Could this kind of trigger effect the standard candle application of Type 1a's? For example, if a black hole triggers a type 1a and that perturbs the type 1a light curve in some way (possibly because less mass could be consumed in the explosion than you would get if one was triggered by mass accretion) and the rate of triggering of this kind changed over time as the universe aged and somehow the population of primordial black holes changed, or the distributions of white dwarf candidates and pbhs changed...
They did some modeling in a previous paper of how this would impact Ia supernovae and it depends on whether the supernova is driven by Kelvin-Helmholtz instabilities or not. In the case that it is, this would only trigger Ia supernovae for white dwarfs which are already very close to the Chandrasekhar mass. In this case the standard candles would be pretty much the same.
In the case that KH instabilities are weaker they claim that you can get supernovae at masses farther from the Chandrasekhar limit. This could plausibly have more of an impact on Ias as standard candles. (Though perhaps less than you might think becauseit would also likely have an effect on the shape of the light curve, and Ias are normalized based on their light curve shape.)
All that said, even if this process does occur, I doubt the rates would be high enough for it to be a substantial fraction of observed Ias.
Many physicists have pointed out several flaws in the dark forest theory, which makes for a great read but doesn’t really carry over to the real universe 1:1.
Can you point me to more info on that or just tell me? I am curious about reasons to be more optimistic than that book lays out. I would much prefer the Carl Sagan view of the Cosmos as one where it simply makes no physical nor cultural sense at all to be aggressive toward other stellar civilizations.
"Dark forest" doesn't work from a game-theoretical standpoint. It assumes that it's cheap to destroy entire planets and solar systems. Yet no-one seems to be colonizing other systems.
The optimal strategy in this case is to expand as quickly as possible, before others can grab or destroy resources.
I think one idea is that there aren't very many habitable planets. The Trisolarians are coming to Earth because it's their only option, not because they want to destroy humanity.
In the book, the trisolarans aren't coming to earth just because is the only habitable planet, it's because it's the closest one too. The don't have FTL and they spend the full resources of their dying civilization to build a fleet that will reach earth in ~400 years.
So yeah, a lot of prime real state but no way to reach it.
400 years is nothing. At this speed, all the Galaxy would have been colonized long ago.
This subplot in the book is at least reasonable. Somehow aliens capable of pico-scale engineering can't make a telescope to observe the nearby solar systems, but OK, whatever. Cultural blindness and all that.
It's the later plot with the "dark forest" that makes no sense. There are ships capable of moving at relativistic velocities and spacetime-altering weapons.
If you're colonizing systems so stealthily that it's not visible, then why bother doing that at all? Even a single solar system has more than enough resources.
Entropy and thermodynamics exist. It would be impossible to colonize every system we see without the tremendous heat energy expenditure needed to do so being obvious, and obviously not natural. The background temperature of space is so regular and predictable that any deviation is noticeable.
Barring some magical woo-woo technology that someone will probably insist must exist because we foolish humans are simply too stupid to understand anything, this isn't something you can just cheat. There ain't no stealth in space[0].
its a few years since I read Liu Cixin's books and even longer since I read Greg Bear's, but the technology was very different, and it was not as uniformly hostile. The primary technology used to destroy civilisations in Bear's books was self-replicating machines, and there was an advanced civilisation that tries to defend or rescue those attacked, and punish the aggressors - so its a bit less bleak.
There are loads of issues with it as hard sci-fi, but the bigger issue is that it's meant as a political allegory far more than it's meant to be hard sci-fi. Where I think it shines to some extent in the latter case is its ability to explore scale and build intuition about the vast scales involved in space.
Otherwise though? Sophons destroy the entire premise of the "Dark Forest"! Still as I said the series is far more concerned with overt allegories (West vs East, Collectivism vs Individualism, etc), and more covert allegories that allegedly criticize the CCP's way of doing things.
I don't read Mandarin, but I suspect the ability to do so and the high context nature of the language, helps a lot in getting that across.
Culture at some level grows out of biology and physics, it's downstream of those things. The material basis of a civilization will have a tremendous long term impact on its culture.
I love Sean Carroll (Something Deeply Hidden and From Eternity to Here are the root of my fascination with physics and endless pondering of the nature of time) but I have to disagree with his take on this.
Hypothesis - a proposed explanation for something (such as a phenomenon of unknown cause) that is tentatively assumed in order to test whether it agrees with facts that are known or can be determined.
Theory - a scientifically acceptable or plausible general principle or body of principles based on data and offered to explain phenomena
Just because those outside of scientific fields use them interchangeably doesn't change the fact that they carry different meanings in scientific contexts.
I think a fragile world hypothesis is more interesting and scary.
Instead of a superintelligence killing any emerging intelligence, superintelligence is so smart that it can perturb spacetime in ways that easily kill itself.
Kind of like the idea that LLMs will give anyone with a garage the ability to create killer viruses (wild claim), a superintelligence might trivially create black holes that engulf it. If the intelligence is distributed across many agents (or nations), someone will try something stupid that kills the entire population.
It'd be even scarier if they could accidentally collapse the supposed vacuum state. Universal annihilation at the speed of light just because you got too smart.
Fragile world / fragile universe meets "too smart for your own good".
Leaving aside the fact that there's no evidence superintelligence is even possible, no amount of intelligence alone will let you "trivially" create black holes. Creating black holes requires a ludicrous amount of energy. Planet-scale energy, maybe solar-scale energy. Energy is conserved. You can't just think really hard and have it. At minimum you have to already have the energy and materials to build a machine that will let you (mostly build another machine that lets you) harness that much energy.
It's at least not something you'll do by accident.
It's inherent to the math that defines the entire concept of a black hole, or "spacetime" in general. So to the extent we can contemplate the question at all, we can be pretty confident that creating black holes is Very Hard.
There's a lot we don't know, but the fact that the universe is consistent means it has to be consistent with what we do know already. Don't be so openminded your brain falls out.
See this is what I'm talking about as far as being too open-minded. Consider what it would mean for the universe to be inconsistent, particularly in relation to the astronomical observations that are the basis of this conversation.
All we can say is that the universe has been consistent so far, during the brief time we observed a small part of it given the instruments we have.
We update our model(s) so that it keeps being consistent and predictable to us (that’s human nature), but no model can be probably correct and complete.
You are not grappling with the full consequences of the universe being inconsistent. If the universe is inconsistent, science is dead. Why the fuck on HN of all places do I need to defend the idea that science is possible? Back to philosophy class, all of you.
Because you're being too narrow minded. Hubble Tension exists, the universe is not consistent. We take cosmological homogeneity as an axiomatic assumption and we keep being proved wrong.
The only thing we can say with confidence is that the base laws of physics appear to be mostly consistent everywhere we've looked in the last hundred or two years. But also only across relatively recent history. The laws of physics were very different early on. The electic and magnetic field used to be separate things and now they aren't.
None of this is incompatible with science as a concept.
Sounds logical to me. It's already remarkable that we haven't done this with fission weapons. It's not unreasonable to assume that within a century we'll have antimatter weapons. Destructive potential only goes up.
We could not come close to destroying the world with fission weapons. We might make things very hard for humanity, but the world and life would continue, perhaps even benefit.
Anyone have guesses about how a transiting primordial black hole would effect a Sun like star? Paper is about tidal forces inducing supernova in white dwarfs. For that matter how might it effect sea tides?
Note that the orbital perturbation of Juno in 1839 was of rather low magnitude, and could have been caused by an asteroid as small as ~1km diameter. Based on current models, there are potentially more than a million rocks that big in the belt still undiscovered.
Depends on what "low mass" means. An earth-mass black hole lasts 10^50 years. A black hole the mass of Mount Everest lasts 10^21 years.
Black holes on the order of metric tons would have evaporated by now. But primordial black holes can come in any size, and there is a vast range of them that will exist much longer than the universe has already existed.
We have constraints that primordial black holes must be less than the size of a large asteroid. They would be gravitationally insignificant to the Earth unless they actually passed through it.
I also don't think it would really be detectable in the Sun. Perhaps there would be some transient astroseismology signature.
I didn't understand how a black hole could pass through a star when I read this. I think of black holes as large. Apparently a primordial black hole can have the mass of an asteroid compressed into a space smaller than a proton. I also thought very small black holes evaporated quickly via Hawking radiation. I was wrong on the scale there too. A PBH with the mass of an asteroid can easily live for longer than the universe has been around. Something about the very very early universe let matter collapse into these things without the normal processes that form stellar sized black holes.
Wouldn't Type Ia supernovas caused by blackholes have a different brightness?
That could mean the entire cosmic ladder needs to be revised, maybe this could resolve the crisis in cosmology..
Kind of chilling to think about these tiny black holes. If they have enough gravitational pull to destabilize a white dwarf, I don't want to know what they'd do to our solar system.
These supernova-generating black holes are atomic scale (Schwartzchild radius of 15pm to 15nm), yet they carry the momentum of a large asteroid. If one of these hit the earth, they would cause a life-ending apocalypse like the event that ended the dinosaurs. The fact that this has not happened yet is encouraging.
> The total energy created by a PBH roughly equals the energy produced by the detonation of one tonne of TNT, but this energy is the total energy it deposits along its path through the Earths diameter, not the energy it produces on impact. So don’t expect a magnificent explosion, we’d be lucky to see a spark as it hits the ground.
It looks at pairs of seismic events that trace line through the earth and are timed correctly.
> Two sets of reports were found in the 1993 database that fit all the criteria for a linear source. The model and residuals (observed minus predicted arrival times) for the first event are given in Table 1. The RMS residual is 0.73 sec. This RMS value would indicate a good fit for a well-located earthquake.
The drag is insufficient to stop it and it would go right through the earth without stopping. It would cause earthquake of 4 magnitude, which is barely detectable.
PBH (if they exist) are microscopic in size. If they're real and qualify as a potential dark matter candidate they have passed our solar system many times with the only thing happening being undetectable gravitational tugs.
This is one of those headlines where I simultaneously think "cool" and now have a new source of low-grade background anxiety about. It can have a seat next to false vacuum collapse.
Take comfort in the fact that compared to the size of the universe, the speed of light is like molasses in January. Cosmological eschatology is a very slow game, and the odds of you being alive and in the right place to be a spectator are literally astronomically small.
The bad news is that if a black hole is not primordial, the minimum mass is high enough (2-4 M_sol) that it doesn't so much "pass through our system" as "we pass through its".
I'm not 100% confident, but rough approximation suggests that a close approach of even 5 AU even at typical interstellar velocities might have an unplesant climate impact by increasing the eccentricity of our orbit.
Déstabilise orbits - definitely, but the same would be true of a star or other celestial body.
But our risk of getting sucked into a black hole is really tiny. (Although personally if I had a chance to enter a black hope, I would. I’m just naturally curious.)
We know what something with about 2 solar masses looks like at about 5 light years, because there is such a thing a bit closer: the Alpha Centauri system.
So (and again, this is very rough approximation) I mean AU: consider the high speed of interstellar encounters so it won't be there for long, and that it takes the full pull of Sol 6 months to turn us around 180°.
Also, yes, in general this would cause a lot of the Oort cloud to destabilise and a long period of bombardment of all the planets.
At 5 AU, gravitational force would be 1/25 or 4% the strength of the sun at 1 AU. If the black hole was four solar masses, it would exert a pull about 16% as strong as the sun. Probably not enough to rip us out of orbit, but enough to seriously perturb it. I think it's at least an end-of-civilization event.
5 AU is the perfect distance to really wreck Jupiter, though.
Not an astrophysicist, but I'm thinking 5 AU could quickly fry the Earth - because it takes very little in the way of solar comets, asteroids, and dust to build a temporary accretion disk around such a black hole. That disk might have a temperature of >1M degrees. Plus the dynamo effects of the disk's interactions with the solar magnetic field? Yeah. 5 ly sounds much safer.
Yeah, I'm sure you're right. I was looking purely at orbital mechanics and gravity, but I think a four-stellar-mass black hole would certainly have other harmful environmental effects that would be felt at that range.
I clearly could've phrased this better though: I was aiming for "here is an example distance which *is* bad", not as it appears to have been understood "here is the distance where it is *not* bad".
I mostly noticed your "might have an unplesant climate impact by increasing the eccentricity of our orbit", and thought that'd be the least of Earth's worries.
Black hole gravity is ruthless about turning nearby mass into deadly fireworks.
In the case that KH instabilities are weaker they claim that you can get supernovae at masses farther from the Chandrasekhar limit. This could plausibly have more of an impact on Ias as standard candles. (Though perhaps less than you might think becauseit would also likely have an effect on the shape of the light curve, and Ias are normalized based on their light curve shape.)
All that said, even if this process does occur, I doubt the rates would be high enough for it to be a substantial fraction of observed Ias.
This might be a better one.
https://medium.com/predict/why-the-dark-forest-theory-is-pro...
This video is pretty good.
https://www.youtube.com/watch?v=X0SvgT9Lc2M
This post attempts a formal refutation.
https://www.pgmusings.ca/journal/dfh
The optimal strategy in this case is to expand as quickly as possible, before others can grab or destroy resources.
seems like an odd thing to claim, given that we have no idea what's going on on any planet outside of our solar system
Still makes no sense.
So yeah, a lot of prime real state but no way to reach it.
This subplot in the book is at least reasonable. Somehow aliens capable of pico-scale engineering can't make a telescope to observe the nearby solar systems, but OK, whatever. Cultural blindness and all that.
It's the later plot with the "dark forest" that makes no sense. There are ships capable of moving at relativistic velocities and spacetime-altering weapons.
Barring some magical woo-woo technology that someone will probably insist must exist because we foolish humans are simply too stupid to understand anything, this isn't something you can just cheat. There ain't no stealth in space[0].
https://www.projectrho.com/public_html/rocket/spacewardetect...
I don't remember any other of his books that might apply, but I haven't read all of them. (I probably should. What I have read was great.)
Otherwise though? Sophons destroy the entire premise of the "Dark Forest"! Still as I said the series is far more concerned with overt allegories (West vs East, Collectivism vs Individualism, etc), and more covert allegories that allegedly criticize the CCP's way of doing things.
I don't read Mandarin, but I suspect the ability to do so and the high context nature of the language, helps a lot in getting that across.
Hypothesis - a proposed explanation for something (such as a phenomenon of unknown cause) that is tentatively assumed in order to test whether it agrees with facts that are known or can be determined.
Theory - a scientifically acceptable or plausible general principle or body of principles based on data and offered to explain phenomena
Just because those outside of scientific fields use them interchangeably doesn't change the fact that they carry different meanings in scientific contexts.
Even more because the confidence changes all the time, but people do go around renaming well known ideas
Instead of a superintelligence killing any emerging intelligence, superintelligence is so smart that it can perturb spacetime in ways that easily kill itself.
Kind of like the idea that LLMs will give anyone with a garage the ability to create killer viruses (wild claim), a superintelligence might trivially create black holes that engulf it. If the intelligence is distributed across many agents (or nations), someone will try something stupid that kills the entire population.
It'd be even scarier if they could accidentally collapse the supposed vacuum state. Universal annihilation at the speed of light just because you got too smart.
Fragile world / fragile universe meets "too smart for your own good".
It's at least not something you'll do by accident.
"It Really Brings the Room Together" https://m.xkcd.com/1680/
M87 Size Comparison https://m.xkcd.com/2135/
Black Hole Moon https://what-if.xkcd.com/129/
We are primitive apes. We are all uniformly dumb.
There's a lot we don't know, but the fact that the universe is consistent means it has to be consistent with what we do know already. Don't be so openminded your brain falls out.
We don't know this either.
We are very limited in detection. Our energies are small.
How "standard" are standard candles and other references? Are the facts that stand as the basis for our theories even correct?
We are too primitive to be dealing in absolutes.
> We don't know this either.
See this is what I'm talking about as far as being too open-minded. Consider what it would mean for the universe to be inconsistent, particularly in relation to the astronomical observations that are the basis of this conversation.
We update our model(s) so that it keeps being consistent and predictable to us (that’s human nature), but no model can be probably correct and complete.
The only thing we can say with confidence is that the base laws of physics appear to be mostly consistent everywhere we've looked in the last hundred or two years. But also only across relatively recent history. The laws of physics were very different early on. The electic and magnetic field used to be separate things and now they aren't.
None of this is incompatible with science as a concept.
I am, however, reminded that the orbit of the asteroid Juno (~250km diameter) permanently changed in 1839 without an obvious cause.
And the referenced papers:
Probing primordial black holes and dark matter clumps in the Solar System with gravimeter and Global Navigation Satellite Systems networks - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
Close encounters of the primordial kind: A new observable for primordial black holes as dark matter - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
And the PBS Spacetime: How Many Black Holes Are In The Solar System? - https://youtu.be/wh75ubECL8I
Black holes on the order of metric tons would have evaporated by now. But primordial black holes can come in any size, and there is a vast range of them that will exist much longer than the universe has already existed.
I also don't think it would really be detectable in the Sun. Perhaps there would be some transient astroseismology signature.
A physics stack exchange answer about it: https://physics.stackexchange.com/a/55184
The most relevant part:
> The total energy created by a PBH roughly equals the energy produced by the detonation of one tonne of TNT, but this energy is the total energy it deposits along its path through the Earths diameter, not the energy it produces on impact. So don’t expect a magnificent explosion, we’d be lucky to see a spark as it hits the ground.
Two Seismic Events with the Properties for the Passage of Strange Quark Matter Through the Earth - http://www.geology.smu.edu/~dpa-www/sqm/pdf/sqm_lanl.pdf
It looks at pairs of seismic events that trace line through the earth and are timed correctly.
> Two sets of reports were found in the 1993 database that fit all the criteria for a linear source. The model and residuals (observed minus predicted arrival times) for the first event are given in Table 1. The RMS residual is 0.73 sec. This RMS value would indicate a good fit for a well-located earthquake.
A BBC article about the paper: http://news.bbc.co.uk/2/hi/science/nature/2502755.stm
[1]: https://arxiv.org/pdf/1203.3806
PBS Spacetime - How Many Black Holes Are In The Solar System? https://youtu.be/wh75ubECL8I
And then How to spot tiny black holes that might pass through the solar system - https://www.sciencenews.org/article/primordial-black-holes-s...
That references two papers:
Probing primordial black holes and dark matter clumps in the Solar System with gravimeter and Global Navigation Satellite Systems networks - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
Close encounters of the primordial kind: A new observable for primordial black holes as dark matter - https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
I think there's a PBS Space Time on it (of course)
adding: yup! love that show
* https://www.youtube.com/watch?v=Q6kJaMf3Lgo
https://web.archive.org/web/20260310115201/https://www.willi...
I'm not 100% confident, but rough approximation suggests that a close approach of even 5 AU even at typical interstellar velocities might have an unplesant climate impact by increasing the eccentricity of our orbit.
But our risk of getting sucked into a black hole is really tiny. (Although personally if I had a chance to enter a black hope, I would. I’m just naturally curious.)
So (and again, this is very rough approximation) I mean AU: consider the high speed of interstellar encounters so it won't be there for long, and that it takes the full pull of Sol 6 months to turn us around 180°.
Also, yes, in general this would cause a lot of the Oort cloud to destabilise and a long period of bombardment of all the planets.
5 AU is the perfect distance to really wreck Jupiter, though.
Well yeah.
I clearly could've phrased this better though: I was aiming for "here is an example distance which *is* bad", not as it appears to have been understood "here is the distance where it is *not* bad".
Black hole gravity is ruthless about turning nearby mass into deadly fireworks.
But never zero.