"A search for the X-ray signatures of low-mass black hole binaries in the Chandra data turned up 12 within three light-years of Sgr A*."
Three light years is not that big of a distance in the grand scheme of things. For reference, the nearest star to Earth is Proxima Centauri, which is 4.2 light years away. Having 12 binaries within 3 ly sounds really dense. Having several hundred sounds crazy.
AFAIK, we are unable to see the center of the galaxy with visible-spectrum sensors due to the immense amount of dust and gas. We can see the center with IR sensors, however.
> the nearest star to Earth is Proxima Centauri, which is 4.2 light years away. Having 12 binaries within 3 ly sounds really dense. Having several hundred sounds crazy.
Not at the center of the galaxy. Stars are much closer together on average there than they are way out here in the boonies where we are.
Which makes me think - if the area is relatively dense with black holes, quite often (on galactic time scale) there must be super close encounters with stars, sometimes BH swinging right through a sun (that might be a bit of a stretch)! Imagine that spectacle, devouring whole sun throwing off/swallowing it potential planets. I am sure we would be able to see it as huge burst with our current sensors.
Plus there might be huge amount of smaller and tiny BH wreaking all kinds of havoc to everything. Pretty wild place to be
Roughly around the end of the Napoleonic era, call it 1815, 9/10ths of humans lives in what we would call abject poverty. today it is reversed and only 1/10th does. (This is still a travesty, but it is objectively better)
In that period we have seen incredible technological, political and economic improvements. But it's not clear if we will continue to see them "we might have invented everything" is a fairly common refrain (if not on HN!)
So can we say anything about where we are in this period of chnage - near the end? Well with no other information we can only plump for "in the middle". Which roughly speaking means we expect to see change on the scale of 19th and 20th Century well into the 2200s.
And part of my monkey brain just recoils at this ... optimism. My monkey brain does not trust the numbers.
But articles like this help me quieten my monkey. We look up into the night sky with powerful telescopes and find events millennia old, light years away and they confirm how we think galaxies are made. We look into the night sky and find Dark matter that we do not even know what it is made of - and I ask my monkey brain, at some point we did not know what was over the oceans, but we predicted new lands, we did not know what the land was made of and they were made of ores and minerals.
I am by nature a skeptical optimist, but the awesomeness of astronomy, it's generally leading place in science, still impresses me.
It looks like a good two centuries to come.
Just sayin'
Bibliography: I am probably stealing from people cleverer than i whom I cannot remember to reference or am too dumb to reference
Edit: I need to write more clearly. I am not arguing that we have invented everything, just that it can feel "where can the next thing possibly come from?". And Astronomy does things like point out "We can see 13 billion years in every direction, and most of it we don't even know what it is made of. Some of it might be useful :-)"
People have been saying "we might have invented everything" for hundreds of years.
I like the "invention wavefront" analogy, but I unfortunately can't remember where I learnt it.
Imagine the high-dimensional space of all possible things that can be invented. In the "centre" of the space is a hypersphere containing everything that has been invented to date. Every new invention is invented by "poking outwards" in one small place on the boundary of this hypersphere (hyperglobule) so that the hyperglobule now contains something that it didn't contain before. All inventions that could possibly be invented right now exist on the surface of the hyperglobule. Think of this as the "invention wavefront". Notice that as the globule expands, the wavefront becomes larger, not smaller. What this means is that as more things get invented, more new inventions become possible (intuitively: you can't invent better brakes for a car until you've invented a car, and so on).
"We might have invented everything" would imply that the space of all possible inventions is bounded, and we're running up against the edges of the box. But I don't see any reason it should be bounded.
>People have been saying "we might have invented everything" for hundreds of years.
No, they really haven't. In fact for a good chunk of centuries (from 16th century onwards), the optimism for the eventual future developments was endless. At some point there was a few scholars saying that during the end of 19th century, but still not some widespread belief.
That said, discovery probably also follows an 80/20 rule, and we're somewhat at the tail end now. We haven't had any major new discoveries, of the kind that we had regularly until the 60s-70s, for decades now.
Progressive refinement (like going from the workstation to mobile phones and watches) yes. But nothing like the advent of the computer, the internet, and so on.
And even less earth-shattering stuff than the time before that (which got us from the steam engine and electricity, to nuclear energy, radio and tv, flight, space exploration, the digital computer, QM and relativity, the DNA, and so on). Stuff like that was coming decade after decade up until the 60s-70s. After that, not so much.
>"We might have invented everything" would imply that the space of all possible inventions is bounded, and we're running up against the edges of the box. But I don't see any reason it should be bounded.
While there's some quasi-religious optimism (like the universe owe us endless discoveries forever), there are real limits, and notions like "low hanging fruit" and "marginal returns" do come into play.
I think that you (and probably many people) have a blind spot with respect to major inventions - they have been in biotechnology recently. I don't know why the popular imagination is captured by things like AI and blockchain instead.
> In fact for a good chunk of centuries (from 16th century onwards), the optimism for the eventual future developments was endless
Really?
I've read some pretty authoritative writings about how humanity always thinks The End is Near, that we live in an era of decay after a lost Golden Age, that today's youth is a uniquely corrupted lost generation and so on.
No major discoveries since the 70's? I think that's just hindsight speaking. It's easier to decide that something was a major discovery after you know how it changed history.
Blockchains are one that I would present. I'm sure experts in other fields would have examples from their worlds as well. We just haven't had time yet to appreciate how dramatic some of the discoveries are going to be.
As a general point , we have to assume that the configurations of matter is limited by some function of mass and available space. For any given space and matter, that matter can only be configured in some finite set of ways.
In that regard, the number of inventions (as subset of all sets of configured matter)- is similarly bound. We might argue that such a bounding is infinitely expanding along with the universe, as space is a important variable in the equation. Even so, my assumption is that space becomes irrelevant after a certain point of expansions. (If I have 2 atoms in a field of a billion of square miles, the number of configurations is only trivially changed by adding a few more square miles.
Once more, even if an infinitely expanding universe equates to an infinitely expanding art of inventions (configurations) - the fact remains that the set is fixed for any given time point.
What if the box IS more-or-less bounded by the limiting cultural restrictions we place on the word "invention"?
In our cultural spectrum, we constrict our inventions to optimize for "use", but perhaps "use" is too narrow.
If you look at cultural events like Burning Man, you see all sorts of completely useless inventions. Fascinatingly useless inventions.
I actually hope that one day when we do enter post-scarcity that we can stop obsessing so much on whether or not something has the subjective quality of "use", and allow the boundaries of our hyperdimentional invention-space to grow exponentially.
I think "toy-space", or "art-space" if you will, is a logical expansion of "invention-space".
A delightful example of an invention outside of our current culturally accepted bounds of invention-space: https://youtu.be/apVR5Htz0K4
You are describing evolution without an utility function. That won't work. We may be able to come up with an alternative utility function but, given past history, I'm afraid we won't and will be aimlessly exploring the solution space.
A good parallel can be draw to evolution in painting. Up until the invention of photography, painting evolved to be photo-realistic. It made amazing strides, with breathtaking results. Once photography made that evolution path obsolete, painting struggled to find a new utility function. Out of that struggle, we got amazing outcomes in conveying feelings, a new utility function. Work in the first half of the XX century, from the likes of Munch, Dali, Picasso, optimized this function up to its limits. From then on? Painting is somewhat lost in the solution space without an utility function.
Utility keeps us honest, we really don't want to end up firing on all cylinders towards the perfect combination of drugs, VR and storytelling that will shut us down forever while explaining the Fermi paradox.
For all practical purposes, I agree with the analogy, but would like to point out that the box might not be infinite so there could be limits to invention.
Take a chess game as an example. No one would say there weren't creative inventions regarding tactics and strategies to win, but the bottom line is that the number of possible chess games, no matter how staggeringly huge, is still finite. In the end, no matter how intelligent the players, there will be a point were nothing will be left to be invented, so perhaps life is also a solved game in that respect.
Also area of that thought ball increase by square. It means every new invention have tons of application in related and unrelated fields, which may help finds another invention. I think we should be able to invent all that is shown in those Hollywood blockbusters by couple of millenium if not more.
I think it's reasonable to assume though that this universe of things which are possible to invent is finite. Certainly we see that in some places. For example, cutlery. We hit the bounding box on inventing new useful cutlery a long time ago. Forks, knives, spoons, chopsticks. Then there wasn't much more to invent once we did all that. Or things like Moore's law slowing down.
For most areas of innovation, we don't seem to be near the limits. Certainly it is a sphere where today we are seeing more opportunities than completed explorations, but that may cease to be true in 50 or 150 or 1500 years.
But, we find new, better steels with some regularity. the challenge in all of this is cost/benefit. Cutlery could get a lot better, but there is no desire to improve it at current costs. Moving that invention boundary takes time and effort.
"This century has been so rich in discovery and so packed with technical innovation that it is tempting to believe that there can never be another like it. That conceit betrays the poverty of our collective imagination."
John Maddox (former editor of Nature, 1998)
>If only we didn't waste all of the antibiotics on non-human animals.
This is the one thing that makes me want to turn vegetarian.
we waste antibiotics on cattle.
regardless those same cattle become reservoirs where new diseases that could kill us are incubated, because they are mammals like is.
It would be very difficult for a plant disease to jump to us.
To be fair, I remember an E Coli outbreak in spinach that laid a lot of people out. (I probably eat as much spinach as I do any meat :| and here I like to say I’m not much of a gambler)
——
Not to take away from your collective points at all. Rehashing the entire situation makes us look like a foolish species to have burned through such an advantageous technology so quickly. One can only hope we might come to yet more elegant solutions.
Well, spinach E Coli is there because we use cattle poop all over it. Nothing better than fertilising our vegetables with manure rich in antibiotics resistant E Coli.
Antibiotics for human use are nothing. There's around 70 billion domesticated land animals being born and dying every year. That's 700 billion Petri dishes with varying antibiotic power in just 10 years, and that number is more than all of the humans that ever lived on Earth. More than enough for some massively superior bacteria to evolve.
> "Roughly around the end of the Napoleonic era, call it 1815, 9/10ths of humans lives in what we would call abject poverty. today it is reversed and only 1/10th does."
There are now 80% more people (according to these figures) who now have enough food that they can worry about bees. That's a good thing if you ask me. Now about those bees...
I'd like to believe you are right and, without any ability to estimate where we are on what seems like an exponential curve, hope that things are evolving towards the positive at an ever increasing pace.
Interesting you should mention monkey brains, because my monkey brain also recoils at this optimism when it understands that most brains are still monkey brains, and I don't trust monkeys that create an arsenal of weapons of mass destruction which can totally wipe out all trace of the things you are rightly passionate about. The evidence is scarce that other than the obvious technological progress there has been any other progress but even that being so, I'm cautiously optimistic that the battle between monkey mind and enlightened mind will eventually be won by the latter rather than monkeys collectively going the way of the dinosaurs.
>I am probably stealing from people cleverer than i whom I cannot remember to reference or am too dumb to reference
Don't remember which book it was, but I remember reading a book where there was a phrase on a page before the first chapter, "All creativity is subconscious plagiarism" :-) Of course this generality can be logically refuted but it's probably something we all do to a degree.
Yeah, that's what I call "creativity". I'd say creativity —without quotes— comes from plagiarising multiple sources at the same time, your past self included, and repeat until the result becomes cohesive.
Check out the Transcension Hypothesis paper by John Smart.
It talks about far future civilizations, hypothesizes they would live in or near the surface of (possibly manufactured) blackholes, and that black holes are actually all over the place.
It also takes the stance that intelligent civilizations (including ours) would be more likely to minitiarize and grow inwards, rather than exploring and spreading throughout the galaxy as per Star Trek.
One way to dispel the idea that everything has been invented is to imagine something small and mundane – but 100 years in the future.
It seems unlikely that people will be writing code or picking out groceries the same way they do today, for example. Some aspects will be the same. But are you sure we won’t be picking out groceries in VR?
Another thing that helps: technological progress seemed exponential over the last century, but in the long term it’s actually sigmoidal. Progress happens in jumps.
> One way to dispel the idea that everything has been invented is to imagine something small and mundane – but 100 years in the future...
Hasn't people always thought there were living in the pinnacle of technology era? I mean, if you look at texts that are 50 or 100 years old, you can see people chest thumping about how they are in the modern world.
> with no other information we can only plump for "in the middle".
This is because the derivative of e^x is e^x, so when undergoing exponential growth the rate of change tells us nothing about where we are on that curve. And this is also why people (not GP, of course) who talk about the 'knee' in an exponential graph really annoy me...!
> So can we say anything about where we are in this period of chnage - near the end? Well with no other information we can only plump for "in the middle". Which roughly speaking means we expect to see change on the scale of 19th and 20th Century well into the 2200s.
We do have information for this. We are either towards the end, or the beginning. The rapid advance of the 19th and 20th centuries were only possible due to our discovery of nearly-unlimited amounts of cheap, easily transportable energy, in the form of fossil fuels.
We've also used up our carbon budget for them (And gone over it, in fact.) There are now three likely outcomes:
1. Renewables reach the break-even point where they can affordably provide ~95% of our energy needs.
2. They don't, and we'll cook ourselves to death with our GHG emissions.
3. They don't, and our grandchildren will be shoveling shit as subsistence farmers.
first time I hear the "we might have invented everything" thing. that's an interesting contrast to what I'm used to hearing, working in AI, with people always raving about terminators coming and what not
Wasn't this some thing that puzzled cosomologists a few years ago that some galaxies emit GRBs at scary intensities?
Suddenly it sounds plausible when we consider that at a certain density of these smaller black holes, the peaceful neighborhood of these other objects and their companion stars can start to get really violent, causing collsions and whatnot which then leads to these GRBs.
There’s a theory which accounts for that called MACHO, for MAssive Compact Halo Object. While it’s possible, over many years of observation it’s very unlikely. You can’t see a black hole directly, unless it’s “eating” of course, but you can see gravitational effects like lensing. If black holes and neutron stars made up most dark matter, we’d expect to see evidence of it, and we don’t. It is still possible, although Weakly Interacting Massive Particles (WIMPs) are more likely, along with Axions and Sterile Neutrinos.
My heretical theory of dark matter is that is just a byproduct of black holes gravitational effects. Probably something about so much mass punching such a deep curve in spacetime creates a widespread effect. Of course this is just a baseless theory, but it seems more reasonable to consider the possibilities of a realm which we know that we know almost nothing about, than inventing new particles or physics to fit the data. Again, not an educated theory.
The trouble with this kind of theory is that for a force like gravity, if you consider the force outside a sphere surrounding the sun, the force is identical no matter how the mass inside is distributed, whether it's the sun or a solar mass black hole inside the sphere.
It would have to be scales beyond the observable universe then, because it appears to operate as expected. If distance scales change things, then nearby galaxies would behave differently from very large clusters, quasars should display odd behavior, smaller galaxies would behave very differently from larger ones.
> Is it possible that black holes could account for a good portion of "dark matter"?
A key issue with this hypothesis is how the holes could have formed. In order to form a black hole, a system has to gravitationally collapse. But that involves emitting a lot of energy, usually in the form of radiation, as the system becomes more and more tightly bound gravitationally.
For ordinary matter, the kind we and visible stars and galaxies are made of, that's not an issue. But there are strong limits on the fraction of the total matter in the universe that can be ordinary matter (basically because of the relative abundances of light elements, mainly deuterium, helium, and lithium, which are highly sensitive to the total number of quarks and leptons--i.e., ordinary matter--present in the early universe). The ordinary matter we can see is basically the same as the limit, which means there can't be a significant amount of ordinary matter we can't see.
But the total amount of dark matter is about an order of magnitude larger than the total amount of ordinary matter in the universe. So if a significant portion of that is black holes, the holes would have to have formed from something that is not ordinary matter. And the problem is that such a something would not be subject to any of the known interactions except gravitation, and hence would have no way to emit enough energy to gravitationally collapse to a black hole. (This is also the reason why dark matter "halos" around galaxies are much more diffuse and spread out than the visible matter--the dark matter can't clump together gravitationally the way the visible matter does.)
All of the above makes it very unlikely that black holes can account for a significant portion of dark matter.
the "missing matter" is not just at the galactic core but assumed distributed more thorough the galaxy. if it just were at the center, star rotational speed would follow keplerian predictions, instead they observed the same rotational speed across whole galaxy disks.
Baryonic matter accelerating into black holes also emits electromagnetic radiation vs. dark matter which does not interact electromagnetically by definition (and observation).
> dark matter is considered rather low mass density i.e. doesn't bend light too much. Black holes would.
Not if the holes were spread out in a very large diffuse cloud around a galaxy. A single hole would bend light significantly, but the averaged effect of a huge diffuse cloud of holes around a galaxy would be basically zero (because there would be as many holes bending light one way as the other, so their effects overall would cancel out).
But it means there is probably more they can't see
>By extrapolating from the properties and distribution of these binaries, the team estimates that there may be 300-500 low-mass binaries and 10,000 isolated low-mass black holes surrounding Sgr A*.
This is just about the center of our galaxy though. There are billions of other galaxies in the observable universe, most of those I assume also have black hole(s) in their center :)
I'm sure this is an oversimplified view, but doesn't it seem like, because black holes are more dense, they'd naturally tend to fall toward and gather around the center of the galaxy? Sort of like how more dense objects tend to be found at the bottom of a pond? So then perhaps it makes a lot of sense that the galactic center would contain a lot of black holes.
Imagine that our sun suddenly collapsed into a 1-solar-mass black hole. What would happen to the orbits of the planets? Nothing. The black hole would still exert the same gravitational pull as the sun did. The same is true if you replace all the planets with equivalent-mass black holes.
Denser objects in an atmosphere or other fluid, where there is friction and buoyancy, will tend to sink to the bottom. However, if you're in the vacuum of space, there is no concept of "sinking". There is nothing to sink in unless you enter the atmosphere of a planet or star.
However, maybe there is enough interstellar dust near the center of the galaxy to produce a non-negligible amount of friction over millions or billions of years.
Mkay. I see my confusion. You need something like a fluid and also in a non-inertial reference frame which is under some force of gravity or acceleration. I guess a supermassive black hole such as Sagittarius A (assuming it exists) could provide a force of gravity. Then you'd need enough dust or something to exert pressure on the objects around it. It seems likely there's not enough of anything remotely like a fluid dispersed throughout the galaxy to have such an effect though who knows? I'm clearly no physicist :).
In a pond, you have the force of gravity (i.e., buoyant force) to do this sorting. This force doesn't exist in space, or at least not in a way that's analogous to the pond.
Let me state up front, I am no fan of the "black hole" and "neutron star" concepts so take the following comments as arising from that basis.
The x-ray data and observations are only "supposed" to be coming from "black holes" as we cannot and have not directly observed any such entities. Now, it may be that there are specific entities involved that are dark body and gravitationally significant. However, as we are unable to directly observed these entities, they may also be quite visible and as well as gravitationally significant in terms of the effects seen.
The current consensus model for the universe entails a belief that General Relativity is correct and at the base of the GR model is a belief that the ONLY significant force at solar, galactic and universal levels is gravity, in whatever form your model of gravity may specifically mean, as in a force or in GR terms a warping of space due to mass.
Since we also know that there are large areas of charged space, we need to be able to ask the question - "are these charged space areas of such significance that they effect large areas of solar, galactic or universal space?"
The thing that we call gravity is of such weakness that even weak electric or magnetic fields completely override any gravitational effects. The simplest example that I use with my grandchildren is rubbing a balloon against my limited coverage of hair on my head and that balloon will stay connected with my hair against any force of gravity that is around me.
Too oft, methinks, the consensus models of the day are considered "holy writ" and ye are considered "blasphemers of the highest order" if one even dares to voice any doubt in those models. We take ourselves so seriously, even though what we should be doing is knuckling down and looking at all the facts before us.
If our models are wrong, so what? Is not the purpose of participating in any science a means to getting a better understanding of the nature of the universe around us? If our models are wrong in any area, let's try something else. To me in a sense, we are still in the mindset of those who came before who fought against a heliocentric view, they would rather add more gears to the geocentric model than consider that maybe another model is more useful in describing the world around us.
Mayhaps, we need to take some steps back from our current models, put aside our pet theories and just look at the data that we have and see if some other pattern arises. It should be no skin off of our noses if the models and theories we have are shown to be wrong.
Let's make science fun again, because it ain't no fun today.
An accretion disk is not a black hole. Current physics have no other explanation for the disks, but it does not mean that the black holes are really there.
There is also some lack of precision on the LIGO experiment that does not invalidate all reasonable alternative explanations.
As people already said, the evident is overwhelming on the side of black holes existing. But we don't have any definitive measurement of them.
I think this is as definitive a proof we'll get until we get close enough to directly measure Hawking radiation. Of course, by that time we should also be close enough to "see" the black hole directly...
It's a bit a matter of definition or interpretation but I would count the LIGO observations as direct observations of black holes. But as others pointed out there's lots of evidence for their existence.
"A search for the X-ray signatures of low-mass black hole binaries in the Chandra data turned up 12 within three light-years of Sgr A*."
Three light years is not that big of a distance in the grand scheme of things. For reference, the nearest star to Earth is Proxima Centauri, which is 4.2 light years away. Having 12 binaries within 3 ly sounds really dense. Having several hundred sounds crazy.