Aren't these 'black holes' are really just worm holes for interstellar travel?
If we're in a simulation, someone hit it with a hammer, please: Milky Way spews up to 100 MEELLLION black holes
A new study shows that there may be up to 100 million black holes scattered around the dark depths of the Milky Way – a number much higher than previously expected. That figure was calculated by University of California at Irvine physicists, who took a closer look at the gravitational waves detected by the LIGO equipment in …
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Wednesday 9th August 2017 06:30 GMT John Smith 19
So it was just a case that no one had bothered to do the calculation?
Which raises another interesting question.
If now the signature of actual black hole collisions does the rate at which they have been found match the rate we would expect to find them?
IOW why did it take so long to find one?
Just a thought.
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Wednesday 9th August 2017 10:11 GMT Doctor Syntax
Re: So it was just a case that no one had bothered to do the calculation?
"IOW why did it take so long to find one?"
Once the instrument had been built it didn't take long. So the real question is why it took so long to build. If you want an answer to that then Google is your friend. Just go and read what it involves.
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Wednesday 9th August 2017 16:41 GMT Anonymous Coward
Re: Answers the Fermi Paradox?
In what way? The volume of the Milky Way is estimated at about 8 trillion cubic light years. 100 million black holes would mean one every 80,000 cubic light years. Not exactly likely to pose a problem for a civilization before it can leave its home solar system, or a navigational hazard once it does.
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Thursday 10th August 2017 07:19 GMT eldakka
Re: " Answers the Fermi Paradox? "
because if there are so many, why did it take us so long to find one.
Obviously you haven't followed Doctor Syntax's advice on your last post of the same question:
If you want an answer to that then Google is your friend. Just go and read what it involves.
In brief - you can't see black holes, because they emit no radiation with which to see them with. Therefore they can only be observed indirectly, from their effect on their surroundings.
Examples:
1) When eating a lot of matter, they generate X-rays and other radiation from the material that is in it's accretion disk, that is, material that is NOT in the blackhole, but is queued up around it waiting to get sucked in. Sorta like a noisy queue standing outside a gloryhole...
2) By the orbits of masses around it, as is with the case with Sagittarius A*, the supermassive black hole at the center of our own galaxy, where they have plotted the orbits of stars around the black hole - well, surmised black hole would be more accurate, as what they do know is to get the stellar orbits that have been observed and measured, you'd need a 4 million solar mass object in an area of only a few million miles, and the only thing we are aware of, even theoretically, that could do that is a black hole.
3) By detecting the gravity waves of colliding black holes.
4) Observing radiation (e.g. light) being bent by an otherwise un-observable object that is small enough to be a black hole (i.e. isn't a vast field of dark matter)
I imagine there are others, but I am not a physicist so am only aware of the generalities. But in short, you can't directly see one, you can only detect one by the effects it has on the observable universe around it.
So, if there is no interaction with physical matter (accretion disks, orbiting matter, bending light), or the rather advanced and expensive technology of detecting gravity waves doesn't exist, then there is no way to detect a black hole. So a black hole sitting in deep space minding it's own business is, essentially, undetectable unless you are vary luck and are observing something on the other side of it and can detect the resultant bending of light.
LIGO, which is the only facility (across 2 sites on opposite sides of the US) currently detecting gravity waves (there is another under construction in India), is, as per wikipedia, the largest and most ambitious project ever funded by the NSF.
It's first phase started in '94, and cost something like US$400 million. It came online in 2002, and for 8 years searched fruitlessly for gravity waves. It was shutdown in 2010 for a 5 year, US$200 million upgrade. When it came online in 2015, it started detected gravity waves within a year of the upgrade.
The science, engineering and construction of LIGO is incredible. It has 2x4km-long arms which are kept in one of the most pure vacuum's in existence, certainly the most pure on anything outside small laboratory-based experimental chambers the size of a fridge. It bounces a laser beam up and down the arms dozens of times (maybe over a hundred?) with nanometer precision. And even then it still has limitations, it can only detect mergers of certain sizes for example.
Now, if you want to learn more, rather than asking the same question again, stop whining and go do your own research.
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Wednesday 9th August 2017 07:22 GMT Chris Miller
Re: Quid of dark matter then ?
Not really. Mass of Milky Way ~6x1011 solar masses, so even a billion solar masses in black holes is less than a rounding error. If dark matter exists (and it's not a failure of understanding of how gravity works at very large scales), there's more than 5x as much of it as there is baryonic matter.
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Wednesday 9th August 2017 13:35 GMT Chris Miller
Re: Quid of dark matter then ?
Should have added that there's been a lot of searching (looking for transient gravitational lensing events) for MACHOs (MAssive Compact Halo Objects) with largely negative results. This would be much more likely to find brown dwarf sized objects rather than black holes (simply because there'd be a lot more of them). Which is why the dark matter search remains focused on WIMPs (Weakly Interacting Massive Particles), but with no more success :).
Anyway, these putative (this is only a computer simulation, no-one's actually found any!) black holes would, as stellar remnants, be mostly within the disk of the Milky Way; which isn't where the dark matter needs to be in order to account for the observed anomalies in galactic rotation rates (it would need to be in a halo surrounding the galaxy).
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Wednesday 9th August 2017 16:46 GMT Mark 85
Re: Quid of dark matter then ?
Anyway, these putative (this is only a computer simulation, no-one's actually found any!) black holes would, as stellar remnants, be mostly within the disk of the Milky Way; which isn't where the dark matter needs to be in order to account for the observed anomalies in galactic rotation rates (it would need to be in a halo surrounding the galaxy).
But would this account for the "missing" matter that so far the scientists believe is out the there but they can't find it?
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Wednesday 9th August 2017 18:15 GMT Destroy All Monsters
Re: Quid of dark matter then ?
No.
The mostly excellent Natalie Wolchover has a writeup at Quanta Magazine: Scientists Unveil a New Inventory of the Universe’s Dark Contents
The analysis, posted on DES’s website today and based on observations of 26 million galaxies in a large swath of the southern sky, tweaks estimates only a little. It draws the pie chart of the universe as 74 percent dark energy and 21 percent dark matter, with galaxies and all other visible matter — everything currently known to physicists — filling the remaining 5 percent sliver.
100 x 10⁶ 30-solar-mass black holes = 3 x 10^9 solar masses.
The Galaxy total (dark and light) is around 7 x 10^11 solar masses., 21% of which is 1.5 x 10^11. So the unseen black holes would be 1% of that DARK MASS (cue ominous Back music on the organ)
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Wednesday 9th August 2017 23:59 GMT Destroy All Monsters
Re: Quid of dark matter then ?
Stupidly I erred in the above calculation, not being helped by El Reg's tendency to delay my missives and pass them by Oompa Loompas of Colour enslaved in disused London underground tunnels and trained to detect dangerous levels of Badthink.
The dark matter content of the galaxy is 80% of its total mass (21 / (21+5)), not 21%, leaving out dark energy (is that right?), so we are looking for 5.6*10^11 dark mass, of which the millions of Black Holes would only be 5 thousands....
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Wednesday 9th August 2017 08:33 GMT hammarbtyp
Seems a bit early to be drawing the curve
As far as I understand it we have had 2 detectable events since LIGO went live.
It seems like an awful small amount of data to make such a statement. i presume if LIGO does not detect another for 20 years, the maximum number of black holes in the galaxy will be reduced?
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Wednesday 9th August 2017 10:56 GMT hammarbtyp
Re: Seems a bit early to be drawing the curve
Yep, just read it again, my bad
Of course there are another of other assumptions in there such as method of the formation of black holes, do stars in binary configurations affect formation, etc. So I guess this the upper figure, not necessarily the definitive value
Presumably as we get more LIGO data we can test that figure and hopefully get some new science
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Wednesday 9th August 2017 12:32 GMT Peter2
If we're in a simulation...
Then we're doomed.
What are the chances of the OS still being supported and patched properly after a few billion years? The big bang must have been last time it crashed and rebooted and you know how skiddies will happily try and crash the host for the lolz at which point if the OS has serious bugs in it then everything is going to go bang!
Not particually worried though. At present there is absolutely no reason to think that we are in a VM beyond the observation "hey, computing power keeps increasing a lot and we might be could be living inside a VM!" There is more credible evidence to prove that a god created the world in 6 days, and then spent the seventh creating a billion galaxies, with over a billion stars in each, and countless billions of planets.
Personally, I am not inclined to beleive either and won't do until somebody produces some convincing evidence.
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Wednesday 9th August 2017 16:45 GMT Anonymous Coward
Re: If we're in a simulation...
Maybe this simulation is based on the following research premise: "What happens if we create a simulation where everything is the same as our reality, except we don't support our systems for more than a few years after sale? Can any civilization survive long enough to leave its solar system and spread out to the stars before a security hole lets hackers take down the worldwide power grid and the population resorts to cannibalism?"
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Wednesday 9th August 2017 23:26 GMT Jim Birch
Re: If we're in a simulation...
If we are in a simulation it may well have started 5 seconds ago. Or, alternately, 5 simulation seconds ago. The initial conditions could include your memories of that sunny afternoon at the beach when you were ten years old looking up at the sky and wondering how the world worked. Biographical details could be input or output. Until you have determined the nature of the simulation (which could be difficult, exceeding difficult, or impossible, depending on the code quality) you must resign to be trapped on a leaf in a vine.
If I recall correctly I wrote this post.
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Wednesday 9th August 2017 14:06 GMT sitta_europea
Er, I'm confused:
Quoting the article:
Fundamentally, the detection of gravitational waves was a huge deal, as it was a confirmation of a key prediction of Einstein's general theory of relativity. But then we looked closer at the astrophysics of the actual result – a merger of two 30-solar-mass black holes.
Quoting later in the article...
if the current ideas about stellar evolution are right, then our calculations indicate that mergers of even 50-solar-mass black holes will be detected in a few years."
So is it harder to detect them if they're bigger?
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Wednesday 9th August 2017 14:38 GMT cbars
the probability of observing such a collision is high, they're saying, because such masses are common. If they were rare, it stands to reason it would take a longer time to detect them as they'd have happened less often (and you might need a more sensitive detector to get the really old ones which are very 'far away')
Bullock said. "We were able to work out how many big black holes should exist, and it ended up being in the millions – way more than I anticipated."
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Wednesday 9th August 2017 16:37 GMT Anonymous Coward
Wouldn't all Population III stars have ended up this way?
Because they were so massive they'd have to leave behind a black hole. In addition, many Population II stars would have been quite large and short lived as well and ended up this way.
To any astronomers reading this: why the heck did you guys name star generations backwards? The first stars should have been Population I, and so on. There have to be a few fourth generation stars around somewhere, what would those be called, Population Zero?
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Wednesday 9th August 2017 19:13 GMT Brewster's Angle Grinder
Re: Wouldn't all Population III stars have ended up this way?
"why the heck did you guys name star generations backwards?"
Because the relative ages of the populations weren't understood when they were named; it was just a spectroscopic survey of the sky showing two distinct types: population I and population II. (Population III being a later addition.)
For an analogue, look at how planet naming practices are producing skew-whiff systems. But once you have literature referring to Gliese 876 b, it's really hard to rename it because you've found another planet closer in.
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Friday 11th August 2017 23:10 GMT Destroy All Monsters
Larry Niven had something to say about that:The Borderland of Sol.
The first Sci-Fi story I got into, and I remember having had to read it several times until the elements made a coherent model.
That was before Hawking Radiation was invented, though.
I always picture Carlos Wu as looking like Ed Witten for some reason. Weird, that.
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