money is being invested, how much money I save through tax and how much money I could have for a rainy day. _If_ I want to know about my investment profile, then hit me with all the jargon in the world. I asked for it.

Lastly, the most important thing to me, how you (the platform) makes money. This part should be absolutely transparent. I should know exactly how you make money, how much money you have made off of me etc.

I'd be more than willing to pay a subscription fee for such a service or a commission fee for the hard work put in.

Lastly, you may say, well these are readily available. Not really. These services are fragmented (not as one platform), not available, at least in India.

</comment><comment><USER11> According to the sub-35 crowd in my office:

1 - Early retirement. Not from the "give it to me" perspective but from the make it easy to budget, save, use frugality as a mechanism to retire early and have reliable 4% withdrawals.

2 - Access to Cryptocurrency trading, and intelligence.

<comment><USER12> What do you mean by "intelligence"?

<comment><USER13> I'm quite certain GP meant intel / information / analysis. Slightly abnormal word choice

<comment><USER14> "intel" is of course a shortened version of "intelligence."

<comment><USER14> @saagarjha

Ambiguity is unfortunately a 'feature' of English and the main complaint of those non-native speakers who learn it, though I agree a more focused version like 'intel' provided the necessary context to non-native speakers or folks unfamiliar with this usage of 'intelligence.'

Just pointing out that 'intelligence' is accurate in this usage.

</comment></comment></comment></comment></comment><comment><USER15> Their actual business model is dependent on mining data from your transactions - by linking your credit card they can track every swipe at Chipotle...

</comment><comment><USER16> Anyone have a non-paywalled link?

<comment><USER17> [http://archive.is/zFppK](http://archive.is/zFppK)

</comment></comment><comment><USER18> We want crypto and that is all. The sooner you realize this the better.

<comment><USER19> Translation: like many generations before us, we are irrationally drawn to get-rich-quick schemes

<comment><USER20> The best investment app is the one where my portfolio goes up a lot.

</comment></comment></comment><comment><USER21> How hard is it to know? Young investors want to invest their free time. Make a product, which lets you invest your time and gives you return on that without doing anything.

For example, if a homeless kid wants to go to Thailand to have fun. BlackRock's startup should offer ROI for doing this.

<comment><USER22> I have no clue what you are trying to say

<comment><USER23> I think she/he is trying to say that young investors want to take their free time and get a strong yield on it with a good ROI. And doing that with a homeless person in Thailand is the correct approach to resolve this difficult situation.</comment></comment></comment>