Some potentially interesting uses for it:
- 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)
- 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...
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?
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.
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.
Takes some careful orbits and a long time, but NASA does it all the time.
So what may happen is if you have a low-thrust engine, you will do a burn at the optimal time, then stop and wait an orbit until you reach the optimal time again. But you're not "stockpiling" anything so much as you are just thrusting at the optimal time. And once you reach escape velocity you have to keep thrusting, there is no more opportunity to do another pass.
Seems like a Jupiter gravity assist would always be much more practical.
I think the mass of the body only matters in how much momentum it has. If you fly by an asteroid you will deflect its course. You could convert the entire mass of earth into spaceships and slingshot them past Jupiter and it would barely register.
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.
Maybe the "right" way to convert potential energy is via conversion to heat and black-body radiation in the accretion disk? Might be difficult to capture significant percentage of that energy, though. See also [1]
Is it still too unrealistic?
For the radiation energy, it sure makes sense! Moreover isn't it any hard radiations emitted when the hadrons' quarks are torn from each other on reaching the events horizon?
By "ropes" I mean charged particles and by alternators I mean just very powerful electromagnets that can extract the energy of the charged particles falling into the black hole.
My point was that things attached to the outer core of an orbital ring are not in 0 G, but they feel the actual gravity at the particular height the orbital ring is orbiting -- on Earth if you would be sitting on an orbital ring situated at a height of say 300km, you would feel as though you were sitting on a 300km mountain; maybe on a primordial black hole you could build an orbital ring just a few km from the black hole and have spokes going down very close to the black hole (maybe active structures to overcome our current material strength limitations) and let charged particles fall into the black hole and extract their energy as they fall into the black hole.
Or maybe the black hole is small enough that a very crude electromagnets field could just encompass all of the black hole and it could very easily extract all that sweet energy of a charged particle falling into the black hole with an electromagnet an amateur could build in his garage.
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.
Because anything in close orbit is by definition plasma.
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.
This is the first order approximation reason.
The earth is orbiting the sun at 30 kilometers per second. So if we launched something into space, since it started on earth, it would have that speed (similar-ish to throwing a ball from a moving car). So that object would now also be orbiting the sun at 30 km/s. We would need to slow it down that much in order to "fall" into the sun.
Once something was in earth orbit, it would only take about 12 km/s of delta v (change in velocity) to escape the solar system.
More info and math here: https://space.stackexchange.com/questions/3612/calculating-s...
At least that's how I see it, but I am far from being an authority on this topic.
Now, the trajectory of an object in solar orbit is exactly at right angles to the direction it needs to go in to hit the sun. No part of this velocity is helpful for getting to the sun - in fact it actively prevents it! The only vector that takes you directly into the sun is one with no sideways component - if you imagine yourself falling right in, any sideways nudge will cause you to miss it by a hair and go flinging off into a highly elliptical orbit. If you just ignore this and just thrust directly at the sun, hoping to overpower everything by brute force, then like a ballerina pulling her arms in, the more you try to get close to the sun with your thrusters, the faster your orbit will go; the closer you manage to get, the further out you'll be flung when you inevitably miss.
All this ignores that the sun is not a point, but quite a large ball - you can get away with some small horizontal velocity. A highly elliptical orbit will still do what you want if its lowest point is below the surface.
You should play Kerbal Space Program. It will very quickly give you an excellent intuition for basic orbital mechanics.
Sad note that also limits your launch window to once every 113 years as I recall from the last time I did the math :-(.
From a technical perspective you push into an elliptical orbit that intersects Venus, you do a slight aerobreak (skim the surface of the atmosphere) to dogleg toward a Mercury intercept, and then as you pass Mercury it tightens your ellipse still further and you head out, and come back and fly through the outer corona of the Sun (which is its hottest point). At which point you're in a degenerate orbit that will go out and come back through the Sun's corona until you've been completely consumed/burned up.
The latter takes a lot less delta v, but it has its drawbacks. Leaving the solar system, you don't have to budget for that rendezvous.
As a counter example, someone mentioned nearly leaving and then cheaply coming back directly into the sun.
While spinning it’s hard to get to the center. Once it stops, it’s easy.
The earth is spinning around the sun. To get to the sun, you need to slow down.
That seems off...googling suggests that the acceleration due to the sun at earth's orbit is a tiny fraction of 1G, and conversely, to have an acceleration of 1G would require going well inside Mercury's orbit.
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.
Yes I agree that currently a Dyson sphere is the most sensible project humanity could ever think of!!
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
At no point on the esacape trajectory can the object's speed fall below √2 times that of a circular orbit at that distance (or else the object would not escape.) At whatever distance you decide to set the controls for the heart of the sun, you must kill its angular velocity with respect to the sun (because, if it has more than a slight angular momentum, it will follow an elliptical orbit that goes around the sun.) Therefore, at every point on the minimal escape trajectory, the delta-v to redirect the payload into the sun is the escape velocity at that distance. With your strategy, the cost of sending the payload into the sun asymptotically decreases towards the cost of sending it on an escape trajectory.
https://en.m.wikipedia.org/wiki/Interplanetary_Transport_Net...
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.
Like was it The Three Body Problem or some other story where an alien species’ faster-than-light travel tech causes the universe to expand faster and faster, making it harder and harder for younger species to produce enough energy for FTL.
The use as an energy source, however, would even outlast the lifetime of the Sun as a star.
When you're in a stable orbit, you are actually spinning around the sun at a huge pace. To gain enough velocity to leave the solar system, you have to increase that pace by an amount that is less than the pace you already have.
As a terrible analogy, it takes less energy to overtake a car that is travelling in front of you at a higher speed than it does to slow yourself to a complete stop.
But to fall to the sun, you need to slow down 75mph. And speeding up and slowing down in space take the same amount of energy.
It is tricky (but possible, with cleverness and a careful schedule) to gain or lose energy this way, but it doesn't matter. If your closest approach is well within the sun's photosphere, it doesn't matter how fast you're going when you get there. So, you can do it with essentially zero delta-v, starting and ending with the same total energy as an object would have co-orbiting with earth, but on an extremely eccentric orbit.
It's not terribly rare (on a geological timeline, at least) for comets to dispose of themselves this way.
Anyway, what is so great about dropping them in the sun? Jupiter swallows comets frequently. Mars is a squalid dump, and so is Venus, at least below the clouds.
The sun is always at one focus of the elliptical orbit. You just can't get the orbit close enough to plasma-brake near perihelion without also pushing your aphelion way out. So you have to aim away from Sol in order to get there at lower energy. Basically, a Voyager probe that stops at the very edge of the gravity well and then plunges straight down. Spiraling down while decelerating is faster, but costs more energy. But as you get closer, you can harvest energy from the solar wind and solar radiation, with solar sails, so the amount of delta-v you have to load onto the launch rocket does not represent your entire delta-v budget.
There are ways to trade off time for delta-v, but at that scale, the ways that really make a difference mean that the person that sets them in motion will be ancient or dead before they finish.
I am only picking at you because you mentioned a rocket. If you said "shoot it to burn in sun" then you would be (mostly) right.
- That's Sun.