- definitive sink to send all of our nuclear waste (it would be the /dev/null of the Solar System)
- gravitational energy generator (limitless, until we have no more mass to throw in)
See also [1].
[1] https://physics.stackexchange.com/questions/25498/the-sun-as...
Basically, gravitational lenses don't have a "focal length" per se. It's not an exact analogy to a classic glass lens. There is a minimum distance you need to be away from an object to use it as a g-lens. But as you get further away than that, it'll work better.
Now, the minimum distance you need to be away from the massive object decreases as the mass of the object increases. So for the sun, you'd have to place a camera about 500AU away to use it. That's too far to be practical at our current technology level. For a smaller object like a planet sized blackhole, you'd have to be orders of magnitude further away. Not very helpful!
Now, it's possible I'm mistaken as I'm thinking about some calculations I did on schwarzchild geometry and I didn't consider what would happen very close to the blackhole where curvature is very high, but my intuition says that it won't be very helpful at all.
That doesn't mean the blackhole won't be helpful though!!! I think there's an ENORMOUS number of useful experiments we could do. And, I think blackholes can be used as very powerful computers, possibly quantum ones, but I don't know the details.
Edit: never mind, I just remembered there's a specific distance from a massive object you have to be to hit the focal length sweet spot. I wonder if having a smaller radius makes the focal length shorter?
Waste implies we have no use for it any further. This concept views the world on very limited time scales (wherein we can continue to take from the world and turn things into waste that we have no use for any longer).
Instead we should always be thinking about reuse of materials. Waste should never be a terminal state so much as the waste products of one process should be converted into a useful input to something else.
Ultimately with limited materials on planet earth, virtually everything needs to exist in a cycle (water cycle, carbon cycle, etc).
The problem with the blackhole idea is that all atoms / baryonic matter could be used for something. When you send them to a blackhole, they literally cease to exist as baryonic matter (or at a minimum are never usable again). Thus, you are literally taking that material out of use (technically they will eventually be converted into energy as hawking radiation).
With enough clean & cheap energy nothing really prevents you from reassembling those particles into something useful.
All the fear mongering around nuclear power is beyond hysterical at this point :(
[0] https://en.wikipedia.org/wiki/Radioactive_waste#Low-level_wa...
Unfortunately both effects do not seem to offer the kind of multiple-orders-of-magnitude gain required to make interstellar travel practical.
https://www.orionsarm.com/eg-article/464790d2497de
The extreme temperatures and pressures in the accretion disk are basically used to fuse the lighter elements together into heavier ones, which are then pulled out by machinery in close orbit.
I thought that just by letting masses getting sucked in while pulling ropes tied to alternators we could generate electricity... is it too naive? The amount of energy given by the fall into the blackhole would be superior than that used to bring the masses there in the first place.
But really it's easier still to manage it on earth itself. Which is why, even at SpaceX prices nobody does that (that and rockets have a nasty habit of suffering rapid unscheduled dissembly.)
Counterintuitively, this is far more expensive than launching it into said black hole, or just out of the Solar System all together.
Load the material into enclosures, bury them hundreds of feet below the sea floor near a subduction zone. Cheaper than rockets, still bloody expensive, and they may be worried about radioactive burps.
That seems like a lot of effort when you can just send it to nowhere and it will very, very, very likely never hit anything, ever.
Quite informative, it seems like the naive approach of going straight into the sun is much more expensive (dv of 24.0 km/s) than escaping the solar system (dv of 8.8 km/s).
But, it seems that there is a trick where you use 8.8km/s to almost escape the solar system, then turn around with very little dv cost and plunge into the sun.
[1] https://en.wikipedia.org/wiki/Delta-v_budget#Interplanetary
Probably the more interesting use is that of an energy source!
- getting nuclear waste out of Earth's gravity well is risky, if the rocket explodes it scatters nuclear waste throughout the atmosphere. And very energetically, given the amount of rocket fuel needed to achieve this kind of flight
- getting to planet 9 (black hole 1?) will require loads of fuel or lots (>100 years) of time. Lots of time for something to go wrong, lots of time for errors in orbital calculations to accumulate, small target to hit
Extremely small. The paper has a to-scale illustration of the hypothesized black hole.
I wonder what happens to a bus-sized object if you send that black hole through it...
That depends on the orientation of this thing. If it is spinning in just the right way, dumping anything into it would be like activating the death star. Even a week astrophysical jet pointed at earth would be a very bad thing. The last place you want to be standing when feeding a black hole is above/below it.
- how is the axis (like finding the head of a fluffy shitzu dog)
- how much is it spinning?
Now, black holes probably aren't known to be gateways to other locations, but that comment made me wonder what if they are, and dumping our hazardous waste in them has far reaching consequences somewhere else, then that in turn made me think of what other cosmic-scale consequences of alien technology might be out there.
I mean, if a civilization has planet-spanning tech, their "waste products" could be on the scale of planets too. Somewhere, a species must be burning through solar systems like we're burning the Amazon.
The use as an energy source, however, would even outlast the lifetime of the Sun as a star.
- That's Sun.
The threshold I could find for surviving since the big bang is around 10^11 kg which is quite a bit smaller than the moon. 10^11 kg is quite a bit compared to human scale, more than the mass of the Three Gorges Dam, but quite small on the astronomical scale (10^11 times smaller than the moon).
So while an earth mass black hole is small (9mm), it will last quite long indeed. The evaporation time is proportional to the mass^3.
A black hole with 10^11 Kg seems to have a temperature of about 1.2 * 10^12 K. Even though it would be small, it would be emitting crazy amounts of all sorts of photons.
So if there's a 1-20 Earth-mass black hole out there, it hasn't evaporated from anything appreciably larger to get to that point.
If anything it'd be a lot more valuable then just finding another rock in space.
It's theorized that the existence of Jupiter played a role in clearing out the inner solar system of kinetic kill vehicles, helping create a stable environment for life to evolve on Earth.
Edit: so, how do we locate it exactly?
More recent solar sails and plasma based propulsion systems have achieves significant improvements since then. If it was a priority I don't see why would couldn't go 10x as far within in the next decade.
To learn that the conditions of the early universe could have create sub-stellar mass black holes means there could be tons of small black holes out there lurking in interstellar space.
What would happen if one of them got close enough to our Sun to begin accreting gas from the Sun?
- Could it eat the entire Sun and cause our solar system to go dark?
- As it gained sufficient mass from the Sun, it would switch from orbiting the Sun to them being a binary system. Would that destabilize the orbits of planets?
- Or disturb a ton of Oort cloud bodies and potentially cause tons of comets and raise the risk of impact events?
- At what point would the Sun's fusion stop?
- Obviously this depends on the binary dance of the 2 bodies, but rapidly the sun would be pulled apart.
- Would there be X-rays and particle jets like a micro-version of a quasar?
I really hope someone is modeling this!
HOWEVER. Getting a black hole into a tight orbit - I don't know how that might happen. A black hole from outside the solar system would be coming in on a parabolic path past the sun. It would shoot right back out of the solar system.
If the BH managed to absorb enough mass from the sun, I would imagine that would throw off it's trajectory enough it could become captured into an orbit. On each subsequent fly by / through the sun, it would capture additional mass. This would reduce the period of the orbit.
In a situation like this, you have an increasingly massive object passing through the solar system in an irregular pattern. That can't be good.
But for it to destabilize the orbit of planets through the orbit of a binary system, it is quite plausible once the blac hole has gained sufficient mass for it to count as a binary system and not simply a planetary mass black hole orbiting a stellar mass sun[1].
[1] https://arstechnica.com/science/2013/01/binary-star-systems-...
First the outer layers of the sun are not very dense, but as a larger fraction of the matter for the black hole comes from the sun the slower (relative to the sun) the black hole would get. The slower the black hole is that closer it would come to the center of the sun. The closer to the center of the sun the denser the sun is.
The pressure of the sun is at least 10,000 times greater than the center of the earth which is 3,500 kilobar. Wouldn't the amazing gravity gradient and the 3,500 kilobar pressure result in a very well fed black hole that would double in mass within say a few days? Sure a accretion disk would form and start pushing back the matter at the north and south poles to reduce the feeding rate.
Sure black holes generally increase is size slowly, but they aren't usually inside a gas cloud of 1.4grams/cm^3 at a pressure of 3,500 kilobar and having an entire suns worth of mass to provide resistance to the accretion disk allowing for matter to fall in quicker.
I've heard numbers like you mentioned for atom sized size black holes that fell within the earth, but the main problem is that the likelyhood of swallowing an atom is so small that it grows incredibly slowly.
Do you have to send a probe close and throw something in it?
One possibility is gravitational lensing. The abstract also mentions detecting "annihilation signals from the dark matter microhalo around the PBH". Not that I understand that completely, and I don't believe (corrections welcome) that dark matter annihilation by black holes has been confirmed experimentally.
I believe high energy particles are released by black holes as they consume matter, so that might be another way to detect a small black hole instead of a similar mass rock.
From a distance there is no difference in lensing between a black hole and an regular object of the same mass.
From close there would be a difference, but if you could resolve something that small you would be able to directly image the object.
However a lensing event seems possible, it greatly increases the effective radius of detection and is much more distinctive. Not sure what the smallest lensing event witnessed is, all the ones I'm aware of were a solar mass or more.
> This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH
We'd basically see extremely energetic particles coming from a nearby source. Since no other known physical process can generate such high energy particles (not even fusion in main sequence stars), we'd have to conclude that there is probably some extremely dense object there.
https://arche-arc.blogspot.com/2018/11/mythcomics-lucifer-ri...
Were such theories about a hypothetical planet beyond Pluto already existent when this series was created, back in the mid-'80s?
I don't have a physics degree, but how close would Earth have to get to such an object before the Earth is within that object's Roche limit?
The radius of the event horizon for a black hole even the size of Jupiter is only 2.5 meters.
Wikipedia gives the formula d=R_m*(2m_M/m_m)^{1/3} which matches that intuition.
Edit: According to https://en.wikipedia.org/wiki/Roche_limit the Roche limit d = Rm * (2 * MM/Mm)^(1/3) for Rm = radius of the satellite, MM = mass of the primary, and Mm = mass of the secondary. So in this case d = 6380 * (2 * 5/1)^(1/3) = 13,745km. In astronomical terms, very nearly a bulls-eye.
It doesn't have any special ability to slingshot things to crazy speeds.
Remember - the slingshot doesn't add speed from the gravity of the object, it ads speed from the rotation of the object around the sun.
https://phys.org/news/2017-08-theory-heavy-elements-primordi...
The good news is it would pass effortlessly through the earth and not go to the earth's core and stay there. After all where is the resistance going to come from?
Now if the blackhole was brought to rest at the earth surface it wouldn't reach escape velocity (11.2 km/sec), but anything coming from way past pluto would likely have a much larger velocity.
The bad news is that having an earth skewer the earth at high speed is going to cause some pretty crazy gravitational interactions.
Also some of the matter falling into the black hole from earth would be consumed, but some of it would radiated out, no idea if that would be worse than the physical disruptions or not.
You'll get a Nobel prize or two if you could prove that..
Just whatever the predominant gravitational influence is
Maybe this semantical exercise doesnt matter here if the mass of the black hole is so small
