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A dozen black holes may lie at the centre of our galaxy

bbc.co.uk

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Re: A dozen black holes may lie at the centre of our galaxy

#51

Post by dbasedweeb »

everdev wrote: post #48

Is it possible that black holes could account for a good portion of "dark matter"? They literally fit the term.

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.

Re: A dozen black holes may lie at the centre of our galaxy

#52

Post by tfha »

jstanley wrote: post #13
lifeisstillgood wrote: post #2

Let me try an optimistic thought experiment. 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 h…

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 s…

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.

Re: A dozen black holes may lie at the centre of our galaxy

#53

Post by tfha »

coldtea wrote: post #37
jstanley wrote: post #13

Earlier quoted context omitted.

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 s…

> 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, a…

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.

Re: A dozen black holes may lie at the centre of our galaxy

#54

Post by abakker »

tfha wrote: post #52
jstanley wrote: post #13

Earlier quoted context omitted.

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 s…

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 se…

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.

Re: A dozen black holes may lie at the centre of our galaxy

#55

Post by perl4ever »

coldtea wrote: post #37
jstanley wrote: post #13

Earlier quoted context omitted.

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 s…

> 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, a…

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.

Re: A dozen black holes may lie at the centre of our galaxy

#56

Post by vkou »

lifeisstillgood wrote: post #2

Let me try an optimistic thought experiment. 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 h…

> 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.

Re: A dozen black holes may lie at the centre of our galaxy

#57

Post by darepublic »

52-6F-62 wrote: post #22
lawlessone wrote: post #16

Earlier quoted context omitted.

>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.

In the pedantic tradition around here: 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…

I can only imagine the aliens are judging us harshly

Re: A dozen black holes may lie at the centre of our galaxy

#58

Post by azernik »

marcosdumay wrote: post #50
azernik wrote: post #34

Earlier quoted context omitted.

They are actually quite visible - their accretion disks (matter falling into the black hole) are very hot and radiate on a broad range of frequencies.

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 t…

We have direct proof of:

* extremely large masses

* in very small volumes

* that are not, themselves, emitting anything

It could be many things, but they pretty much all fit the definition of "black hole".

Re: A dozen black holes may lie at the centre of our galaxy

#59

Post by Koshkin »

lifeisstillgood wrote: post #2

Let me try an optimistic thought experiment. 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 h…

I think there's at least three areas where the possibilities to invent new things are limitless: biology, mathematics, and computer games.

Re: A dozen black holes may lie at the centre of our galaxy

#60

Post by luk32 »

everdev wrote: post #48

Is it possible that black holes could account for a good portion of "dark matter"? They literally fit the term.

I don't think so. I think currently dark matter is considered rather low mass density i.e. doesn't bend light too much. Black holes would.

Think that you have the mass spread out over a whole galaxy, vs just the middle.

From infinity-like large distance it's the same, from galactic it would probably make a difference.

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