Reverse black hole?

[monty]

The "ingenious use of spells" thread got me wondering. What would happen if you cast Reverse Gravity on a black hole? Also, in order for it to have an effect, would you just have to cast it on the core or would you need a ridiculously high caster level to affect the entire volume to the event horizon?

[BizzaroStormy]

It would become a white hole and start expellnig the trapped energy and matter it gained as a black hole.

[FlyMolo]

The spell "reverses gravity" (in the spell text, even), so if you cast it on the core of a black hole, (Possible. Hard to get there, but you could.) the hole would turn itself inside out, throwing all its mass out of the area of the spell. Once outside the area, it would try and recollapse again. At the very least, the amount of mass moved around in the immediate area would play havoc with local spacetime. Gravity waves! BIG ONES!

[Edan]

With all the infinite (theorized) properties of a blackhole, I don't think a finite spell would affect it that much. Perhaps a fluctuation. Have it stop for a bit, like a hiccup. Personally, I would have it stop for 1 Round/Caster Level. Destroying reality and other dramatic effects I think are a bit on the Rule of Cool side of this.

[monty]

With all the infinite (theorized) properties of a blackhole, I don't think a finite spell would affect it that much. Perhaps a fluctuation. Have it stop for a bit, like a hiccup. Personally, I would have it stop for 1 Round/Caster Level. Destroying reality and other dramatic effects I think are a bit on the Rule of Cool side of this.

It really only breaks, though, if it is infinite. I assume that Reverse Gravity basically just reverses the direction of the force vector for gravity within its area of effect. So if a black hole has a gravitational force with a magnitude of ∞ (within the event horizon) directed toward its center, then reversing it would give it a magnitude of ∞ directed away from the center. This would instantly accelerate all of the matter within the effect to c (that is, the speed of light), moving outward from the black hole, which would break all of the laws of relativity and do bad things to the universe.



By the way, how many catgirls do you think we've killed so far?

[FlyMolo]

With all the infinite (theorized) properties of a blackhole, I don't think a finite spell would affect it that much. Perhaps a fluctuation. Have it stop for a bit, like a hiccup. Personally, I would have it stop for 1 Round/Caster Level. Destroying reality and other dramatic effects I think are a bit on the Rule of Cool side of this.

It's a spell that multiplies by -1. Not really finite. And if you shut off a black hole, all the bits would come sproinging out really fast. They're wedged in there pretty tight.

I don't think it would destroy reality, but the bits nearby wouldn't be in very good shape. For a start, they would have large fractions of a solar mass shoved through them quite fast.

If a black hole has infinite curvature of space, a reversed black hole is like a wall. Nothing can get in, because it requires an infinite amount of energy to get past. There's just a mirrored ball, which everything bounces off of.

If you're falling in, a reverse gravity spell targeted on you is the best idea. You'll go zooming off into freedom. At least in theory. Yeah, because the curve is so steep. The gravity is so much stronger at the end where you're at that it shoves you up through the top of your head and out to the end of the field, flinging you a long way. Hopefully. Recast if necessary. Casting it on the black hole is a bad idea, because nobody wants to be vaporized.

[monty]

If you're falling in, a reverse gravity spell targeted on you is the best idea. You'll go zooming off into freedom. At least in theory. Yeah, because the curve is so steep. The gravity is so much stronger at the end where you're at that it shoves you up through the top of your head and out to the end of the field, flinging you a long way. Hopefully. Recast if necessary. Casting it on the black hole is a bad idea, because nobody wants to be vaporized.

Of course, if you're falling in, you're dead anyway. The combination of the massive amounts of radiation and the gravity on your body (the distance between your head and feet is enough that the black hole will start tearing you apart) will probably kill you before you can get a spell off. I was assuming you had some means of casting it that didn't involve you personally being there.

[FlyMolo]

Of course, if you're falling in, you're dead anyway. The combination of the massive amounts of radiation and the gravity on your body (the distance between your head and feet is enough that the black hole will start tearing you apart) will probably kill you before you can get a spell off. I was assuming you had some means of casting it that didn't involve you personally being there.

Contingent Spell and Animate Object. That's clever, no? Throw the pet rock at the hole, then watch the fireworks from a safe vantage points. FAR AWAY.

[Lycan 01]

Mmmm, spagghettification...


I like the whole "universe rips in two" outcome. I mean, black holes are the universes' vaccuum cleaners. They suck up stuff, and that stuff doesn't come back out. If you somehow manage to reverse it (the vaccuum cleaner), then you have random stuff flying out everwhere and a really big mess. Now, lets say a black hole reverses. Well, the laws of physics and space and time and other complex law things just basically got told to drop their pants, and now you have ungodly amounts of mass coming out of nowhere, with nowhere to go. End result? REALLY BAD THINGS!!!


So yeah, I'd just go with "everything dies" to save a lot of time.

[Edan]

One idea. General relativity states that a black hole singularity has 0 volume, but the spell targets a defined cubic area, can it even be affected.

Another question, in the exact words of the spell:

This spell reverses gravity in an area, causing all unattached objects and creatures within that area to fall upward and reach the top of the area in 1 round. If some solid object (such as a ceiling) is encountered in this fall, falling objects and creatures strike it in the same manner as they would during a normal downward fall. If an object or creature reaches the top of the area without striking anything, it remains there, oscillating slightly, until the spell ends. At the end of the spell duration, affected objects and creatures fall downward.

Provided it has something to hold onto, a creature caught in the area can attempt a Reflex save to secure itself when the spell strikes. Creatures who can fly or levitate can keep themselves from falling.

(Emphasis mine)

What would that imply, even if gravity was reversed you would not travel beyond the area of the spell, at least until it ended.

Anyone a physicist and rules lawyer?

PS: We need to kill more catgirls.

[monty]

So yeah, I'd just go with "everything dies" to save a lot of time.

That really doesn't describe it that well. I'd rather go with something like "rapidly expanding sphere of absolute destruction of everything everywhere" or something like that. I mean, can you really even conceive of what an arbitrary quantity of matter moving at the speed of light can do?

[Lycan 01]

Really bad things?


I'm guessing every little particle of matter will be moving at really, really fast speeds, which would allow them to simply rip through everything in their path.

Examples...

Tornados hurl pine straw with enough force to impale it in walls. So lets say the exploding black hole is a really, really, really big tornado. Now add in a bazillion, jillion bits of pine straw. The pine straw then proceeds to impale through everything everywhere at once.

Or, for the hunting types, every piece of birdshot in existance x infinity shoots through every square inch of reality at once.



Destroying the universe is fun.....


So what's this "killing catgirls" joke I keep hearing?

[monty]

One idea. General relativity states that a black hole singularity has 0 volume, but the spell targets a defined cubic area, can it even be affected.

I'd assume that if the singularity is within the area of the spell, it would be affected.

Another question, in the exact words of the spell:

(Emphasis mine)

What would that imply, even if gravity was reversed you would not travel beyond the area of the spell, at least until it ended.

Well, in normal gravity, when you reached the top of the spell area, normal gravity would take over and start to pull you down; hence the oscillation. However, the force of a black hole is only (possibly) infinite within the event horizon; outside of that, it only has regular gravity based on its mass, which is insignificant compared to the force within. So if the singularity was within Reverse Gravity, would the event horizon be reversed (since it is caused by the singularity), normal outside the spell effect (which would cause a rather interesting oscillation effect) or something completely different?

We need to kill more catgirls.

Agreed.

[Edan]

So what's this "killing catgirls" joke I keep hearing?

It is a running meme on the forums that basically goes like this.

"Whenever someone brings up real world physics in a discussion of magic (particularly magic in an FRPG) or science fantasy "technology," a catgirl is killed. The statement "please, think of the catgirls!" is meant to deter such discussions from starting in the first place."

Or we could just make this easier and say this is where spheres of annihilation come from. How they get into statue's mouths, we don't really know.

[Xefas]

Would the multiplanar nature of the D&Dverse effect this at all? Other than that if you managed to escape the Prime and into some alternate plane, the Inevitables would be coming in the millions to teach you a lesson.

"This one just destroyed all the laws of physics at once. Do we have a model of Inevitable for that?"
"Lets just have it be ironic and make a giant sentient Spiked Chain to kick the crap out of him."

[quiet1mi]

i smell an Epic level plot hook... Or it could be the rotting flesh of the poor cat girls...

[Patashu]

Good thing black holes don't exist in the D&D cosmology, eh? ;)

[bosssmiley]

Good thing black holes don't exist in the D&D cosmology, eh? ;)

Errr, they do. As magic items, as monsters and as BBEGs. Sentient vengeful black holes.

A non-catgirl endangering explanation: reversing the gravity of a black hole cause massive structural strain on the surrounding plane and results in the awakening of the Herald of Galactus Thurizdan. Congratulations bub, your Epic version of reverse gravity just started the Apocalypse.

[Tsotha-lanti]

What would happen if you cast Reverse Gravity on a black hole?

Things in the area of the spell would "fall" away from the black hole.

Until they got outside of the spell's effect, when they'd presumably fall back toward the black hole, and enter the spell's area again, and so on until the spell wore out, since the spell only affects gravity in a small area, rather than changing any intrinsic property of anything in the area.

Good luck getting close enough to cast it, though...

[Xsjado]

This would instantly accelerate all of the matter within the effect to c (that is, the speed of light), moving outward from the black hole, which would break all of the laws of relativity and do bad things to the universe.

I'd point out that this breaks no laws of relativity. Objects that started very close to the reversed black hole would indeed be accelerated to near c but nothing says that they would exceed it. Indeed it just turns gravity into a force more similar to the electric force (where it can act as either attractive or repulsive).

Equally nothing says that the black hole would start spewing out matter. The spell just reverses the vector force of gravity, so while it would create an odd effect it wouldn't "break" anything. Current cosmological theory even includes a force which produces exactly this effect: "dark energy."

EDIT: Black holes don't contain infinite mass anyway, they are points of infinite density. This creates very strong gravitational effects, but if they were truly infinite mass then everything would be instantly attracted to them at the speed of light. Gravity is a function of the masses of two objects. If one of those is infinite then the attractive force is infinite.

[Chronos]

Anyone a physicist and rules lawyer?

Not only am I a physicist, I specialize in general relativity, the field directly concerned with black holes and the like. And Reverse Gravity is one of my favorite spells. And I'm afraid to contemplate this combination. If you can content yourself with something tame like blasting away everything in the vicinity at nigh-limitless speed, then I'll leave you to your bliss. Naked singularities are ugly.

"This one just destroyed all the laws of physics at once. Do we have a model of Inevitable for that?"

Actually, they do. There's an epic Inevitable somewhere reserved for folks who tamper with the fabric of space and time. They're called Quaruts, I think.

[FMArthur]

In what ways would this be different from a small-scale "Big Bang" event?

[ikrase]

If you reverse a black hole, it forms a reverse event horizon the same diameter as the original (and a small black hole can have a small event horizon, one inch is theorecially posible). A gravitational shockwave rolls out. This does no damage, but disrupts any planar portal, and destroys Portable Holes, Bag of Holding, ect within several million mile radius, no planar stuff can happen for years.
The material in the hole is ejected as radiation and hydrogen gas and 99.99999% speed of light. WHen the singularity is reduced to zero mass, it disappears. No naked singularity, i am pretty sure. You could kill every planar spell and destroy a solar system.

[SolkaTruesilver]

Hum, if you'd cast Reverse Gravity on a part of a black hole (as some person may suggest would happen), that would create a Pulsar, where the matter is ejected from one side, and re-absorbed be the equator.

The thing is, about the 0-volume thing and spaghettisation, it only appears from the outside perspective of the black hole. If you are going yourself in it, your are staying pretty much the same. The thing is, your time frame is slowing, and you will never really reach the point of time where you reach the black hole itself.

Hurray for relativity!

[Lycan 01]

Can you hear it? Can you hear the screaming? The screaming of all the catgirls you just killed?


Seriously, this topic makes my brain hurt. If I were a DM, and I had to deal with this, I'd save myself and my group a lot of time and brain pain by just saying reality shredded itself slowly and painfully.

[monty]

The thing is, about the 0-volume thing and spaghettisation, it only appears from the outside perspective of the black hole. If you are going yourself in it, your are staying pretty much the same. The thing is, your time frame is slowing, and you will never really reach the point of time where you reach the black hole itself.

You are actually stretched, though, and it doesn't have anything to do with relativity. Since gravitational force is a function of distance, and the top of your body is a different distance from the center as the bottom, the different parts of your body are being pulled with different levels of force. Normally, the difference is insignificant, but with the magnitude of force in a black hole, it will start to stretch you.

[Cuddly]

Can you hear it? Can you hear the screaming? The screaming of all the catgirls you just killed?

Like a million voices cried out and were suddenly silenced....

[Wabbajack]

Wait, isnt a black hole basically only as large as a sphere with a diameter of one planck length, wich means you cant target only one part of it?

[Chronos]

In what ways would this be different from a small-scale "Big Bang" event?

The Big Bang singularity is behind a horizon of sorts. It's a different sort of horizon, being based on an infinite redshift, but it still gets the job done.

The thing is, about the 0-volume thing and spaghettisation, it only appears from the outside perspective of the black hole. If you are going yourself in it, your are staying pretty much the same. The thing is, your time frame is slowing, and you will never really reach the point of time where you reach the black hole itself.

Spaghettification isn't something inherent to black holes; it's just a matter of tidal forces. In the same way that the Moon is stretched into an oblong shape by the Earth, or the Earth and its oceans are stretched into an oblong shape by the Moon and the Sun, things near a black hole will also be stretched. Whether this results in anything lethal or otherwise interesting depends on the mass of the hole, the distance of the object from the hole, and the durability of the object. For a sufficiently large black hole, a human could pass through the event horizon and be completely unharmed.

As for the time thing, you've got it backwards. From the reference frame of someone safely outside the hole, the falling person will never quite reach the horizon. However, from the reference frame of the person falling in, you'll reach the horizon, pass through it, and inevitably hit the singularity, in very short order (a few nanoseconds, for a stellar-sized black hole; perhaps as long as a couple of minutes, for the largest supermassive black holes).

EDIT:

Wait, isnt a black hole basically only as large as a sphere with a diameter of one planck length, wich means you cant target only one part of it?

When one refers to the size of a black hole, one means the size of the region within the event horizon. The event horizon has a radius proportional to the mass of the hole, and works out to be a few kilometers for one of stellar mass. The singularity in the center of a black hole appears, in current models, to be of zero size, but really, it could be anything, so long as it's spherically symmetric and entirely inside the horizon, and the theories all work just as well. It is widely suspected that once we have a working theory of quantum gravity, the singularity will turn out to have a very small but finite size (perhaps the Planck scale), but we don't yet have a working theory of quantum gravity, so that's just pure speculation.

[Flickerdart]

I wonder.

If casting Reverse Gravity on a black hole rapes the universe, could a Genesis spell cast at the right time take advantage of that somehow?